1. MICROWAVE RAINFALL RETRIEVALS AND VALIDATIONS R.M. GAIROLA, S. POHREL & A.K. VARMA OSD/MOG SAC/ISRO AHMEDABAD

2. Development of algorithms for rain rate retrievals over land and oceans Validation & fine-tuning of algorithm using ground based measurements like Doppler Weather Radar (DWR) & rain gauges etc. over Indian region (land & ocean) Study of some cases of monsoon, flash floods & cyclone rainfall using the developed algorithms Study of hydrological processes to assess the accuracy of the retrievals ISSUES AND OBJECTIVES :

5. Physical Approach Forward Modeling (Radiative Transfer Simulations)

7. Water vapour versus simulated TB’s - TMI Channels For Non-Raining Atmospheres:

8. CLW versus Simulated TB’s – TMI Channels

10. Assumption:- For an isotropic field the ratio of the second moment of the radiation field to the mean intensity is everywhere equal to 1/3. RTR for Raining Atmospheres Eddington approximation Assumption:- Cross-polarization is negligible and the scattering phase function follow Henyey-Greenstein equation. Discrete Ordinate Approximation Model used:- Kummerow et al., 1993 Model used:- Liu, 1998

12. Observations from TRMM-TMI and PR (V-Blue, H-Red)

22. Examples from Data: Tropical Rainfall Measuring Mission (TRMM) TRMM Microwave Imager (TMI); 85.5 GHz Precipitation Radar (PR); 13.8 GHz Data Product (Version 6): 2A25 for Radar Reflectivity 1B11 for Brightness Temperature 2A12 for Latent Heat information

23. 300 275 250 225 200 Spatial distribution of BT (85.5 GHz, Vertical) over Eastern India

24. 50 30 20 10 0 Spatial distribution of Near Surface PR Reflectivity (dBZ) over Eastern India

25. Number of Pixels (a)Spatial variation of BT(85.5 GHz) for convective and stratiform region and (b) Corresponding vertical cross section of PR Reflectivity (dBZ) (a) (b)

26. RETRIEVAL ALGORITHMS FOR OCEAN & LAND (MR Approach) OCEANIC RAINFALL Use of emission (at low frequency) & scattering (at high frequency) signatures with suitable statistical model: R = a0+a1.ln(Tb19v–Tb19h)+a2.ln(Tb22v –180)+a3.ln(Tb85v-Tb19v) LAND RAINFALL Use of scattering signatures at high frequencies R = c0 + c1.PCT + c2.SI [PCT=1.818TB85v–0.818TB85h ], [SI=E 85v (10v,19v,21v) – TB85v] E 85v (10v, 19v, 21v) = b0+b1.Tb10v+b2.Tb19v + b3.TB21v (b i coeff. derived for non-raining conditions)

27. TRMM-TMI Rainfall from NASA & Present Algorithms NASA TMI Rain (mm/hr)Present TMI Rain (mm/hr) AUGUST 2, 2002

28. COMPARISON OF RAINFALL FROM NASA, PR & PRESENT ALGORITHMS NASA TMI RAINRATE NASA PR RAINRATE TMI RAINRATE (PRESENT ALGORITHM) OCTOBER 10, 2002

29. TRMM-TMI Rainfall from NASA-GPROF and SAC Algorithm, Aug 2, 2002

30. Output Layer Hidden Layer Input Layer ----- Training ----- Testing Fig. ANN architecture having four inputs as brightness Temp and one output as radar rainfall Fig. 3. ANN error distribution for training

31. Observed Rain Rate ANN Rain Rate RETRIEVAL ALGORITHMS FOR OCEAN & LAND (ANN Approach)

32. Fig. Observed and ANN rain rate for the geographical area used for testing the performance of the ANN. Observed Rain Rate ANN Rain Rate

33. VALIDATIONS

34. GROUND-BASED OBSERVATIONS BY DOPPLER WEATHER RADAR (CHENNAI) Original Image

35. COMPARISON OF TRMM RAINFALL USING DWR DATA OCTOBER 17, 2002 NASA-GPROF RAINFALL PRODUCT

37. TRMM Rain (mm/h) Statistics (17-Oct-02) 1.With 0.5 degree elevation r = 0.67 Total Points: 256 rms diff: 4.592406 2. With 1.5 degree elevation r = 0.63 Total Points: 256 rms diff: 4.725613594 SHAR-DWR Rain (mm/h) Ele: 1.5 SHAR-DWR Rain (mm/h) Ele: 0.5 1845Z 1929Z

38. IR Image WV Image 17-10-2002, 1500hrs [MetSAT-5]

39. Convective Activity on 1-6 th Dec 2002

40. Statistics (6-Dec-02) 1.With 0.5 degree elevation r = 0.45 Total Points: 256 rms diff: 3.13 2. With 1.5 degree elevation r = 0.42 Total Points: 256 rms diff: 3.22 SHAR-DWR Rain (mm/h) Ele: 0.5 SHAR-DWR Rain (mm/h) Ele: 1.5 TRMM Rain (mm/h) 0915Z 1015Z

41. VALIDATION CAMPAIGN (Oct-Nov. 2003)

42. Simultaneous DWR and Disdrometer observations over SHAR on 17-10-03 (0951 IST) SHAR DWR and Disdrometer Observations

43. PPI Plot (06 Nov,2003) DWR (SHAR)

44. PR Scan (06 Nov, 2003) Orbit No. 34082

45. (a) DWR (b) PR Magnified View of near simultaneous Observations of (a) DWR and (b) PR (TRMM) Reflectivity on 06 Nov, 2003

46. Scatter plots (a) PR estimated dBZ versus DWR estimated dBZ (b) PR estimated Rainfall intensity versus DWR estimated Rainfall intensity (a) (b)

47. TMI DWR-25 km PR DWR-4 km 6 Nov. 2003

48. Applications: Some Examples

49. TRMM Rainfall Anomalies 1998-2004

50. MODIS Water Vapor Obs. 2001-2004

51. TRMM Seasonal Rainfall (2001-2004)

52. TRMM Rainfall Rates (mm/h) 1998-2004

56. Time Latitude Plot of TPW from MODIS 75 0 -85 0

57. Time Longitude Plot of TPW from MODIS 5 0 -15 0

58. Hydrological Studies from Microwave Measurements: Evaporation Estimates from Microwave Measurements – examples from TRMM Precipitation Estimates from Microwave Measurements – examples from TRMM Fresh water fluxes (E-P) - examples from TRMM

59. E-P for July 1, 2003 (mm/day)

60. E-P for July, 2003 (mm/month)

61. Conclusions and Concerned Areas: Beam Filling Problem Horizontal and vertical inhomogenity Drop size distribution Melting layer Inversion Techniques