Tropical Cyclone Structural Changes in Response to Ambient Moisture Variations Qinghong Zhang and Yue Ying Dept. of Atmospheric and Oceanic Sciences, Peking University, China [email protected]Rapid Change Phenomena in Tropical Cyclones Nov. 7 th 2012 Kaikou, Hainan Island
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Tropical Cyclone Structural Changes in - files/7 Nov/QHZhang.pdf · Tropical Cyclone Structural Changes in ... 2012 Kaikou , Hainan Island. ... TC size change, as well as TC intensity
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Tropical Cyclone Structural Changes in
Response to Ambient Moisture
Variations
Qinghong Zhang and Yue Ying Dept. of Atmospheric and Oceanic Sciences,
Intensifying TCs are associated with more ambient moisture Hendricks et al. 2010
2001~2011 intensity and structure western North Pacific
• JTWC Best Track intensity: Max wind speed
size: radius of 34 knot
• Moisture: TRMM, SSM/I microwave Precipitable Water
Intensity & size change • DEF: change in ±6h
“weakening” 12hΔVmax<‐3 m s ‐1
“contracting” 12hΔSize<‐20 km
“growing” 12hΔSize>20 km
“intensifying” 12hΔVmax>3 m s ‐1
“growing & intensifying”: More environment moisture. “contracting & weakening”: More dry air instrun from north
average contracting growing
intensifying
weakening
Moisture Anomaly with TC intensity & Size Change In the western North Pacific Ocean 2001‐2011
Both positive & negative Anomaly in moisture: Angular Momentum conserved
Average
Moisture Anomaly with TC intensity & Size Change
contracting growing
intensifying
weakening
Summary‐1
TC size change, as well as TC intensity change may related to ambient moisture, in the western North Pacific.
• Growing and intensifying TCs, comparing with contracting and weakening ones, displayed more ambient moisture content, their moisture fields are more axi‐symmetric.
• Grow‐weaken & contract‐intensify TCs, both negative and positive y moisture abnormally exist
Q1: Does moisture do matter with TC structure evolution from observation?
• In sheared environment, TC outer rainbands are sensitive to their upstream moisture supply. Both the amount and the location of moisture is important in this case.
Moist
Dry
Q2: What if TC is in vertically sheared environment?