Extended Abstract (2.0M)3.3
Extremes and millennial trends in the Carpathian Basin using the Rethly documentary collection
Judit Bartholy, Eötvös Loránd University, Budapest, Hungary; and R. Pongracz and Z. Molnar
According to the IPCC Third Assessment Report regional impacts of global climate change tend to intensify extremes and contribute to more frequent occurrence of the extreme climatological events. In order to provide regional climate scenarios for any particular area past climate tendencies and climatological extremes must be analysed. Since regular observations being reliable cover only a century or two, other historical information from documentary sources must be taken into consideration for the earlier periods. In historical documents, diaries, annals, farm and estate records, logs, account rolls, letters, newspapers or other written reports, unusual and extreme events are mentioned and possibly recorded more or less objectively. These historical sources can be used to evaluate the occurrence, duration and geographical location of extreme climatic events of the past centuries when no or only scarce instrumental time series are available. Antal Réthly (1879-1975), the Hungarian meteorologist, professor and director of the former National Meteorological and Earth Magnetism Institute did a pioneer work in documentary research on the meteorological extremes occurred in Central/Eastern Europe. He collected the historical documents (in their original form) related to meteorology into a four-volume-long book (around 2500 pages altogether), titled "Meteorological events and natural disasters in Hungary". In order to facilitate the detailed analysis of these documentary sources a special code system using hierarchical subclasses has been defined and applied to the approximately 15000 collected climatological items. The applied code system distinguishes three main categories of climate information: temperature, precipitation and wind related events, containing about 3800, 10000, and 1300 information items, respectively. Furthermore, the three level subclass system involves 10 second-level classes and 61 third-level classes. In case of temperature reports on cold conditions dominate (65%), while in case of wind most of the archive records mention the strength. Precipitation information takes 66% of the total collection and the most often reported event is the 'rain' (not extreme categories, i.e., heavy rain, extended heavy rain, rainstorm), which can be explained by the source types (many estate records and account rolls) and by the agricultural importance of water. Other frequent classes of precipitation include thunderstorm, hail, flood, and drought. Besides the event classification the coded database contains full geographical information about the location of the meteorological events, e.g., the code for the settlement itself, the geographical coordinates, and the identification number of the subregion. Spatial and temporal distribution of precipitation, temperature, and wind related climate events and extremes has been evaluated using settlement and subregional scales. Also, geographical distribution of extreme climatological events has been mapped. Annual and seasonal time series have been analysed for the Carpathian Basin, and compared to other reconstructed temperature and precipitation index time series from other geographical locations in Central/Eastern Europe.
Session 3, Extreme Weather and Climate (Room 3A)
Tuesday, 13 January 2004, 3:30 PM-4:15 PM, Room 3A
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