Abstract
Passive microwave radiometers have merits of comparatively light weight and small electric power when loading on satellites, and capabilities of observing many geophysical parameters under all weather conditions. The Special Sensor Microwave / Imager (SSM/I) aboard the U.S. Defense Meteorological Satellite Program is considered to become a level of an operational sensor, after several experimental sensors were developed from early 1970’. The data of the SSM/I are open to the public not only in U.S., but also in other countries. Recent results of earth observations obtained by the SSM/I are presented, focusing on water vapor content over the ocean, precipitation, marine wind speed, and land surface temperature .
