# Presentation: 883093

## Global Precipitation Measurement (GPM) Progress

***Taipei, Taiwan***
***September 20, 2005***

*Ramesh K. Kakar , Steven P. Neeck*
*NASA Headquarters*
*John Durning, Arthur Hou*
*NASA Goddard Space Flight Center*

***Global Precipitation Measurement (GPM) Progress***

## Introduction

***Will Increase our Understanding of the Water Cycle and How it is Used***
*Builds upon the highly successful NASA-JAXA TRMM experience*
*Extends precipitation measurement globally with greater frequency and accuracy*
***Earth Observing “System of Systems”***
*Heterogeneous constellation*
*Integrates previously planned and dedicated missions*
*Evolvable to incorporate new capabilities as they become available*
*Implementation approach highly consistent with goals from Earth Observing Summit*
***Includes Many Nations and Agencies***
*Japan is primary partner*
*ESA has studied the contribution of a constellation satellite, EGPM*
*France and India have expressed interest in participating through the Megha-Tropiques Project*
*Taiwan is studying the contribution of a constellation satellite*
*Brazil and others have expressed interest in participating*
*	*
***Currently in Formulation Phase (Phase B) engaged in preliminary design***
***Target Launches 2010 - 2012***

## Science Objectives

***Improving flood hazard & basin-scale hydrological predictions****** -- through more frequent sampling and full-earth coverage of precipitation measurements***
***Improving climate  prediction****** -- through better understanding of water cycling and accompanying accelerations -- decelerations of atmospheric and surface branches of water cycle***
***Improving weather forecasting****** -- through better methods of rainfall data assimilation and more accurate & precise measurements of instantaneous rainrates***
***Applications Impacting the World’s Population Will Be Enabled In:***
***Freshwater Utilization and Resource Management***
***Global Water Cycle Trends***
***Natural Hazard Monitoring/Prediction***
***Flood Warnings***
***Tropical Cyclone Observation***
***Winter Weather Events***
***Weather Forecasting***
***Climate Change Assessment***
***Agriculture***
***Transportation***
***Policy and Planning***

**GPM is Being Formulated within Context of GWEC ****Focusing On:**

## GPM Reference Concept

_***Core Spacecraft***_
***Dual Frequency Radar***
***Multi-frequency Radiometer***
***H-IIA Launch***
***TRMM-like Spacecraft***
***Non-Sun Synchronous Orbit***
***~65° Inclination***
***~400 km Altitude***
***~5 km Horizontal Resolution***
***250 m Vertical Resolution***

_***Constellation Satellites***_
***Multiple Satellites with Microwave Radiometers***
***Sampling Sufficient to Resolve the Diurnal Cycle***
***Sun-Synchronous Polar Orbits***
***~600 km Altitude***

***  ******Understand the Horizontal and Vertical Structure of Rainfall and Its Microphysical Element.  Provide Training for Constellation         Radiometers.***

***  ******Provide Enough Sampling to Reduce Uncertainty in Short-term Rainfall Accumulations.  Extend Scientific and Societal Applications.***

_***Global Precipitation Processing System***_
***Capable of Producing Global Precipitation Data Products from Diverse Sensors and Sources***
***Cooperative International Partnerships***

_***Precipitation Validation Sites  ***_
***Ground Truth and Calibration***
***Cooperative International Research***

***MISSION:  Improve climate, weather, and hydrological forecasts through more frequent and more accurate measurement of precipitation.***

## Partner Responsibilities

***NASA is responsible for***
*Key elements of the Core observatory (spacecraft, ground system, and the GMI instrument) *
*One constellation spacecraft and its ground system*
*Precipitation Processing System (PPS)*
*Two Ground Validation Supersites*
***JAXA is responsible for ***
*The Ka-band Precipitation Radar (to fly on the Core spacecraft)*
*The Ku-band Precipitation Radar (to fly on the Core spacecraft)*
*The launch vehicle for the Core spacecraft*
***Other US agencies (i.e. DOD & NOAA) ***
*Will contribute radiometer rainfall measurement data streams from existing and planned satellites for ingest by the to PPS *
***Other international partners ***
*Invited to support GPM by providing spacecraft, instruments, rain gauge networks, ground validation facilities, etc.*

## Constellation Build-Up

**90**

**98**

**14**

**12**

**10**

**02**

**96**

**00**

**88**

**92**

**94**

**04**

**06**

**08**

**16**

**18**

***Megha Tropiques***

***Partner-2***

**SSM/I Era**

**GPM Era**

**TRMM Era**

**Systematic Measurement Era**

**Adjunct**
**Base**

**Breakthrough:**

**Integrated**
**Precipitation**
**Data System**
**Experiment**

**High Spatial-Temporal Resolution & Calibrated GPM Demo**

**Science Quality Tropical Rainfall Measurements**

**Reliable**
**Radiometric Rainfall Estimation**

**Mature Global Precipitation Observing System**

- Local Time (AN)

- 19:30

- N/A

- N/A

- 2:30

- TBD

- 22:30

- 13:30

- 20:30

- 17:30

- Inclination

- 98.6o

- 22o

- 35o/65o

- 97.9o

- TBD

- 98.6o

- 98.2o

- 98.7o

- 98.7o

**3-****Hour Sampling Coverage**

**35%**

**45%**

**70%**

**85%**

**Years**

**EGPM**

**DMSP**
**SSM/I**

**DMSP**
**SSM/I**

**DMSP**
**SSMIS**

**DMSP**
**SSMIS**

**NPOESS**
**CMIS**

**NPOESS**
**CMIS**

**AQUA**
**AMSR**

**GCOM-W**
**AMSR**** F/O**

**NPOESS**
**CMIS**

**TRMM**
**TMI + PR**

**GPM Core**
**GMI + DPR**

**NASA Const**

## NASA Space Segment Contributions 

***Core Spacecraft***
*Dual-frequency Precipitation Radar (provided by JAXA/NICT)*
*GPM Microwave Imager*
*407 km altitude, 65 degree inclination*
*3200 kg, 1650 W*
*Nearly continuous downlink via TDRSS (TDRSS-MA ~230 kbps, TDRSS-SA ~4Mpbs)*
*H2A-202 launch (proposed by JAXA) from TnSC (Japan)*
*3 year lifetime (expendables sized for 5 years)*
***NASA Constellation Spacecraft***
*GPM Microwave Imager*
*635 km altitude, inclination and TAN will be based on coverage studies*
*500 kg, 400 W*
*Nearly continuous downlink via TDRSS (TDRSS-MA ~50 kbps)*
*Taurus-class launch from VAFB*
*3 year lifetime (expendables sized for 5 years)*

## GPM Microwave Imager (GMI)

**Ball Aerospace and Technology **
**Corporation (BATC) design:**

**2.4 ****m**

**1.0 ****m**

**1.2 ****m**

_**GMI Key Parameters**_
- Mass:~100 kg
- Power:~90 W
- Data Rate:~25 kbps
- Antenna Size:~1.2 m Diameter
- Channel Set:
- 10.65 GHz, H & V Pol
- 18.7 GHz, H & V Pol
- 23.8 GHz, V Pol
- 36.5 GHz, H & V Pol
- 89.0 GHz, H & V Pol
- (166 GHz, H & V Pol, and 183 GHz GHz, H & V Pol enhancement options)

## GMI Required Frequencies

| Chan. | CenterFreq. [GHz] | Pol. | Band-width [MHz] | Cent. Freq.  Stab. [MHz] | Sample Interval [ms] | NET [K] | Beam-width [deg.] |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 10.65 | V | 100 | 10 | 3.6 | 0.91 | 1.75 |
| 2 | 10.65 | H | 100 | 10 | 3.6 | 0.91 | 1.75 |
| 3 | 18.7 | V | 200 | 20 | 3.6 | 0.77 | 1.00 |
| 4 | 18.7 | H | 200 | 20 | 3.6 | 0.77 | 1.00 |
| 5 | 23.8 | V | 200 | 20 | 3.6 | 0.84 | 0.90 |
| 6 | 36.5 | V | 1000 | 50 | 3.6 | 0.45 | 0.90 |
| 7 | 36.5 | H | 1000 | 50 | 3.6 | 0.45 | 0.90 |
| 8 | 89.0 | V | 6000 | 200 | 3.6 | 0.55 | 0.40 |
| 9 | 89.0 | H | 6000 | 200 | 3.6 | 0.55 | 0.40 |

## GMI High Frequency Channel Option

- Additional four channels at millimeter-wave frequencies,  i.e. 166 GHz (‘window channel’)  and 183.31 GHz (‘water vapor absorption line’).
- A decision to exercise this option was made last week.
- Channels will permit advancement of retrievals of light rain and snow over land and ocean at the higher latitudes observed by GPM.

## GMI High Frequency Channel Characteristics

| Chan. | CenterFreq. [GHz] | Pol. | Band-width [MHz] | Cent. Freq.  Stab. [MHz] | Samp.Interv.[ms] | NET [K] | Beam-width [deg.] |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 10 | 166.0 | V | 4000 | 200 | 3.6 | 1.2 | 0.40 |
| 11 | 166.0 | H | 4000 | 200 | 3.6 | 1.2 | 0.40 |
| 12 | 183.31 ±  3.0 | V | IF  2500
RF  5000 | 100 | 3.6 | 1.2 | 0.40 |
| 13 | 183.31 ± 9.0 | V | IF  3000 
RF  6000 | 100 | 3.6 | 1.3 | 0.40 |

## GMI Instantaneous Field-of-Views

- _GPM / GMI at 407 km_

- _TRMM / TMI at 350 km_

## Ground Segment Overview

***Mission Operations System***
*Nearly continuous downlink of GMI data through TDRSS allows “virtual broadcast” of precipitation data*
*IP return and forward link space-ground data transmissions*
*Substantial autonomy*
***Precipitation Processing System***
*Evolution of TRMM Data Information System (TSDIS)*
*Prototyping to aid in GPM development *
*3B42 3 hour product (TRMM, SSMI, Geo IR)*
*GV pilot projects*
***Ground Validation System***
*Rainfall measurement validation and error characterization*
*Integrated component of Ground Segment*

## Ground Validation Objectives

***Error Characterization of the Satellite Retrievals***
*Quantifies the error in the satellite products independent of observations at the GV Sites.*
*Provides bias estimation and error covariance estimation.*
*Addresses error characterization of satellite retrieval products such as rainfall rate (Rsrfc), integrated liquid water content (ILWC), and drop size distribution (DSD).*
***GPM Satellite Algorithm Improvement***
*Radiometer Algorithms, Dual-Frequency Precipitation Radar (DPR), and Combined Algorithms.*
*Improvement through evaluation and increased understanding of the physical assumptions upon which the retrieval algorithms rely.*
***Research***

## GPM Standard Data Product Types

***Continuously Updated Rainmap***
*Target users:  outreach, general public*
*Radiometer level 2 rain retrieval from all partner radiometers*
***Quick-access (quasi realtime) Global Precipitation Products***
*Target users: applications researchers and modelers*
*Constellation radiometer data “reference calibrated” by core satellite instruments*
*Rain rate retrievals from radar, radiometer*
*NASA GMI radiometer available in less than 20 minutes from collection*
*Other data available within ~10 minutes of receiving from partners*
*3 hour gridded merged product including IR data *
*Available upon completion of product *
***Research products***
*Target users: precipitation research scientists*
*Swath products from all instruments and satellites (similar to current TRMM products)*
*Gridded products that combine retrievals from all instruments at various time and space sampling.*
*Gridded/merged product that blends rain retrievals from all instruments including IR where necessary to achieve completeness*
*Available no later than 48 hours after receiving all required input data*

## Status 

***Technical***
*Formulation Phase (Phase B) continues with emphasis on preliminary design*
*GPM Microwave Imager development proceeding*
*Contracted awarded to Ball Aerospace Technologies Corporation*
*Delivery in 2009*
*Rapid Spacecraft Acquisition (RSA) of Core Spacecraft*
*Phase A Studies by 3 vendors completed*
*Proposals for Phase B Follow-on Study contracts under review*
*Dual-frequency Precipitation Radar development proceeding*
*KuPR engineering model in development*
*KaPR engineering model undergoing testing*
***Budget***
*FY2005 Budget funds GPM at $29M *
*President’s FY2005 proposed budget funds GPM at $24M in FY2006*
***International Partnerships***
*This 2nd International Ground Validation Workshop *
*5th GPM Workshop scheduled for November 2005*