Global Precipitation Measurement by Satellites for Water Budget Study

1
Global Precipitation Measurement by Satellites
for Water Budget Study
Kenji Nakamura (1), Riko Oki (2), Shinsuke Satoh
(2), and Toshio Iguchi (3) (1) Hydrospheric
Atmospheric Research Center (HyARC), Nagoya
University (2) National Space Development Agency
of Japan (NASDA) (3) Communications Research
Laboratory (CRL) 30 June 2003 IUGG,
JWM01_at_Sapporo
TRMM
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Precipitation Measurement from Space

• Precipitation Radar (PR)
• 3D rain profiles
• Fine structure ( 5 ?5 ?0.25 km )
• Over sea and land
• Microwave Radiometer (MWR)
• Wide observation swath width (few sampling
  errors)
• Over sea (uncertain rain estimates over land)

GPM Core Satellite (2008? )
TRMM Satellite (1998 2004?)
3
Local Time of Peak Rain derived by 3-years TRMM
PR observation
1998-2000
over 3 years Version 5 Rain certain 3 hour
moving average rain event gt1
LT
2 4 6 8 10 12 14 16 18 20 22
(Local Time)
4
Storm Height (1998-2000)
JAN
JUL
MAR
SEP
NOV
MAY
Height more than two consecutive bins with gt
17 dBZ
5
From TRMM to GPM
Demonstration of the worlds first space-borne
precipitation radar

• Scientific achievements
• Accurate observation of the rainfall in tropics
  and sub-tropics (PRTMI)
• Diurnal, annual, and climate change of
  precipitation (PRTMI)
• Three dimensional observation of precipitation
  (PR)
• Accurate rainfall observation over sea and land
  (PR)
• Improvement of weather forecast accuracy using
  4DDA (TMI, PR)

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The Concept of Global Precipitation Measurement
(GPM)

• Core Satellite
• Dual-frequency Precipitation Radar (DPR)
• Microwave Radiometer
• Accurate High-sensitivity precipitation
  measurement
• Calibration for constellation radiometers

• Constellation Satellites
• Microwave Radio-meters installed on each
  countrys satellite
• Frequent precipitation measurement

Expected Partners NASA, NOAA (US),
ESA (EU), NASDA, China, Korea, others
NASDA (Japan) DRP, H-IIA Launcher NASA
(US) Spacecraft, MWR
3-hourly global rainfall map
Blue Inclination 65º (GPM core) Green
Inclination 35º (TRMM)
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One-day orbit observations of the GPM core
satellite
Radar (DPR)
MWR (GMI)
Inclination 65 Altitude 407 km
Color orbit num
To measure global precipitation frequently, MWR
observation data has to been used not only over
sea but also over land.
The orbit data was calculated by Y.Iida (Osaka
Prefecture Univ)
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MWR 3 hourly Global Rain Map
TRMM Research Product in NASA/GSFC 3B40RT
TMISSMI?3 - GPROF-TMI (2A12) - GPROF-SSMI
3B41RT Geo-stationary IR data 3B42RT TMISSMI
IR Online data available within near-real time
(? 6 hours)
3 Hourly Global Rainfall
Week of Global Rainfall Accumulation
TRMM 3B40RT 3-hourly, 0.25?0.25 grid
http//trmm.gsfc.nasa.gov/
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Comparison between 3B40RT and AMeDAS Daily
Rainfall over Land
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Comparison between 3B40RT and AMeDAS Daily
Rainfall (sampling error ignored )
AMeDAS
3B40RT TMISSM/I?3
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Comparison between 3B40RT and AMeDAS Daily
Rainfall ( lacking data corrected)
AMeDAS
3B40RT TMISSM/I?3
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Comparison between 3B40RT and AMeDAS Daily
Rainfall ( more than 20 mm/day )
3B40RT original
AMeDAS
3B40RT corrected lacking data
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DPR Dynamic Database for MWR precipitation
retrieval algorithms
Dual-frequency Precipitation Radar (DPR) on the
GPM core satellite will be used to calibrate MWR
precipitation estimates using Dynamic global
Database (renewal every 3-10 days). The
precipitation parameters vary in seasons, times,
and areas.

• Database of precipitation parameter
• DSD parameter (D0)
• Rain type (conv, strat, shallow,)
• Freezing level (0?C height)
• Storm height
• (Rainfall uniformity information)
• Mean precipitation profile

Rain-bands in a Typhoon
Snow clouds in the winter monsoon
MWR algorithms
More accurate precipitation estimated by MWRs on
the GPM constellation satellites
Stationary front and cloud clusters
Tropical cloud clusters
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Concept of a DPR-calibrated MWR precipitation
algorithm
Global Precipitation Map
NASA, ESA, China, (Quasi-real-time data)
Cut-off time
MWR L1 data
Precipitation Retrieval
L2 (precip) data Composition
Pre-proc

• Quality check
• Rain/no-rain
• Conv/Strat percentage
• In-homogeneity

Unavailable data
DPR data proc system (NASDA)
DPR dynamic Database
Look-up Tables for each MWR (TBs vs Precip)
RTM Calc.
Antenna Convolution

• DSD, Precip-class
• Storm height
• Freezing level
• Mean Precip profile
• (Ocean/Land/Conv/Strat)

• Surface temp
• Humidity

GANAL

• Surface condition (emissivity)

Surface DB
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Time and space Interval of the DPR database
3-days orbit
0.5?0.5deg
?100 pixels
?100 pixels
Color IFOV pixel num
DPR dynamic database will be renewed in 15 deg ?
5 deg grids every 3-10 days
The orbit data was calculated by Y.Iida (Osaka
Prefecture Univ)
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Summary

• Space-borne Precipitation Radar (PR) on TRMM has
  revealed tropical and sub-tropical water budget.
• 2. To observe global precipitation more
  frequently, MWR data have to been used not only
  over sea but also over land.
• 3. In the GPM era, more accurate precipitation
  retrieved by MWR are expected.

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Backup Slides
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Concept of precipitation measurement by the GPM
core satellite
Dual-frequency precipitation radar (DPR) consists
of Ku-band (14GHz) radar KuPR and Ka-band
(35GHz) radar KaPR
Flight direction
GMI
DPR
Range resolution 250m
KuPR (13.6 GHz) swath width245 km
Microwave radiometer swath width 800km
KaPR (35.5 GHz) swath width100 km
5km
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Precipitation measurement with DPR
Detectable range of KaPR (35 GHz) ( cannot
measure heavy rainfall )
Matched beam of KuPR and KaPR
Detectable range of KuPR (14 GHz) ( cannot
measure light rain or snowfall)
Height
Sensitive observation by the KaPR
ICE
SNOW
Discrimination of snow and rain using
differential attenuation
Snowfall measurement in the frigid zones
MELTING LAYAR
KuPR
KaPR
RAIN
Accurate rainfall estimation using differential
attenuation (DSD parameter estimation)
Accurate rainfall measurement in the tropics and
the temperate zones
Radar reflectivity
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DPR Specifications (Requirements)

• Sensitivity is calculated by equiv-SNR at the
  top of precipitation (SNR1 in 1-pulse). Noise
  sampling
• number is 4-times as much as the averaging
  sampling number. Rain rate is defined by
  Z200R1.6

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Concept of the DPR antenna scan
49
37
49
38
13
12
1
1
KaPR 120 km (24 beams)
KuPR 245 km (49 beams)
In the interlacing scan area ( ), the KaPR can
measure snow and light rain in a high-sensitivity
mode with a double pulse width.
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Problems of over-land precipitation retrieval by
MWR
Scatter signals from ice particles in high
frequency are not consistent with surface
precipitation rate
TRMM/PR cannot measure weak precip (ice/snow)
It is difficult to calculate RTM using TRMM PR
profiles
Height
Ground-based radar
TRMM/PR
Emission from land surface is larger than the
emission from precipitation (low-freq)
Radar reflectivity
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Strategy to develop a new MWR retrieval algorithm
3B40RT data TMISSMI (AMSR)
Evaluate over-land rainfall estimates by GPROF
TRMM match-up data set
1B11 2A12 2A25
AMeDAS data
RTM
Development of a new MWR precipitation
retrieval algorithm
Precipitation Parameter
Dynamic database in the GPM/DPR era
GANAL (Surface temp)
RTM
Land surface Data base
MP-radar observation
Variation of Emissivity over land
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Scientific and Social Significance of GPM

• Precision brought by DPR
• High sensitivity to detect light rain and snow
• Accurate estimation of rainfall rate
• Separation of snow from rain

• 3-hourly global rain map by GPM
• Climate change assessment
• Improvement in weather forecasts
• Flood forecasting (Flood Alert System)
• Water resource management
• Agricultural production forecasting

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Observation by Constellation Satellites with
Microwave Radiometer
1
Observation area with MWRs in 3 hours (1, 2, 4
and 8 satellites from top to bottom)
2
Coverages by TRMM PR and GPM DPR in a day
4
8
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International Satellite Constellation
G
TRMM PR,TMI
GPM core DPR,GMI
P
8
NPOESS-1,2,3 CMIS
7
Megha-Tropique
6
M
Number of Satellites
5
4
3
AMSR Follow-on
2
DMSP SSM/I
DMSP SSMIS
NPOESS CMIS
1
90
98
14
12
10
02
96
00
88
92
94
04
06
08
16
18
Year
Obs. Interval (Hour)
16
11
7
5
4
3
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DPR Products (draft)
It is possible to process the level-2 and 3
data in the scene unit of 1/2 or 1/3 orbit
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DPR/MWR Combined Products (Global Precipitation
Map)