engleski

Self-organizing-maps-derived air temperature and precipitation patterns over the Adriatic-Ionian region and their relation to hemispheric indices

Air temperature and precipitation patterns from monthly data series collected at 28 in situ meteorological stations in the Adriatic-Ionian region between 1961 and 2015 were mapped by using the self-organizing maps method and connected with hemispheric indices in the atmosphere. Four indices were used: North Atlantic Oscillation (NAO), East Atlantic (EA), East Atlantic/West Russia (EAWR) and Scandinavian (SCA). Two experiments were conducted: the first combined temperatures with the indices and the second combined precipitation with the indices. Both air temperature and precipitation patterns largely exhibit region-wide changes, with more pronounced variability in precipitation than temperature inside the investigated region. The extreme positive and negative anomaly patterns in both precipitation and air temperature are related to hemispheric indices: positive NAO and EAWR and negative SCA indices are responsible for the northern Adriatic droughts and vice versa, while the EA index dominantly drives the extreme air temperature anomaly over the whole central Mediterranean (the positive EA is associated with a pronounced temperature anomaly and vice versa). There is mirroring in the MSLP over Europe between these extreme patterns. Most other precipitation and air temperature patterns that exhibit opposite positive vs. negative anomalies also exhibit opposite associated indices, indicating connectivity between the anomalies and the indices. The relations between hemispheric indices and precipitation anomalies indicate a nonlinear connection, similar to the NAO index, while other hemispheric indices (such as the SCA index) are linearly related to the anomalies.

Self-organizing maps ; air temperature ; precipitation ; hemispheric indices ; central Mediterranean

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