The GPM Microwave Imager (GMI) successfully completed Pre-Environmental Review (PER) on July 19-20, 2011, at Ball Aerospace in Colorado, which marks another key milestone for the GMI instrument. The GMI will undergo acoustic testing, vibration testing, and electromagnetic and thermal vacuum testing starting in August 2011. The GMI instrument is a multi-channel, conical-scanning, microwave radiometer, enabling the GPM Core Observatory to serve as a radiometric reference and also a transfer standard for the other GPM constellation members. Learn more about the GMI

Typhoon Ma-On formed from an area of disturbed weather in the northwest Pacific halfway between Wake Island and the Northern Marianas on the 11th of July 2011. The system slowly developed and became a typhoon two days later on the 13th as it continued tracking westward. Ma-On then reached its maximum intensity on the 15th with sustained winds estimated at 115 knots (~132 mph), making it a Category 4 typhoon, before turning northward towards southern Japan. Ma-On began to weaken as it neared the southeast coast of Japan where it briefly made landfall in southern Tokushima Prefecture on the

The TRMM satellite had an excellent view of hurricane Dora in the eastern Pacific Ocean southwest of Mexico when it passed over on 20 July 2011 at 1015 UTC. Dora is predicted to become a powerful category 3 hurricane but stay well off the Mexican coast.

Typhoon MA-ON had weakened to a strong tropical storm with wind speeds of about 60 kts (69 mph) when the TRMM satellite again flew over on 19 July 2011 at 2348 UTC. The rainfall analysis above using TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data was overlaid on a daylight visible/infrared image from TRMM's Visible and InfraRed Scanner (VIRS) instrument. It reveals that although weaker MA-ON was dropping heavy rainfall over southern areas of the Japanese Island of Honshu. A red tropical storm symbol shows the location of MA-ON's center of circulation at that time. Click here to