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Seen from Space 2004

Africa's Seasonal Variation Seen from Soil Moisture

 
Fig. 1. Distribution of soil moisture during February 2003 Fig. 2. Distribution of soil moisture during August 2003
>>See the map of Africa

Expansive deserts spread across North Africa. West, Central and East Africa have tropical rain forests surrounded by savannas in the western area of the coast through the Congo River basin. South Africa is mostly savannas and desert. Africa thus has many different types of vegetation and various aspects of climatology. The different vegetation and climatology can to some extent be seen from satellite data.

Figures 1 and 2 represent soil moisture (*1) distribution during February 2003 and August 2003. This data was acquired by Aqua satellite's onboard AMSR-E. Red indicates low amount of soil moisture, while blue indicates higher amounts of soil moisture . In North Africa, no area has rain all year, though it rains heavily in the Mediterranean region and in a narrow area of the south. It is not uncommon for the Sahara Desert to be without rain throughout the year. In the satellite image, North Africa has a low level of soil moisture (indicated in red and yellow), except for the Mediterranean region from Morocco to Tunisia, which has a high level of soil moisture (indicated in blue).

During the summer of the southern hemisphere (October to March), a well-developed low pressure brought heavy rains to South Africa and Madagascar. During the winter, from April to September, the atmosphere was dry with no clouds in the sky. Figure 1 depicts the rainy season, where we can see that almost all of South Africa has much soil moisture, except for the Namib Desert on the Atlantic Ocean side. Figure 2 depicts the dry season, where South Africa is as dry as North Africa.

West, Central and East Africa have tropical rain forests and savannas. The western coast has the greatest amount of precipitation, and there is rainfall all year round in the tropical rain forests. In the satellite image for February, a less rainy season, the northern limit of the abundant soil moisture area is lower than that of the satellite image of August, a more rainy season. In the tropical rain forests, there is enough soil moisture in both Figs. 1 and 2 (*2).

Soil moisture data acquired by satellites will play an important role in managing regional agriculture as well as in improving models to predict global climates.



(*1) The weight of water included in soil per unit.
(*2) Soil moisture distribution determined by AMSR-E may be influenced by vegetation of the area.

Explanation of the image
Satellite: Aqua (NASA)
Sensor: Advanced Microwave Scanning Radiometer for EOS-PM (AMSR-E) (JAXA)
Date: February 2003 (Fig. 1), August 2003 (Fig. 2)

Related sites
Version upgrade and new release of AMSR-E geophysical products
Soil Moisture Maps of Mongol Plateau --Soil Moisture Observation from Satellites Now Practical--
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