Verification of Hydrometeor Properties Simulated by a Cloud-Resolving Model Using a Passive Microwave Satellite and Ground-Based Radar Observations for a Rainfall System Associated with the Baiu Front

Abstract

This paper compares satellite microwave radiometer and ground-based radar observations with the Japan Meteorological Agency nonhydrostatic model (JMA-NHM) simulations, using a bulk microphysical parameterization, for a typical rainfall system associated with the Baiu front around the Okinawa Islands, Japan, on 8 June 2004.The JMA-NHM correctly replicated the shape, location and intensity of the precipitation associated with the observed rainfall system. Radar reflectivities and microwave brightness temperatures (TBs) were simulated using output from the JMA-NHM simulations. They were then compared with concurrent corresponding observations by the National Institute of Information and Communications Technology (NICT), CRL Okinawa Bistatic Polarimetric Radar (COBRA), and Advanced Microwave Scanning Radiometer for EOS (AMSR-E). Fairly good agreement was obtained between the simulated and observed reflectivities under the melting layer and TBs at low frequency (18.7 GHz), indicating that the JMA-NHM adequately simulated the amount of liquid hydrometeors. However, the intensity of scattering in the simulations was stronger than that in the COBRA observations above the melting layer and the AMSR-E observations at high frequencies (36.5 and 89.0 GHz). This was due to the fact that the JMA-NHM overestimated the amount and size of snow particles as a result of large depositional growth.The excessive snow contents were reduced by adjusting some of the microphysical processes in the JMA-NHM: the snowfall speeds were increased and a riming threshold for snow to graupel conversion was changed. These adjustments helped to reduce the amount and size of snow, resulting in further agreement with the COBRA observations. These adjustments also further improved the simulated TBs at high frequencies, especially at 36.5 GHz. However, differences still exist between the simulated and the observed TBs at high frequencies, suggesting that additional adjustment to and improvement of the snow microphysical processes are needed for the application of the model to microwave remote sensing of precipitation.

Extension of a Multisensor Satellite Radiance-Based Evaluation for Cloud System Resolving Models

“…The dual-polarized microwave radiometer operates at each frequency for both the vertical and horizontal polarizations. The polarization differences between the vertically and horizontally polarized TBs at 18.9 GHz (D19; Liu and Curry 1998;Eito and Aonashi 2009) and the polarization corrected 89-GHz TBs (PCT89; Spencer et al 1989) are derived from AMSR-E L2A (Ashcroft and Wentz 2013), which has a spatial resolution of 39 km and 12 km at 18.7 GHz and 89.0 GHz, respectively. D19 represents the atmospheric emission from liquid water and is close to 0 in strong emission areas (Liu and Curry 1998).…”

“…Previous studies have used microwave observations to evaluate CSRM precipitation systems (Eito and Aonashi 2009;Matsui et al 2009;Han et al 2010). For example, Eito and Aonashi (2009) used the Japan Meteorological Agency non-hydrostatic model (JMA-NHM) and observations from the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) to obtain an agreement between the simulated and observed brightness temperatures (TBs) at 18.7 GHz.…”

“…For example, Eito and Aonashi (2009) used the Japan Meteorological Agency non-hydrostatic model (JMA-NHM) and observations from the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) to obtain an agreement between the simulated and observed brightness temperatures (TBs) at 18.7 GHz. However, simulated scattering intensities at high frequencies (36.5 GHz and 89.0 GHz) were stronger than that observed.…”

Evaluation of Cloud Microphysics in JMA-NHM Simulations Using Bin or Bulk Microphysical Schemes through Comparison with Cloud Radar Observations

“…This scheme is a single-moment bulk accounting for explicit classes, two of water and three of ice: cloud water, rain, cloud ice, snow, and graupel (Lin et al 1983;Ikawa and Saito 1991;Eito and Aonashi 2009). The amount of cloud water is calculated using an instantaneous saturation adjustment.…”

Development of spaceborne radar simulator by NICT and JAXA using JMA cloud-resolving model

“…The IS1 and IS2 schemes are explicit three-ice bulk microphysics schemes [2] based on [4]. The differences between IS1 and IS2 are forecasts of number concentrations of snow and graupel in the IS2 [5]. The newly developed FH scheme is fundamentally different from the others and an explicit four-ice bulk microphysics scheme [6] based on [7] and [8].…”