Real-time imagery explains anomalies seen in CM SAF climate datasets

Explaining features seen in CM SAF datasets

May 2015

Real-time imagery explains anomalies seen in CM SAF climate datasets
Real-time imagery explains anomalies seen in CM SAF climate datasets

Features seen in the CM SAF climate datasets have been explained by looking at real-time satellite imagery.

Last Updated

14 September 2022

Published on

21 May 2015

By Zanita Avotniece (LVGMC)

 Summer mean surface incoming shortwave radiation (W/m2) 1990–2005
Figure 1: Summer mean surface incoming shortwave radiation (W/m2) 1990–2005

The CM SAF radiation data provides climate quality information on radiation, water vapour and cloudiness.

Figure 1 shows the summer mean surface solar radiation for the Baltic region over the period from 1990 to 2005.

There seems to be a mismatch between the coastline and the pattern in the radiation. Can this be explained looking at the meteorology at the time?

The animated gif of the Natural Colour RGB, Meteosat-10, 28 May 09:00–12:00 UTC (Figure 2) shows the same region. Note: this image has been created by using chrominance of the Natural Colors RGB and luminance of the HRV channel.

Notice how the clouds develop over land and gradually move to east in the westerly flow.

In Latvia in the summer time it is common to have weak convective clouds developing over the land areas and to be later transferred further to the east by the main flow.

 Natural Colour RGB, Meteosat-10, 28 May 09:00–12:00 UTC
Figure 2: Meteosat-10 Natural Colour RGB, 28 May 09:00–12:00 UTC

On Figure 2 you can also see how the clouds dissipate over the cold water of Lake Peipsi in Estonia and the western part of the Gulf of Riga. This process leads to the lower values seen in the radiation plot in Figure 1.

This is a small example that shows the validity of the CM SAF data and the possibility to detect local phenomena in the data.

 
 MODIS True Colour RGB, 10:50–10:55 UTC, 21 May (left) & 25 May (right).
Figure 3: MODIS True Color RGB, 10:50–10:55 UTC, 21 May (left) & 25 May (right).

Figure 3 shows similar True Color RGB examples from Aqua satellite overpasses at 10:50–10:55 UTC on 21 and 25 May.