1.
Brázdil, Rudolf, et al.
(author)
European climate of the past 500 years: new challenges for historical climatology
2010
In: Climatic Change. - Netherlands : Springer. - 0165-0009 .- 1573-1480. ; 101:1-2, s. 7-40
Journal article (peer-reviewed) abstract
Temperature reconstructions from Europe for the past 500 years basedon documentary and instrumental data are analysed. First, the basic documentarydata sources, including information about climate and weather-related extremes, aredescribed. Then, the standard palaeoclimatological reconstruction method adoptedhere is discussed with a particular application to temperature reconstructions fromdocumentary-based proxy data. The focus is on two new reconstructions; January–April mean temperatures for Stockholm (1502–2008), based on a combination ofdata for the sailing season in the Stockholm harbour and instrumental temperaturemeasurements, and monthly Central European temperature (CEuT) series (1500–2007) based on documentary-derived temperature indices of the Czech Republic,Germany and Switzerland combined with instrumental records from the samecountries. The two series, both of which are individually discussed in greater detail in subsequent papers in this special edition, are here compared and analysed usingrunning correlations and wavelet analysis. While the Stockholm series shows apronounced low-frequency component, the CEuT series indicates much weaker lowfrequencyvariations. Both series are analysed with respect to three different longperiodreconstructions of the North Atlantic Oscillation (NAO) and are comparedwith other European temperature reconstructions based on tree-rings, wine-harvestdata and various climate multiproxies. Correlation coefficients between individualproxy-based series show weaker correlations compared to the instrumental data.There are also indications of temporally varying temperature cross-correlationsbetween different areas of Europe. The two temperature reconstructions have alsobeen compared to geographically corresponding temperature output from simulationswith global and regional climate models for the past few centuries. The findingsare twofold: on the one hand, the analysis reinforces the hypothesis that the indexdatabased CEuT reconstruction may not appropriately reflect the centennial scalevariations. On the other hand, it is possible that climate models may underestimateregional decadal variability. By way of a conclusion, the results are discussed froma broader point of view and attention is drawn to some new challenges for futureinvestigations in the historical climatology in Europe.
2.
Dobrovolný, Petr, et al.
(author)
Monthly, seasonal and annual temperature reconstructions for Central Europe derived from documentary evidence and instrumental records since AD 1500
2010
In: Climatic Change. - Netherlands : Springer. - 0165-0009 .- 1573-1480. ; 101:1-2, s. 69-107
Journal article (peer-reviewed) abstract
Monthly temperature series for Central Europe back to AD 1500 aredeveloped from documentary index series from Germany, Switzerland and theCzech Republic (1500–1854) and 11 instrumental temperature records (1760–2007).Documentary evidence from the Low Countries, the Carpathian Basin and Polandare used for cross-checking for earlier centuries. The instrumental station recordsare corrected for inhomogeneities, including insufficient radiation protection ofearly thermometers and the urban heat island effect. For overlapping period (1760–1854), the documentary data series correlate with instrumental temperatures, moststrongly in winter (86% explained variance in January) and least in autumn (56%in September). For annual average temperatures, 81% of the variance is explained.Verification statistics indicate high reconstruction skill for most months and seasons.The last 20 years (since 1988) stand out as very likely the warmest 20-year period,accounting for the calibration uncertainty and decreases in proxy data quality beforethe calibration period. The new reconstruction displays a previously unobserved long-term decrease in DJF, MAM and JJA temperature variability over last fivecenturies. Compiled monthly, seasonal and annual series can be used to improve therobustness of gridded large-scale European temperature reconstructions and possibleimpact studies. Further improvement of the reconstruction would be achieved ifdocumentary data from other European countries are further developed.
3.
Luterbacher, Jürg, et al.
(author)
Circulation dynamics and its influence on European and Mediterranean January–April climate over the past half millennium : results and insights from instrumental data,documentary evidence and coupled climate models
2010
In: Climatic Change. - Netherlands : Springer. - 0165-0009 .- 1573-1480. ; 101:1-2, s. 201-234
Journal article (peer-reviewed) abstract
We use long instrumental temperature series together with available field reconstructions of sea-level pressure (SLP) and three-dimensional climate modelsimulations to analyze relations between temperature anomalies and atmospheric circulation patterns over much of Europe and the Mediterranean for the late winter/early spring (January–April, JFMA) season. A Canonical Correlation Analysis(CCA) investigates interannual to interdecadal covariability between a new gridded SLP field reconstruction and seven long instrumental temperature series covering the past 250 years. We then present and discuss prominent atmospheric circulation patterns related to anomalous warm and cold JFMA conditions within different European areas spanning the period 1760–2007. Next, using a data assimilation technique, we link gridded SLP data with a climate model (EC-Bilt-Clio) for a better dynamical understanding of the relationship between large scale circulationand European climate. We thus present an alternative approach to reconstruct climate for the pre-instrumental period based on the assimilated model simulations.Furthermore, we present an independent method to extend the dynamic circulation analysis for anomalously cold European JFMA conditions back to the sixteenth century. To this end, we use documentary records that are spatially representative for the long instrumental records and derive, through modern analogs, large-scale SLP, surface temperature and precipitation fields. The skill of the analog method is tested in the virtual world of two three-dimensional climate simulations (ECHOGand HadCM3). This endeavor offers new possibilities to both constrain climate model into a reconstruction mode (through the assimilation approach) and to better assess documentary data in a quantitative way.
4.
Trachsel, Mathias, et al.
(author)
Multi-archive summer temperature reconstruction for the European Alps, AD 1053-1996
2012
In: Quaternary Science Reviews. - : Elsevier. - 0277-3791 .- 1873-457X. ; 46, s. 66-79
Journal article (peer-reviewed) abstract
We present a multi-archive, multi-proxy summer temperature reconstruction for the European Alpscovering the period AD 1053-1996 using tree-ring and lake sediment data. The new reconstruction isbased on nine different calibration approaches and errors were estimated conservatively. Summertemperatures of the last millennium are characterised by two warm (AD 1053-1171 and 1823-1996) andtwo cold phases (AD 1172-1379 and 1573-1822). Highest pre-industrial summer temperatures of the12th century were 0.3 degC warmer than the 20th century mean but 0.35 degC colder than proxy derivedtemperatures at the end of the 20th century. The lowest temperatures at the end of the 16th centurywere ~1 degC lower than the 20th century mean.
5.
Zorita, Eduardo, et al.
(author)
European temperature records of the past five centuries based on documentary/instrumental information compared to climate simulations
2010
In: Climatic Change. - Netherlands : Springer. - 0165-0009 .- 1573-1480. ; 101:1-2, s. 143-168
Journal article (peer-reviewed) abstract
Two European temperature reconstructions for the past half-millennium,January-to-April air temperature for Stockholm (Sweden) and seasonal temperaturefor a Central European region, both derived from the analysis of documentarysources and long instrumental records, are compared with the output of climate simulations with the model ECHO-G. The analysis is complemented by comparisonswith the long (early)-instrumental record of Central England Temperature(CET). Both approaches to study past climates (simulations and reconstructions)are burdened with uncertainties. The main objective of this comparative analysisis to identify robust features and weaknesses in each method which may help toimprove models and reconstruction methods. The results indicate a general agreementbetween simulations obtained with temporally changing external forcings andthe reconstructed Stockholm and CET records for the multi-centennial temperaturetrend over the recent centuries, which is not reproduced in a control simulation.This trend is likely due to the long-term change in external forcing. Additionally,the Stockholm reconstruction and the CET record also show a clear multi-decadalwarm episode peaking around AD 1730, which is absent in the simulations. Neitherthe reconstruction uncertainties nor the model internal climate variability caneasily explain this difference. Regarding the interannual variability, the Stockholmseries displays, in some periods, higher amplitudes than the simulations but thesedifferences are within the statistical uncertainty and further decrease if output froma regional model driven by the global model is used. The long-term trend of theCentral European temperature series agrees less well with the simulations. Thereconstructed temperature displays, for all seasons, a smaller difference between thepresent climate and past centuries than is seen in the simulations. Possible reasons forthese differences may be related to a limitation of the traditional ‘indexing’ techniquefor converting documentary evidence to temperature values to capture long-termclimate changes, because the documents often reflect temperatures relative to thecontemporary authors’ own perception of what constituted ‘normal’ conditions. Bycontrast, the amplitude of the simulated and reconstructed inter-annual variabilityagrees rather well.
