# Presentation: 250905

## TRMM and GPM research activities in Japan

_***Riko Oki ***_***(JAXA/EORC)******Tetsuo Nakazawa (MRI) ****** Kenji Nakamura (Nagoya Univ./HyARC)******Toshio Iguchi (NICT)***

## TRMM science teams in Japan

*5 times of research announcement. The first started  before the launch*
*Approx.20-30 PIs have been organized as science teams every time*
*Project scientists: *
*Prof. Tsuyoshi Nitta (Univ. of Tokyo) *
*Prof. Kenji Nakamura (Nagoya Univ.)*
*Dr. Tetsuo Nakazawa (MRI) *
*International PR team lead by Prof. Okamoto*
*JAXA, Dr. R. Meneghini, Prof. J. Awaka, Dr. T. Iguchi, Prof. Kozu and several people. *
*The 5**th** science team in Japan covers TRMM and GPM sciences as Precipitation Mission science from JFY07 to JFY09. *

## TRMM results in Japan

*Demonstration of high quality and high reliability of a satellite onboard precipitation radar*
*Accurate observation by the multiple sensors*
*Improvement of MWR precipitation retrieval by PR 3D observation*
*Pioneering precipitation system climatology by PR observation*
*Long term observation beyond 10 years. Uniform information by PR. *
*Tropical cyclones*
*Diurnal variation**・**seasonal variation of rainfall*
*El Nino and La Nina*
*Retrieval of latent heating profile*
*Operational use*
*Near real time distribution & Long term continuation of TRMM/TMI data initiated the use of MWR data from EO satellites in the NWP system at JMA. *
*Flood warning system by IFNet. *
*Development of new products*
*Soil moisture by PR*
*Sea Surface Temperature by TMI*
*Global rain map (GSMaP)*
*Significance of long term observation*
*Expanding application use of the data in various fields*
*More reliable climatology and statistics of precipitation data*
*Expectation of data continuity to GPM*

## High Stability of PR

*High Stability of PR*

*Characteristics of PR*
***Use of solid-state power amplifiers (SSPA) in the transmitter.***
***No high-voltage power supply required.***
***Active phased array antenna for fast scanning.***
***No mechanical component in the system***
*Monitoring the PR calibration factor and its long term variation*
***Monitoring the health of PR’s various components by using the internal calibration and operation analysis mode, and transmitting power monitor******⇒All components including the 128 T/R elements are working properly.***
***External calibration of the over-all performance by using an active radar calibrator (ARC) twice a year. ******⇒PR’s absolute calibration accuracy is better than ±1 dB***

- 2004/4/1

- 2007/4/1

**Long term variation is less than 0.2 dB**

- Variation of daily averages of the sea surface scattering cross section in no-rain conditions at the incidence angle of 6.4 degrees

- PR is extremely stable.  PR’s long term stability that is estimated from the variation of sea surface scattering cross sections in no rain conditions is better than 0.2 dB.

- PR can be used as a flying radar calibrator that realizes intercomparisons between ground-based radars.

- For more than 10 years, PR has been working flawlessly.  All components including the 128 elements of the T/R system have shown no sign of trouble.  It has provided high quality three-dimensional rain data steadily. It is used as a intercalibration tool for ground-based radars.

**0.2dB**

## Accurate observation of rainfall by the multiple sensors

- annual・longitude average rain amount(mm/month)

- More than 100% difference between the max. and min. was seen before TRMM(left, red lines). TRMM reduced the differences and in the current V6 products the differences are less than 10% over the ocean (upper right) and approx. 20% over land (lower right).

- Red:Rain retrievals by MWR algorithms before TRMM
- Black: Retrieved rainfall by TRMM version-5 algorithms

- Equator

**Ocean**

**Land**

- Longitudinal average of rainfall of V6. Red: PR, Blue: TMII. (J. Stout, NASA/GSFC)

-  (NASA/GSFC)

**From Ver.5 to ****  ****Ver.6**

**TRMM Products**

**Before TRMM**

**TRMM V5**

- TRMM以前のマイクロ波放射計アルゴリズムによる降水推定のばらつき

- Difference between PR and TMI in V5

## Diurnal cycle of rainfall observed by PR

** ****Morning rain**

**Afternoon rain**

**March, 1998****-****February, 1999**

- 10

- -10

- (Nakamura et al., Nagoya University)

- Although only points data were available before TRMM (upper left), diurnal cycle of rainfall has been observed by PR all over the tropics (upper right). Afternoon rain (red) is dominant over the lands and morning rain (blue) is dominant over the ocean. Time difference of max. rain peak depending to the size of the islands is clear. Information obtained by TRMM/PR can be utilized to improve climate models whose spatial and temporal resolution becomes finer to simulate diurnal cycle.

**Example of diurnal cycle of rainfall in Tropics observed by ground observations**

- 10-year averaged diurnal cycle of rainfall at 4 points on the East cost of the Malay Peninsula. Clear peak in afternoon.  (Oki and Mushiake, 1994)

**Morning**

**Afternoon**

**Wide area is covered by PR**

**Diurnal cycle of rain observed by PR**

## Classification of Rain Systems

**DJF 2001**** ****thrsh=15**

**(Land)**** **
**0: Severe Thunderstorm**
**1: Afternoon Shower**
**2: Shallow**
**3: Ext-trop Frontal Systems **
**4: Organized **
**5: High Land**
**(Ocean)**** **
**6: Shallow**
**7:Ext-trop Frontal Systems **
**8:Transition Z.**
**9: Organized **

**SON 2001 ****  ****thrsh=15**

**   ****0      1      2      3     4      5      6      7      8     9**
**                  ****Land****                    |          ****Ocean**

- Takayabu and Katayama

- 3mo, 2.5degx2.5deg

**Notes:**
Applying this algorithm in 2.5degx2.5deg grid for 3months, we could identify 10 classes of the dominant rain systems. Those are, .....
These results are utilized in other projects such as the high-accuracy and high-resolution precipitation mapping ‘GSMaP’. 

## Estimations of latent heating profile 

**8km**

**5km**

**2km**

**Monthly averaged surface rainfall **

**(Left) Estimated latent heating ratio at different heights. ****Red: heating, ****Blue: cooling. **(Takayabu et al., University of Tokyo)

*Estimations of latent heating profile *

- Atmospheric heating profile has been estimated by SLH algorithm using PR3D information. The data can be utilized for evaluation of global water & energy cycle and for improvement of climate models.

- To estimate latent heat profile is listed up as one of the scientific goals of TRMM mission.

- ←relationship between tropical rainfall and general circulation (NASA)

## Near real-time high resolution global precipitation map product

- Utilizing the results of the GSMaP(Global Satellite Mapping of Precipitation) project sponsored by the Japan Science and Technology Agency
- 0.1 degree grid, one hour averaged precipitation map
- Use Microwave Radiometer & sounder data  such as AMSR-E, SSM/I, TRMM/TMI, AMSU-A/B
- Available on the web about four hours after observations (http://sharaku.eorc.jaxa.jp/GSMaP/)

## Correction of PR estimated rain after the boost

## Issues toward GPM

***Precipitation observation in tropics to the globe***
***Accurate observation of liquid phase precipitation (***_***strong to weak***_***) ***
***    ******and ***_***solid phase***_*** precipitation (snowfall******・******hail******)***
***Improvement of MWR algorithms using DPR in mid-high ***
***    ******latitude including over ***_***land***_
*→ **high sensitivity observation by GPM/DPR*
***Limitation of single frequency observation of PR***
***The difference between PR and TMI***
***Over ocean: 40%  in Ver.4******(******1998.Oct******)******, 24% in Ver.5******(******1999.November******) ***
***    ******and 10% Ver.6******(******2004.June) . Over land: bigger than 20%. ***
***    ******Also depends on seasons and regions. ***
***User requirement is 10% error in monthly average. To realize this level of accuracy, dual frequency observation is necessary. ***
*→ **dual frequency (Ku and Ka) observation by GPM/DPR*
***Frequent observation***
***Frequent data is necessary for operational uses***
*→ **utilization of MWRs and MW sounders in entire GPM mission*
***Long term continuation of precipitation observation***
***Important to accumulate radar and MWR observation from TRMM PR/TMI to GPM DPR/GMI***
***Near real time data use***
***Need continuation of near real time data distribution for operational users such as NWF and flood warning systems***

- GPM

- 観測値(黒)とモデルによる降雨の緯度分布(Gates et al. (1999)による)

- TRMM

## Objectives of the JAXA’s GPM/DPR Project

- Mission requirements of the GPM total system realized by international cooperation

- Global precipitation observation including solid precipitation

- Highly accurate observation
- ・Observation of the vertical structure of precipitation
- ・Identification of solid precipitation
- ・Observation of the weak rain and snowfall
- ・Estimation of DSD
- ・Improvement of the precipitation estimation accuracy of MWRs using DPR data

- Highly frequent observation
- ・Diurnal cycle observation
- ・Highly frequent observation, and near real-time data processing and distribution to users

- Continuous observation of the precipitation with the sensitivity of 0.2mm/h from the non sun-synchronous orbit (inclination: 65 degrees)

- ±10% accuracy achievement of the latitude distribution of the monthly averaged global precipitation

- Near real-time distribution of the GMI and other constellation satellite data, and the global precipitation map product

- Mission Requirements of GPM/DPR system

- Daily averaged rainfall estimation accuracy of better than ±40% for the basin area larger than 20000m2

***Objectives of the JAXA’s GPM/DPR Project***

- Demonstration of the technology of the DPR

- Highly accurate & frequent global precipitation observation for climate and water cycle change

- Near real-time global precipitation map distribution
- Data utilization method development

- Development and demonstration of the improved precipitation derivation method of the MWRs using DPR data

- Application demonstration for operational use, such as flood prediction, numerical weather forecast, prevention of the damage from a storm and flood

- Objectives of  GPM/DPR project

## GPM Progress and Status – Program Level -

*Review results by the government*
*Japanese Space Activity Committee (SAC) reviewed moving of the GPM/DPR project from phase B to phase C/D in July-August, and it was approved.*
*Council for Science and Technology Policy  (CSTP) reviewed the GPM/DPR project in Sep. – Oct., and it was concluded that GPM/DPR is the very important project in the long range view.*
*Letter exchange between Dr.Stern and Dr.Horikawa to re-confirm GPM core observatory launch in the summer of 2013.*

## The new science team

- JAXA selected new PIs to cover JFY07-09 TRMM/GPM science activities through th 5th RA by TRMM budget and organized a new science team
- Focusing research areas
- (1) Research to contribute to understand climate change and global water cycle
- (2) Synergy of TRMM and other satellite data
- (3) Advanced utilization of TRMM/PR data for GPM
- (4) Climatological research using long-period TRMM data
- (5) Research for operational purposes
*Members*
*Through the 5**th** Precipitation Science Mission RA 14 PIs were selected. *
*Started a new cooperative/contract research with 3 TRMM/PR standard algorithm developers. *
*Started a new contract research with 1  DPR/GMI combined algorithm developer. *
*totally18 PIs*
*1**st** meeting was held on 15**th** August*
*A new GPM algorithm team under this science team*
*Leaders*
*entire team: Prof. Nakamura, DPR: Dr. Iguchi, combined: Prof. Masunaga, Map: Dr. Aonashi*
*1**st** meeting was held in October. Once per 2 months. *

## Algorithm development by the GPM algorithm team

*Level 1 algorithm of DPR is investigated by JAXA.*
*We are now creating simulation Level 0 data for the science telemetry format of DPR.*
*carried out *_*the experiment for KaPR geometric simulation data*_* using TRMM PR in March 2007.*
*Higher level DPR algorithms are investigated by algorithm developers in GPM science team.*
*Finished 4-year (2-year * 2) joint research activities based on Research Invitation*
***just started  new algorithm developing activities*
*DPR/GMI combined algorithm has been investigated by the algorithm development team. *
*** **Started a contract research to Nagoya University. (JFY2007)*
*Development of precipitation map algorithm including microwave radiometer algorithm has been continued cooperation with GSMaP project. JAXA will succeed activities of GSMaP under the GPM project. *

## Summary

*By Japanese bureaucracy, TRMM is known as a successful mission in science and also in international relationships. *
*Japan has made a lot of efforts to develop PR and its algorithms. **** demonstration of the first space borne precipitation radar. *
*Many important scientific results have been obtained especially using PR data.  **** ‘Precipitation system climatology’ *
*Near real time distribution of TRMM data had big impacts for operational users. (Weather forecasts and flood warning) *
*GPM mission in Japan owes everything on the** “**full” success of TRMM.*
*Japan will focus on DPR, its algorithm development and Ground Validation through validation of DPR data. *
*Has a meaning of ‘bridge mission’ to operational system. *