Winter temperature covariances in the middle and the lower troposphere over Europe and the North Atlantic Ocean

In this work, the variability and covariability of winter temperatures in the middle and the lower troposphere are studied over Europe and the North Atlantic Ocean. Temperature variations of the middle and the lower troposphere are examined in terms of (a) 500–700 hPa and 700–l000 hPa thickness and (b) air temperature on the isobaric surfaces of 500 hPa and 700 hPa. At first, factor analysis (FA) defined areas with characteristic temperature variability in each layer (and on each isobaric surface) and then, canonical correlation analysis (CCA) revealed areas in both layers (and on both isobaric surfaces) presenting common temperature variations. A temperature see‐saw between N Europe and W Asia was revealed for both layers and isobaric surfaces implying that temperature changes in these areas are vertically spread. Another well‐defined area, appearing in both analyses, is the area of the Labrador Sea and S Greenland. This region is also teleconnected to other regions, though not very clearly in every height. These temperature patterns are mainly attributed to the Eurasian (EU) and North Atlantic Oscillation (NAO) circulation patterns, which are responsible for large air mass exchanges in the area, being vertically extended in the middle and the lower troposphere. Copyright © 2001 Royal Meteorological Society