Christoph Beck - Academia.edu (original) (raw)

Papers by Christoph Beck

... Affiliation: AA(Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climat... more ... Affiliation: AA(Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research, D-82467 Garmisch-Partenkirchen, Germany, patrick.laux@kit.edu), AB(Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research, D-82467 ...

Annals of The New York Academy of Sciences, 2008

We review recent advances in classifications of circulation patterns as a specific research area ... more We review recent advances in classifications of circulation patterns as a specific research area within synoptic climatology. The review starts with a general description of goals of classification and the historical development in the field. We put circulation classifications into a broader context within climatology and systematize the varied methodologies and approaches. We characterize three basic groups of classifications: subjective (also called manual), mixed (hybrid), and objective (computer-assisted, automated). The roles of cluster analysis and principal component analysis in the classification process are clarified. Several recent methodological developments in circulation classifications are identified and briefly described: the introduction of nonlinear methods, objectivization of subjective catalogs, efforts to optimize classifications, the need for intercomparisons of classifications, and the progress toward an optimum, if possible unified, classification method. Among the recent tendencies in the applications of circulation classifications, we mention a more extensive use in climate studies, both of past, present, and future climates, innovative applications in the ensemble forecasting, increasing variety of synoptic–climatological investigations, and steps above from the troposphere. After introducing the international activity within the field of circulation classifications, the COST733 Action, we briefly describe outputs of the inventory of classifications in Europe, which was carried out within the Action. Approaches to the evaluation of classifications and their mutual comparisons are also reviewed. A considerable part of the review is devoted to three examples of applications of circulation classifications: in historical climatology, in analyses of recent climate variations, and in analyses of outputs from global climate models.

Atmospheric Pollution Research, 2014

Atmospheric circulation affects local concentrations of particulate matter with an aerodynamic di... more Atmospheric circulation affects local concentrations of particulate matter with an aerodynamic diameter of 10 μm or less (PM 10 ) in different ways: Via the determination of local meteorological conditions favoring or suppressing the formation and the accumulation of PM 10 , and through its control on short-and long-range transport of particles and precursors. The quantitative assessment of the connections between the large-scale atmospheric circulation and local PM 10 is relevant not only for the understanding of observed variations in PM 10 concentrations. It is even more important for estimating the potential effects of projected future changes in large-scale atmospheric circulation on PM 10 . In this contribution, daily atmospheric circulation types (CTs), resulting from variants of three different classification methods, and their monthly occurrence frequencies have been utilized in three different downscaling approaches for estimating monthly indices of PM 10 for the period 1980-2010 at 16 locations in Bavaria (Germany). All variants of approaches have been evaluated via a leave-one-out cross validation procedure in order to attain reliable performance ratings to detect the most suitable downscaling approaches. Results indicate that the highest performance of downscaling approaches is achieved in winter when the best performing models explain on average roughly 50% of the observed PM 10 variance. From this it can be concluded that classification-based approaches are generally suitable for the downscaling of PM 10 , particularly during winter when PM 10 concentrations in Bavaria reach maximum values. As preferable settings of the downscaling approaches, the usage of rather small spatial domains and a relatively high number of classes for circulation type classification and furthermore the utilization of multiple linear regression analyses or random forest analyses for relating CTs to PM 10 have been ascertained. These findings provide the basis for further enhancements of the classification-based downscaling of monthly PM 10 that will be realized in successive investigations.

The Iceberg in the Mist: Northern Research in pursuit of a “Little Ice Age”, 2001

220 JUCUNDUS JACOBEIT ET AL. pressure difference (high zonality with higher pressure situated in ... more 220 JUCUNDUS JACOBEIT ET AL. pressure difference (high zonality with higher pressure situated in the south) means that great parts of Europe are affected by a vigorous flow of winds from the westerly sector accompanied by high cyclonic activity and a maritime regime over the ...

Physics and Chemistry of the Earth, Parts A/B/C, 2010

In the present study, we use a Principal Component Analysis (PCA) to characterize the surface 6-h... more In the present study, we use a Principal Component Analysis (PCA) to characterize the surface 6-h circulation types related to substantial lightning activity over the Catalonia area (north-eastern Iberia) and the Principality of Andorra (eastern Pyrenees) from January 2003 to December 2007. The gridded data used for classification of the circulation types is the NCEP Final Analyses of the Global Tropospheric Analyses at 1°resolution over the region 35°N-48°N by 5°W-8°E. Lightning information was collected by the SAFIR lightning detection system operated by the Meteorological Service of Catalonia (SMC), which covers the region studied. We determined nine circulation types on the basis of the S-mode orthogonal rotated Principal Component Analysis. The ''extreme scores" principle was used previous to the assignation of all cases, to obtain the number of final types and their centroids. The distinct differences identified in the resulting mean Sea Level Pressure (SLP) fields enabled us to group the types into three main patterns, taking into account their scale/dynamical origin. The first group of types shows the different distribution of the centres of action at synoptic scale associated with the occurrence of lightning. The second group is connected to mesoscale dynamics, mainly induced by the relief of the Pyrenees. The third group shows types with low gradient SLP patterns in which the lightning activity is a consequence of thermal dynamics (coastal and mountain breezes).

The Global Precipitation Climatology Centre (GPCC, http://gpcc.dwd.de) provides global monthly pr... more The Global Precipitation Climatology Centre (GPCC, http://gpcc.dwd.de) provides global monthly precipitation analyses for monitoring and research of the earth's climate. The centre is a German contribution to the World Climate Research Programme (WCRP), to the Global Climate Observing System (GCOS), and to the Global Earth Observation System of Systems (GEOSS). It contributes to water resources assessments, flood and drought monitoring,

The existence of weekly cycles in occurrence frequency distributions of circulation types is exam... more The existence of weekly cycles in occurrence frequency distributions of circulation types is examined on the basis of a comprehensive data base of automated circulation-type classifications for the greater North Atlantic European region and sub-domains during the period 1957-2002. The main result is that the percentage of circulation types for which a statistical significant weekly cycle (95% level of confidence) could be detected by a chi-square goodness-of-fit test does not exceed the number that would be expected by chance. Thus it is concluded that no consistent weekly cycles in occurrence frequencies of circulation types exist.

ABSTRACT Circulation type classifications may be utilised for the downscaling of local climatic a... more ABSTRACT Circulation type classifications may be utilised for the downscaling of local climatic and environmental target variables in different methodological settings. In this contribution we apply and compare two different classification based approaches for downscaling of monthly indices of PM10 concentrations (monthly mean and number of days exceeding a certain threshold) at different stations in Bavaria (Germany) during the period 1979 to 2010. The first approach uses monthly frequencies of circulation types as predictors in multiple linear regression models (stepwise regression) to estimate monthly predictand values (monthly PM10 indices). The second approach utilizes type specific mean values of the target variable - determined for a calibration period - to estimate predictand values in the validation period. Both approaches are run using varying circulation classifications. This comprises different methodological concepts for circulation classification (e.g. threshold based methods, leader algorithms, cluster analysis) and as well different temporal (1-day or multiple day sequences) and spatial domains (synoptic to continental scale). All models are applied to multiple calibration and validation samples and different skill scores (e.g. reduction of variance, Pearson R) are estimated for each of the validation samples in order to quantify model performance. As main preliminary findings we may state that: - the regression based downscaling approach in most cases clearly outperforms the approach that uses type specific mean values (reference forecasting), - best skill is reached in winter (DJF) and spring (MAM), - comparable model skill is reached for the downscaling of monthly means and extremes indicators (number of days exceeding a certain threshold).

ABSTRACT The database of classifications of atmospheric circulation patterns, which was produced ... more ABSTRACT The database of classifications of atmospheric circulation patterns, which was produced within the COST733 Action, consists in its version v2.0 of 423 different classifications for each of 12 domains over Europe. The classifications differ from each other in five characteristics: (i) the classification method used, (ii) the number of types, (iii) the classified variable, (iv) sequentiality (whether instantaneous circulation patterns or their 4-day sequences are classified), and (v) the seasonality of definition (whether classifications are defined for a whole year or separately for each season). The goal of the study is to evaluate how successful are the classifications in characterizing (stratifying) surface climate elements, viz., daily minimum and maximum temperature and precipitation. To this end, we employ several criteria: explained variance, pseudo-F statistic, and Kolmogorov-Smirnov statistic. Both station datasets (ECA&D) and reanalysis (ERA-40) are used. The classifications are ranked in each domain separately. This allows one to evaluate the effect the options (i) to (v) have on the quality of classifications in terms of the stratification of surface temperature and precipitation, to compare the performance among the criteria, and to assess the geographical dependence of the findings.

ABSTRACT Excessive large-scale precipitation events cause an increasing risk of severe floodings.... more ABSTRACT Excessive large-scale precipitation events cause an increasing risk of severe floodings. For example in 2002 and 2005 Vb cyclones led to extreme flooding events in Central Europe. The aspect of ongoing climate change makes a valid assessment of the regional flooding potential in dependence of different circulation types and cyclone track types even more important. The present study refers to Southern Germany and Austria for which a gridded daily precipitation set with 6km horizontal resolution is available for the 1951-2007 period. S-mode principal component analysis (PCA) is applied to determine regions with similar precipitation variability. Extreme precipitation events are defined by the 95th percentiles of daily precipitation during the standard seasons (DJF, MAM, JJA, SON). Large-scale circulation types are derived by different statistical methods using the COST733 classification software and different re-analysis data. To assess the performance of particular circulation type classifications with respect to regional precipitation extremes, the Brier-Skill-Score (BSS) has been applied. For Southern Germany and Austria the regionalization of precipitation variability results in seasonally varying numbers and spatial extents of 'rainfall regions'. Concerning relationships between large-scale dynamics and regional impacts, the general conclusion is that in more sub-continental regions, the dependency between circulation types and precipitation extremes is less pronounced than in sub-oceanic regions. This fact is much clearer in winter than in summer. Further results show that in these two areas different classification methods (threshold-based and optimizing ones) lead to most valid results. After further improving the performance of circulation type classifications, future extreme precipitation events under enhanced greenhouse warming conditions will be estimated by using output from CMIP5 Global Climate Models for the synoptic downscaling from large-scale circulation types to regional rainfall extremes. Investigations are performed in context of the WETRAX project (WEather Patterns, Cyclone TRAcks and related precipitation EXtremes), funded by the Austrian Lebensministerium and the Bavarian Landesamt für Umwelt.

... Affiliation: AA(Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climat... more ... Affiliation: AA(Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research, D-82467 Garmisch-Partenkirchen, Germany, patrick.laux@kit.edu), AB(Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research, D-82467 ...

Annals of The New York Academy of Sciences, 2008

We review recent advances in classifications of circulation patterns as a specific research area ... more We review recent advances in classifications of circulation patterns as a specific research area within synoptic climatology. The review starts with a general description of goals of classification and the historical development in the field. We put circulation classifications into a broader context within climatology and systematize the varied methodologies and approaches. We characterize three basic groups of classifications: subjective (also called manual), mixed (hybrid), and objective (computer-assisted, automated). The roles of cluster analysis and principal component analysis in the classification process are clarified. Several recent methodological developments in circulation classifications are identified and briefly described: the introduction of nonlinear methods, objectivization of subjective catalogs, efforts to optimize classifications, the need for intercomparisons of classifications, and the progress toward an optimum, if possible unified, classification method. Among the recent tendencies in the applications of circulation classifications, we mention a more extensive use in climate studies, both of past, present, and future climates, innovative applications in the ensemble forecasting, increasing variety of synoptic–climatological investigations, and steps above from the troposphere. After introducing the international activity within the field of circulation classifications, the COST733 Action, we briefly describe outputs of the inventory of classifications in Europe, which was carried out within the Action. Approaches to the evaluation of classifications and their mutual comparisons are also reviewed. A considerable part of the review is devoted to three examples of applications of circulation classifications: in historical climatology, in analyses of recent climate variations, and in analyses of outputs from global climate models.

Atmospheric Pollution Research, 2014

Atmospheric circulation affects local concentrations of particulate matter with an aerodynamic di... more Atmospheric circulation affects local concentrations of particulate matter with an aerodynamic diameter of 10 μm or less (PM 10 ) in different ways: Via the determination of local meteorological conditions favoring or suppressing the formation and the accumulation of PM 10 , and through its control on short-and long-range transport of particles and precursors. The quantitative assessment of the connections between the large-scale atmospheric circulation and local PM 10 is relevant not only for the understanding of observed variations in PM 10 concentrations. It is even more important for estimating the potential effects of projected future changes in large-scale atmospheric circulation on PM 10 . In this contribution, daily atmospheric circulation types (CTs), resulting from variants of three different classification methods, and their monthly occurrence frequencies have been utilized in three different downscaling approaches for estimating monthly indices of PM 10 for the period 1980-2010 at 16 locations in Bavaria (Germany). All variants of approaches have been evaluated via a leave-one-out cross validation procedure in order to attain reliable performance ratings to detect the most suitable downscaling approaches. Results indicate that the highest performance of downscaling approaches is achieved in winter when the best performing models explain on average roughly 50% of the observed PM 10 variance. From this it can be concluded that classification-based approaches are generally suitable for the downscaling of PM 10 , particularly during winter when PM 10 concentrations in Bavaria reach maximum values. As preferable settings of the downscaling approaches, the usage of rather small spatial domains and a relatively high number of classes for circulation type classification and furthermore the utilization of multiple linear regression analyses or random forest analyses for relating CTs to PM 10 have been ascertained. These findings provide the basis for further enhancements of the classification-based downscaling of monthly PM 10 that will be realized in successive investigations.

The Iceberg in the Mist: Northern Research in pursuit of a “Little Ice Age”, 2001

220 JUCUNDUS JACOBEIT ET AL. pressure difference (high zonality with higher pressure situated in ... more 220 JUCUNDUS JACOBEIT ET AL. pressure difference (high zonality with higher pressure situated in the south) means that great parts of Europe are affected by a vigorous flow of winds from the westerly sector accompanied by high cyclonic activity and a maritime regime over the ...

Physics and Chemistry of the Earth, Parts A/B/C, 2010

In the present study, we use a Principal Component Analysis (PCA) to characterize the surface 6-h... more In the present study, we use a Principal Component Analysis (PCA) to characterize the surface 6-h circulation types related to substantial lightning activity over the Catalonia area (north-eastern Iberia) and the Principality of Andorra (eastern Pyrenees) from January 2003 to December 2007. The gridded data used for classification of the circulation types is the NCEP Final Analyses of the Global Tropospheric Analyses at 1°resolution over the region 35°N-48°N by 5°W-8°E. Lightning information was collected by the SAFIR lightning detection system operated by the Meteorological Service of Catalonia (SMC), which covers the region studied. We determined nine circulation types on the basis of the S-mode orthogonal rotated Principal Component Analysis. The ''extreme scores" principle was used previous to the assignation of all cases, to obtain the number of final types and their centroids. The distinct differences identified in the resulting mean Sea Level Pressure (SLP) fields enabled us to group the types into three main patterns, taking into account their scale/dynamical origin. The first group of types shows the different distribution of the centres of action at synoptic scale associated with the occurrence of lightning. The second group is connected to mesoscale dynamics, mainly induced by the relief of the Pyrenees. The third group shows types with low gradient SLP patterns in which the lightning activity is a consequence of thermal dynamics (coastal and mountain breezes).

The Global Precipitation Climatology Centre (GPCC, http://gpcc.dwd.de) provides global monthly pr... more The Global Precipitation Climatology Centre (GPCC, http://gpcc.dwd.de) provides global monthly precipitation analyses for monitoring and research of the earth's climate. The centre is a German contribution to the World Climate Research Programme (WCRP), to the Global Climate Observing System (GCOS), and to the Global Earth Observation System of Systems (GEOSS). It contributes to water resources assessments, flood and drought monitoring,

The existence of weekly cycles in occurrence frequency distributions of circulation types is exam... more The existence of weekly cycles in occurrence frequency distributions of circulation types is examined on the basis of a comprehensive data base of automated circulation-type classifications for the greater North Atlantic European region and sub-domains during the period 1957-2002. The main result is that the percentage of circulation types for which a statistical significant weekly cycle (95% level of confidence) could be detected by a chi-square goodness-of-fit test does not exceed the number that would be expected by chance. Thus it is concluded that no consistent weekly cycles in occurrence frequencies of circulation types exist.

ABSTRACT Circulation type classifications may be utilised for the downscaling of local climatic a... more ABSTRACT Circulation type classifications may be utilised for the downscaling of local climatic and environmental target variables in different methodological settings. In this contribution we apply and compare two different classification based approaches for downscaling of monthly indices of PM10 concentrations (monthly mean and number of days exceeding a certain threshold) at different stations in Bavaria (Germany) during the period 1979 to 2010. The first approach uses monthly frequencies of circulation types as predictors in multiple linear regression models (stepwise regression) to estimate monthly predictand values (monthly PM10 indices). The second approach utilizes type specific mean values of the target variable - determined for a calibration period - to estimate predictand values in the validation period. Both approaches are run using varying circulation classifications. This comprises different methodological concepts for circulation classification (e.g. threshold based methods, leader algorithms, cluster analysis) and as well different temporal (1-day or multiple day sequences) and spatial domains (synoptic to continental scale). All models are applied to multiple calibration and validation samples and different skill scores (e.g. reduction of variance, Pearson R) are estimated for each of the validation samples in order to quantify model performance. As main preliminary findings we may state that: - the regression based downscaling approach in most cases clearly outperforms the approach that uses type specific mean values (reference forecasting), - best skill is reached in winter (DJF) and spring (MAM), - comparable model skill is reached for the downscaling of monthly means and extremes indicators (number of days exceeding a certain threshold).

ABSTRACT The database of classifications of atmospheric circulation patterns, which was produced ... more ABSTRACT The database of classifications of atmospheric circulation patterns, which was produced within the COST733 Action, consists in its version v2.0 of 423 different classifications for each of 12 domains over Europe. The classifications differ from each other in five characteristics: (i) the classification method used, (ii) the number of types, (iii) the classified variable, (iv) sequentiality (whether instantaneous circulation patterns or their 4-day sequences are classified), and (v) the seasonality of definition (whether classifications are defined for a whole year or separately for each season). The goal of the study is to evaluate how successful are the classifications in characterizing (stratifying) surface climate elements, viz., daily minimum and maximum temperature and precipitation. To this end, we employ several criteria: explained variance, pseudo-F statistic, and Kolmogorov-Smirnov statistic. Both station datasets (ECA&D) and reanalysis (ERA-40) are used. The classifications are ranked in each domain separately. This allows one to evaluate the effect the options (i) to (v) have on the quality of classifications in terms of the stratification of surface temperature and precipitation, to compare the performance among the criteria, and to assess the geographical dependence of the findings.

ABSTRACT Excessive large-scale precipitation events cause an increasing risk of severe floodings.... more ABSTRACT Excessive large-scale precipitation events cause an increasing risk of severe floodings. For example in 2002 and 2005 Vb cyclones led to extreme flooding events in Central Europe. The aspect of ongoing climate change makes a valid assessment of the regional flooding potential in dependence of different circulation types and cyclone track types even more important. The present study refers to Southern Germany and Austria for which a gridded daily precipitation set with 6km horizontal resolution is available for the 1951-2007 period. S-mode principal component analysis (PCA) is applied to determine regions with similar precipitation variability. Extreme precipitation events are defined by the 95th percentiles of daily precipitation during the standard seasons (DJF, MAM, JJA, SON). Large-scale circulation types are derived by different statistical methods using the COST733 classification software and different re-analysis data. To assess the performance of particular circulation type classifications with respect to regional precipitation extremes, the Brier-Skill-Score (BSS) has been applied. For Southern Germany and Austria the regionalization of precipitation variability results in seasonally varying numbers and spatial extents of 'rainfall regions'. Concerning relationships between large-scale dynamics and regional impacts, the general conclusion is that in more sub-continental regions, the dependency between circulation types and precipitation extremes is less pronounced than in sub-oceanic regions. This fact is much clearer in winter than in summer. Further results show that in these two areas different classification methods (threshold-based and optimizing ones) lead to most valid results. After further improving the performance of circulation type classifications, future extreme precipitation events under enhanced greenhouse warming conditions will be estimated by using output from CMIP5 Global Climate Models for the synoptic downscaling from large-scale circulation types to regional rainfall extremes. Investigations are performed in context of the WETRAX project (WEather Patterns, Cyclone TRAcks and related precipitation EXtremes), funded by the Austrian Lebensministerium and the Bavarian Landesamt für Umwelt.