Daily images of rainfall and sea surface temperature observed by TRMM, and satellite orbit information can be found at "Monitoring" page. Information of events such as heavy rainfall and El Nino is archived at "Topics" page.
First Hurricane over the South Atlantic
Tropical Cyclone 01L
A hurricane was observed over the South Atlantic, where no tropical cyclone observed at all since 1960s when meteorological satellite observation began on March 27, 2004.
This extremely rare hurricane has observed by the Tropical Rainfall Measuring Mission (TRMM) satellite and the Aqua satellite. It was born east of Brazil on March 25, then moved westward as it grew, eventually hitting Santa Catorina, Brazil.
Figure 1 indicates the rain rate near the surface observed by the Precipitation Radar, PR(*1), on board the TRMM satellite, overlaid with cloud images derived from the Visible Infrared Scanner, VIRS. Red represents intense rain. There is no rain in the center of the hurricane.
Hurricanes are considered unlikely to occur over the South Atlantic because wind speeds between upper air and lower air are very different(*); this also applies to this case.
It seem that a temperate cyclone changed and developed into a tropical cyclone. Scientists question whether this cyclone can be defined as a regular hurricane or not.
(*) The conditions for hurricane generation are a sea-surface temperature exceeding 27 degrees (except near the equator), a small difference of air temperature between north and south, and a small difference of wind speed between upper and lower air masses. Low latitude sea areas, excluding the South Atlantic and South Pacific near Peru, generally satisfy these conditions.
Figure 2 depicts the three-dimensional rainfall structure acquired by PR observation and precipitation along A to B in Fig. 1. The top of the rainfall isn't so high, about 8km, but you can find intense rainfall areas (red, yellow and green) outside the eye in this figure.
Figure 3 illustrates the water vapor content of air observed by AMSR-E on board the Aqua satellite. Heavy rain can occur where the water vapor content of air is high. You can see much water vapor in the air (red and yellow) is distributed in a spiral around the hurricane (*). This hurricane has the typical structure of a tropical cyclone because of the intense rain outside the eye and the large volume of water vapor contained in the air.
(*) The gray area in the center of hurricane indicates that AMSR-E is unable to estimate water vapor content because of the heavy rainfall.