6533b861fe1ef96bd12c42d2

RESEARCH PRODUCT

Spatial distribution of the precipitation in Dobruja (Romania/Black Sea)

subject

description

An original dataset for the Dobruja, a low plateau region of southeastern Romania, is used to perform a statistical study of the spatial distribution of rainfall at annual and seasonal time-scales. A principal component analysis (PCA) is carried out to identify the precipitation regimes. The high eigenvalue of PC1 attests of the prevailing temperate-continental regime, with a relatively dry winter opposed to a late spring and early summer rainfall maximum. PC2 shows the specific pattern of the coast, with a small secondary maximum in November. In spite of the relatively flat topography, annual rainfall is characterized by a strong gradient between the coast and the interior. Particularly low amounts are observed along the Black Sea coast. This spatial distribution arises from a combination of specific seasonal patterns among which the warm season presents the most acute spatial differentiation. Altitude and distance from the Black Sea are analysed as potential factors of this spatial distribution, reinforced during the warm season. Correlation and stepwise regression indicate that the altitude effect is moderate compared with the distance from the sea. During autumn and winter the sea-surface temperature (SST) is 2 or 3°C higher than that of the land surface: air instability is increased along the coast. During spring and summer, an opposite pattern is observed, with differences exceeding 6°C. A strong sea–land thermal gradient generates frequent sea-breeze circulations. Convective storms developing along the landward moving sea-breeze front, approximately 30–35 km inland, explain the high rainfall amount recorded over the plateau. In contrast, the Black Sea coast experiences dry and sunny summers. Copyright © 2000 Royal Meteorological Society