Vliv dlouhodobých změn atmosférické cirkulace na pozorované trendy přízemních klimatických prvků v ČR a Evropě

(English) RNDr. Monika Cahynová: The influence of long-term changes of atmospheric circulation on observed trends of surface climatic elements in the Czech Republic and Europe The aim of this thesis is to quantify the links between recent atmospheric circulation changes over Europe and local surface climatic trends. We employ several parallel classifications of circulation types that were collected and developed within the COST733 Action "Harmonisation and Applications of Weather Types Classifications for European Regions". To our knowledge, such a comparative approach has not been used so far. Atmospheric circulation changes over Europe were studied in terms of changing seasonal frequency and persistence of daily circulation types in the second half of the 20th century. The extensive collection of both subjective and objective catalogues of circulation types in European regions from the COST733 Action served as a platform for comparison of different classification methods, varying numbers of circulation types, and spatial scale of circulation processes. The most prominent trend - winter increase in the number of days with westerly flow - clearly stems from the strengthening of the North Atlantic Oscillation. The objective classifications did not show any systematic change of persistence of...(česky) RNDr. Monika Cahynová: Vliv dlouhodobých změn atmosférické cirkulace na pozorované trendy přízemních klimatických prvků v ČR a Evropě Cílem této práce je kvantifikovat vztahy mezi současnými změnami atmosférické cirkulace v Evropě a lokálními klimatickými trendy. K tomuto účelu používáme několik paralelních klasifikací cirkulačních typů, které byly shromážděny a vyvinuty v rámci projektu COST733 "Harmonizace a využití klasifikací typů počasí v evropských regionech". Pokud je nám známo, nebyl dosud takový srovnávací přístup uplatněn. Změny atmosférické cirkulace v Evropě byly studovány pomocí trendů sezónní četnosti a persistence (doby trvání) denních cirkulačních typů ve druhé polovině 20. století. Rozsáhlý soubor subjektivních a objektivních katalogů cirkulačních typů z projektu COST733 sloužil ke srovnání různých metod klasifikace, rozdílného počtu cirkulačních typů a prostorového rozsahu cirkulačních procesů. Nejvýraznější trend - zimní nárůst počtu dní se západní složkou proudění - je způsobován zesilováním Severoatlantické oscilace. V objektivních klasifikacích nebyla zjištěna žádná systematická změna v době trvání synoptických situací ve sledovaném období, zatímco v subjektivních katalozích (Brádkův český-československý, německý Hesse a Brezowského, maďarský Péczely) se projevují...Department of Physical Geography and GeoecologyKatedra fyzické geografie a geoekologieFaculty of SciencePřírodovědecká fakult

Subseasonal temperature trends in Europe (1961-2000) and their links to atmospheric circulation

We use daily maximum and minimum temperatures and the daily temperature range from 136 stations in Europe in the period 1961–2000 to precisely locate their seasonal and subseasonal trends within the year. Linear trends are calculated for moving “subseasons” of 10, 20, 30, 60, and 90 days, each shifted by one day. Over most of Europe, the observed warming is greatest in winter. In Iceland and the Mediterranean, a pronounced warming is only present in summer. Significant autumn cooling was found in Eastern and Southeastern Europe for both TX and TN. Other non-warming periods occur in Western and Central Europe in February, April, and late June. Trends of DTR are inconclusive. Changes in the frequency of atmospheric circulation types usually explain a substantial part of the observed climatic trends; however, the influence varies between regions, times of the year, subseason lengths, numbers of circulation types, and input variables for the classification of circulation types

The influence of long-term changes of atmospheric circulation on observed trends of surface climatic elements in the Czech Republic and Europe

(English) RNDr. Monika Cahynová: The influence of long-term changes of atmospheric circulation on observed trends of surface climatic elements in the Czech Republic and Europe The aim of this thesis is to quantify the links between recent atmospheric circulation changes over Europe and local surface climatic trends. We employ several parallel classifications of circulation types that were collected and developed within the COST733 Action "Harmonisation and Applications of Weather Types Classifications for European Regions". To our knowledge, such a comparative approach has not been used so far. Atmospheric circulation changes over Europe were studied in terms of changing seasonal frequency and persistence of daily circulation types in the second half of the 20th century. The extensive collection of both subjective and objective catalogues of circulation types in European regions from the COST733 Action served as a platform for comparison of different classification methods, varying numbers of circulation types, and spatial scale of circulation processes. The most prominent trend - winter increase in the number of days with westerly flow - clearly stems from the strengthening of the North Atlantic Oscillation. The objective classifications did not show any systematic change of persistence of..

Changes in atmospheric circulation in Central Europe and their influence on climate in the Czech Republic

This work is concerned with the influence of changes of atmospheric circulation (represented by the Hess-Brezowsky and Brádka’s subjective catalogues of synoptic types) on observed linear trends of 11 climatic elements from 21 stations in the Czech Republic in the period 1961-1998. The ratio of "hypothetical" (caused only by changes in the frequency of synoptic types) and observed trends shows that changes in atmospheric circulation are the primary cause of massive winter warming, and autumn cooling connected with increasing precipitation and humidity. In spring and summer, the influence is insignificant except for precipitation, relative humidity and cloudiness changes that are related to trends in the Hess-Brezowsky catalogue, mostly in spring

Vliv severoatlantické oscilace na sezonní teploty vzduchu ve střední Evropě

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Trendy v kalendáři povětrnostních situací HMÚ/ČHMÚ v období 1946-2002

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Classifications of atmospheric circulation patterns

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