# Presentation: 130914

##  Variability of Indian Summer Monsoon Rainfall

**Eric A. Smith (1),**
**Kwo-Sen Kuo (2), Amita V. Mehta (3), and Song Yang (4)**
**(1)**	NASA/Goddard Space Flight Center, Laboratory for Atmospheres (Code 613.1), Greenbelt, MD  20771, USA  [301-614-6286 / eric.a.smith@nasa.gov]
**(2)**	Kwo-Sen Kuo, Goddard Earth Sciences & Technology Center / Caelum Research Corporation ; NASA/Goddard Space Flight Center, Laboratory for Atmospheres (Code 613.1), Greenbelt, MD  20771, USA  [301-6146277 / kskuo@radar.gsfc.nasa.gov]
**(3)**	Joint Center for Earth Systems Technology, Univ. of Maryland in Baltimore County (Baltimore, MD, 21228) @ NASA/GSFC, Laboratory for Atmospheres (Code 613.1), Greenbelt, MD  20771, USA  [301-614-6270 / amita@radar.gsfc.nasa.gov]
**(4)**	I. M. Systems Group, Satellite Meteorology & Climatology Division, Center for Satellite Applications & Research, 5200 Auth Road (WWB - Room 712), Camp Springs, MD  20746, USA  [301-763-8208 / song.2.yang@noaa.gov]

***3rd International TRMM Conference***
***[4 - 8 February 2008 ; ******Las Vegas, NV******]***

**A Tribute to Professor T. N. Krishnamurti**

## Scientific Objectives of Study

**Utilizing most recent and highest-quality global rainfall and climate reanalysis data sets -- i.e., TRMM satellite and ECMWF ERA-40 data products -- develop updated climatological understanding of Indian Monsoon precipitation processes and its various modes of variability.**
**Investigate clarity of relationship between ENSO Index variability and mean rainy season inter-annual anomalies in precipitation -- over monsoon domain.**
**Test validity of ideas from 1970s and 1980s concerning phase-shifted sequence of meteorological events, involving Indian Ocean lower tropospheric ****e**** and ****e**** gradient increases, ABL moisture increases, and 850 hPa zonal KE increases -- followed by surges of rainfall over Indian Sub-continent -- but which at time, were based on results derived from less than ideal rainfall and global analysis data sets.**

## Review of TRMM Blended Algorithm 3b42 Procedure Used for NASA’s Mainstream Estimates of Continuous Surface Precipitation

**[George Huffman and Colleagues}**

**	****TRMM Standard Algorithm 3b42 3-Hourly Product: ****Blended (averaged) rainfall produced from PR, PMW, and IR satellite measurements out to 55o latitudes over 3-hour intervals:**
**1st pass ****fills in ~45% of space-time data field**** ****with rain rate (RR) estimates obtained by averaging instrument-specific PMW retrievals from conical-scan TMI, AMSR-E, SSM/I, & SSMIS radiometer measurements, all vicariously calibrated to high-quality estimates obtained from TRMM ****Combined PR-TMI Standard Algorithm 2b31**** -- invoking multi-satellite averaging calculations every 3 hours.**
**2nd pass ****fills in ~40% of remaining space-time data gaps**** with RR estimates obtained by averaging instrument-specific PMW retrievals from through-nadir-scan AMSU-B & AMSU-E radiometer measurements -- also vicariously calibrated to 2b31 RR estimates.**
**3rd pass ****fills in final ~15% space-time data gaps**** with GEO-IR RR estimates -- produced by probability matching method (PMM) which uses respective IR-EBBT & PMW-RR probability density functions (pdfs).**
**4th pass applies ****final “ground-truth” adjustments**** of satellite estimates using quality controlled / large-area-averaged raingauge rainfall measurements -- affecting mostly continental regions.**

## 9-Year Mean Rainfall (1998-2006) during Indian Summer Monsoon Period (JJAS) from TRMM Blended Algorithm 3b42 (0.25ox0.25o spatial resolution)

**Time Scales:**** (a) hourly / diurnal, (b) daily, (c) monthly, (d) seasonal / intra-seasonal, & (e) inter-annual**

**9-Year Mean Rainfall (1998-2006) during Indian Summer Monsoon Period (JJAS) from TRMM Blended Algorithm 3b42 (0.25ox0.25o spatial resolution)**

## 9-Year Mean Rain Rate (1998-2006) during Indian Summer Monsoon Period (JJAS) from TRMM Blended Algorithm 3b42 (0.25ox0.25o spatial resolution)

**9-Year Mean Rain Rate (1998-2006) during Indian Summer Monsoon Period (JJAS) from TRMM Blended Algorithm 3b42 (0.25ox0.25o spatial resolution)**

## Slide 6

## Annual-Seasonal (JJAS) Rain Rate Anomalies 

**In this short record, no obvious relationship is evident linking ONI with corresponding Monsoon rainfall production.**

## BUT ---- Embedded within Large-scale Southwesterly Flow

**BUT ---- Embedded within Large-scale Southwesterly Flow**
**Westerly Propagating MCSs**
**Below: Two Flood-generating Cases over NW Sub-division (3b42 data)**

**3-hourly time-step for 1 - 20 Aug 2006**
**[units in mm hr****-1****]**

**3-hourly time-step for 1 - 31 Jul 1998**
**[units in mm hr****-1****]**

## Bandpass Filtered (20 - 60 day) Monsoon Season (JJAS)

**Time Series for 9 Years (1998 - 2006) for Circumambient IO**

## Bandpass Filtered (20 - 60 day) Monsoon Season (JJAS)

**Time Series for 9 Years (1998 - 2006) for Indian Sub-continent**

## JJAS Daily Rainfall Time Series (1998-2006 9-year composite), Autocorrelation Structure, & Power Spectrum

## Spatial Cross-Correlation 

**Spatial Cross-Correlation **

## Monthly PDFs of Rain Rate for 2004 at Three Spatial Scales

**Monthly PDFs of Rain Rate for 2004 at Three Spatial Scales**
**[TRMM Combined PR-TMI Algorithm 2b31]**

**Red lines indicate 5 mm hr****-1**** extreme event threshold (over 0.5 deg x 0.5 deg area) -- equivalent to ~150,000 m****3**** of water per hour or ~1.5 10****8**** kg.**

**May is only month indicating significant extreme rainfall.**

## 8-Year (1998-2005) Mean Seasonal Diurnal Cycle of Rainfall

**8-Year (1998-2005) Mean Seasonal Diurnal Cycle of Rainfall**
**[Standard Level 2 TRMM PR-Only Algorithm 2a25]**

**SUMMARY**
**NW Subdivision exhibits continental diurnal signature for three seasons but exhibits oceanic signature during Summer.**
**Indian Sub-continent exhibits uniform continental diurnal signature during Spring and Autumn, while during Winter and Summer, diurnal signature is mixed continental-oceanic.**
**Surrounding Indian Ocean regions exhibit oceanic diurnal signature for most part during Winter, Summer, and Autumn -- during Spring, Indian Ocean becomes largely continental vis-à-vis its diurnal character.**

## Inter-Annual Seasonal / Diurnal Rainfall Sequences (1998 - 2005)

**Summer (JJA)**

**Inter-Annual Seasonal / Diurnal Rainfall Sequences (1998 - 2005)**
**[Standard Level 2 TRMM PR-Only Algorithm 2a25]**

**Autumn (SON)**

## Yang, S., and E.A. Smith, 2006:  Mechanisms for diurnal variability of global tropical rainfall observed from TRMM.  J. Clim., 19, 5190–5226.

**Yang, S., and E.A. Smith, 2008:  Convective - stratiform precipitation variability at seasonal scale from eight years of TRMM observations: Implications for multiple modes of diurnal variability.  *****J. Clim., *****accepted.**
**Yang, S., K.-S. Kuo, and E.A. Smith, 2008:  ****Persistent nature of secondary diurnal modes of precipitation over oceanic and continental regimes****.  *****J. Clim., *****accepted.**

## 9-Year Averaged [1998-2006] Rainy Season Daily Rain Rates

**9-Year Averaged [1998-2006] Rainy Season Daily Rain Rates**
**From TRMM Algorithm 3b42**

## Rainy Season Mean Daily Rain Rates for 9 Individual Years [1998-2006]

**Rainy Season Mean Daily Rain Rates for 9 Individual Years [1998-2006]**

## 7-Year (1998 - 2004) Climatological Daily Mean Rain Rates &

**Total 850 hPa KE within Arabian Sea**** [from ERA-40 Reanalysis]**

**Research from 1970s-1980s, based on less than ideal rainfall and global analysis data, suggested following phase-shift sequence: (1) IO lower tropospheric ****e**** increase and IO-India ****e**** gradient increase; (2) IO ABL moisture build-up; (3) IO 850 hPa zonal KE amplification; and (4) rainfall surge over India.**

## Six Conclusions

**1.****	****TRMM enables very detailed Southwest - East Asian Monsoon seasonal rainfall climatology including its mesoscale elements -- exhibiting its close ties to orographic & surface thermal features -- and provides ****much more refined component-wise depiction**** of large-scale Indian Monsoon.  **
**2.****	****Relationship between inter-annual mean rainy-season precipitation anomalies and ENSO ONI ****is weak -- at best****.**
**3.****	****Precipitation power spectrum is red with significant power in intra-seasonal band -- but ****no other modes ****at Indian Sub-continent scale.**
**4.****	****(a)**** Modal variability properties at circumambient Indian Ocean and Indian Sub-continent scales are ****very different**** ****but with nearly equivalent**** auto-correlation properties -- changing entirely at sub-divisional scale; ****(b)**** spatial cross-correlation properties are scale-dependent with ****strong month-to-month variations****; ****(c)**** extreme events are ****confined to May**** -- not during active monsoon months.**
**5.****	****Diurnal rainfall variability is both ****spatially and temporally complex**** -- only Winter season exhibits expected strong contrast in preferred diurnal period of maxima vis-à-vis late night-morning for Indian Ocean (water) and afternoon-evening for Indian Sub-continent (land).**
**6.****	****Sequential, phase-shifted behavior between lower tropospheric ********e**** & ********e**** gradient, ABL moisture, and 850 hPa zonal KE, followed by rainfall  surges over India, ****has not been found**** using modern rainfall & climate reanalysis data sets -- reinforcing notion that Southwest Monsoon rainfall surges are ****too complex & nonlinear to permit event-sequence forecast schemes****.**

## Thank You

## Backup Slides

## Global Water Cycle -- Recent View

## 1.	NASA/JAXA TRMM Experimental Low Inclination LEO NSS Satellite: Through-Nadir-Scan/Ku-band (35 GHz) Precipitation Radar (PR) & Conical Scan/Multi-Channel TRMM Microwave Imager (TMI) PMW Radiometer

**2.****	****3 IPO DMSP Operational LEO SS Satellites: ****Special Sensor Microwave Imager (SSM/I) & Special Sensor Microwave Imager-Sounder (SSMIS) Conical-Scan/Multi-Channel PMW Radiometers**
**3.****	****NASA AQUA Experimental LEO SS Satellite: ****Conical-Scan/Multi-Channel Advanced Microwave Scanning Radiometer for EOS (AMSR-E)**
**4.****	****5 International Operational GEO Satellites (2 GOES, 1 GMS, 1 METEOSAT, & 1 MSG): ****IR Window Channels on Imaging Telescope-Radiometers**
**5.****	****2 NOAA POES Operational LEO and 1 NASA AQUA Experimental LEO SS Satellites: ****Through-Nadir-Scan/Multi-Channel Advanced Microwave Sounding Units (AMSU-B & AMSU-E)**

**Review of Current Satellites, Satellite Instruments, & Blended Algorithm Procedure Used for NASA’s Mainstream Estimates of Continuous Precipitation (1)**

## 6.	NASA/CSA CloudSat Experimental LEO SS Satellite: Nadir-Pointing/Non-Scanning W-band (94 GHz) Cloud Profiling Radar (CPR)

**7.****	****TRMM Standard Algorithm 3b42 Delayed Realtime 3-Hourly Product: ****Blended (averaged) precipitation estimates produced from PMW and IR satellite measurements out to 55o latitudes over 3-hour intervals:**
**1st pass produces multi-satellite rain rate (RR) estimates by averaging instrument-specific PMW retrievals from conical-scan TMI, AMSR-E, SSM/I, & SSMIS radiometer measurements, all vicariously calibrated to RR estimates from Standard TRMM Combined PR-TMI Algorithm 2b31 -- invoking multi-satellite averaging calculations every 3 hours -- process which ****fills in ~45% space-time data field**
**2nd pass ****fills in ~40% of remaining space-time data gaps**** with RR estimates obtained by averaging instrument-specific PMW retrievals from through-nadir-scan AMSU-B & AMSU-E radiometer measurements -- also vicariously calibrated to 2b31 RR estimates**
**3rd pass ****fills in final ~15% space-time data gaps**** with GEO-IR RR estimates -- produced by probability matching method (PMM) which uses respective IR-EBBT & PMW-RR probability density functions (pdfs)**
**4th pass finalizes RR estimates by adjusting satellite-only RR estimates (from 3rd pass) with QC’d/large-area-averaged rain-gauge rainfall measurements -- invoked mostly over continental regions**

**Review of Current Satellites, Satellite Instruments, & Blended Algorithm Procedure Used for NASA’s Mainstream Estimates of Continuous Precipitation (2)**

## India’s Political Boundaries & Homogeneous Monsoon Rainfall Regions

**India’s Political Boundaries & Homogeneous Monsoon Rainfall Regions**

**  ****1. Andaman & Nicobar Islands**
**  ****2. Arunachal Pradesh**
**  ****3. Assam & Meghalaya**
**  ****4. Naga., Mani., Mizo., & Tripura**
**  ****5. Sub-Him. West Bengal & Sikkim**
**  ****6. Gangetic West Bengal**
**  ****7. Orissa**
**  ****8. Jharkhand**
**  ****9. Bihar**
**10. East Uttar Pradesh**
**11. West Uttar Pradesh**
**12. Uttaranchal**
**13. Haryana, Chandigarh, & Delhi**
**14. Punjab**
**15. Himachal Pradesh**
**16. Jammu & Kashmir**
**17. West Rajasthan**
**18. East Rajasthan**
**19. West Madhya Pradesh**
**20. East Madhya Pradesh**
**21. Gujarat**
**22. Saurashtra, Kutch, & Du**
**23. Konkan & Goa**
**24. Madhya Maharashtra**
**25. Marathwada**
**26. Vidarbha**
**27. Chattisgarh**
**28. Coastal Andhra Pradesh**
**29. Telangana**
**30. Rayalaseema**
**31. Tamil Nadu & Pondicherry**
**32. Coastal Karnataka**
**33. North Interior Karnataka**
**34. South Interior Karnataka**
**35. Kerala**
**36. Lakshadweep**

## Climatological Precipitation Properties of Indian Summer Monsoon Over Range of Space-Time Scales During 1998 - 2006 Time Period

## Rainfall Animation over NW Sub-division

**Rainfall Animation over NW Sub-division**
**TRMM Algorithm 3b42 Observations**
**[3-hourly time-step for 1 - 31 July 1998 : units in mm hr****-1****]**

## Rainfall Animation over NW Sub-division

**Rainfall Animation over NW Sub-division**
**TRMM Algorithm 3b42 Observations**
**[3-hourly time-step for 1 - 20 August 2006 : units in mm hr****-1****]**

## Rainfall Animation over NW Sub-division

**Rainfall Animation over NW Sub-division**
**TRMM Algorithm 3b42 Observations**

**3-hourly time-step for 1 - 20 Aug 2006 [units in mm hr****-1****]**

**3-hourly time-step for 1 - 31 Jul 1998 [units in mm hr****-1****]**

## Bandpass Filtered (20 - 60 day) Monsoon Season (JJAS) Time Series for 9 Years (1998 - 2006) for NW Sub-division

**Bandpass Filtered (20 - 60 day) Monsoon Season (JJAS) Time Series for 9 Years (1998 - 2006) for NW Sub-division**

## Inter-Annual Seasonal / Diurnal Rainfall Sequences (1998 - 2005)

**Winter (DJF)**

**Spring (MAM)**

**Inter-Annual Seasonal / Diurnal Rainfall Sequences (1998 - 2005)**
**[Standard Level 2 TRMM PR-Only Algorithm 2a25]**

## Diurnal Cycle of Seasonal Rainfall for 8 Years (1998 - 2005) at 3 Spatial Scales

**Diurnal Cycle of Seasonal Rainfall for 8 Years (1998 - 2005) at 3 Spatial Scales**
**[Level 2 Standard TRMM Combined PR-TMI Algorithm 2b31]**

**Yang, S., and E.A. Smith, 2006:  Mechanisms for diurnal variability of global tropical rainfall observed from TRMM.  *****J. Clim.*****, ****19****, 5190–5226.**
**Yang, S., and E.A. Smith, 2007:  Convective - stratiform precipitation variability at seasonal scale from eight years of TRMM observations: Implications for multiple modes of diurnal variability.  *****J. Clim., *****accepted.**
**Yang, S., K.-S. Kuo, and E.A. Smith, 2007:  ****Persistent nature of secondary diurnal modes of precipitation over oceanic and continental regimes****.  *****J. Clim., *****accepted.**

## Diurnal Cycle of Seasonal Rainfall for 8 Years (1998 - 2005) over Circumambient IO

**Diurnal Cycle of Seasonal Rainfall for 8 Years (1998 - 2005) over Circumambient IO**
**[Three Level 2 Standard TRMM Algorithms: PR-Only (2a25), TMI-Only (2a12), & PR-TMI Combined (2b31)]**

## Diurnal Cycle of Seasonal Rainfall for 8 Years (1998 - 2005) over Indian Sub-Continent

**Diurnal Cycle of Seasonal Rainfall for 8 Years (1998 - 2005) over Indian Sub-Continent**
**[Three Level 2 Standard TRMM Algorithms: PR-Only (2a25), TMI-Only (2a12), & PR-TMI Combined (2b31)]**

## Diurnal Cycle of Seasonal Rainfall for 8 Years (1998 - 2005) over NW Sub-Division

**Diurnal Cycle of Seasonal Rainfall for 8 Years (1998 - 2005) over NW Sub-Division**
**[Three Level 2 Standard TRMM Algorithms: PR-Only (2a25), TMI-Only (2a12), & PR-TMI Combined (2b31)**