Mesoscale Atmospheric Processes Joint Seminar: Masaki Satoh and Tempei Hashino

AORI, University of Tokyo

Title: Global nonhydrostatic simulation by 3.5km-mesh NICAM

Presenter: Prof. Masaki Satoh a@ AORI, University of Tokyo.

Abstract: The Nonhydrostatic Icosahedral Atmospheric Model, NICAM, is used to simulate multi-scale structure of tropical convective system. During the Year of Tropical Convection (YOTC), we chose an event related to Tropical Cyclone Fengshen (2008) and performed a global nonhydrostatic simulation with mesh size approximately 3.5 km for the period June 15-25, 2008. A weak MJO is coming near the maritime continent during this period and surface westerlies became stronger near the equatorial western Pacific; this is a favorable condition for the TC-genesis in the north-western Pacific.
The simulation reproduced the TC-genesis and the track of Fengshen quite well. We found that a sequence of equatorial waves and TD-type disturbances contributed the TC-genesis. We also found that a coupling of middle-level and low-level vorticities associated with two different cloud systems caused a deepening of the cyclone in the genesis stage. This vorticity coupling is observed at the PALAU-2008 field experiment. The simulation and the field experiment clarified that the TC-genesis of Fengshen is described by such a combination of multiscale disturbances related to MJO, synoptic-scale waves, and MCSs.The cloud properties of the NICAM simulations are evaluated using the J-simulator, which is integrated through the future JAXA-ESA joint satellite mission, EarthCARE. The multiple sensor signals are compared between NICAM and existing satellite observations, CloudSat/CALIPSO. Further results will be introduced by Dr. Hashino.

Title: Validation of cloud microphysical statistics simulated by a global cloud-resolving model with active satellite measurements

Presenter: Dr. Tempei Hashino @ AORI, University of Tokyo.

Abstract:Global satellite observation provides valuable information not only to the retrievals of physical quantities relevant to aerosol and clouds but also to the validation of these simulated by GCMs and cloud resolving models. The aim of this paper is to evaluate cloud microphysical variables simulated by a global cloud-resolving model (GCRM) through use of a satellite signal simulator and direct comparison against satellite observation. It is important to understand the differences in the cloud microphysical variables based on those in the radiative variables in order to improve the simulated clouds. This paper discusses the methodology for evaluating the cloud microphysical variables with use of a merged dataset for CloudSAT CPR radar and CALIPSO lidar. The GCRM to be validated is the Nonhydrostatic Icosahedral Atmospheric Model (NICAM). The simulation of 2008 tropical cyclone Fengshen is validated with use of the Joint Simulator for Satellite Sensors (J-simulator) being developed under JAXA/EarthCARE mission. The preliminary results show that NICAM tends to have larger effective radius and smaller ice water content near the cloud top due to snow. The vertical profiles of signals are analyzed in terms of temperature to gain a better insight in the cloud microphysics. The statistics on vertical profiles of signals from the observation and model as well as a possible way of improving the bulk microphysical parameterization will be discussed.