Spatial and temporal 850 hPa air temperature and sea‐surface temperature covariances in the Mediterranean region and their connection to atmospheric circulation

Abstract

The spatial and temporal covariability between the lower troposphere and sea surface temperatures (SSTs) are studied in the Mediterranean basin for the period 1958-98. Monthly air temperature anomalies for the 850 hPa pressure level (T-850hPa) at 2.5°× 2.5°grid points and SST anomalies in 5°× 5°grid boxes are utilized. As a first step, factor analysis is applied on both sets of data in order to reduce their dimensionality. Then, canonical correlation analysis is applied and this leads to one statistically significant pair of canonical variates for winter and to two pairs for summer. In winter, a teleconnection (see-saw) between western Europe and the eastern Mediterranean at the 850 hPa level is revealed, and a corresponding weaker one between the areas of central-west and eastern Mediterranean for SST. The correlation between T-850hPa and SST appears higher over the eastern Mediterranean. In summer, the first pair of canonical variates reveals a covariability between T-850hPa and SST in the western Mediterranean, and the second one shows a covariability in the eastern Mediterranean, without the existence of any strong spatial teleconnection. The analysis is repeated, using time lags of 1 month, or longer, in order to detect any possible non-synchronous relation. Statistically significant results are found only when T-850hPa leads SST with a time lag of 1 month. In particular, the results are statistically significant for winter only, and the findings are similar to those of the first analysis. Therefore, the existence of a 1 month time scale SST persistence is detected for winter months.

Climatic characteristics of summer human thermal discomfort in Athens and its connection to atmospheric circulation

“…The increase in human thermal dis- comfort noted here for Athens after the early 1980s matches with similar trends during the same period found by others either for mean summer air temperature or for the frequency of extreme high temperature events, which have been reported to be a result of the predominance of warmer air masses in the lower troposphere over the southern Balkans and the intensification of urbanization in the city of Athens over recent years (e.g. see Philandras et al, 1999;Lolis et al, 2002;Kioutsioukis et al, 2010;Founda, 2011).…”

Comprehensive analysis of the climate variability in the eastern Mediterranean. Part I: map‐pattern classification

“…In the same context, Xoplaki et al (2000) examined connections between large scale circulation and winter precipitation over Greece and extended this to the variability of summer air temperature (Xoplaki et al, 2003). Lolis et al (2002) used a similar methodology and investigated the covariability between the lower troposphere and sea-surface temperatures (SST) in the Mediterranean. Kassomenos et al (1998) developed a manual classification based on 850 hPa weather map recognition.…”

Relation between sensible and latent heat fluxes in the Mediterranean and precipitation in the Greek area during winter

“…Since then, many researchers have also detected it, on various 1959 1963 1967 1971 1975 1979 1983 1987 1991 1995 -3 parameters (sea-surface temperature, upper air temperature, relative vorticity, etc.) by utilizing and applying various indices and methods (Kutiel and Maheras, 1998;Maheras and Kutiel, 1999;Bartzokas and Lolis, 2000;Lolis et al, 2002), but it is not a dominant teleconnection on the variation of every meteorological parameter.…”