COST 733 - WG4: Applications of weather type classification

The main objective of the COST Action 733 is to achieve a general numerical method for assessing, comparing and classifying typical weather situations in the European regions. To accomplish this goal, different workgroups are established, each with their specific aims: WG1: Existing methods and applications (finished); WG2: Implementation and development of weather types classification methods; WG3: Comparison of selected weather types classifications; WG4: Testing methods for various applications. The main task of Workgroup 4 (WG4) in COST 733 implies the testing of the selected weather type methods for various classifications. In more detail, WG4 focuses on the following topics:• Selection of dedicated applications (using results from WG1), • Performance of the selected applications using available weather types provided by WG2, • Intercomparison of the application results as a results of different methods • Final assessment of the results and uncertainties, • Presentation and release of results to the other WGs and external interested • Recommend specifications for a new (common) method WG2 Introduction In order to address these specific aims, various applications are selected and WG4 is divided in subgroups accordingly: 1.Air quality 2. Hydrology (& Climatological mapping) 3. Forest fires 4. Climate change and variability 5. Risks and hazards Simultaneously, the special attention is paid to the several wide topics concerning some other COST Actions such as: phenology (COST725), biometeorology (COST730), agriculture (COST 734) and mesoscale modelling and air pollution (COST728). Sub-groups are established to find advantages and disadvantages of different classification methods for different applications. Focus is given to data requirements, spatial and temporal scale, domain area, specifi

COST 733 – WG4: Applications of weather type classifications

Presentación realizada para: European Geosciences Union General Assembly celebrado del 19-24 de abril de 2009 en Viena

A collection of sub-daily pressure and temperature observations for the early instrumental period with a focus on the \u27year without a summer\u27 1816

The eruption of Mount Tambora (Indonesia) in April 1815 is the largest documented volcanic eruption in history. It is associated with a large global cooling during the following year, felt particularly in parts of Europe and North America, where the year 1816 became known as the “year without a summer”. This paper describes an effort made to collect surface meteorological observations from the early instrumental period, with a focus on the years of and immediately following the eruption (1815–1817). Although the collection aimed in particular at pressure observations, correspondent temperature observations were also recovered. Some of the series had already been described in the literature, but a large part of the data, recently digitised from original weather diaries and contemporary magazines and newspapers, is presented here for the first time. The collection puts together more than 50 sub-daily series from land observatories in Europe and North America and from ships in the tropics. The pressure observations have been corrected for temperature and gravity and reduced to mean sea level. Moreover, an additional statistical correction was applied to take into account common error sources in mercury barometers. To assess the reliability of the corrected data set, the variance in the pressure observations is compared with modern climatologies, and single observations are used for synoptic analyses of three case studies in Europe. All raw observations will be made available to the scientific community in the International Surface Pressure Databank

A collection of sub-daily pressure and temperature observations for the early instrumental period with a focus on the "year without a summer" 1816

The eruption of Mount Tambora (Indonesia) in April 1815 is the largest documented volcanic eruption in history. It is associated with a large global cooling during the following year, felt particularly in parts of Europe and North America, where the year 1816 became known as the "year without a summer". This paper describes an effort made to collect surface meteorological observations from the early instrumental period, with a focus on the years of and immediately following the eruption (1815-1817). Although the collection aimed in particular at pressure observations, correspondent temperature observations were also recovered. Some of the series had already been described in the literature, but a large part of the data, recently digitised from original weather diaries and contemporary magazines and newspapers, is presented here for the first time. The collection puts together more than 50 sub-daily series from land observatories in Europe and North America and from ships in the tropics. The pressure observations have been corrected for temperature and gravity and reduced to mean sea level. Moreover, an additional statistical correction was applied to take into account common error sources in mercury barometers. To assess the reliability of the corrected data set, the variance in the pressure observations is compared with modern climatologies, and single observations are used for synoptic analyses of three case studies in Europe. All raw observations will be made available to the scientific community in the International Surface Pressure Databank.Peer reviewe

Krakow polar meteorological and climatological research

W opracowaniu przedstawiono najważniejsze informacje o badaniach meteorologicznych i klimatycznych prowadzonych w obszarach polarnych przez pracowników Uniwersytetu Jagiellońskiego. Po omówieniu krótkiej historii badań polarnych i udziale w nich poszczególnych osób związanych z ośrodkiem krakowskim przedstawiono przegląd najważniejszych problemów podejmowanych w czasie tych badań. Dotyczyły one różnych szczegółowych zagadnień obejmujących przede wszystkim Spitsbergen.The study describes general information about meteorological and climatological research conducted in polar regions by the Jagiellonian University staff members as well as people from other institutions from Krakow. The short history of the polar studies and the scientific contribution of particular people is followed by the survey of main research domains, topics and problems investigated during the expeditions. They concerned detailed issues connected mainly with Spitsbergen

Total cloudiness with relation to the atmospheric circulation in the European polar region

Analizowano wielkość zachmurzenia ogólnego w zależności od kierunku adwekcji mas powietrza. Materiał badawczy stanowiły dane gridowe pochodzące z bazy danych ERA 40 (1961-2000) oraz dane stacyjne z bazy danych ORNL/CDIAC – 123 NDP-026C (1972-1996). Cyrkulację atmosferyczną ujęto jako obraz pola wiatru geostroficznego. Warunki makrocyrkulacyjne powodują duże zróżnicowanie regionalne wzajem-nych zależności pomiędzy cyrkulacją a zachmurzeniem na badanym terenie. Różnice wielkości zachmurzenia podczas adwekcji mas powietrza z poszczególnych kierunków są bardziej wyraźne w analizach wykorzystują-cych dane stacyjne. Występujące różnice między wynikami analiz przeprowadzonych z wykorzystaniem danych gridowych i stacyjnych wynikają głównie z trudności w dopasowaniu położenia stacji do punktów węzłowych siatki geograficznej oraz z samego charakteru danych.The main aim of the study was the quantitative estimation of the influence of the air advection on the total cloudiness in the European polar zone. The area of interest was defined as the region located over the northern polar circle. That territory covers the large part of the Arctic Ocean with the arctic archipelagos such as: Spitsbergen, Franz Josef Land, Novaya Zemlya, and the separate islands. The northern part of the Scandinavian Peninsula with the Kola Peninsula were also taken into considerations. The source data contain daily total cloudiness data originated from reanalyses ERA-40 (developed by ECMWF) for the period 1961-2000. Simultaneously, daily resolution station data from 5 stations originated from CDIAC database for the period 1972-1996 have been taken into account. Atmospheric circulation was performed as the geostrophic wind field. Geostrophic wind vectors were calculated using splines and on their basis the 9 main circulation types were distinguished (modified Ustrnul’s circulation classification). The crucial method was the calculation of anomalies of the total cloud cover in particular air flow types in two thermal and circulation different months: January and July. The analysis of cloudiness showed large regional diversity of this element in the polar zone of Europe. The relations of the total cloud cover with atmospheric circulation in maritime area were weaker than in the continental parts of research domain. On the basis of many cases was founded that cloudiness was also under influence of orography, type of the active surface, sea and atmosphere interactions. Large scale circulation with the mentioned factors causes significant regional differen-tiation of mutual connections between cloudiness and geostrophic wind vector

OBJECTIVE LOCAL WEATHER TYPES WITH APPLICATIONS IN CLIMATE CHANGE DETECTION

Objective classification of daily weather is performed for 9 vs. 5 stations of Poland and Hungary based on 30 years periods (1966-1995 and 1961-1990, respectively). Eight weather elements were pre-selected, and reduced to four, by Factor Analysis. They are the mean temperature, relative humidity, cloudiness and wind speed. The redundant elements are diurnal temperature amplitude, water vapour pressure, precipitation and sunshine duration. The omitted elements will be used for independent validation of the classification. Next, hierarchical cluster analysis is performed, having tested various other approaches, leading to six classes in Hungary and southern Poland and to eight classes in the rest of Poland, as the most frequent number of classes in all months and stations. Termination of the clustering, i.e. selection of the number classes is performed in an objective process applying three numerical criteria concerning the within-classes cumulated distance measures. Finally, the types have been re-defined by the method of K-means clustering. The obtained local classifications are compared to the macro-circulation types, based on variance “explaining” capacity concerning the above four basic and four independent variables. In overwhelming majority of the 12 months and 14 stations and 8 variables the obtained local types reduce the variances more effectively than the compared Péczely (1957) types for Hungary and the amalgamated Hess-Brezowsky (1969) types (Mika et al., 1999). These types are important tools in understanding the role of weather in the environmental indicators and in detection of climate change by presenting the processes in terms of weather types. Examples of both applications will be presented in the lecture and in its written version