Japan Geoscience Union Meeting 2014

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International Session (Oral)

Symbol A (Atmospheric, Ocean, and Environmental Sciences) » A-CG Complex & General

[A-CG06_29AM2] Satellite Earth Environment Observation

Tue. Apr 29, 2014 11:00 AM - 12:45 PM 315 (3F)

Convener:*Riko Oki(Japan Aerospace Exploration Agency), Yoshiaki Honda(Chiba University, Center for Environmental), Kenlo Nishida Nasahara(Institute of Agricultural and Forest Engineering, University of Tsukuba), Takashi Nakajima(Tokai University Department of Network and Computer Engineering, School of Information and Design Engineering), Taikan Oki(Institute of Industrial Science, The University of Tokyo), Yokota Tatsuya(Center for Global Environmental Research, National Institute for Environmental Studies), Yukari N. Takayabu(Atmosphere and Ocean Research Institute(AORI), The University of Tokyo), Hiroshi Murakami(Earth Observation Research Center, Japan Aerospace Exploration Agency), Hajime Okamoto(Research Institute for Applied Mechanics,Kyushu University), Chair:Taikan Oki(Institute of Industrial Science, The University of Tokyo), Yoshiaki HONDA(Center for Environmental Remote Sensing, Chiba University)

11:00 AM - 11:15 AM

[ACG06-14] Characteristic differences between the heaviest rainfall and the strongest convection

*Atsushi HAMADA1, Yukari TAKAYABU1 (1.Atmosphere and Ocean Research Institute, The University of Tokyo)

Keywords:precipitation, extreme event, TRMM

Regional and seasonal differences in the rain characteristics between rain-rate and convection extreme events are examined using 11-yr measurements from the Precipitation Radar (PR) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. After defining a rainfall event as a set of contiguous rainy pixels of TRMM PR measurements, three different types of regional extreme rainfall events are defined, using the maximum values of near-surface rainfall rate (NSR) and 30-dBZ echo top height (ETH30) in rainfall event; Rainfall events of which the maximum NSR is within top 0.1% at a grid but the ETH30 is not are defined as R-only extreme events, those of which the maximum ETH30 is within top 0.1% but the NSR is not are defined as H-only extreme events, and those of which both of the maximum NSR and maximum ETH30 are within top 0.1% are defined as RH extreme events. This is done on a local basis with 2.5 x 2.5 degree horizontal resolution to examine regional extreme events.It is shown that the fractional occurrence of RH extreme events are less than 30% in most regions, indicating that only a few dozen percent of convection extremes are related to rain rate extremes. There are robust differences in echo profiles, rainfall characteristics, and local environments between R-only and H-only extreme events. These characteristic differences are basically independent on region and season, except for their seasonal occurrence. R-only extreme events exhibit lower echo-top height than H-only extremes, linear downward increase of radar reflectivity (Ze) below freezing level, and sharp upward decrease of Ze in 5-7 km, whereas H-only extreme events exhibit slight downward decrease of Ze below freezing level. R-only extreme events are almost in phase with mean monthly rainfall, while H-only extremes tend to peak slightly out of phase with rainy season. Local environments related to R-only extremes are less convectively unstable, wetter in the low-middle troposphere, and larger moisture flux convergence in the lowermost troposphere, compared with those related to H-only extremes. The features related to R-only extreme events imply a dominance of warm-rain process.