TRMM

October 4, 0320UTC	October 8, 0245 UTC	October 8, 0245 UTC PR Vertical slice

TRMM WATCHES AS MA-ON STRENGTHENS TO A SUPER TYPHOON AND HEADS FOR JAPAN

The Tropical Rainfall Measuring Mission or TRMM satellite provides unique images of tropical cyclones that can be used to provide valuable information on their intensity and location, especially over remote parts of the open ocean. These images from TRMM show Typhoon Ma-on (26W) in the West Pacific as it evolved from a weak tropical depression to a very powerful super typhoon back to a typhoon as it approached Japan. The first image was taken at 03:20 UTC on the 4th of October 2004. At the time of this image, Ma-on was categorized as a tropical depression by the Joint Typhoon Warning Center with maximum sustained winds estimated at just 30 knots (35 mph). The image shows a horizontal map of the near surface rainfall intensity obtained from the TRMM satellite. Rain rates in the center portion of the swath are from the TRMM Precipitation Radar or PR, the first and only precipitation radar in space. The PR provides fine resolution rainfall data and details on its vertical structure. Rain rates in the outer swath are from the TRMM Microwave Imager or TMI. The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). This first image shows a large area of light (blue areas) to moderate intensity (green areas) rainfall with several embedded, localized areas of intense rainfall (dark red areas) with rain rates on the order of 2 inches per hour. The rain field, however, is still loosely organized with a slight amount of of banding evident by the arcs in the moderate (green) intensity rain. Ma-on became a tropical storm a short time later. Ma-on intensified slowly at first, remaining a tropical storm on the 5th and becoming a Category 1 typhoon on the 6th. On the 7th of October, Ma-on underwent what is known as rapid intensification and jumped from a Category 1 storm to a Category 5 storm in the span of just 24 hours. The second image was taken at 02:54 UTC on the 8th just after Ma-on had completed its cycle of rapid intensification. This TRMM image reveals a small, tight eye surrounded by a complete, symmetrical eyewall of moderate (green) to intense rain (red areas), characteristic of a mature, intense cyclone. [Note, the lower right portion of the eyewall is missing due to an artifact in the data] At the time of this second image, Ma-on was estimated to have sustained winds of 140 knots (161 mph), a powerful Category 5 super typhoon. The next image was taken at the same time and shows a vertical slice through the center of Ma-on looking from the west taken by the PR. The image shows an area of extremely intense rain (black vertical spike) extending vertically upward associated with the eyewall. This rain extends well above the melting band (horizontal area of brighter yellows) and indicates very strong convection.

The final image was taken at 05:16 UTC on the 9th of October just before Ma-on hit eastern Japan. TRMM reveals that Ma-on has weakened significantly. In contrast to the symmetrical structure of the eye at the previous time, the eye now appears elliptical and is open on the southeast quadrant. A band of intense rain (dark red arc) marks the northern half of the eyewall. Overall, the vast majority of the rain associated with Ma-on is north of the center (broad blue and green area). At the time of this image, Ma-on was a much weaker but still strong typhoon. Its maximum sustained winds dimished from an estimated 115 knots (132 mph) at 00:00 UTC to 90 knots (104 mph) by 06:00 UTC just after this image was taken. Ma-on originally began as a tropical depression on the 28th of September east of the Northern Mariana Islands.