1999

[Behringer 1999]
Influence of climate on mentalities. Witches prosecuted during sixtheenth century because of association with hail storms...
Witches, NAO,Little Ice Age
[Briffa and Osborn 1999]
Some uncertainties and discussion on limitations of present global scale temperature proxy reconstructions.
Temperatures, reconstructions, paleoclimate, tree-ring, ice-core.
[Burkhardt 1999]
Downscaling of precipitation for the Alps in 1-CO2 and 3-C02 scenarios with echam3. Statistical model is applied to the spatial variation of the geopotential to substract influence of temperature
Precipitation scenarios, statistical downscaling, cca.
[Busuioc et al. 1999]
Downscaling of precipitation for Romania 1900-1990 using observations and the ECHAM3 model in t21 and t42 resolution. The work is oriented towards the validation of the model in reproducing the mean climate, the large to regional scale relationships and the validity of the cca downscaling model in 2XC02 scenario.
Precipitation scenarios, statistical downscaling, cca, model validation.
[Cavazos 1999]
Application of SOMs and neural networks to predict precipitation in Mexico. Enso effects.
Downscaling, neural networks, som
[Charles et al. 1999]
Use Regional Climate Model to validate climate downscaling for precipitation in Australia. Use Nonhomogeneous Hidden Markov Model.
Downscaling, Markov Model, Regional Climate Models RCM.
[Cook et al. 1999]
Summer drought reconstructions for USA in a 2x3 grid using tree-ring chronologies and the Palmer Drought Severity Index for the perido 1700-1978. Used point-by-point regression. Dust bowl arises as the most important period.
Temperatures, reconstructions, paleoclimate, tree-ring, hidrology.
[Corti et al. 1999]
They use atmospheric circulation data from the Northern Hemisphere to show that recent climate change can be interpreted in terms of changes in the frequency of occurrence of natural atmospheric circulation regimes. They conclude that recent NH warming may be mroe directly related to thethermal structure of these circualtion regimes than to any anthropogenic forcing pattern itself.
Anthropogenic warming, circulation regimes, slp, modes of circulation.
[Dickson 1999]
Description of Arctic dynamics during some epysodes on the 1990's
Arctic, sst, NAO.
[Doherty et al. 1999]
Gridded reconstruction of land and ocean precipitation for the period 1974-1994. Should be referenced also when working with Hulme's precipitation dataset.
Precipitation, data sets.
[Frei et al. 1999]
ABSTRACT:Historical fluctuations of North American snow extent from November through March are reconstructed back to 1900 using a combination of satellite and station observations. Using results of principal components analyses (PCA) from a companion study (Frei, A. and Robinson, D.A. Int. J. Climatol., this volume), simple and multiple linear regression models are used to take advantage of the spatial coverage of satellite observations and the temporal extent of station observations. This analysis more than triples the remotely-sensed record length, which begins in 1972. Model results indicate that North American winter snow extent tended to increase between the 1930s and around 1980, followed by a subsequent decrease during the 1980s. Long-term trends during November are less dramatic, with small increases since the 1960s. During March a different signal is observed, with snow extent decreasing since the 1950s. These results suggest a possible shift in the snow season. Historical signals from smaller regions within North America are identified during December and January. During December, the continental-scale signal is driven mainly by fluctuations over the western US, while January fluctuations are more strongly driven by an eastern signal. Models are sufficiently accurate to estimate changes in interannual variability over North America only during February, as well as over the eastern portion of the continent during December and January. Continental-scale interannual variability during February has been high since the mid-1970s compared to any previous time this decade. Regional-scale interannual variability over eastern North America in January has also been higher in recent years, but in December the highest interannual variability occurred during the 1940s.
Snow cover variations
[Fyfe et al. 1999]
Study of AO and AAO in canadian model under scenario simulations. Simulation of realistic NAO. Increase of NAO intensity with GHG. Also increase of AAO intensity with GHG but takes off sooner (1920). Relationship with stratosphere [Shindell et al. 1999a] not supported.
AO, AAO
[Gong and Wang 1999]
Definition of AAO index
AAO,SAM index
[Haigh 1999]
Review of model runs assessing the impact of solar variability taking into account only variations in amplitude of the solar constant and other stratospheric models also with ozone specification. New results suggest that solar forcing can excite the same mode of variability in the northern hemisphere winter troposphere/stratosphere as is excited by the injection of volcanic aerosol into the lower stratosphere. Model runs should have an adequate representation of the stratosphere.
GCMs, solar variability, external forcing, climate, ozone, stratosphere.
[Harris and Gosnold 1999]
Temperature depth profiles measured in boreholes contain a record of temperature changes at the Earth s surface. The degree to which these profiles and surface air temperature records track each other is quantitatively assessed for the northern plains of the USA. Surface air temperature records are used as a forcing function to generate synthetic transient temperature profiles which are compared with transient temperatures derived from borehole temperature depth data. These comparisons indicate that surface air and ground temperatures are correlated. Furthermore, these comparisons yield a long-term mean temperature tied to the meteorological record which provides a context for interpreting contemporary warming trends. Our results indicate that warming recorded in surface air temperature time series represents a positive departure above baseline temperature estimates. Key words: climate, geothermics, heat flow.
Climate reconstructions, last millennium, borehole
[Huth 1999]
Comparison of several linear methods for statistical downscaling of daily temperature 1982-1990 in central/north Europe using surface and upper air thermal predictors (geopotential, thickness). Pointwise regression was best.
Statistical downscaling, linear, cca, regression, temperature, NCEP.
[Indermuehle et al. 1999b]
CO2 holocene variations at Taylor Dome. Slight variations in last 1000 years respect to [Etheridge et al. 1996]. They show that the global carbon cycle has not been in steady state during the past 11000 years. analysis of the CO2 concentration and caarbon stable isotope records, using a one dimennsional carbon cycle model suggests that changes in terrestrial biomass and sea surface temperrature were largely responsible for the observed millennial scale changes of atmospheric co2 cocentrations.
Paleoclimate, forcing, Taylor Dome, co2
[Indermuehle et al. 1999a]
Comment on [Wagner et al. 1999]. Indermuhle et al. state their co2 values for the early holocene are reliable and the high values in Wagner et al questionable. See other respones to Wagner et al in the same pages.
Paleoclimate, forcing, Taylor Dome, co2, stomatal co2
[Jones et al. 1999]
Reconstructions of gridded SLP for Europe back to AD 1780 within project ADVICE. Uses technique of [Jones 1987]. Uses 51 sites and the UKMO SLP dataset. Takes into account homogenization (subjective).
SLP reconstructions. Homogenization. Quality.
[Keigwin and Pickart 1999]
During the negative phase of the NAO convection is enhanced on the Greenland and Sargasso seas, the slope water current strengthens and moves northward. Also maybe there is increased transport of overflow water in the DWBC. They find warming in sediment cores from the Laurentian Fan during the LIA. They propose that the slope water current is responsable for local warming in the laurentian fan during the LIA, by moving northward. The subtropical sst gyre cooled 1 to 2 degrees diring this period. The authors predict the sst histories north and south of 44 N should be out of phase.
sst, sediment cores, NAO.
[Kohl 1999]
Abstract The topographical perturbation of steady-state subsurface temperature fields has been an important issue in geothermal interpretations throughout the past century. This paper reports a numerical study, which considers the possible influence of terrain topography on transient temperature signals. Typical morphological situations over wide areas in central Europe affect most likely that same depth range which also contains the temperature signals resulting from the most interesting ground surface temperature changes (i.e. during the last 200 years). The evaluation of the interaction is performed on a synthetic sinusoidal topography with varying wavelength and amplitude. Vertical profiles (i.e. temperature logs) were extracted from these numerical forward 2-D calculations. Thereby, the error could be estimated by comparing ground surface temperature time-histories inverted from temperature logs both with and without topographic correction. The results show that a topographic correction of temperature data is absolutely necessary to achieve a consistent inversion result. Even rather flat topographies with 20-km wavelengths and 100-m amplitudes may introduce topographical effects which confuse the inversion process. On the other hand, the palaeoclimatically induced temperature signal persists even in rough topographies and will show correct inversion results when data are adequately treated. Only extreme situations cause a lateral interference of these transient signals with depth. The results from such 2-D synthetic models have been confirmed by an analysis of a real situation. The example chosen is the area surrounding the German Continental Deep Drilling (KTB) project. The area is situated in a moderately undulating surface topography with maximum altitude variations of the order of 250 m. The additional 3-D simulation demonstrates that a strong topography-dependent variation of the transient temperature signal can occur even at greater depths. The introduction of corrections for topography influence, reduces apparent differences in profiles from different locations in the surroundings of the KTB site to a maximum of 0.2 K. Ó 1999 Elsevier Science B.V. All rights reserved.
Borehole inversions, topography effects
[Koslowski and Glaser 1999]
Reconstruction of ice extension in the western Baltic and relationship to NAO.
Ice extension, NAO,Little Ice Age
[Kushnir 1999]
Comments on [Rodwell et al. 1999]. Briefs hipothesys of atmosphere damping the sst changes.
Good transparencie.
[Limpasuvan and Hartmann 1999]
Abstract. The dominant modes of month-to-month variation in the troposphere are realistically simulated in a general circulation model whose lower boundary is prescribed with realistic topography and seasonally varying, climatological sea surface temperatures. In both hemispheres, these internal modes describe a nearly zonally symmetric, North- South shifting of the zonal jets as anomalous westerlies vacillate between high (50N-60N) and low (30N -40N) latitudes. The eddy structures evolve with the jets, and the corresponding eddy momentum forcings support the shifts in jet position. Stationary (synoptic) wave variations mainly account for the total eddy forcings in the Northern (Southern) Hemisphere. Pronounced eddy variations occur over the North Atlantic sector.
SAM
[Livezey and Smith 1999]
Comments on [Barnett and Preisendorfer 1987]. They comment on two aspects related to eof prefiltering of cca analysis: data weighting and pc truncation. Concerning weighting, they advise to follow the order of standardizing, area weighting and then calculating covariance matrix. Concerning pc truncation they seem to advise a heuristic approach determining with crossvalidation what is the best pc truncation, instead of proceeding with a priori reasoning.
CCA analysis, downscaling, pc/eof prefiltering, pc truncation, data weighting.
[Luterbacher et al. 1999]
Reconstruction of NAO1, NAO2, EU1 and EU2 indices 1675-1990. Quality is dependent on season, number, quality and spatial distribution of predictors. Correlation coeficientes with other NAO indixes are good and not significant with those based on treerings and ice accumulation rates.
NAO, EU reconstructions.
[Lynch-Stieglitz 1999]
New method for the quantitative reconstruction of upper ocean flows for during times in the past. Reference for [Lund and Curry 2006]
Benthic foraminifera, florida current, geostrophic transport
[Majorowicz et al. 1999]
Abstract New temperature logs in wells located in the grassland ecozone in the Southern Canadian Prairies in Saskatchewan, where surface disturbance is considered minor, show a large curvature in the upper 100 m. The character of this curvature is . consistent with ground surface temperature GST warming in the 20th century. Repetition of precise temperature logs in . southern Saskatchewan years 1986 and 1997 shows the conductive nature of warming of the subsurface sediments. The . . magnitude of surface temperature change during that time 11 years is high 0.3 0.48C . To assess the conductive nature of temperature variations at the grassland surface interface, several precise air and soil temperature time series in the southern . Canadian Prairies 1965 1995 were analyzed. The combined anomalies correlated at 0.85. Application of the functional . space inversion FSI technique with the borehole temperature logs and site-specific lithology indicates a warming to date of approximately 2.58C since a minimum in the late 18th century to mid 19th century. This warming represents an approximate increase from 48C around 1850 to 6.58C today. The significance of this record is that it suggests almost half of the warming occurred prior to 1900, before dramatic build up of atmospheric green house gases.
Paleoclimate, multiproxy reconstructions, NH mean temperature.
[Mann et al. 1999]
Extended reconstruction (only for NH temporal) of [Mann et al. 1998] temperatures to 1000-1998. Discussion on PC1 of ITRDB and corrections. Middle ages warming but 20th century warmest. Most proxies are tree data. 1998 warmest year.
Paleoclimate, multiproxy reconstructions, NH mean temperature.
[Mart&́#305;n-Vide and Gómez 1999]
Analysis of dry spells for Spain with Markov chains from 1st to tenth order. Daily data within the period 1950-90. Regionalization of Spain according to the fit to Markov chains. The northern part fits to markovian precipitation both for short and longer spells. Central Spain shows good general agreement with notable discrepancies in values estimated for the longer spells. The southern area cannot be considered to follow a markovian process.
Iberian daily precipitation, Markov chains, regionalization.
[Mitchell and Hulme 1999]
Regional climate prediction is not an insoluble problem, but it is a pro b l e m characterized by inherent uncertainty. There are two sources of this uncertainty: the unpre-dictability of the climatic and global systems. The climate system is rendered unpredictable by deterministic chaos; the global system renders climate prediction uncertain through the unpre-dictability of the external forcings imposed on the climate system. It is commonly inferred from the differences between climate models on regional scales that the models are deficient, but climate system unpredictability is such that this inference is premature; the differences are due to an unresolved combination of climate system unpredictability and model deficiencies. Since model deficiencies are discussed frequently and the two sources of inherent uncertainty are discussed only rarely, this review considers the implications of climatic and global system unpredictability for regional climate prediction. Consequently we regard regional climate prediction as a cascade of uncertainty, rather than as a single result process sullied by model deficiencies. We suggest three complementary methodological approaches: (1) the use of multiple forcing scenarios to cope with global system unpredictability; (2) the use of ensembles to cope with climate system unpredictability; and (3) the consideration of the entire response of the climate system to cope with the nature of climate change. We understand regional climate change in terms of changes in the general circulations of the atmosphere and oceans; so we illustrate the role of uncertainty in the task of regional climate prediction with the behaviour of the North Atlantic thermohaline circulation. In conclusion we discuss the implications of the uncertainties in regional climate prediction for research into the impacts of climate change, and we recognize the role of feedbacks in complicating the relatively simple cascade of uncertainties presented here.
Climate change projections, regional climate simulations, uncertainty
[New et al. 1999]
The construction of a 0.58 lat 3 0.58 long surface climatology of global land areas, excluding Antarctica, is described. The climatology represents the period 1961 90 and comprises a suite of nine variables: precipitation, wet-day frequency, mean temperature, diurnal temperature range, vapor pressure, sunshine, cloud cover, ground frost frequency, and wind speed. The climate surfaces have been constructed from a new dataset of station 1961 90 climatological normals, numbering between 19 800 (precipitation) and 3615 (wind speed). The station data were interpolated as a function of latitude, longitude, and elevation using thin-plate splines. The accuracy of the interpolations are assessed using cross validation and by comparison with other climatologies. This new climatology represents an advance over earlier published global terrestrial climatologies in that it is strictly constrained to the period 1961 90, describes an extended suite of surface climate variables, explicitly incorporates elevation as a predictor variable, and contains an evaluation of regional errors associated with this and other commonly used climatologies. The climatology is already being used by researchers in the areas of ecosystem modelling, climate model evaluation, and climate change impact assessment. The data are available from the Climatic Research Unit and images of all the monthly fields can be accessed via the World Wide Web.
Precipitation data set
[Osborn et al. 1999]
Description of NAO and how HADCM2 simulates its spatial and temporal characteristics. Realistic patterns and time simulation. Interesting discussion.
NAO, climate variability, GCMs, slp, temperature, precipitation, stormtracks, climate change.
[Rind et al. 1999]
Showed an ensemble of experiments with a lower resolution GCM coupled to a simplified ocean indicating also that the solar forcing is not sufficient to produce the rapid warming of the last decades.
Paleo simulations, climate variability, solar forcing, gglobal warming
[Rodwell et al. 1999]
Sea surface temperature characteristics are communicated to the atmosphere through evaporation, precipitation and atmospheric heating processes leading to changes in temperature, precipitation and storminess over Europe.
Implications for predictability of NAO and effects over Europe.
Influence of SST on NAO. Forcin oc-at? at-oc? Prediction of NAO.
[Rodrigo et al. 1999]
Reconstruction of precipitation index in Andalucia back to 1500.
Iberian precipitation. NAO. Climate reconstructions.
[Roeckner et al. 1999]
Transient climate change simulations with the ECHAM model. Bad references for N2O data in our simulations.
Model simulations, ECHAM, anthropogenic warming.
[Romero et al. 1999c]
Analysis of 30-year data set of daily precipitation described in [Romero et al. 1998]. Regionalization of precipitation according to PCA results of days with precipitation over a certain threshold. Heavy precipitation events show similar PCA patterns. Thus precipitations follows the same structures both for heavy and normal events with a clear orographic influence.
Spanish Mediterranean daily precipitation. PCA. Regionalization.
[Romero et al. 1999b]
Two regionalizations of spanish mediterranean daily precipitation with rotated and unrotated PCs. Effects of orography to influence of flows from the Atlantic and Mediterranean.
Spanish Mediterranean daily precipitation. PCA. Regionalization.
[Romero et al. 1999a]
Abstract: This study investigates the synoptic atmospheric circulations associated with 11 typical spatial patterns for significant rainfall days for Mediterranean Spain, which have been identified in an earlier paper. Using cluster analysis on the most relevant T-mode principal components, a classification into 19 fundamental circulations emerged, based only on geopotential fields at 925 and 500 hPa, using ECMWF gridded data for the period 1984–1993. The derived atmospheric patterns comprise a wide variety of flows over the Iberian Peninsula, with a clear distinction between Atlantic and western Mediterranean disturbances. Distinct seasonal distributions are also observed. Despite the comparatively higher resolution of the rainfall patterns, and the uncertainty derived from working with a daily time scale, a clear association emerged between each of the circulation types and a small number of the characteristic rainfall patterns. These associations can be physically interpreted in terms of the position of the 500 hPa trough, disturbances at the 925 hPa level, and the interaction of the surface rain bearing flows with the complex topography of the region. The final part of the analysis concentrated on establishing links between identified circulation patterns and notable (torrential) precipitation events recorded during the 1984–1993 decade. Some of the identified circulations that are important for the occurrence of significant rainfalls, produce few or no torrential rainfall episodes. Most torrential rainfall events in Mediterranean Spain are associated with disturbances located near or over the south of the Iberian Peninsula. Copyright © 1999 Royal Meteorological Society.
Objective classification, cluster analysis, circulation types
[Schellnhuber 1999]
Optical magnification instruments once brought about the Copernican revolution that put the Earth in its correct astrophysical context. Sophisticated information-compression techniques including simulation modelling are now ushering in a second Copernican revolution. The latter strives to understand the Earth system as a whole and to develop, on this cognitive basis, concepts for global environmental management.
Un autentico conhazo
EMICS, climate change
[Serrano et al. 1999]
Precipitation EOFs in the Iberian Peninsula. About 40 stations.
Variability, precipitation, Iberian Peninsula
[Soon et al. 1999]
Uncertainties in climate models for prediction of climate change. No clear evidence of the global effects of an increase of atmospheric CO2 on climate. Integrated assessments are not yet possible. Interesting and clear.
Climate change, CO2
[Spellman 1999]
Reviewed paper of Greg Spellman.
Precipitation. Spain
[Shindell et al. 1999a]
Usefulness of studying the AO because of warming related to changes in atmospheric circulation. AO trend only captured by CCMs with relative representation of stratosphere. Changes in ozones concentrations do not affect. Suggest the stratosphere influences climate at the surface by modulating energy propagation out of the troposfere. Changes in the stratosphere may all affect surface climate.
Latitudinal temperature gradient near the tropopause increases [Shindell et al. 1998] due to warming of tropics and cooling of polar areas. This enhances zonal wind and deflection of high latitude wave energy away from the lower stratosphere. The zonally averaged vertical circulation is enhanced with greater rising motion in polar latitudes and descent between 40 and 55 N, continuously from surface to midle stratosphere due to barotropic nature of AO. This would enhance NAO.
NAO. Climate models. Stratospheric influence.
[Shindell et al. 1999b]
Show how stratospheric ozone can amplify the 11-yr solar cycle using a model that takes into account atmospheric chemistry and the tropospheric-stratospheric coupling.
stratosphere-troposphere coupling. O3.
[Stenseth 1999]
NAO influence in Canada contributes to similar dynamic structure of the Lynx populations in three different climatic regimes.
NAO, ecology.
[Stockton and Glueck 1999]
Reconstruction of NAO from tree-ring from Morocco and Finland as weel as ice core data.
NAO reconstructions, paleoclimate, tree ring, ice core.
[von Storch 1999]
Problems with inflation of predictions to reproduce variance of observations. The mean error of the inflated estimator is larger. It makes implicit assumption that all variability in predictions are related to variability in predictors. Recomends adding noise.
Downscaling, inflation of variance. What happens with correlations then?
[Tett et al. 1999]
Observations of the Earth s near-surface temperature show a global-mean temperature increase of approximately 0.6 K since 1900 (ref. 1), occurring from 1910 to 1940 and from 1970 to the present. The temperature change over the past 30 50 years is unlikely to be entirely due to internal climate variability 2 4 and has been attributed to changes in the concentrations of green-house gases and sulphate aerosols 5 due to human activity. Attri-bution of the warming early in the century has proved more elusive. Here we present a quantification of the possible contribu-tions throughout the century from the four components most likely to be responsible for the large-scale temperature changes, of which two vary naturally (solar irradiance and stratospheric volcanic aerosols) and two have changed decisively due to anthro-pogenic influence (greenhouse gases and sulphate aerosols). The patterns of time/space changes in near-surface temperature due to the separate forcing components are simulated with a coupled atmosphere ocean general circulation model, and a linear com-bination of these is fitted to observations. Thus our analysis is insensitive to errors in the simulated amplitude of these responses. We find that solar forcing may have contributed to the temperature changes early in the century, but anthropogenic causes combined with natural variability would also present a possible explanation. For the warming from 1946 to 1996 regard-less of any possible amplification of solar or volcanic influence, we exclude purely natural forcing, and attribute it largely to the anthropogenic components.
Climate change detection, hadcm, observed trends, warming
[Uppenbrink 1999]
Despcriptive note on the NAO. Relationship to the stratosphere, to changes in wind stress curl, to oceanic masses, to the tropical climate...
NAO, decadal variability.
[Wagner et al. 1999]
Present a high resolution record of leaf stomatal index from which they reconstruct the concetnration of atmospheric co2 in the early Holocene. The CO2 record from the ice core of Taylor Dome considered the most reliable and precise reconstruction of atmospheric CO2 over the Holocene has a low temperoal resolution in the early Holocene. They find high values for that period. Theyy claim that the conccept of relatively stable Holocene co2 concetnrations of 270 to 280 ppmv until the Industrial revolution is falsified by their results.
Paleoclimate, forcing, co2.
[Wood et al. 1999]
The heat transported northwards by the North Atlantic thermo- haline circulation warms the climate of western Europe 1±3 . Previous model studies 4±6 have suggested that the circulation is sensitive to increases in atmospheric greenhouse-gas concentra- tions, but such models have been criticised for the use of unphysical 'flux adjustments' (articial corrections that keep the model from drifting to unrealistic states), and for their inability to simulate deep-water formation both north and south of the Greenland±Iceland±Scotland ridge, as seen in observations 10,11 . Here we present simulations of today's thermo- haline circulation using a coupled ocean±atmosphere general circulation model without flux adjustments. These simulations compare well with the observed thermohaline circulation, includ- ing the formation of deep water on each side of the Greenland- Iceland-Scotland ridge. The model responds to forcing with increasing atmospheric greenhouse-gas concentrations by a collapse of the circulation and convection in the Labrador Sea, while the deep-water formation north of the ridge remains stable. These changes are similar in two simulations with different rates of increase of CO2 concentrations. The effects of increasing atmospheric greenhouse-gas concentrations that we simulate are potentially observable, suggesting that it is possible to set up an oceanic monitoring system for the detection of anthropogenic in¯uence on ocean circulation.
thermohaline circulation, climate change, hadcm
[Wunsch 1999]
NAO and SOI have the structure of red noise process. Synthetic simulations are similar in structure to NAO index. Generates time series with observed spectrum. Discussion of dangers of vissual correlations and the importance of threshold crossing statistics. Also nonnormal statistics and non-stationarity.
NAO, stochastic processes.
[Zorita and von Storch 1999]
Comparison of downscaling methods: analog, cca, CRT and neuronal network. The analog method performs better and the cca method illustrates the physical links.
Precipitation. Spain. Downscaling.
[Zorita 1999]
Descripción del estado del arte en predicción climatica. Explicativo
Climate models. Climate change.