Basis of GV for Japans

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• Basis of GV for Japans
• Hydro-Meteorological Process Modelling Research

GPM Workshop Sep. 27 to 30, Taipei,
Taiwan Toshio Koike, Tobias Graf, Mirza Cyrus
Raza, Thomas Pfaff, University of Tokyo and
JAXA tgraf_at_hydra.t.u-tokyo.ac.jp
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Overview

• Remote Sensing of Solid Precipitation
• Ground Based Radiometer
• Observation of Snowfall over the Ocean
• Cloud Microphysics Data Assimilation System
• GV Needs

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Methodology

• Physical Based Retrieval of Snowfall
• Minimizing the difference between modeled and
  observed brightness temperature data.
• Consider all parameters effecting radiative
  transfer.

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Model Parameterisation

• Many parameters need to be considered in RTM,
  which can be derived from additional data
  sources
• Humidity, Pressure,Temperature Observation, NWP
  Model Output/AIRS
• Cloud Position Satellite Observation in
  Infra-red Region, Ceilometer
• Boundary Condition
• Ocean gt Wind Speed
• Space
• Missing
• Snowfall
• Cloud Water

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Snow Water Path/Cloud Water

• TB observation is only integrated view of all
  parameters
• can't get Profile of Snowfall and Cloud Water
• assume uniform profile (integrated snowfall)
• Model Parameterisation

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Wakasa Bay 2003

• Application
• AMSR/AMSR-E Validation Project
• Data
• Humidity, Temperature Pressure gt Global
  Reanalysis (GANAL) Data, Radio Sonde
• Cloud Top gt MODIS Product, GMS
• Wind Speed gt AMSR-E Product
• Brightness Temperature gt AMSR-E, Ground Based
  Radiometer
• Comparison with Radar Observation and Gauge Data

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• Ground-Based Radiometer Snowfall Observation

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Methodology

• Relative Humidity, Temperature and Pressure
  Profile
• Cloud Top and Bottom

lt Radiosonde lt fixed (1000 m 3000 m)
Passive Microwave Brightness Temp. at 36.5 and
50.8 GHz
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Results
Snow Retrieval Validation
Problem Time Gap between Radiometer and Gauge
Results
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Consider Cloud Movement
Radar images at 2000 m
gauge site
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Averaged Snowfall Results
Good agreement within the range of uncertainty
when averaged over periods of cloud scale movement
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• Satellite Snowfall Observation over Ocean

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Results Snowfall Jan. 29, 2003 at 0331z

• Similar pattern can be observed
• results are slightly shifted
• results are more spread

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Scatter Plot

• Shift between Radar Satellite

R2 0.69
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Problems

• Slant Path
• AMSR-E observation at an
• incident angle of 55º
• Snowfall
• Blur Snowfall
• Shift of results
• Footprint Size Cloud Heterogeneity
• (36.5 and 89 GHz)
• gt Beam Filling Problem

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Summary

• Reasonable results for both approaches, but
• at the moment only integrated snowfall content
  (uniform snowfall rate) possible
• Problems due to cloud heterogeneity and cloud
  movement

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• Cloud Microphysics Data
• Assimilation System

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CMDAS/IMDAS Approach
Precipitation Estimation by ARPS
ARPS Model Output (Initial Guess)
Cloud Parameter Update
Model Operator (Assim. ParameterICLWC, IWV)
No
Optimized Initial Condition
Yes
Observation Operator (RTM) (Tbmod)

Global Minimization Scheme (Shuffled Complex
Evolution) Duan et al, 1992
Cost (J) (Tbmod - Tbobs )2
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Cloud Water Content Jan 25th
AMSR-E Product
Assimilation Result
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Analysis
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No Assimilation
Precipitation Rate(mm/hr)
Assimilation
29th Jan, 2000z
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Summary

• CMDAS IMDAS both improve the performance of
  cloud microphysics scheme significantly
  ?heterogeneity into external GANAL data,
  ?Improved atmospheric initial conditions
• With improved IC by assimilation systems, ARPS
  model has improved the estimation of cloud
  distribution short range precipitation forecast
  but its over estimated at few places.

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GV Needs

• Comprehensive Atmospheric Data Set for
  Application and Validation of Algorithms and RTM
• Water Vapour and Cloud Water Content Profiles
• RTM Detailed Information of solid precipitation
  (type, drop size distribution etc.)
• Snowfall Profiles gt Radar ? Observationliquid ?
  solid
• Precise (spatial) Information about cloud cover

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Basic Concept

• Satellite only provides observation during
  overpassgt Continuous Representation of
  Precipitationgt Data Assimilation
• Data Assimilation of Cloud Water and Water
  Vaporgt (Solid) Precipitation in Future

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Assimilation Window