NOAA-NESDIS
Regional And Mesoscale Meteorology Team
Daily Satellite Discussion
Wednesday October 22,1997
GMS Visible Image of Super Typhoons Ivan and Joan
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GMS Visible Image of Super Typhoon Ivan
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GMS Visible Image of Super Typhoon Joan
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Today's images highlight two Super Typhoons in the West Pacific, Ivan (on the left) and Joan. These are the 8th and 9th Super Typhoons to form this year in this area of the Pacific. It is an unusual occurence for two storms of this strength to occur at the same time. The images originate from the GMS-5 satellite. GMS-5 is a Japanese satellite in geostationary orbit over the equator at approximately 140E. The satellite is equipped with the Visible and Infrared Spin Scan Radiometer (VISSR) imaging sensor, which uses the spin motion of the satellite to scan the earth in the East-West direction. At the satellite subpoint, the visible(0.5-0.75 um) channel has a resolution of 1.25 km.

The times of the images were coincident to reports of 150 to 160 knot winds, which puts them both at a Category 5 on the Saffir-Simpson scale. The eye of Joan is seen crossing directly over Guam and Saipan in the Commonwealth of the Mariana Islands, while Ivan is headed for the Phillipines. With the locality of the storms so close to satellite subpoint, the shape of the eyewall (especially in Joan) is clearly sloping inward as it goes down. This is called the stadium effect. Notice also the outflows of the two storms. Ivan's extends to the north-east while Joan's stretches to the south-west. The significance of this is, that even with their close proximity, the two outflows are not affecting one another. Daily Global Analysis SST anomaly charts, a product of NOAA/NESDIS (not shown), show that the storms produce a cold wake through upwelling. The NOAA/NESDIS SST anomalies can be found at: NOAA/NESDIS SST

Carol Vaughn

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