Professor of the Marine Systems Institute at Tallinn University of Technology Sirje Keevallik tells us about the weather in March.

Why was March in Estonia so cold this year?
A high-pressure area was staying above us and warmer low-pressure areas, coming from the Atlantics, had not been able to dislodge it for a long time.

How is the cold weather in March related to the global warming?
The trend does not mean that change moves only in one direction. Each year is different. In some years, the average temperature can be 3-4 degrees higher than in previous years and in the following years it could be colder in turn. The trend is a barely noticeable change of the average, and it only reflects the past, not the future. For example, it is well known that there is a decreasing trend in the annual snow cover duration. If we pursued this trend to predict when Estonia will be completely free of snow, we could also extend this back in time and ask when did Estonia have snow on the ground all year round?

Estonian Meteorological and Hydrological Institute said that March was warmer in two previous years.
If we look in the past, in the middle of the 20th century the last week of March always had crisp skiing weather. Meanwhile it seemed that it all has gone down in history, but now we are starting to see other signs again. Me and the leading researcher of TUT, academician Tarmo Soomere, have done a research on the average airflow above Estonia in March, on the altitude of ca 1.5 km. From there you can clearly derive the shifting of the beginning of spring: in 1955-1966 March airflow came from the north-west and brought along the cold, in 1967-1995 the average airflow came from the south-west, consequently warm weather came earlier, in 1996-2007 the previous situation, where the average airflow came from the north-west and spring came later, recurred. Mach is a very interesting month by itself, since the sun, moving more towards the north, warms up a ground surface and it is impossible to predict how the air will flow above it.

You can read the article of Tallinn University of Technology (TUT) researchers Sirje Keevallik and Tarmo Soomere “Shifts in early spring wind regime in North-East Europe (1955–2007)” in journal Climate of the Past :
www.clim-past.net/4/147/2008/c...

( Questions were asked by the Public Relations Officer of TUT Krõõt Nõges.)

Tallinn University of Technology Press Release
April 1st 2013

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