2003

[Adler et al. 2003]
GPCP data set.
Global precipitation data
[Ammann et al. 2003]
A new monthly volcanic forcing dataset is included in a coupled GCM for a more physically consistent treatment of the stratospheric sulfate aerosol history from explosive volcanism. The volcanic forcing is different from previous versions in that there is an individual evolution of the aerosol for each event. Thus the seasonal and latitudinal dependence of the volcanic aerosol can affect global climate in a more realistic way prior to the satellite period, compared to earlier volcanic forcing datasets. Negative radiative forcing from volcanic activity is greatest in the early 20th century prior to 1915 and in the late 20th century after 1960. The combination of volcanic and solar forcing contributes to an early-20th century warming, followed by relative cooling in late 20th century. Consequently, the addition of natural forcing factors to the anthropogenic GHG forcing in late 20th century is required to simulate the observed late 20th century warming.
Volcanic forcing
[Bauer et al. 2003]
This paper follows conceptually that of [Crowley 2000]. Using that forcing runs the EMIC CLIMBER to find that the overstimation of instrumental temperatures in the 20th century by his EBM is due to deforestation through increase of albedo.
EMIC, paleoclimate simulations, deforestation, forcing.
[Bell et al. 2003]
Comparison of instrumental data, observations and control model simulations in terms of their basic statistics (variance range) and spectral shapes. The majority of models overestimate the obsreved variances. This is so even if they are not affected by external forcing.
Paleoclimate, GCMs, proxy reconstructions.
[Beltrami et al. 2003]
ABSTRACT Past changes in the Earth s surface energy balance are recorded in the ground as perturbations of the subsurface thermal regime. Here we reconstruct ground surface temperature histories (GSTH) from temperature versus depth profiles measured at 246 sites distributed across Canada. We show that the ground has warmed about 0.7 K in the last 100 years. Spatial variability is significant and indicates that the largest warming is in the southern areas of Canada. The apparent signal for the Little Ice Age (LIA) does not appear to be homogeneous across Canada.
Paleoclimate, boreholes, temperature reconstructions.
[Bradley et al. 2003a]
The balance of evidence does not point to a high medieval period that was as warm or warmer than the 20th century. Ill defined evidence for a range of climate anomalies ocurring over a wide time interval has created the notion that the MWE was a definitive global phenomenom.
Paleoclimate reconstructions, temperature.
[Bradley et al. 2003b]
Review about holocene and millennial climate variability. Proxy oriented
Paleoclimate reconstructions, temperature.
[Brown et al. 2003]
ABSTRACT Evaluation of snow cover in GCMs has been hampered by a lack of reliable gridded estimates of snow water equivalent (SWE) at continental scales. In order to address this gap, a snow depth analysis scheme devel-oped by Brasnett (1999) and employed operationally at the Canadian Meteorological Centre (CMC), was applied to generate a 0.3° latitude/longitude grid of monthly mean snow depth and corresponding estimated water equiv-alent for North America to evaluate GCM snow cover simulations for the Atmospheric Model Intercomparison Project II (AMIP II) for the period 1979 96. Approximately 8000 snow depth observations per day were obtained from U.S. cooperative stations and Canadian climate stations for input to the analysis. The first-guess field used a simple snow accumulation, aging and melt model driven by 6-hourly values of air temperature and precipita-tion from the European Centre for Medium-range Weather Forecasting (ECMWF) ERA-15 Reanalysis with exten-sions from the Tropical Ocean Global Atmosphere (TOGA) operational data archive. The gridded snow depth and estimated SWE results agree well with available independent in situ and satellite data over mid-latitudinal regions of the continent, and the snow depth climatology exhibited several improvements over Foster and Davy (1988). The monthly snow depth and estimated SWE climatologies are available for downloading from the Canadian Cryospheric Information Network (http://www.ccin.ca).
Snow cover
[Celik 2003b]
ABSTRACT:Estimation of energy output for small-scale wind power generators is the subject of this article.Monthly wind energy production is estimated using the Weibull-representative wind data for a total of 96 months,from 5 different locations in the world.The Weibull parameters are determined based on the wind distribution statistics calculated from the measured data, using the gamma function.The wind data in relative frequency format is obtained from these calculated Weibull parameters.The wind speed data in time-series format and the Weibull- representative wind speed data are used to calculate the wind energy output of a speci c wind turbine.The monthly energy outputs calculated from the time-series and the Weibull- representative data are compared. It is shown that the Weibull-representative data estimate the wind energy output very accurately. The overall error in estimation of monthly energy outputs for the total 96 months is 2.79 $\%$ .
Wind Energy, weibull, wind power.
[Celik 2003a]
ABSTRACT: Three functions have so far predominantly been used for fitting the measured wind speed probability distribution in a given location over a certain period of time, typically monthly or yearly. In the literature, it is common to fit these functions to compare which one fits the measured distribution best in a particular location. During this comparison process, parameters on which the suitability of the fit is judged are required. The parameters that are mostly used are the mean wind speed or the total wind energy output (primary parameters). It is, however, shown in the present study that one cannot judge the suitability of the functions based on the primary parameters alone. Additional parameters (secondary parameters) that complete the primary parameters are required to have a complete assessment of the fit, such as the discrep-ancy between the measured and fitted distributions, both for the wind speed and wind energy (that is the standard deviation of wind speed and wind energy distributions). Therefore, the secondary statistical parameters have to be known as well as the primary ones to make a judgement about the suitability of the distribution functions analysed. The primary and second-ary parameters are calculated from the 12-month of measured hourly wind speed data and detailed analyses of wind speed distributions are undertaken in the present article.
Wind Energy, weibull, wind power.
[Celik 2003c]
ABSTRACT: The electric generating capacity of Turkey must be tripled by 2010 to meet Turkeys elec- tric power consumption,if the annual 8pc growth in electric power consumption continues. Turkey has to make use of its renewable energy resources,such as wind and solar,not only to meet the increasing energy demand,but also for environmental reasons.Studies show that Iskenderun (36 v 35 0 N;36 v 10 0 E)located on the Mediterranean coast of Turkey is amongst the possible wind energy generation regions.In the present study,the wind energy potential of the region is statistically analyzed based on 1-year measured hourly time-series wind speed data.The probability density distributions are derived from time-series data and distribu- tional parameters are identi ed.Two probability density functions are tted to the measured probability distributions on a monthly basis.The wind energy potential of the location is studied based on the Weibull and the Rayleigh models.
Wind Energy, weibull, wind power.
[Celik 2003c]
ABSTRACT: The present article presents the development of compressed wind speed data to be used in wind energy and performance calculations of stand alone or hybrid wind energy systems.Compressed data attempts to represent the important statistics of an entire month of days with d selected days,where d is less than the actual number of days in the month.In the present article,compressed wind speed data are generated based on the Weibull wind speed distribution model.Two different sets of wind speed data are generated, three- and four-day month,each month being represented by 72 and 96 h of wind speed,respectively. The three- and four-day month wind speed data are then used to calculate the monthly energy yields, which,in turn, are compared to those calculated from the measured hourly time series data.A total of eight years long of measured hourly time series data from ve di
Wind Energy, weibull, wind power.
[Chiang et al. 2003]
ABSTRACT: Recent paleoproxy records suggest that the mean latitude of the Atlantic Intertropical Convergence Zone (ITCZ) varied synchronously with North Atlantic climate over a range of timescales throughout the Holocene and Last Glacial Maximum. We show that the present-day meridional mode of atmosphere-ocean variability in the tropical Atlantic is a potentially useful model for understanding these paleoclimate changes. The tropical Atlantic in a coupled atmospheric general circulation and slab ocean model responds to Last Glacial Maximum conditions with a southward displacement of the ITCZ. This response arises primarily through the land ice sheet that forces increased North Atlantic trades analogous to the forcing on the present-day meridional mode. Changes to sea ice coverage and to ocean heat transport associated with a weakened Atlantic thermohaline circulation also cause a meridional mode response, though through different mechanisms. Our results highlight the potential for tropical Atlantic paleoclimate to be driven from the high latitude influences, in particular, land ice on glacial-interglacial timescales.
ITCZ, LGM, North Atlantic
[Crowley et al. 2003]
The EBM model of [Crowley 2000] is fitted to observations and proxy rec to adjust the level of climate sensitivity. Simulates changes in ocean heat content for individual forcings along the last millennium. The model simulates the observed late 20th century ocean heat content increase and a comparable Little Ice Age minimum. When glacial advances are factored in, these results imply a sea level fall after the Middle Ages that is consistent with some geologic data. The present ocean heat content increase can be traced back to the mid-19th century, with a near-linear rate of change during the 20th century.
Paleoclimate reconstructions, GCM simulations, ocean heat content, external forcing.
[Dai et al. 2003]
Abstract: The Common Land Model (CLM) was developed for community use by a grassroots collaboration of scientists who have an interest in making a general land model available for public use and further development. The major model characteristics include enough unevenly spaced layers to adequately represent soil temperature and soil moisture, and a multilayer parameterization of snow processes; an explicit treatment of the mass of liquid water and ice water and their phase change within the snow and soil system; a runoff parameterization following the TOPMODEL concept; a canopy photo synthesis-conductance model that describes the simultaneous transfer of CO2 and water vapor into and out of vegetation; and a tiled treatment of the subgrid fraction of energy and water balance. CLM has been extensively evaluated in offline mode and coupling runs with the NCAR Community Climate Model (CCM3). The results of two offline runs, presented as examples, are compared with observations and with the simulation of three other land models [the Biosphere-Atmosphere Transfer Scheme (BATS), Bonan's Land Surface Model (LSM), and the 1994 version of the Chinese Academy of Sciences Institute of Atmospheric Physics LSM (IAP94)].
CLM
[Davis et al. 2003]
The accuracy with which seafloor heat flow is determined depends on the temporal stability of bottom water temperature. Indirect tests for stability are provided most commonly by observing the uniformity of heat flow with depth. This criterion is met to a high degree of certainty at two sites in the eastern North Pacific Ocean, where colocated high-quality probe and borehole heat flow data can be compared. A more direct test for stability is provided by long-term observations of bottom water temperature. Previously published records and new data show temperature variations of only a few hundredths of a degree at sites in the central and eastern North Atlantic and the eastern North Pacific. Resultant gradient perturbations are geothermally insignificant (<5 mK molsi 1 ) at depths greater than 1 2 m below the seafloor, consistent with the uniformity of heat flow with depth observed in these areas. Geothermally problematic bottom water temperature variations are observed or inferred in the western North and South Atlantic and western South Pacific. Variations range up to ±0.15 K and are capable of producing gradient perturbations of up to 5 mK molsi1 at depths as great as 5 m below the seafloor. While these data are instructive, their distribution is not adequate to provide general guidelines for estimating geothermal gradient perturbations. Data from shallower sites are needed in all oceans to define depth limits of acceptable bottom water temperature variability, and from other deep-ocean locations where near-source bottom water transients or vigorous deep-water circulation dynamics are likely to be present.
Boreholes, ocean crust heat flow
[Dorn et al. 2003]
Hirham4 and Echam4 experiments for the Arctic region. Influence of nao and greenhouse gas changes in the region. Changes associated to NAO compete with those of anthropogenic natuure in the Arctic.
NAO, Arctic, greenhouse gases, echam4, hirham
[Dunkeloh and Jacobeit 2003]
CCA Analysis using large scale NCEP 500 and 1000 geopotential height and Mediterranean precipitation (the gridded dataset of New et al, 2000). Analysis is made for winter (ONDJFM), spring (AM) and summer (JJAS). Dont use validation but some means of significance testing. Regional trends are directed by large scale circulation in the 1948-98 period.
NCEP reanalysis, Mediterranean precipitation, CCA, downscaling.
[Fisher et al. 2003]
ABSTRACT: 10 12 h, followed by rinsing in water. Characterization Current voltage (I V) curves were measured using a voltage ramp rate of 0.05 V s 21 in the dark and under illumination from a 250-W tungsten lamp (Oriel, 6129), with intensity measured using a radiometer (IL1700, International Light). The fill factor was calculated at 1,000 Wm 22 by dividing the maximum product of current and voltage from the illuminated I V curve by the product of open-circuit voltage and short-circuit current at the same illumination. The spectral response was determined using a 150-W Xe lamp and monochromator (Oriel 7240). IPCE was calculated from the current density under short-circuit conditions and the photon flux as measured by the radiometer. The optical absorbance (and absorption efficiency, hg(1g)) of the dye on the device surface and dye photon absorption was determined from the transmission and reflectance of a device fabricated on a transparent substrate before and after application of the dye, using an integrating sphere (LabSphere) and fibre-optic coupled monochromator (Ocean Optics). Free-solution dye absorbance was measured with an optical spectrometer (UV-1610, Shimadzu). Dye loading was determined by detaching the dye from the activated device surface in 1 mM NaOH solution, and determining the amount removed from the difference in optical absorbance at 511 nm of the NaOH solution. Received 17 July; accepted 18 November 2002; doi:10.1038/nature01316. 1. Chapin, D. M., Fuller, C. S. and Pearson, G. L. A new silicon p-n junction photocell for converting solar radiation into electrical power. J. Appl. Phys. 25, 676 677 (1954). 2. Archer, M. D. and Hill, R. (eds) Clean Electricity from Photovoltaics (Series on Photoconversion of Solar Hydrothermal circulation within the sea floor, through litho-sphere older than one million years (Myr), is responsible for 30 $\%$ of the energy released from plate cooling, and for 70 $\%$ of the global heat flow anomaly (the difference between observed thermal output and that predicted by conductive cooling models) 1,2 . Hydrothermal fluids remove significant amounts of heat from the oceanic lithosphere for plates typically up to about 65 Myr old 3,4 . But in view of the relatively impermeable sedi-ments that cover most ridge flanks 5 , it has been difficult to explain how these fluids transport heat from the crust to the ocean. Here we present results of swath mapping, heat flow, geochemistry and seismic surveys from the young eastern flank of the Juan de Fuca ridge, which show that isolated basement outcrops penetrating through thick sediments guide hydrother-mal discharge and recharge between sites separated by more than 50 km. Our analyses reveal distinct thermal patterns at the sea floor adjacent to recharging and discharging outcrops. We find that such a circulation through basement outcrops can be sustained in a setting of pressure differences and crustal proper-ties as reported in independent observations and modelling studies.
Heat flow, ocean crust
[González-Rouco et al. 2003a]
Validation of the borehole reconstructions using the Erik simulation.
AOGCM, paleoclimate, reconstructions, NH temperature
[Gosselin and Mareschal 2003]
Abstract Several temperature depth profiles recorded at Pipe Mine, 32 km southwest of Thompson, Manitoba, in central Canada, exhibit a marked departure from the equilibrium gradient. These profiles could be interpreted as indicating strong warming (up to 4.5 K) of the ground surface during the last 200 years. All the temperature profiles at Pipe Mine show perturbations stronger than at the others sites in the Thompson Nickel Belt. Temperature profiles recorded near the town of Thompson show a moderate warming ( c1 2 K) trend, while temperature profiles at Soab, 45 km southwest of Pipe Mine, indicate very moderate cooling ( c0.5 K). There was little human activity in this part of Manitoba before the development of the mining camp of Thompson in the late 1950s. Our study shows the variability of ground surface temperature histories at a very local scale (i.e. < 1 km) with much stronger signals at some of the Pipe Mine drill holes than at others. These holes are located within 500 m of the highway and a power line built after 1955, at c3 km from the now abandoned open pit mine. The ground surface temperature history (GSTH) obtained by the inversion of Pipe Mine temperature profiles suggests that a recent (50 years) and strong ( c1 2 K) ground surface warming is superimposed on a 1 2 K warming trend that started 200 years ago, without any indication of a cold (little ice ages) episode before. The recent warming (40 years) at Pipe Mine is only a local effect and is likely to be related to the presence of the highway. Before 1960, the ground surface temperature history for Pipe is similar to other sites in the Thompson region. Ground surface temperature histories from other profiles within and near the city of Thompson seem less affected by environmental perturbations and their trends are parallel to that of the meteorological records in the Canadian Prairies.
Paleoclimate, borehole temperatures
[Fernández and Sáenz 2003]
Downscaling of monthly precipitation in the Cantabrican coast. Comparison of linear (CCA SDS) and non linear (pca-analog and cca-analog) approaches. CCA analog is superior, not in terms of correlation but in infraestimating less variancce and in reproducing downscaling estimates with a more realistic distribution. CCA linear tends to normalize downscaled estimates.
AOGCM, paleoclimate, Iberian precipitation, Cantabrican, cca, cca analog, pca analog.
[Gerber et al. 2003]
ABSTRACT: The response of atmospheric CO2 and climate to the reconstructed variability in solar irradiance and radiative forcing by volcanoes over the last millennium is examined by applying a coupled physical biogeo- chemical climate model that includes the Lund- Potsdam-Jena dynamic global vegetation model (LPJ-DGVM)and a simpli ed analogue of a coupled atmosphere ocean general circulation model.The modeled variations of atmospheric CO2 and Northern Hemisphere (NH)mean surface temperature are com- patible with reconstructions from different Antarctic icecores and temperature proxy data.Simulations where the magnitude of solar irradiance changes is increased yield a mismatch between model results and CO2 data, providing evidence for modest changes in solar irradi- ance and global mean temperatures over the past mil- lennium and arguing against a signi cant ampli cation of the response of global or hemispheric annual mean temperature to solar forcing.Linear regression (r = 0.97)between modeled changes in atmospheric CO2 and NH mean surface temperature yields a CO2 increase of about 12 ppm for a temperature increase of 1 C and associated precipitation and cloud cover changes.Then, the CO2 data range of 12 ppm implies that multi-decadal NH temperature changes between 1100 and 1700 AD had to be within 1 C.Modeled preindustrial variations in atmospheric d 13 C are small compared to the uncer-tainties in ice core d 13 C data.Simulations with natural forcings only suggest that atmospheric CO2 would have remained around the preindustrial concentration of 280 ppm without anthropogenic emissions.Sensitivity experiments show that atmospheric CO2 closely follows decadal-mean temperature changes when changes in ocean circulation and ocean-sediment interactions are not important.The response in terrestrial carbon storage to factorial changes in temperature,the seasonality of temperature,precipitation,and atmospheric CO2 has been determined.
Last millennium, temperature reconstructions, uncertainties
[González-Rouco et al. 2003b]
Description of temperature response in millennial simulations with the echo-g model under anthropogenic and natural forcings.
Model simulations, aogcm, paleoclimate, anthropogenic warming, temperature.
[Hegerl et al. 2003]
Detection of solar, volcanic and co2 forcing in climate reconstructions. Volcanic is very clear and presents a realistic temporal pattern in the model simulations. CO2 is also well detected and solar only in some periods. So far so good... but obscure at times.
Paleoclimate reconstructions, ebm simulations, climate change detection.
[Holland and Bitz 2003]
Abstract: The Northern Hemisphere polar amplification of climate change is documented in models taking part in the Coupled Model Intercomparison Project and in the new version of the Community Climate System Model. In particular, the magnitude, spatial distribution, and seasonality of the surface warming in the Arctic is examined and compared among the models. The range of simulated polar warming in the Arctic is from 1.5 to 4.5 times the global mean warming. While ice-albedo feedback is likely to account for much of the polar amplification, the strength of the feedback depends on numerous physical processes and parametrizations which differ considerably among the models. Nonetheless, the mean sea-ice state in the control (or present) climate is found to influence both the magnitude and spatial distribution of the high-latitude warming in the models. In particular, the latitude of the maximum warming is correlated inversely and significantly with sea-ice extent in the control climate. Additionally, models with relatively thin Arctic ice cover in the control climate tend to have higher polar amplification. An intercomparison of model results also shows that increases in poleward ocean heat transport at high latitudes and increases in polar cloud cover are significantly correlated to amplified Arctic warming. This suggests that these changes in the climate state may modify polar amplification. No significant correlation is found between polar amplification and the control climate continental ice and snow cover.
Polar amplification
[Jones et al. 2003]
Study of changes in the seasonal range (summer-winter) using observations and documentary reconstructions. While regional annual temperature averages have warmed during the 20th century, the sr have lowered. In general, warmer periods in the past are associated with lower summer/winter differences. Periods with warmer annual mean temperatures are more likely, to be due more to milder wintres than hotter summers and vice versa for colder periods.. Summer trends are less representative of annual trends than winter trends. Seasonal contrasts have reduced over the past two centuries. Current NH reconstructions are possibly biased to warm season temperatures.
Documentary data, paleoclimate, seasonal range. Useful for complex demodulation.
[Jones and Widmann 2003]
An estimate of the strength of the austral summer Antarctic Oscillation using station sea level pressure records for the period 1878 2000 is presented, the first to the authors knowledge. The reconstruction was obtained by relating the Antarctic Oscillation (AAO) intensity derived from NCEP NCAR reanalysis data to the leading principal components of station records using multiple regression analysis. Particular effort has been made to fit the model in a way that is robust to the questionable trends in the NCEP NCAR data in the Southern Hemisphere. The trends in the reconstruction are derived from the station data, not from the NCEP data. Crossvalidation with the NCEP data and comparison with other analyses of the AAO over the late instrumental period give confidence that this station-based reconstruction can be regarded as trustworthy. With regard to the whole reconstruction period, some unquantifiable uncertainty stems from potential instability of the statistical relationships. To extend this record further back, a reconstruction using tree-ring chronologies back to 1743 has also been undertaken. Comparison with the station-based reconstruction shows moderate agreement on interannual and decadal timescales, but the comparison also points toward the inherent uncertainties of proxy-based climate reconstructions. In particular, it was found that this tree-based reconstruction may have been influenced by a warming that is not related to changes in the Antarctic Oscillation index during the twentieth century. Comparison of the tree-based reconstruction with a published reconstruction of zonal flow over New Zealand before the twentieth century shows common features. The temperature and precipitation signals of the Antarctic Oscillation have been calculated and show that the response of the chronologies to Antarctic Oscillation variability is physically plausible. In addition, it was shown that a substantial fraction of the observed warming over much of Antarctica between the late 1950s and the 1980s can be linked to changes in the Antarctic Oscillation, whereas the observed warming over New Zealand is related to other influences.
AAO reconstruction„ tree ring, instrumental.
[Landberg et al. 2003]
This article gives an overview of the different ways the wind resource at a site can be estimated. Eight separate ways have been identified. Each of these will be described in some detail, and advantages and disadvantages of each of them will be discussed.
Wind resource estimation
[Lin et al. 2003]
Temperature changes at the Earth surface propagate into the subsurface and leave a thermal signature in the underlying soil and rock. Inversions of subsurface temperature measurements yield reconstructions of ground surface temperature (GST) histories that provide estimates of climatic changes. A question remaining in the interpretation of reconstructed GST histories is the extent to which GST changes reflect changes principally in surface air temperature (SAT), or whether other factors may be significant. Here we use a Land Surface Processes (LSP) model to examine the influence of precipitation changes on GST and subsurface temperature and moisture fields on annual to decadal timescales. We model soil and vegetation conditions representative of a prairie region in the southern Great Plains of North America and force the model with meteorological data synthesized from a typical year in the region. Model responses are observed after changes in the amount of daily precipitation, the intensity and frequency of daily precipitation, and the diurnal and seasonal timing of precipitation. We show that: (1) increasing daily precipitation cools mean annual GST, (2) increasing the intensity and reducing the frequency of daily precipitation, while holding the annual amount of precipitation constant, cools mean annual GST, and (3) shifting maximum precipitation to occur in the warmest months cools mean annual GST. We compare modeled results to observed precipitation changes during the 20th century and conclude that the observed precipitation changes would cause only small changes to GST within the modeled region, on the order of 0.1 K or less.
Borehole reconstructions, sat-gst coupling, precipitation
[Mann et al. 2003a]
Paper with alternative reconstructions of global temperatures using grided and non gridded borehole data. Very critical with the approach of Huang et al. Supports that Huang's estimations overestimate global temperature averages and that their new reconstructions are in the context of tree-ring and other proxy reconstructions.
Last Millenium, Global and hemispheric temperatures reconstructions. Borehole data. Optimal methods.
[Mann et al. 2003b]
Continues discussion about Soon and Balliunas Climate Research paper.
Last Millenium, Global and hemispheric temperatures reconstructions.
[Mann and Schmidt 2003]
Use terrestrial deep soil temperature from model integrations during the reanalysis period to check that the borehole reeconstructions mainly focus on summer variability and that winter changes are biased by potential effects of isolation with snow cover. Winter temperatures depend on snow cover and the temperature of the preceeding summer.
Last Millenium, Global and hemispheric temperatures reconstructions. Borehole data. Optimal methods. Model.
[Mann and Jones 2003]
Reconstructions of hemispheric temperatures since 200 AD using typical composite plus scale (CPS) methods.
Last Millenium, Global and hemispheric temperatures reconstructions.
[Marshall 2003]
Several papers have described a significant trend toward the positive phase of the Southern Hemisphere annular mode (SAM) in recent decades. The SAM is the dominant mode of atmospheric variability in the Southern Hemisphere (SH) so such a change implies a major shift in the broadscale climate of this hemisphere. However, the majority of these studies have used NCEP NCAR reanalysis (NNR) data, which are known to have spurious negative trends in SH high-latitude pressure. Thus, given that the SAM describes the relative atmospheric anomalies at mid- and high southern latitudes, these errors in the NNR data have the potential to invalidate the published findings on changes in the SAM. Therefore, it is important that a true benchmark of trends in the SAM is available against which future climate scenarios as revealed through climate models can be examined. In this paper this issue is addressed by employing an empirical definition of the SAM so that station data can be utilized to evaluate true temporal changes: six stations are used to calculate a proxy zonal mean sea level pressure (MSLP) at both 408 and 658S during 1958 2000. The observed increase in the difference in zonal MSLP between 408 (increasing) and 658S (decreasing) is shown to be statistically significant, with the trend being most pronounced since the mid-1970s. However, it is demonstrated that calculated trends in the MSLP difference between 408 and 658S and the SAM itself are exaggerated by a factor of 3 and 2, respectively, in the NNR. The SH high-latitude errors in the early part of this reanalysis are greatest in winter as are subsequent improvements. As a result, the NNR shows the greatest seasonal trend in the SAM to be in the austral winter, in marked contrast to observational data, which reveal the largest real increase to be in summer. Equivalent data from two ECMWF reanalyses, including part of the new ERA-40 reanalysis, are also examined. It is demonstrated that ERA-40 provides an improved representation of SH high-latitude atmospheric circulation variability that can be used with high confidence at least as far back as 1973 and is therefore ideal for examining the recent trend in the SAM and with more confidence than the NNR right back to 1958.
SAM, AAO index
[McIntyre and McKitrick 2003]
List of errors and problems in [Mann et al. 1998]. The final impact of them being that the temperatures around the 15th century were not as low as reported, thus the 20th century is not as unusual. This papers brings lots of controversy. EandE is not fully reviewed I think, or at least politically oriented.
Last Millenium, Global and hemispheric temperatures reconstructions. Multiproxy reconstructions.
[Oppenheimer 2003]
Ice cores from both the Arctic and Antarctic record a massive volcanic eruption in around AD 1258. The inter-hemispheric transport of ash and sulphate aerosol suggests a low-latitude explosive eruption, but the volcano responsible is not known. This is remarkable given estimates of the magnitude of the event, which range up to 5 × 1014 2 × 1015 kg (200 800 km3 of dense magma), which would make this the largest eruption of the historic period, and one of the very largest of the Holocene. The associated collapse caldera could have had a diameter up to 10 30 km. Palaeoclimate reconstructions indicate very cold austral and boreal summers in AD 1257 59, consistent with known patterns of continental summer cooling following tropical, sulphur-rich explosive eruptions. This suggests an eruption in AD 1257, producing a stronger climate forcing than hitherto recognized
Volcanic activity, 1258 eruption
[Oreskes 2001]
The role of quantitative models in science
Model validation, models.
[Pielke 2003]
Heat storage and changes
Temperature reconstructions, borehole reconstructions, heat storage.
[Rutherford et al. 2003]
Test reconstruction of climate fields using the RegEM approach in the context of instrumental data and gfdl model data. They perform several analysis incrasing the number of missing data and assessing the impact of no variations in external forcing, trends due to internal variability and variations in external forcing, both in the calibration and verification period.
Temperature reconstructions, paleoclimate, pseudo proxies.
[Pauling et al. 2003]
Evaluation of the performance of different proxy records using a psedoproxy comparison framework in temperature reconstructions. Documentary data tend to perform better in winter. Tree-rings perform better for the warm season.
Last Millenium, Global and hemispheric temperatures reconstructions. Multiproxy reconstructions. Documentary data.
[Rayner et al. 2003]
We present the Met Office Hadley Centre’s sea ice and sea surface temperature (SST) data set, HadISST1, and the nighttime marine air temperature (NMAT) data set, HadMAT1. HadISST1 replaces the global sea ice and sea surface temperature (GISST) data sets and is a unique combination of monthly globally complete fields of SST and sea ice concentration on a 1° latitude-longitude grid from 1871. The companion HadMAT1 runs monthly from 1856 on a 5° latitude-longitude grid and incorporates new corrections for the effect on NMAT of increasing deck (and hence measurement) heights. HadISST1 and HadMAT1 temperatures are reconstructed using a two-stage reduced- space optimal interpolation procedure, followed by superposition of quality-improved gridded observations onto the reconstructions to restore local detail. The sea ice fields are made more homogeneous by compensating satellite microwave-based sea ice concentrations for the impact of surface melt effects on retrievals in the Arctic and for algorithm deficiencies in the Antarctic and by making the historical in situ concentrations consistent with the satellite data. SSTs near sea ice are estimated using statistical relationships between SST and sea ice concentration. HadISST1 compares well with other published analyses, capturing trends in global, hemispheric, and regional SST well, containing SST fields with more uniform variance through time and better month-to- month persistence than those in GISST. HadMAT1 is more consistent with SST and with collocated land surface air temperatures than previous NMAT data sets.
ENSO Index, global temperatures, instrumental data
[Roeckner et al. 2003]
A detailed description of the fifth-generation ECHAM model is presented. Compared to the previous version, ECHAM4, a number of substantial changes have been introduced in both the numerics and physics of the model. These include a flux-form semi-Lagrangian transport scheme for positive definite variables like water components and chemical tracers, a new longwave ra- diation scheme, separate prognostic equations for cloud liquid water and cloud ice, a new cloud microphysical scheme and a prognostic-statistical cloud cover parameterization. The number of spectral intervals is increased in both the longwave and shortwave part of the spectrum. Changes have also been made in the representation of land surface processes, including an implicit cou- pling between the surface and the atmosphere, and in the representation of orographic drag forces. Also, a new dataset of land surface parameters has been compiled for the new model. On the other hand, horizontal and vertical diffusion, cumulus convection and also the spectral dynamics remain essentially unchanged.
MPI report ECHAM5
[Sclater 2003]
Comments on [Fisher et al. 2003]. Heat regime is conduction in ocean floor sediment areas and the output hydrology in convection areas is ballanced by specific imput in particular spots, not the whole basin. This has relevance for models of ocean litospheric crust.
Ocean floor, boreholes, heat flow in ocean crust.
[Shindell et al. 2003]
The climate response to variability in volcanic aerosols and solar irradiance, the primary forcings during the preindustrial era, is examined in a stratosphere-resolving general circulation model. The best agreement with historical and proxy data is obtained using both forcings, each of which has a significant effect on global mean temperatures. However, their regional climate impacts in the Northern Hemisphere are quite different. While the short-term continental winter warming response to volcanism is well known, it is shown that due to opposing dynamical and radiative effects, the long-term (decadal mean) regional response is not significant compared to unforced variability for either the winter or the annual average. In contrast, the long-term regional response to solar forcing greatly exceeds unforced variability for both time averages, as the dynamical and radiative effects reinforce one another, and produces climate anomalies similar to those seen during the Little Ice Age. Thus, long-term regional changes during the preindustrial appear to have been dominated by solar forcing.
Volcanic, solar forcing, LIA
[Smerdon et al. 2003]
Heat conduction and SAT-GST coupling at fargo.
Last Millenium, Global and hemispheric temperatures reconstructions. Multiproxy reconstructions.
[Soon and Balliunas 2003]
Discussion about the Soon and Balliunas paper and Mann et al EOS paper 2003. Usual stuff. Answer in [Mann et al. 2003b]
Last Millenium, Global and hemispheric temperatures reconstructions. Multiproxy reconstructions.
[Stieglitz et al. 2003]
Abstract: Air temperatures at high latitudes are expected to rise significantly as anthropogenic carbon builds up in the atmosphere. There is concern that warming of the ground in permafrost regions will result in additional release of carbon to the atmosphere. Recent emphasis has thus been on predicting the magnitude and spatial distribution of future warming at high latitudes. Modeling results show that changes in below ground temperatures can be influenced as much by temporal variations of snow cover as by changes in the near-surface air temperature. The recent (1983 1998) changes in permafrost temperatures on the North Slope of Alaska are consistent with decadal scale variability in snow cover. The implication of these results is that a better understanding of how winter precipitation patterns at high latitudes will change over the coming decades is needed to comprehend evolving permafrost temperatures.
borehole reconstructions, permafrost
[Sutton and Hodson 2003]
Influence of changing conditions on North Atlantic ocean on the atmosphere is analysed through the use of ensemble simulations with the UKMO model. There is an oncean impact on the atmosphere on interannual and decadal timescales. Supports influence of thc. The principal mode is NAO but there are others. There is enso influence and they detect some nonstationarity in link, indicative of nonlinear relationships.
Atmosphere ocean interaction, nao, enso, ensemble simulations, non stationarity.
[Trenberth and Otto-Bliesner 2002]
A discussion of how to jointly analyse proxies and model simulations.

Paleoclimate, proxy reconstructions, model simulations.
[Usoskin et al. 2003]
Reconstruction of sunspot number time series from be10 and comparison with scaled series from c14. Conclude that the level of solar activity in the 20th century is umprecedent since 850 AD.
Climate reconstructions. Solar activity, cosmogenic isotopes, sunspot number, be10, c14.
[Widmann et al. 2003]
Statistical downscalling of reanalysis precipitation. Relevant for implications concerning quality of reanalysis.
Precipitation, reanalysis, statistical downscaling.
[Wijngaard et al. 2003]
Daily European station series (1901 99) of surface air temperature and precipitation from the European Climate Assessment dataset are statistically tested with respect to homogeneity. A two-step approach is followed. First, four homogeneity tests are applied to evaluate the daily series. The testing variables used are (1) the annual mean of the diurnal temperature range, (2) the annual mean of the absolute day-to-day differences of the diurnal temperature range and (3) the wet day count (threshold 1 mm). Second, the results of the different tests are condensed into three classes: useful , doubtful and suspect . A qualitative interpretation of this classification is given, as well as recommendations for the use of these labelled series in trend analysis and variability analysis of weather extremes.
Pettit test, homogeneization, temperature precipitation, daily parameters.
[Xoplaki et al. 2003a]
Statistical downscalling of large scale fields to summer temperature in Greece. Reanalysis period. Interesting in combination with [Xoplaki et al. 2003b]
Precipitation, reanalysis, downscaling.
[Xoplaki et al. 2003b]
Statistical downscalling of large scale fields to summer temperature over Mediterranean area. Reanalysis period. Interesting in combination with [Xoplaki et al. 2003a]. Inference back to 19th century of influence of large scale on surface temperature
Precipitation, reanalysis, downscaling.
[Zorita et al. 2003]
Validation of the Mann et al (1999) method in paleo reconstructions. Number of ideal proxies, etc.
AOGCM, paleoclimate, reconstructions, NH temperature