The use of weather types in the definition of seasons: the case of southern Balkans
- PDF / 9,590,282 Bytes
- 21 Pages / 595.276 x 790.866 pts Page_size
- 72 Downloads / 119 Views
ORIGINAL PAPER
The use of weather types in the definition of seasons: the case of southern Balkans C. J. Lolis 1 & G. Kotsias 1 Received: 23 April 2020 / Accepted: 26 August 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The use of weather types for the definition of seasons is examined. Specifically, an objective definition of seasons is attempted for the southern Balkans based on the intra-annual variations of the frequencies of the objectively defined weather types. The methodology includes a combined application of Principal Component Analysis and k-means Cluster Analysis on daily grid point meteorological data obtained from the ERA5 database, for the 40-year period 1979–2018. The methodology is used at first for the classification of weather types and then for the definition of seasons based on the intra-annual variations of the weather types’ frequency. The application of the methodology results in nine weather types and four seasons. The characteristics of the defined weather types are connected to the prevalence of specific atmospheric circulation patterns, the windward or leeward character of the various sub-regions, and the thermal characteristics of the earth’s surface. The four seasons generally correspond to the conventional ones, but they present differences regarding their onset and cessation dates and their duration.
1 Introduction Synoptic climatology is a scientific field which has been gaining research attention since the nineteenth century, when Abercromby (1883) studied the main types of weather in Britain. Many years later, Christensen Jr and Bryson (1966) used hourly surface observations to determine the feasibility of establishing weather classifications and Bradka (1966) used atmospheric circulation patterns for season delineation. In the 1970s, Barry and Perry (1973) analyzed various statistical techniques used in Synoptic Climatology and Blasing (1975) studied climatic anomaly patterns comparing map-pattern correlation with Principal Component Analysis results. Many years later, in 2008, a review article on the classifications of circulation patterns, which is a specific research area within the scientific field of synoptic climatology, was published (Huth et al. 2008). The classification of weather types is a research subject which has been extensively studied by many researchers in the past (e.g., Maheras 1984; Littmann 2000; Labosier et al. 2015; Piotrowicz and Ciaranek 2020). A
* C. J. Lolis [email protected] 1
Laboratory of Meteorology, Department of Physics, University of Ioannina, 45110 Ioannina, Greece
weather type (WT) is a specific characteristic type of meteorological conditions prevailing over a specific geographical area. These conditions can be quantified with the use of the corresponding values of the various meteorological parameters and they are connected to the atmospheric circulation characteristics prevailing over the greater geographical area of interest. Many methods have been used for the definition of WTs. Some of them are primarily s
Data Loading...
