Geoscience Reference
In-Depth Information
rainfall data on the ground and satellite signals. The Northeast Region (“Nordeste”)
in Brazil will also be studied in order to study sea-breeze fronts.
Meteosat
MSG
Visible
one channel (5 km)
4 channels with a High
Resolution Visible of 1 km
Medium infrared
one channel (10 km)
3 channels (3 km)
Thermal infrared
one channel (10 km)
5 channels (3 km)
Frequency of images
30 minutes
15 minutes
Table 3.1.
A comparison of performances produced by Meteosat and MSG
3.3.2.
Monitoring sea-breeze fronts in the northeast region of Brazil
Coastlines are the areas where specific climatic and meteorological conditions
develop, and in particular, the development of mesoscale patterns, such as sea
breezes. Such mesoscale patterns lead to the creation of weather phenomena that
only occur along the coast or in coastal areas that have an extensive land border.
These areas tend to be relatively fresh, humid, and sunny in comparison to the
interior regions of the country. This type of weather also has an influence on human
activity, and influences activity such as tourism, atmospheric pollution, etc. The sea
breeze that develops along the coastline is marked by a change in the wind direction
on the surface of the land that runs along the specific coastline in question. In
addition to a change in the wind direction, the wind's speed also increases and there
is a decrease in temperature as well as an increase in relative humidity and a change
in cloud cover. Sea air is denser, more stable and fresher than continental air, and
due to these three facts the sea air is able to raise the warmer, more instable
continental air, which, in turn, speeds up the rate of convection of the sea-breeze
front, and as a result, a line of cumulus type clouds are formed. This line of clouds is
formed parallel to the coast and is then pushed further inland by the sea breeze.
Thanks to this type of cloud cover created further inland, it is possible to clearly see
the sea-breeze front on satellite images as the coastline and the land that runs along
the coast benefit from a clear sky [PLA 06]. Remote sensing has often been used to
demonstrate such cloud activity associated with sea breezes, however, no systematic
analysis of this phenomenon has ever taken place.
In the example, visible images from the GOES-8 satellite were used (they have
wavelengths which range between 0.58 and 0.68 Pm). These images are used
because recordings that are made within this range of wavelengths means that it is
possible to distinguish between different cloud types in relation to their albedo: the
albedo of the cloud types varies in relation to a cloud's thickness and its density.
The images created are used to identify the extent and edges of the clouds, as well as
to identify cloud formations. The images are also used to distinguish between low-
lying cloud, which is present on the land or on the sea. For the purposes of this
