2005

1. [Anderson and Woodhouse 2005]
   A discussion on the [Moberg et al. 2005] NH temperature reconstruction. The use of wavelets allows for including the different timescales in which each proxy is efficient. This accounts for the title... really? title sounds as indirect reference to scientific discussion.
   Paleoclimate reconstructions, multy proxy, wavelet.

2. [Barnett et al. 2005]
   A warming signal has penetrated into the world s oceans over the past 40 years. The signal is complex, with a vertical structure that varies widely by ocean; it cannot be explained by natural internal climate variability or solar and volcanic forcing, but is well simulated by two anthropogenically forced climate models. We conclude that it is of human origin, a conclusion robust to observational sampling and model differences. Changes in advection combine with surface forcing to give the overall warming pattern. The implications of this study suggest that society needs to seriously consider model predictions of future climate change.
   Warming, climate change, hadcm3, detection, attribution

3. [Beltrami and Chapman 2005]
   General description of the potential of borehole data. Non climatic noise can be avoided resampling through time
   Paleoclimate reconstructions, borehole profiles, ground surface temperature

4. [Bartlett et al. 2005]
   ABSTRACT: Changes in snow s influence on surface ground temperature (SGT) could create a bias in the borehole temperature record of climate change. Using a snow-ground thermal model which predicts changes in the mean annual offset between SGT and surface air temperature (SAT), we calculate the response of SGT to changes in seasonal snow cover in North America from 1950 to 2002, the period for which comprehensive snow and air observations exist across the region. Daily snow and SAT observations come from the U.S. Historical Climatology Network, the Canadian Daily Climatic Dataset, and a set of National Weather Service cooperative stations in Alaska. For the period 1961 1990 the mean snow onset date in North America is 15 December, with mean snow cover duration of 81 days. There are no significant trends in either onset or duration from 1950 to 2002. Winter season air temperature, however, has warmed during this period, particularly from 1970 to 2002. The effect of the combination of a relatively stationary snow season with winter season SAT warming has been to diminish the mean annual SGT-SAT offset by 0.05 K/decade over the past 30 years. This effect is most pronounced between 50olsiand 75olsiN in west central North America, coincident with the location of greatest winter season warming since 1970. Although comprehensive snow cover data do not exist prior to 1950, this analysis quantifies the changes in snow cover required to account for the difference between borehole temperature and multiproxy climate reconstructions.
   Snow cover, borehole temp, sat-gst coupling

5. [Beltrami et al. 2005]
   ABSTRACT: Underground temperatures contain a record of past changes in the energy balance at the Earth s surface, such that borehole temperature data can be used to reconstruct long-term trends of ground surface temperature (GST) changes. In addition to surface air temperature, however, GST is the response of the ground to other near surface processes that govern the surface energy balance. In order to compare GST histories constructed from geothermal data with surface air temperature (SAT) data, it is necessary to ascertain the relationship between these quantities. Here we jointly interpret four borehole temperature logs within a small area and SAT records from a nearby station. The subsurface temperature anomalies are consistent with the SAT data even in the presence of a variable snow regime, and different surface conditions. Our results indicate that borehole records are robust long-term paleoclimatological indicators
   Paleoclimate reconstructions, borehole profiles, ground surface temperature

6. [Brook 2005]
   ABSTRACT: During the past 200 years, humans have caused a remarkable change in the levels of several atmospheric greenhouse gases. We know this from direct measurements that started in the latter half of the 20th century, but for earlier times we rely on tiny samples of the atmosphere trapped in polar ice. Coring the polar ice sheets provides access to these samples and allows us to place modern changes in the context of long-term natural cycles in greenhouse gases. Until recently, the longest of these ice core records (from Vostok Station in Antarctica) extended back 440,000 years (1). Now, reports by Siegenthaler et al. on page 1313 (2) and by Spahni et al. on page 1317 (3) extend our window into the past an additional 210,000 years.
   Paleoclimate reconstructions, borehole profiles, ground surface temperature

7. [Brown and Johnson 2005]
   Comparison of high-resolution paleoclimate records from Lake Malawi and the Cariaco Basin reveals a consistent tropical behavior during the Little Ice Age. These records, which are interpreted to represent southward excursions of intertropical convergence zone position over southern tropical East Africa and northeastern South America, are characterized by subcentennial variability superimposed on a ramp of increasing intensity from CE 1400 to 1800. This response appears similar to that of “cold” episodes during the Late Glacial. The synchrony of these records suggests a teleconnection in tropical climate that may be a manifestation of persistent ENSO-like conditions.
   ITCZ, Cariaco Basin

8. [Bryden et al. 2005]
   The Atlantic meridional overturning circulation carries warm upper waters into far-northern latitudes and returns cold deep waters southward across the Equator 1 . Its heat transport makes a substantial contribution to the moderate climate of maritime and continental Europe, and any slowdown in the overturning circula-tion would have profound implications for climate change. A transatlantic section along latitude 25 N has been used as a baseline for estimating the overturning circulation and associated heat transport 2 4 . Here we analyse a new 25 N transatlantic section and compare it with four previous sections taken over the past five decades. The comparison suggests that the Atlantic meridional overturning circulation has slowed by about 30 per cent between 1957 and 2004. Whereas the northward transport in the Gulf Stream across 25 N has remained nearly constant, the slowing is evident both in a 50 per cent larger southward-moving mid-ocean recirculation of thermocline waters, and also in a 50 per cent decrease in the southward transport of lower North Atlantic Deep Water between 3,000 and 5,000 m in depth. In 2004, more of the northward Gulf Stream flow was recirculating back southward in the thermocline within the subtropical gyre, and less was returning southward at depth.
   Atlantic overturning, climate change

9. [Buerger and Cubasch 2005]
   64 climate reconstructions, based on regression of temperature fields on multi-proxies and mutually distinguished by at least one of six standard criteria, cover an entire spread of millennial histories. No single criterion is accountable for the spread, which appears to depend on a complicated interplay of the criteria. The uncertainty is traced back to the fact that regression is applied here in an extrapolative manner, with millennial proxy variations exceeding the standard calibration scale by a factor of 5 and more. Even if linearity still holds for that larger domain the model error propagates in a way that is proportional to both the estimation error and the proxy variations, and is thus extrapolated accordingly. This is particularly critical for the parameter-loaded multiproxy methods. Without a model error estimate and without techniques to keep it small, it is not clear how these methods can be salvaged to become robust. the amplitude of the reconstructions ranged between about 20$\%$ and 100$\%$ of the true (simulated) millennial history. Whether or not these results extend to the real-world case, i.e. whether or not the MBH98 and relative approaches are robust.
   Paleoclimate reconstructions,variations of the Mann et al reconstruction

10. [Casty et al. 2005]
    Recurrent climate winter regimes are examined from statistically reconstructed and modelled 500 hPa geopotential height elds over the North Atlantic/ European sector for the period 1659 1990.We investi- gate the probability density function of the state space spanned by the rst two empirical orthogonal functions of combined winter data.Regimes are detected as pat- terns that correspond to areas of the state space with an unexpected high recurrence probability using a Monte Carlo approach.The reconstruction and the model re- veal four recurrent climate regimes.They correspond to the two phases of the North Atlantic Oscillation and two opposite blocking patterns.Complemented by the investigation of the temporal evolution of the climate regimes this leads to the conclusion that the recon- structed and the modelled data for this geographic sector reproduce low-frequency atmospheric variability in the form of regime-like behaviour.The overall evidence for recurrent climate regimes is higher for the model than for the reconstruction.However,comparisons with independent data sources for the period 1659 1990 re- vealed a more realistic temporal evolution of the regimes for the reconstructed data.
    NAO, echog, geopotential reconstructions

11. [Cohen et al. 2005]
    Evaluation of NAO teleconection patterns in a set of AMIP2 runs. No significant relation of atmosphere-ocean interaction which leads to NAO variability, nor variations in snow pack are found.
    NAO, AMIP2.

12. [Delworth et al. 2005]
    ABSTRACT: Observational analyses have documented increases in global ocean temperature, heat content, and sea level in the 20th century. Previous studies argued that the observed ocean warming is a response to increasing greenhouse gases. We use a new climate model to decompose simulated ocean temperature changes into components attributable to subsets of anthropogenic and natural influences. The model simulates a positive trend in global ocean volume mean temperature from the mid 1950s to 2000, consistent with observational estimates. We show that for the period 1861 2000 aerosols have delayed the onset of ocean warming by several decades and reduced the magnitude of the transient warming by approximately two-thirds when compared to the response that arises solely from increasing greenhouse gases. The simulated cooling signature from large volcanic eruptions in the late 19th and early 20th centuries is clearly visible in the subsurface ocean well into the middle part of the 20th century.
    Climate change, gcms, ocean, aerosols

13. [Denton et al. 2005]
    ABSTRACT: A case is made that seasonality switches dominated by wintertime were instrumental in abrupt climate changes in the North Atlantic region during the last glaciation and into the Holocene.The primary evidence comes from mismatches between mean annual temperatures from Greenland ice cores in comparison with snowline changes in East Greenland,northern Europe,and North America.The most likely explanation is a shutdown (or reduction in strength)of the conveyor.This allows the spread of winter sea ice across the North Atlantic,thus causing the northern region to experience much colder winters.Because they mimic the Greenland temperature rather than the snowline signal,changes in the Atlantic Intertropical Convergence Zone and the Asian monsoon may also share a winter linkage with Greenland.Thus the paleoclimate record is consistent with the notion that a huge continental sector of the Northern Hemisphere,stretching from Greenland to Asia,was close to an extreme winter threshold during much of the last glaciation.Winter climate crossed this threshold repeatedly,with marked changes in seasonality that may well have ampli ed and propagated a signal of abrupt change throughout the hemisphere and into the tropics.
    Abrupt climate change, seasonality, greenland

14. [Déqué et al. 2005]
    Abstract Four high resolution atmospheric general cir- culation models (GCMs) have been integrated with the standard forcings of the PRUDENCE experiment: IPCC-SRES A2 radiative forcing and Hadley Centre sea surface temperature and sea-ice extent. The response over Europe, calculated as the difference between the 2071– 2100 and the 1961–1990 means is compared with the same diagnostic obtained with nine Regional Climate Models (RCM) all driven by the Hadley Centre atmospheric GCM. The seasonal mean response for 2m temperature and precipitation is investigated. For temperature, GCMs and RCMs behave similarly, except that GCMs exhibit a larger spread. However, during summer, the spread of the RCMs—in particular in terms of precipi- tation—is larger than that of the GCMs. This indicates that the European summer climate is strongly controlled by parameterized physics and/or high-resolution pro- cesses. The temperature response is larger than the sys- tematic error. The situation is different for precipitation. The model bias is twice as large as the climate response. The confidence in PRUDENCE results comes from the fact that the models have a similar response to the IPCC- SRES A2 forcing, whereas their systematic errors are more spread. In addition, GCM precipitation response is slightly but significantly different from that of the RCMs.
    RCM prudence ensembles cordex

15. [D&́#305;ez et al. 2005]
    Statistical downscaling of seasonal precip over the IP with DEMETER models using dynamical and statistical approaches. The statistical approach is a particular implementation of the standard analogue technique based on close neighbours of the predicted atmospheric geopotential and humidity patterns and applied to the output of the DEMETER models (ecmwf and ukmo models). The dynamicalmodel is the Rossby Centre Climate Atmospheric model (RCA), nested to the ecmwf model, run in climate mode for 6 months. The skill of the forecasts greatly fluctuates from season to season. Overall the highest skills over Spain are associated with early and late spring, summer and autumn season at 0 and 1 lead times. There is feasibility in the approach and mixing statistical and dynamical methods improves the result.
    Downscaling, demeter, precip Iberian Peninsulalt

16. [Dong and Sutton 2005]
    Abstract: Interdecadal variability of the Atlantic thermohaline circulation (THC) is studied in the third version of the Hadley Centre global coupled atmosphere ocean sea-ice general circulation model (HadCM3). A diagnostic approach is used to elucidate the mechanism that governs the variability and its impacts on climate. An irregular and heavily damped THC oscillation with a period around 25 yr is identified. The oscillation appears to be forced by the atmosphere but the ocean is responsible for setting the time scale. Following a minimum in the THC, the mechanism for phase reversal involves the accumulation of cold water in the subpolar gyre, leading to an acceleration of the gyre circulation and the North Atlantic Current. This acceleration increases the transport of saline waters into the regions of active deep convection, raising the upper-ocean density and leading, after adjustment, to acceleration of the THC. The atmosphere stimulates this THC variability in two ways: 1) by forcing the subpolar gyre through (North Atlantic Oscillation) NAO-related wind stress curl and heat flux anomalies; and 2) by direct forcing of the region of active deep convection, also through wind stress curl and heat flux anomalies. The latter is not closely related to the NAO. The mechanism for phase reversal has many similarities to that found in a previous study with a much lower resolution coupled model, suggesting that this mechanism may be quite robust. However the time scale, and details of the atmospheric forcing, differ. The THC variability in HadCM3 has significant impacts on the atmosphere not just in the Atlantic region but also more widely, throughout the global Tropics. The mechanism involves modulation by the THC of the cross-equator SST gradient in the tropical Atlantic. The SST anomalies induce a displacement of the ITCZ in the Atlantic basin with knock-on effects over the other ocean basins. These findings highlight the potential importance of the Atlantic THC as a cause of interdecadal climate variability on a global scale.
    THC, MOI, MOC, hadcm3.

17. [Emanuel 2005]
    Theory and modelling predict that hurricaane intensity should increase with increasing global mean temperatures, buut work on the detection of trends in hurricane activity has focused mostrly on their frequency and shows no trend. He defines an index of the potentail destructivenness of hurricanes based on the total dissipation of power, integrated over the lifetime of the cyclone and shows that this index has increased markedly since the mid-1970s
    Tropical cyclogenesis, climate change, hurricanes.

18. [EPICA 2005]
    The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok. The earlier period, between 740,000 and 430,000 years ago, was characterized by less pronounced warmth in interglacial periods in Antarctica, but a higher proportion of each cycle was spent in the warm mode. The transition from glacial to interglacial conditions about 430,000 years ago (Termination V) resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases, but there are significant differences in the patterns of change. The interglacial stage following Termination V was exceptionally long 28,000 years compared to, for example, the 12,000 years recorded so far in the present interglacial period. Given the similarities between this earlier warm period and today, our results may imply that without human intervention, a climate similar to the present one would extend well into the future.
    Tropical cyclogenesis, climate change, hurricanes.

19. [Ferguson and Beltrami 2006]
    Subsurface temperatures have been shown to be useful for obtaining robust reconstructions of climatic changes for the last five centuries. Recently, interest has focused on determining the effects of land-use changes on ground surface temperatures (GST), which could potentially create a bias on these records and should thus be considered in the interpretation of GST reconstructions. To date, studies have focused on the one-dimensional effect of land-use changes on heat flow. In this study, temperature anomalies resulting from lateral heat flow were assessed for different scales of land-use change. Numerical simulations indicate that land-use changes over large areas may cause significant changes in subsurface temperatures reaching beyond the extent of the affected area at the surface. We provide guidelines for future surveys and for correcting existing data. D 2005 Elsevier B.V. All rights reserved.
    Paleoclimate reconstructions, borehole reconstructions, land use changes.

20. [Fischer-Bruns et al. 2005]
    Abstract The output of several multi-century simulations with a coupled ocean atmosphere general circulation model is examined with respect to the variability of global storm activity in winter on time scales of decades and longer.The frequency of maximum wind speed events within a grid box,using the lower limits on the Beaufort wind speed scale of 8 and 10 Bft as thresholds, is taken as the characteristic parameter.Two historical climate runs with time-dependent forcing of the last ve centuries,one control simulation,and three climate change experiments are considered.The storm frequency shows no trend until recently.Global maps for the industrially in uenced period hardly differ from pre-industrial maps,even though signi cant temperature anomalies temporarily emerge in the historical runs. Two indicators describing the frequency and the re- gional shift of storm activity are determined.In histor- ical times they are decoupled from temperature. Variations in solar and volcanic forcing in the historical simulations as well as in greenhouse gas concentrations for the industrially in uenced period are not related to variations in storm activity.Also,anomalous tempera- ture regimes like the Late Maunder Minimum are not associated with systematic storm conditions.In the climate change experiments,a poleward shift of storm activity is found in all three storm track regions.Over the North Atlantic and Southern Ocean,storm activity increases,while it decreases over the Paci c Ocean.In contrast to the historical runs,and with the exception of the North Paci c storm frequency index,the storm indices parallel the development of temperature, exceeding the 2 r range of pre-industrial variations in the early twenty- rst century.
    Paleoclimate simulations, echog, storm activity, climate change.

21. [Goosse et al. 2005]
    Ensemble of experiments with the ECBILT-CLIO-VECODE model scaling them to the variability of the CSM (Kaspar Amman) and the ECHO-g runs. The differences between the CSM and ECHO simulations can be attributed to the different climate sensitivities and not to the forcing variantions.
    Paleoclimate simulations, echog, csm ecbilt-clio

22. [Goosse and Renssen 2005]
    Centennial variability over the last millennium in antarctic ocean sea ice area. Natural and anthropogenic forcing influence comparison. Trend assessment in comparison to available reconstructions. Recommend that any GCM simulation should have an spin up long enough (at least two centuries) for the sea ice extension to achieve a reasonable state.
    Paleoclimate simulations, echog, csm ecbilt-clio, sea ice extent, antarctic ocean.

23. [Goto et al. 2005]
    Abstract The changes in the temperature on the Earth s surface in the past have penetrated into the subsurface and have been recorded as transient temperature perturbations to the background thermal field. In this study, we reconstruct the ground surface temperature (GST) history of the last 300 years by analysing three borehole temperature profiles in Ulsan, the southeastern part of the Republic of Korea. The borehole temperature profiles show positive temperature anomalies caused by recent warming. The reconstructed GST history showed a cold period in the late 19th century and subsequent warming in the present time. After the cold event, the GST increased by 1.5 K up to 1980. The warming trend from 1900 to 1980 was 2.0 K century. We compare the GST history with proxy temperature reconstructions obtained by other studies in Northeast Asia. The result suggests spatial variability of the climate in Northeast Asia.
    Paleoclimate reconstructions, borehole temperatures.

24. [Gutierrez et al. 2005a]
    They use SOM to analyze atmospheric maps in the area of Peru and use it to downscale seasonal precipitation. They consider two nearby stations in northern Peru with different precipitation regimes. They use the DEMETER forecasts to estimate changes in seasonal precipitation. El Nino events can be predicted with some months in advance. They use the SOMs to produce clusters of psinoptic types. They assign accordingly local precipitation daily averages to each psinoptic type. The basic climatology is funded on the era40 dataset.
    Downscaling, som, analogs, seasonal predictions

25. [Harrison and Stephenson 2005]
    Galactic cosmic ray (GCR)changes have been suggested to affect weather and climate,and new evidence is presented here directly linking GCRs with clouds.Clouds increase the diffuse solar radiation,measured continuously at UK surface meteorological sites since 1947.The ratio of diffuse to total solar radiation the diffuse fraction (DF) is used to infer cloud,and is compared with the daily mean neutron count rate measured at Climax, Colorado from 1951 2000,which provides a globally representative indicator of cosmic rays.Across the UK,on days of high cosmic ray ux (above 3600 ! 2 neutron counts h K , which occur 87$\%$of the time on average)compared with low cosmic ray ux,(i)the chance of an overcast day increases by (19 G $\%$,and (ii)the diffuse fraction increases by (2 G 3)$\%$.During sudden transient reductions in cosmic rays (e.g.Forbush events), simultaneous decreases occur in the diffuse fraction.The diffuse radiation changes are, therefore,unambiguously due to cosmic rays.Although the statistically signi cant non- linear cosmic ray effect is small,it will have a considerably larger aggregate effect on longer timescale (e.g.centennial)climate variations when day-to-day variability averages out.
    Cosmic rays, clouds,diffuse radiation

26. [Hartmann and Rath 2005]
    Analysing borehole temperature data in terms of ground surface history can add useful information to reconstructions of past climates. Therefore, a rigorous assessment of uncertainties and error sources is a necessary prerequisite for the meaningful interpretation of such ground surface temperature histories. This study analyses the most prominent sources of uncertainty. The diffusive nature of the process makes the inversion relatively robust against incomplete knowledge of the thermal diffusivity. Similarly the influence of heat production is small. It turns out that for investigations of the last 1000 to 100 000 years the maximum depth of the temperature log is crucial. More than 3000 m are required for an optimal inversion. Reconstructions of the last one or two millennia require only modestly deep logs (300 m) but suffer severely from noisy data.
    Borehole reconstructions

27. [Hansen et al. 2005]
    The net radiation heat flux at the top of the atmosphere is out of ballance by about 0.85 $wm^{-2}$. This coincides in both model simualtions and observations and is related to ocean thermal inertia. The observed 1880 to 2003 global warming is 0.6 to 0.7 C, which is the full response to nearly 1 $W/m2$ of forcing. Of the 1.8 $w/m2$ forcing, 0.85 $w/m2$ remain, i. e. additional global warming of 0.85 * 0.67 = 0.6 C is 'in the pipeline' and will occur in the future even if atmospheric composition and climate forcings remain fixed to today's values... this paper is the closest to appocalypse I have read... but reasonable though.
    Radiation ballance, climate change, warming.

28. [Hasanean 2005]
    ABSTRACT: A robust subtropical circulation index (SCI) is defined as the difference between the North Atlantic subtropical high and the Indian monsoon low. The SCI is negatively correlated to air temperatures over Egypt and is associated with large-scale climate indices of the tropical and subtropical Atlantic sector.
    Summer temperature, Egipt

29. [Hu and Feng 2005]
    Latitudinal averages of SAT and DST changes in the last 60 years over Eurasia show that dst track sat changes. Precipitation has an influence (negative correlation) though values of correlation are low (seasonal, interannual timescales).
    Paleoclimate reconstructions, borehole temperatures, precipitation effect, Eurasia

30. [Houghton 2005]
    Global warming is a phrase that refers to the effect on the climate of human activities, in particular the burning of fossil fuels (coal, oil and gas) and large-scale deforestation, which cause emissions to the atmosphere of large amounts of greenhouse gases , of which the most important is carbon dioxide. Such gases absorb infrared radiation emitted by the Earth s surface and act as blankets over the surface keeping it warmer than it would otherwise be. Associated with this warming are changes of climate. The basic science of the greenhouse effect that leads to the warming is well understood. More detailed understanding relies on numerical models of the climate that integrate the basic dynamical and physical equations describing the complete climate system. Many of the likely characteristics of the resulting changes in climate (such as more frequent heat waves, increases in rainfall, increase in frequency and intensity of many extreme climate events) can be identified. Substantial uncertainties remain in knowledge of some of the feedbacks within the climate system (that affect the overall magnitude of change) and in much of the detail of likely regional change. Because of its negative impacts on human communities (including for instance substantial sea-level rise) and on ecosystems, global warming is the most important environmental problem the world faces. Adaptation to the inevitable impacts and mitigation to reduce their magnitude are both necessary. International action is being taken by the world s scientific and political communities. Because of the need for urgent action, the greatest challenge is to move rapidly to much increased energy efficiency and to non-fossil-fuel energy sources.
    Paleoclimate reconstructions, borehole temperatures, precipitation effect, Eurasia

31. [Huybers 2005]
    Normalization in MM05 was inadequate. The bias in MBH98 is present but not so exagerated if full standardisation is made. Also RE values in MM05 are understimated since Monte Carlo simulationns are not considering realistic instrumental variance levels.
    Paleoclimate reconstructions, MBH,multiproxy, NH temperature.

32. [Jungclaus et al. 2005]
    Abstract:Analyses of a 500-yr control integration with the non-flux-adjusted coupled atmosphere sea ice ocean model ECHAM5/Max-Planck-Institute Ocean Model (MPI-OM) show pronounced multidecadal fluctuations of the Atlantic overturning circulation and the associated meridional heat transport. The period of the oscillations is about 70 80 yr. The low-frequency variability of the meridional overturning circulation (MOC) contributes substantially to sea surface temperature and sea ice fluctuations in the North Atlantic. The strength of the overturning circulation is related to the convective activity in the deep-water formation regions, most notably the Labrador Sea, and the time-varying control on the freshwater export from the Arctic to the convection sites modulates the overturning circulation. The variability is sustained by an interplay between the storage and release of freshwater from the central Arctic and circulation changes in the Nordic Seas that are caused by variations in the Atlantic heat and salt transport. The relatively high resolution in the deep-water formation region and the Arctic Ocean suggests that a better representation of convective and frontal processes not only leads to an improvement in the mean state but also introduces new mechanisms determining multidecadal variability in large-scale ocean circulation.
    Ocean circulation, THC, MPI-OM, MOI, MOC.

33. [Kavak-Akpinar and Akpinar 2005b]
    Wind speed is the most important parameter in the design and study of wind energy conversion systems. In this study,statistical methods were used to analyze the wind speed data of Keban-Elazig in the east region of Turkey.Measured hourly time series of wind speed data were obtained from the State Meteo- rological Station in Keban-Elazig over a ve year period from 1998 to 2002.The probability density dis- tributions are derived from the time series data and the distributional parameters are identi ed.Two probability density functions are tted to the measured probability distributions on a yearly basis.
    wind, wind power, energy, weibull distribution, rayleigh distribution.

34. [Kavak-Akpinar and Akpinar 2005a]
    This paper presents seasonal variations of the wind characteristics and wind turbine characteristics in the regions around Elazig,namely Maden,Agin and Keban.Mean wind speed data in measured hourly time series format is statistically analyzed for the six year period 1998 2003.The probability density distribu- tions are derived from the time series data and their distributional parameters are identi ed.Two proba- bility density functions are tted to the measured probability distributions on a seasonal basis.The wind energy characteristics of all the regions is studied based on the Weibull and Rayleigh distributions.Energy calculations and capacity factors for the wind turbine characteristics were determined for wind machines of different sizes between 300 and 2300 KW. Maden is the best region...
    wind, wind power, energy, weibull distribution, rayleigh distribution.

35. [Levitus et al. 2005]
    During the period 1955-98 ocean has warmed accummulating $14.5 10^22$ J. Continents in turn $0.9 10^22$ J and atmosphere $0.8 10^22$ J.
    ABSTRACT: We present new estimates of the variability of ocean heat content based on: a) additional data that extends the record to more recent years; b) additional historical data for earlier years. During 1955 1998 world ocean heat content (0 3000 m) increased 14.5 10 22 J corresponding to a mean temperature increase of 0.037 C at a rate of 0.20 W/m2 (per unit area of Earth s total surface area).
    Paleoclimate reconstructions, climmate change, heat content, borehole.

36. [Mann et al. 2005]
    Tests the fidelity of climate field reconstruction methods (CFR) and composite plus scale (CPS) methods usin ccm simulations as test bed for the methods. It critizices the [von Storch et al. 2004] and the [Moberg et al. 2005] papers. They find no evidence for the CFR methods to understimate. Both CPS and CFR methods are likely to produce faithfull estimates of past climate variations. CFR understimates high frequency events related to volcanic eruptions. CPS underestimates long term mean changes modestly.
    Paleoclimate reconstructions, climmate change, heat content, borehole.

37. [McGuffie and Henderson-Sellers 2005]
    A Climate Modelling Primer
    climate models, history, description

38. [Min et al. 2005a]
    Tests the fi
    Paleoclimate reconstructions, climmate change, heat content, borehole.

39. [Min et al. 2005b]
    Tests the fi
    Paleoclimate reconstructions, climmate change, heat content, borehole.

40. [McIntyre and McKitrick 2005a]
    Calculation of anomalies in MBH98 previous to PCA generates spurious trends in red noise pseudoproxies withought trend. Artificial hockey sticks arise. RE statistic lacks any clear distribution and in this case it is not representative of the method in validation period. Monte Carlo analysis shows that confidence limits are under stated in the original MBH98.
    Paleoclimate reconstructions, multy proxy, MBH98.

41. [McIntyre and McKitrick 2005b]
    They state full standardization busts the unusual behaviour of a couple of undesired time series. They state a number of noew unertainties in Huyberts approach. About the RE argument: ok, but the R2 is still correctly depicting 0 validation correlation. Sometimes seems as if they were talking about different papers...
    Paleoclimate reconstructions, multy proxy, MBH98.

42. [McIntyre and McKitrick 2005c]
    They argue VZ did not really replicate the MBH method. They argue that they cannot replicate the AHS because their pseudoproxies are too good in the sense that their correlations to actual gridpoint temperature are too high.
    Paleoclimate reconstructions, multy proxy, MBH98.

43. [Moberg et al. 2005]
    Reconstruction of NH temperatures from treerings using wavelet analysis
    Paleoclimate reconstructions, multy proxy, wavelet.

44. [Mottaghy and Rath 2005]
    Abstract: In cold regions the thermal regime is strongly affected by freezing or melting processes, consuming or releasing large amounts of latent heat. This changes enthalpy by orders of mag-nitude. We present a numerical approach for the implementation of these effects into a 3-D finite-difference heat transport model. The latent heat effect can be handled by substituting an apparent heat capacity for the volumetric heat capacity of unfrozen soil in the heat trans-fer equation. The model is verified by the analytical solution of the heat transport equation including phase change. We found significant deviations of temperature profiles when applying the latent heat effect on forward calculations of deep temperature logs. Ground surface temperature histories derived from synthetic data and field data from NE Poland underline the importance of considering freezing processes. In spite of its limitations, the proposed method is appropriate for the study of long-period climatic changes.
    Paleoclimate reconstructions, multy proxy, wavelet.

45. [Nitoiu and Beltrami 2005]
    Analyse effects of deforestation and transient recovery in subsurface temperatures. Propose approach to correct borehole temperature profiles affected by such problem.
    Paleoclimate reconstructions, multy proxy, borehole data deforestation

46. [Oerlemans 2005]
    I constructed a temperature history for different parts of the world from 169 glacier length records. Using a first-order theory of glacier dynamics, I related changes in glacier length to changes in temperature. The derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions. Moderate global warming started in the middle of the 19th century. The reconstructed warming in the first half of the 20th century is 0.5 kelvin. This warming was notably coherent over the globe. The warming signals from glaciers at low and high elevations appear to be very similar.
    Last millennium, climate change, glaciers, global temperature

47. [Pasquale et al. 2005]
    Borehole temperature inversions in eight boreholes at the east and west of the Apennines(Adriatic and Tyrrhenian side). Good correspondence with meterological observations in the western side... in the eastern side potential effect of local changes. Also sea [Pasquale et al. 2000].
    Borehole temperature reconstructions, Italy.

48. [Pollack et al. 2005]
    Uses two types of subsurface tempraturre models to fit dst from sat inputs to the model. Uses a fictitious layer with an effective diffusivity which translates the SAT varaiability to dst changes for different meteorological conditions. What does it add to [Beltrami 2001a]?
    Borehole temperature reconstructions, effective diffusivity.

49. [Pryor et al. 2005b]
    This paper presents a novel approach to developing empirically downscaled estimates of near-surface wind speed and energy density and results from application of the technique to multiple stations in northern Europe. The downscaling takes a probabilistic approach in that it uses the mean and standard deviation of relative vorticity at 500 hPa and mean sea level pressure gradients computed using output from the ECHAM4/OPYC3 atmosphere-ocean general circulation model as the predictors and parameters of the wind speed probability distribution at surface stations as the predictands. We demonstrate that this approach generates accurate depictions of the wind climate during the conditioning period and then apply the downscaling technique to examine changes between 1961 1990 and 2071 2100, which are compared to the results of dynamical downscaling. The empirically downscaled results for 1961 1990 and 2071 2100 show some evidence for small decreases in mean wind speed, 90th percentile wind speed, and energy density in 2071 2100 relative to 1961 1990. The projected changes are larger than the mean errors in the training period but smaller than current interannual variability. Rossby Centre regional climate model (RCM) derived grid cell mean wind speeds exhibit a high degree of agreement with the empirically downscaled station wind speeds. However, in contrast to the empirical downscaling, simulations conducted using the Rossby Centre RCM indicate evidence for a small increase in the annual wind energy resource over northern Europe between the end of the 20th century and the end of the 21st century.
    Downscaling of weibull parameters with multiple linear regression.
    Wind, wind energy, regional climate models, empirical models, climmate change.

50. [Pryor et al. 2005c]
    Abstract There is considerable interest in the potential impact of climate change on the feasibility and pre- dictability of renewable energy sources including wind energy.This paper presents dynamically downscaled near-surface wind elds and examines the impact of climate change on near-surface ow and hence wind energy density across northern Europe.It is shown that:Simulated wind elds from the Rossby Centre coupled Regional Climate Model (RCM)(RCAO) with boundary conditions derived from ECHAM4/ OPYC3 AOGCM and the HadAM3H atmosphere- only GCM exhibit reasonable and realistic features as documented in reanalysis data products during the control period (1961 1990).The near-surface wind speeds calculated for a climate change projection period of 2071 2100 are higher than during the con- trol run for two IPCC emission scenarios (A2,B2)for simulations conducted using boundary conditions from ECHAM4/OPYC3.The RCAO simulations conducted using boundary conditions from ECHAM4/OPYC3 indicate evidence for a small increase in the annual wind energy resource over northern Europe between the control run and climate change projection period and for more substantial increases in energy density during the winter season.
    Downscale wind fields for climate change conditions with RCAO from ECHAM4/OPYC3. Calculates energy density using Weibull fit
    Wind, wind energy, regional climate models

51. [Pryor et al. 2005a]
    ABSTRACT: We present empirical downscaling of 5 state-of-the-art AOGCMs (Atmosphere-Ocean General Circulation Models) to investigate potential changes in wind speeds and energy density in northern Europe. The approach is based on downscaling the Weibull parameters of wind speed prob-ability distributions from AOGCM-derived 500 hPa relative vorticity and sea-level pressure gradi-ents, and is demonstrated to generate accurate depictions of the wind climate during the transfer function conditioning period. Bootstrapping is used to develop 100 realizations for each downscaling period and these are used to assess the uncertainty in the results due to stochastic effects in the AOGCM-derived downscaling predictors. Projected changes in the wind speed probability distribu-tion vary with the AOGCMs from which the predictors are derived, but generally it is shown that mean wind speeds, 90th percentile wind speeds and energy density are slightly lower in the 2081 2100 climate projection period than during 1961 1990 at the majority of the 46 stations studied. Conversely it is found that there is no significant difference between conditions during 2046 2065 and 1961 1990 based on the ensemble of downscaling results. Equally, the winter time of 2046 2065 is largely indistinguishable from 1961 1990 for the majority of stations, while the winters of 2081 2100 appear to be associated with lower mean and 90th percentile wind speeds and energy density.
    Empirical downscaling of climate change scenarios

52. [Raible et al. 2005]
    ABSTRACT: The decadal trend behavior of the Northern Hemisphere atmospheric circulation is investigated utilizing long-term simulations with different state-of-the-art coupled general circulation models (GCMs) for present-day climate conditions (1990), reconstructions of the past 500 yr, and observations. The multimodel simulations show that strong positive winter North Atlantic Oscillation (NAO) trends are connected with the underlying sea surface temperature (SST) and exhibit an SST tripole trend pattern and a northward shift of the storm-track tail. Strong negative winter trends of the Aleutian low are associated with SST changes in the El Niño Southern Oscillation (ENSO) region and a westward shift of the storm track in the North Pacific. The observed simultaneous appearance of strong positive NAO and negative Aleutian low trends is very unlikely to occur by chance in the unforced simulations and reconstructions. The positive winter NAO trend of the last 50 yr is not statistically different from the level of internal atmosphere ocean variability. The unforced simulations also show a strong link between positive SST trends in the ENSO region and negative Aleutian low trends. With much larger observed SST trends in the ENSO region, this suggests that the observed negative Aleutian low trend is possibly influenced by external forcing, for example, global warming, volcanism, and/or solar activity change.
    Empirical downscaling of climate change scenarios

53. [Renssen et al. 2005]
    Abstract The response of the climate at high northern latitudes to slowly changing external forcings was studied in a 9,000-year long simulation with the coupled atmosphere-sea ice-ocean-vegetation model ECBilt- CLIO-VECODE. Only long-term changes in insolation and atmospheric CO2and CH4 content were prescribed. The experiment reveals an early optimum (9 8 kyr BP) in most regions, followed by a 1 3C decrease in mean annual temperatures, a reduction in summer precipitation and an expansion of sea-ice cover. These results are in general agreement with proxy data. Over the continents, the timing of the largest temperature response in summer coincides with the maximum insolation difference, while over the oceans, the maximum response is delayed by a few months due to the thermal inertia of the oceans, placing the strongest cooling in the winter half year. Sea ice is involved in two positive feedbacks (ice-albedo and sea-ice insulation) that lead regionally to an amplification of the thermal response in our model (7C cooling in Canadian Arctic). In some areas, the tundra-taiga feedback results in intensified cooling during summer, most notably in northern North America. The simulated sea-ice expansion leads in the Nordic Seas to less deep convection and local weakening of the overturning circulation, producing a maximum winter temperature reduction of 7C. The enhanced interaction between sea ice and deep convection is accompanied by increasing interannual variability, including two marked decadal-scale cooling events. Deep convection intensifies in the Labrador Sea, keeping the overall strength of the thermohaline circulation stable throughout the experiment.
    Holocene, ECBilt-Clio-VECODE

54. [Rahmstorf et al. 2005]
    We present results from an intercomparison of 11 different climate models of intermediate complexity, in which the North Atlantic Ocean was subjected to slowly varying changes in freshwater input. All models show a characteristic hysteresis response of the thermohaline circulation to the freshwater forcing; which can be explained by Stommel’s salt advection feedback. The width of the hysteresis curves varies between 0.2 and 0.5 Sv in the models. Major differences are found in the location of present-day climate on the hysteresis diagram. In seven of the models, present-day climate for standard parameter choices is found in the bi-stable regime, in four models this climate is in the mono-stable regime. The proximity of the present-day climate to the Stommel bifurcation point, beyond which North Atlantic Deep Water formation cannot be sustained, varies from less than 0.1 Sv to over 0.5 Sv. Citation: Rahmstorf, S., et al. (2005),
    MOC, Hysteresis

55. [Rutherford et al. 2005]
    ABSTRACT: Results are presented from a set of experiments designed to investigate factors that may influence proxy-based reconstructions of large-scale temperature patterns in past centuries. The factors investigated include 1) the method used to assimilate proxy data into a climate reconstruction, 2) the proxy data network used, 3) the target season, and 4) the spatial domain of the reconstruction. Estimates of hemispheric-mean temperature are formed through spatial averaging of reconstructed temperature patterns that are based on either the local calibration of proxy and instrumental data or a more elaborate multivariate climate field reconstruction approach. The experiments compare results based on the global multiproxy dataset used by Mann and coworkers, with results obtained using the extratropical Northern Hemisphere (NH) maximum latewood tree-ring density set used by Briffa and coworkers. Mean temperature reconstructions are com-pared for the full NH (Tropics and extratropics, land and ocean) and extratropical continents only, with varying target seasons (cold-season half year, warm-season half year, and annual mean). The comparisons demonstrate dependence of reconstructions on seasonal, spatial, and methodological considerations, em-phasizing the primary importance of the target region and seasonal window of the reconstruction. The comparisons support the generally robust nature of several previously published estimates of NH mean temperature changes in past centuries and suggest that further improvements in reconstructive skill are most likely to arise from an emphasis on the quality, rather than quantity, of available proxy data.
    CFR, CPS, NH reconstructions, climate field reconstructions, last 1000 years

56. [Scafetta and West 2005]
    Whereas the Intergovernmental Panel on Climate Change [2001] attributes most of recent surface warming to human activities, Scafetta and West [2005] claim that the Sun contributed at least 10 30$\%$ to global surface warming of 0.40 +- 0.04 K from 1980 to 2002. But their claim depends crucially on the solar irradiance time series adopted for this period; nor is it reproduced by a multivariate linear regression analysis of the solar, anthropogenic and climate data.
    Climate change and solar irradiance

57. [Sotillo et al. 2005]
    ABSTRACT: A 44-year (1958 2001)high-resolution atmo- spheric hindcast for the whole Mediterranean Basin was performed within the EU-funded Hindcast of Dynamic Processes of the Ocean and Coastal Areas of Europe (HIPOCAS)Project.The long-term hindcasted data set, which comprises several atmospheric parameters at dif- ferent levels,was produced by means of dynamical downscaling from the NCEP/NCAR global reanalysis using the atmospheric limited area model REMO.The REMO hindcast has been exhaustively validated.On that score,various hindcasted surface parameters,such as 10-m wind eld,2-m temperature and mean sea level pressure,have been compared to satellite data (ERS-1/2 scatterometer)and in-situ measurements from offshore stations.In addition,two ocean models (waves and sea level) have been forced with REMO hindcasted fields (mean sea level pressure and 10-m wind eld).The validation of these ocean runs,performed through com- parisons of simulated waves and sea level with oceanographic measurements,allows to evaluate indirectly the quality of the REMO hindcasted data used as atmospheric forcing.Once the quality of the hindcasted data was veri ed,the e ciency of the regional enhancement performed through dynamical downscal- ing on the NCEP global reanalysis was assessed.The regional improvement was evaluated through compari- sons of REMO and NCEP performance in reproducing observations.The important improvement obtained in the characterization of extreme wind events is particularly remarkable.
    Regional climate, remo model, precipitation, temperature, wind.

58. [Stainforth et al. 2005]
    ABSTRACT: The range of possibilities for future climate evolution 1 3 needs to be taken into account when planning climate change mitigation and adaptation strategies. This requires ensembles of multi-decadal simulations to assess both chaotic climate variability and model response uncertainty 4 9 . Statistical estimates of model response uncertainty, based on observations of recent climate change 10 13 , admit climate sensitivities defined as the equili-brium response of global mean temperature to doubling levels of atmospheric carbon dioxide substantially greater than 5 K. But such strong responses are not used in ranges for future climate change 14 because they have not been seen in general circulation models. Here we present results from the climateprediction.net experiment, the first multi-thousand-member grand ensemble of simulations using a general circulation model and thereby explicitly resolving regional details 15 21 . We find model versions as realistic as other state-of-the-art climate models but with climate sensitivities ranging from less than 2 K to more than 11 K. Models with such extreme sensitivities are critical for the study of the full range of possible responses of the climate system to rising greenhouse gas levels, and for assessing the risks associated with specific targets for stabilizing these levels.
    Climate sensitivity, climate change, GCMs.

59. [von Storch and Zorita 2005]
    Implement the AHS within the ECHO-g simulations. They find the effect is not relevant in comparison with previous underestimation in [von Storch et al. 2004]
    Paleoclimate reconstructions, last millennium, multi proxy.

60. [Uppala et al. 2005]
    The ERA-40 reanalysis project.
    Reanalysis

61. [Wang et al. 2005]
    We use a flux tanrsport model to simulate the evolution of the Sun's total and open magnetic flux over the last 26 solar cycles (1713-1996).
    Reanalysis

62. [Widmann 2005]
    Math analysis/discussion and performance in the case of the AAOI of obtaining a time series of expansion coefficientes using CCA and SVD.
    CCA,SVD pattern projection.

63. [Siegenthaler et al. 2005b]
    The most direct method of investigating past variations of the atmospheric CO2 concentration before 1958, when continuous direct atmospheric CO2 measurements started, is the analysis of air extracted from suitable ice cores. Here we present a new detailed CO2 record from the Dronning Maud Land (DML) ice core, drilled in the framework of the European Project for Ice Coring in Antarctica (EPICA) and some new measurements on a previously drilled ice core from the South Pole. The DMLCO2 record shows an increase from about 278 to 282 parts per million by volume (ppmv) between AD 1000 and AD 1200 and a fairly continuous decrease to a mean value of about 277 ppmv around AD 1700. While the new South Pole measurements agree well with DML at the minimum at AD 1700 they are on average about 2 ppmv lower during the period AD 1000 1500. Published measurements from the coastal high-accumulation site Law Dome are considered as very reliable because of the reproducibility of the measurements, high temporal resolution and an accurate time scale. Other Antarctic ice cores could not, or only partly, reproduce the pre-industrial measurements from Law Dome. A comparison of the trends of DML and Law Dome shows a general agreement. However we should be able to rule out co-variations caused by the same artefact. Two possible effects are discussed, first production of CO2 by chemical reactions and second diffusion of dissolved air through the ice matrix into the bubbles. While the first effect cannot be totally excluded, comparison of the Law Dome and DML record shows that dissolved air diffusing to bubbles cannot be responsible for the pre-industrial variation. Therefore, the new record is not a proof of the Law Dome results but the first very strong support from an ice core of the Antarctic plateau.
    CO2 forcing, epica

64. [Siegenthaler et al. 2005a]
    A record of atmospheric carbon dioxide (CO2) concentrations measured on the EPICA (European Project for Ice Coring in Antarctica) Dome Concordia ice core extends the Vostok CO2 record back to 650,000 years before the present (yr B.P.). Before 430,000 yr B.P., partial pressure of atmospheric CO2 lies within the range of 260 and 180 parts per million by volume. This range is almost 30$\%$ smaller than that of the last four glacial cycles; however, the apparent sensitivity between deuterium and CO2 remains stable throughout the six glacial cycles, suggesting that the relationship between CO2 and Antarctic climate remained rather constant over this interval.
    CO2 forcing, epica

65. [Washington and Parkinson 2005]
    Introduction to three dimensional climate modeling
    Storms, regional climate, Baltic

66. [Xoplaki et al. 2005]
    ABSTRACT: We evaluate variability, trends, uncertainties, and change of extremes of reconstructed and observed European spring and autumn temperature back to 1500. Spring and autumn temperature experienced systematic century-scale cooling compared to present conditions. The coldest springs appeared during the Maunder Minimum (DT = 1 K wrt 1901 2000). The amplitude of spring temperature variations at decadal and multidecadal scales doubles that of autumn and is most expressed in northeastern Europe. The decade 1995 2004 was very likely the warmest of the last half millennium. Anomalously warm springs and autumns have generally become more extreme in recent decades. However, the recent changes are statistically not significant with respect to the pre-industrial period. Citation: Xoplaki, E., J. Luterbacher, H. Paeth, D. Dietrich, N. Steiner, M. Grosjean, and H. Wanner (2005), European spring and autumn temperature variability and change of extremes over the last half millennium.
    Temperature paleoclimate reconstructions, Europe

67. [Weisse et al. 2005]
    ABSTRACT: An analysis of the storm climate of the Northeast Atlantic and the North Sea as simulated by a regional climate model for the past 44 years is presented. The model simulates the period 1958-2001 driven by the National Center for Environmental Prediction s (NCEP s) weather re-analysis. Comparison with observations shows that the model is capable of reproducing impact related storm indices such as the number of severe and moderate storms per year or the total number of storms and upper intra-annual percentiles of near-surface wind speed. The indices describe both, the year-to-year variability of the frequency as well as changes in the average intensity of storm events. Analysis of these indices reveals that the average number of storms per year has increased near the exit of the North Atlantic Storm track and over the Southern North Sea since the beginning of the simulation period (1958), but the increase has attenuated later over the North Sea and the average number of storms per year is decreasing over the Northeast Atlantic since about 1990-1995. The frequency of the most severe storms follows a similar pattern over the Northeast North Atlantic while there occurred too few severe storms in other areas of the model domain preventing a statistical analysis for these areas.
    Storms, regional climate, Baltic

68. [Yin 2005]
    ABSTRACT: A consistent poleward and upward shift and intensification of the storm tracks is found in an ensemble of 21st century climate simulations performed by 15 coupled climate models. The shift of the storm tracks is accompanied by a poleward shift and upward expansion of the midlatitude baroclinic regions associated with enhanced warming in the tropical upper troposphere and increased tropopause height. The poleward shift in baroclinicity is augmented in the Southern Hemisphere and partially offset in the Northern Hemisphere by changes in the surface meridional temperature gradient. The poleward shift of the storm tracks also tends to be accompanied by poleward shifts in surface wind stress and precipitation, and a shift towards the high index state of the annular modes. These results highlight the integral role that the storm tracks play in the climate system, and the importance of understanding how and why they will change in the future.
    Paleoclimate simulations, echo-g.

69. [Zhang 2005]
    ABSTRACT:The presence of seasonal snow cover during the cold season of the annual air temperature cycle has significant influence on the ground thermal regime in cold regions. Snow has high albedo and emissivity that cool the snow surface, high absorptivity that tends to warm the snow surface, low thermal conductivity so that a snow layer acts as an insulator, and high latent heat due to snowmelt that is a heat sink. The overall impact of snow cover on the ground thermal regime depends on the timing, duration, accumulation, and melting processes of seasonal snow cover; density, structure, and thickness of seasonal snow cover; and interactions of snow cover with micrometeorological conditions, local microrelief, vegetation, and the geographical locations. Over different timescales either the cooling or warming impact of seasonal snow cover may dominate. In the continuous permafrost regions, impact of seasonal snow cover can result in an increase of the mean annual ground and permafrost surface temperature by several degrees, whereas in discontinuous and sporadic permafrost regions the absence of seasonal snow cover may be a key factor for permafrost development. In seasonally frozen ground regions, snow cover can substantially reduce the seasonal freezing depth. However, the influence of seasonal snow cover on seasonally frozen ground has received relatively little attention, and further study is needed. Ground surface temperatures, reconstructed from deep borehole temperature gradients, have increased by up to 4olsiC in the past centuries and have been widely used as evidence of paleoclimate change. However, changes in air temperature alone cannot account for the changes in ground temperatures. Changes in seasonal snow conditions might have significantly contributed to the ground surface temperature increase. The influence of seasonal snow cover on soil temperature, soil freezing and thawing processes, and permafrost has considerable impact on carbon exchange between the atmosphere and the ground and on the hydrological cycle in cold regions/cold seasons.
    Snow cover, soil temperatures

70. [Zhang et al. 2005]
    ABSTRACT: Most climate records and climate change scenarios projected by general circulation models are for atmospheric conditions. However, permafrost distribution as well as ecological and biogeochemical processes at high latitudes is mainly controlled by soil thermal conditions, which may be affected by atmospheric climate change. In this paper, the changes in soil temperature during the twentieth century in Canada were simulated at 0.5 latitude/longitude spatial resolution using a process-based model. The results show that the mean annual soil temperature differed from the mean annual air temperature by 2 to 7 C, with a national average of 2.5 C. Soil temperature generally responded to the forcing of air temperature but in complex ways. The changes in annual mean soil temperature during the twentieth century differed from that of air temperature by 3 to 3 C from place to place, and the difference was more significant in winter and spring. On average, for the whole of Canada the annual mean soil temperature at 20 cm depth increased by 0.6 C, while the annual mean air temperature increased by 1.0 C. Three mechanisms were investigated to explain this differentiation: air temperature change, which altered the thickness and duration of snow cover, thereby altering the response of soil temperature; seasonal differences in changes of air temperature; and changes in precipitation. The first two mechanisms generally buffer the response of soil temperature to changes in air temperature, while the effect of precipitation is significant and varies with time and space. This complex response of soil temperature to changes in air temperature and precipitation would have significant implications for the impacts of climate change.
    Soil temperatures, lsm, air-ground interaction

71. [Zhu and Liang 2005]
    Abstract: The fifth-generation PSU-NCAR Mesoscale Model (MM5)-based regional climate model (CMM5) capability in simulating the U.S. soil temperature and soil moisture annual cycle and interannual variability is evaluated by comparing the 1982 2002 continuous integration driven by the NCEP-DOE AMIP II reanalysis (R-2) with observations, the R-2 derivatives and North American Land Data Assimilation System (NLDAS) products. For the annual cycle, the CMM5 produces more realistic regional details and overall smaller biases than the driving R-2 and NLDAS outputs. The CMM5 also faithfully simulates interannual variations of soil temperature over the central United States and soil moisture in Illinois and Iowa, where observational data are available. The existing CMM5 differences from observations in soil temperature (moisture) cannot be fully explained by model biases in surface air temperature (precipitation). Inconsistencies between measurements taken under short grass versus model representations beneath other land cover types may play an important role. In particular, such measurements overestimate soil temperature in summer and fall while generating a 1-month phase lead in the soil moisture annual cycle with respect to croplands in the model. The result emphasizes the need for more comprehensive study on model evaluation and bias understanding of soil temperature and soil moisture.
    Geothermal regime, model simulations

72. [Zorita et al. 2005]
    Temperature response in 1000 year paleo simulations continued under A2 scenario with the echo-g model. The trend response can be structured in a global ocean-land warming pattern plus regionnal responses in relationship with atmospheric circulation.
    Paleoclimate simulations, echo-g.

73. [Zorita and von Storch 2005]
    The performance of two methods to reconstruct Northern Hemisphere temperature histories of the past millennium is analyzed by applying them to the known development of an extended climate model simulation. The MBH-method underestimates low-frequency variability signi¯cantly, whereas Moberg's method operates satisfactorily. Some caveats apply.
    The suggested approach deals only with the methodological issues of deriving low-frequency non-local climate variability from a set of proxies, which are station- arily related to their climatic environment. In case of the MBH reconstructions other problems with the quality and stationarity of the proxy data may, or may not, prevail (McIntyre and Mckitrick (2005)). In our analysis we have tried to simulate the real situation; this goal has certainly be achieved only to a limited extent. We had to assume that both the errors in the proxy data and the contaminations of the link with instrumental data take the form of stationary Gaussian random variables. Likely, this assumption is not well ful¯lled. It is plausible that the process of archiving of climate data in proxy data was disturbed in an irregular, non-random manner by var- ious factors; also the climatic information archived in the proxies will quite possibly have undergone signi¯cant variations. This means, that the skill of the reconstructions methods is likely overestimated.
    Paleoclimate simulations, pseudo reconstructions.