Long Term Variability of Sea Level and Atmospheric
Pressure in the Mediterranean Region
F. Raicich
1 Introduction
The Mediterranean is a bordering region that feels the dynamics of the circulation
of both the mid latitudes and the Tropics. The seasonal cycle regulates the transition
from the winter regime, which is dominated by the mid-latitude westerly flow,
although strongly modified by local orography, to the summer regime, when the
westerlies weaken and a meridional circulation develops over the eastern basin. This
paper summarizes some features of atmospheric pressure and sea level variability in
the Mediterranean region at different time scales over the last 130 years.
2 Data and Methods
Time series of atmospheric pressure (AP) and sea level (SL) were formed for
locations in the Mediterranean region. The locations were selected on the basis of
the availability of SL time series, which were taken from the Permanent Service for
Mean Sea Level data bank (Spencer and Woodworth, 1993). Time series were
formed on a regional basis using the available stations, preferably if associated to a
Revised Local Reference (RLR); data from nearby stations were intercompared and
normalized to each other to obtain as complete and long series as possible. As a
result eight SL time series were obtained, constructed from the time series of Tarifa
(representing Alboran Sea), Alicante, Marseille and Genoa (Northwest
Mediterranean), Trieste and Venice (North Adriatic), Split (East Adriatic), Varna
and Burgas (West Black Sea), Sevastopol (itself) and Alexandria (South Levantine).
In the case of South Levantine, based on Alexandria data, no RLR is available,
however the series was retained since it appears to be homogeneous and is the only
one available in that important region of the Mediterranean Sea. Finally. East
Adriatic and West Black Sea were excluded from further analyses since the time
series are very similar to and shorter than North Adriatic and Sevastopol,
respectively. For the selected location (Alboran, NW Med, N Adriatic, Black Sea
and S Levantine) time series of AP were extracted by interpolation from the UK
MetOffice 5x 5' gridded data set (Jackson, 1986). In this paper variability is
Pressure in the Mediterranean Region
F. Raicich
1 Introduction
The Mediterranean is a bordering region that feels the dynamics of the circulation
of both the mid latitudes and the Tropics. The seasonal cycle regulates the transition
from the winter regime, which is dominated by the mid-latitude westerly flow,
although strongly modified by local orography, to the summer regime, when the
westerlies weaken and a meridional circulation develops over the eastern basin. This
paper summarizes some features of atmospheric pressure and sea level variability in
the Mediterranean region at different time scales over the last 130 years.
2 Data and Methods
Time series of atmospheric pressure (AP) and sea level (SL) were formed for
locations in the Mediterranean region. The locations were selected on the basis of
the availability of SL time series, which were taken from the Permanent Service for
Mean Sea Level data bank (Spencer and Woodworth, 1993). Time series were
formed on a regional basis using the available stations, preferably if associated to a
Revised Local Reference (RLR); data from nearby stations were intercompared and
normalized to each other to obtain as complete and long series as possible. As a
result eight SL time series were obtained, constructed from the time series of Tarifa
(representing Alboran Sea), Alicante, Marseille and Genoa (Northwest
Mediterranean), Trieste and Venice (North Adriatic), Split (East Adriatic), Varna
and Burgas (West Black Sea), Sevastopol (itself) and Alexandria (South Levantine).
In the case of South Levantine, based on Alexandria data, no RLR is available,
however the series was retained since it appears to be homogeneous and is the only
one available in that important region of the Mediterranean Sea. Finally. East
Adriatic and West Black Sea were excluded from further analyses since the time
series are very similar to and shorter than North Adriatic and Sevastopol,
respectively. For the selected location (Alboran, NW Med, N Adriatic, Black Sea
and S Levantine) time series of AP were extracted by interpolation from the UK
MetOffice 5x 5' gridded data set (Jackson, 1986). In this paper variability is