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

The TRMM satellite flew over tropical storm Bret in the Atlantic Ocean north of the Bahamas on 19 July 2011 at 1118 UTC ( 7:18 AM EDT). This early morning pass showed that BRET was very small, but TRMM's Precipitation Radar (see below) showed that the storm had some powerful thunderstorms reaching to heights of 15km (9.3 miles).

The TRMM satellite saw typhoon MA-ON on 18 July 2011 at 2306 UTC and again on 19 July 2011 at 0221 UTC. The rainfall analysis above used TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data from both orbits. It shows that bands of very heavy rainfall of over over 50 mm (~2 inches) were falling over both of the Japanese island of Shikoku and Honshu. At the time of the later TRMM orbit MA-ON's winds had weakened to about 67 kts (~77 mph) making it a category 1 typhoon on the Saffir/Simpson scale. MA-ON is expected to move toward the east-southeast and weaken as it continues to affect

Typhoon MA-ON was a category 2 typhoon on the Saffir/Simpson scale with wind speeds of about 85 kts (~98 mph) when the TRMM satellite captured those data shown above on 18 July 2011 at 0316 UTC. MA-ON had weakened considerably from a very powerful category four typhoon with wind speeds of 115 kts (~132 mph) on 15 July 2011. TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data were used to produce the rainfall analysis shown above. This TRMM analysis shows that MA-ON still contained organized bands of very intense rainfall with the most intense precipitation located in the eastern