Quick Look

Given that the SST in the upwelling area is locally 3 degrees lower than in the surrounding sea it is interesting to investigate if this local SST anomaly has an influence on the local pressure field. Since Masirah is located on an island in the middle of the upwelling region we therefore investigated the surface pressure Salalah and Masirah and also the pressure difference in both stations.

Climatology
The climatology plots for Salalah and Masirah (figures 1b and 2b) show that in both stations the pressure is lower in summer than in winter. The stations are in this following a usual trend of continental climate.
Also the difference of pressure between Masirah and Salalah shows a seasonal cycle (figure 3a): in Summer the pressure in Masirah is lower than in Salalah and in winter it is the other way around. This behavior can be explained with large-scale climate features: Masirah lies much further east and is under the influence of the pressure trough over Tibet, the same one that also leads to the development of the monsoon. Thus if the local SST anomalies would have influence on the pressure in the Arabian Sea it is canceled out by the comparably much stronger large-scale pressure field.
(check also the quick-looks on the regional pressure field for more information).

Change in pressure
Interestingly the time series of difference in pressure between Masirah and Salalah show that the pressure difference between both stations has increased in summer and decreased in winter during the years 1987 to 1999. This is even better visible when looking at the pressure difference in the month of July alone. We do not have an interpretation for this development yet. However it is an interesting feature to keep in mind when further investigating on changing climate over the region.

Data
To create the pictures on this page we used the dataset provided by NNDC climate stations online. More information on the dataset can be found in the section “dataset information”.

Salalah [17.02, 54.05], elevation 20m

Picture is still missing
figure 1a: monthly averages of pressure in Salalah, measured 1987 - 1999

figure1b: climatology of pressure in Masirah, calculated for the years 1987 –1999

figure1c: anomalies of pressure in Salalah, calculated as measured pressure (figure 1a) minus climatology (figure 1b)

Masirah [20.40, 58.54] , elevation = 19m

Picture is still missing
figure 2a: monthly averages of pressure in Masirah, measured 1987 - 1999


figure2b: climatology of pressure in Masirah, calculated for the years 1987 –1999


figure2c: anomalies of pressure in Masirah, calculated as measured pressure (figure 2a) minus climatology (figure 2b)

Difference between pressure in Masirah and Salalah

Picture is still missing
figure 1a: monthly averages of pressure in Salalah, measured 1987 – 1999

difference between pressure in Masirah and Salalah

figure 3a: climatology of the difference in pressure between Masirah and Salalah


figure 3b: difference of pressure between Masirah and Salalah


figure 3c: difference of pressure between Masirah and Salalah plotted for the month of July only