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Version up of all weather wind speed retrieval algorithm Akira Shibata JAXA AMSR-E meeting, at Asheville, June 29-30, 2011. What is all weather wind speed algorithm ?. • To combine 6H and 10H lower frequencies; less contaminated by rain
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Version up of all weather wind speed retrieval algorithm Akira Shibata JAXA AMSR-E meeting, at Asheville, June 29-30, 2011
What is all weather wind speed algorithm ? • To combine 6H and 10H lower frequencies; less contaminated by rain H-pol; more sensitive to ocean wind • To retrieve wind speed under rain, in particular for typhoons and hurricanes
Contents • To widen a swath; input data L1B → L1A • Non-linear curve for atmospheric correction • Dependency on relative wind direction (RWD) • Comparison between AMSR and SeaWinds wind speeds
Widening the swath Jul. 18, 2002 Path 197 L1B L1A Unit;Kelvin
Scanbias for 6H and 10H 243 1 10H 6H 3.5K over ocean 30S ~ 30N Tb correction 6H = 6H × ( 1 + α ) α depends on scan position
Atmospheric correction new 6H- old W6 10H- (K)
Calculated Tb of 6H and 10H Roughened by wind W6 calm
Anisotropic feature of W6 depending on RWD cross down W6 (K) up SeaWinds wind speed (m/s)
Anisotropic features of 6H* and 10H* Shibata (2006)
Comparison between AMSR and SeaWinds wind speeds • 54 collocated data for typhoons and hurricanes • 14 data for the Hurricane Isabel
Comparison of W6 with NHC data (AMSR-E) Shibata (2006) Shibata (2006)
Hurricane Isabel Sep. 11, 2003 Ascending AMSR SeaWinds NHC 125 kt → 56m/s 1-min 10-min
Hurricane Isabel Sep. 11, 2003 Descending AMSR SeaWinds NHC 140 kt → 63m/s
Hurricane Isabel Sep. 15, 2003 Ascending AMSR SeaWinds NHC 130 kt → 58m/s
Hurricane Isabel Sep. 15, 2003 Descending AMSR SeaWinds NHC 120 kt → 54m/s
Hurricane Isabel Sep. 16, 2003 Ascending AMSR SeaWinds NHC 105 kt → 47m/s
Hurricane Isabel Sep. 16, 2003 Descending AMSR SeaWinds NHC 95 kt → 43m/s
Typhoon 0310 Aug. 6, 2003 Descending AMSR SeaWinds JMA 40m/s
Typhoon 0310 Aug. 6, 2003 Ascending AMSR SeaWinds JMA 40m/s
Summaries • Anisotropic features of W6 cross > up > down • In many cases, high winds of AMSR are found in front or right hand of typhoons and hurricanes • Since Tb of 6H may increase by foam or whitecaps over the ocean surface, the above results indicate that foam or whitecaps are more distributed in those areas.