Indian Institute of Tropical Meteorology (IITM)

1. Increasing Trend of Extreme Rain Events Over Central India in a Warming Environment B. N. Goswami Indian Institute of Tropical Meteorology (IITM)

2. IPCC AR4 WG-1 summary

3. Trend in temp. is similar to global temp. trend. Much faster during past 50 years

4. All India Rainfall Climatological Mean (JJAS) Interannual Variability

5. S. Sen Roy & R. C. Balling, 2004, Int. J. Climatology, 24, 457 130 Stations, 91 years (1910-2000) 7 Variables: Total Precipitation Largest 1 day rainfall Largest 5 day total Largest 30 day totals Extreme freq. (90pctl.) Extreme freq. (90pctl.) Extreme freq. (90pctl.)

7. Klein Tank et al. 2006, JGR Stations used for Temp. Stations used for Precp.

8. Cold (TN10) Nights Warm(TN90) nights Warm(TX90) Days Cold (TX10) Days

9. Ratio of index of precipitation falling on extreme days (R99) to total precipitation (in %)

10. Possible Reasons: 1. Homogeneity in variability Mean Variance 2. Small scale character , Large No. Stations required Sampling error 3. Orographic influence ,

11. High resolution daily rainfall 1803 stations used Period : 1950-2003 Daily Analysed into 1o X 1o boxes Quality Controlled Rajeevan et al, 2006, Curr. Sci. 91,

12. Climatoogical mean variance of daily rainfall during JJAS

13. Variance of total daily anoms Variance of HP filt anoms (<10d) Variance of 10-30 d filt anoms Variance of 30-90 d filt anoms

14. Variance of daily rainfall over CI during JJAS CoV (S.D/mean) daily rainfall over CE, JJAS SST anom during JJAS over tropical Indian Ocean (50E-100E,20S-20N)

15. Contributions of HP, 10-20 day mode , 30-60 day mode to the trend of total daily rainfall variance.

17. Time series of count over CI Low & Moderate events Heavy events (>10cm) V. Heavy events (>15cm)

18. Increase in intensity of extreme events Time series of av. Intensity of four largest events in a year

19. Why no trend in the seasonal mean ?

20. Minimum area required for identification of statistically significant trend

21. CONCLUSION • Frequency of occurrence as well as intensity of heavy and very-heavy rainfall events have highly significant increasing trends over Central India • Low and moderate events have significant decreasing trend over CI • The seasonal mean does not have a trend because decreasing contribution from low and moderate events are compensated by increasing contribution from heavy events. • Arial aggregate of intense events over a a reasonable large homogeneous region is required for identifying statistically significant trend.

22. IMPLICATIONS • The trend of extreme events indicate that rain related disasters are going to increase over the CI. Disaster preparedness must be enhanced over the entire region! • Since the low frequency variability of the mean monsoon is influenced by the extreme events, for seasonal and decadal predictability of the Indian monsoon, correct simulation of the statistics of the extreme events by climate models is imperative.

23. Interdecadal ~60 years Interannual 2-4 yrs Short-rain events Extreme events 1-3 hrs Weather Lows & Depressions 5-d Multi-scale Interactions of monsoon Sub-seasonal Active-break spells 15-d, 40-d

24. Major Experiments Planned:2008-2010 to be Led by IITM B. N. Goswami Indian Institute of Tropical Meteorology (IITM)

25. Two Major Experiments are planned • Interaction between microphysics of rain formation (clouds) and the environment • Aerosol-Cloud interaction and physics of rain enhancement

26. Interaction between microphysics of rain formation and environment • Understanding interaction between tropical clouds and its large scale environment crucial for better parameterization of convection in weather and climate models. • No simultaneous high resolution observation of clouds, their microphysical properties and large scale environment exists over the subcontinent. • The subcontinent is host to a variety of cloud processes and their interaction with the environment (e.g. west of western Ghat  shallow clouds give heavy rain while in central and eastern India deep clouds are associated with heavy rain

27. Interaction between microphysics of rain formation and environment • Multi-parameter dual polarization Doppler radar system to provide cloud microphysical parameters as well as environmental parameters. (an X-Band radar and a Ka-Band radar) • GPS Radiosonde • Duel polarization Micro Pulsed LIDAR

28. Multi parameter Radar system at TsukubaLeft : MP-Ka/w Right : MP-X

29. Likely Specifications of radar system to be developed

30. Interaction between microphysics of rain formation and environment Campaigns: One summer Season at Pune One summer at a station in west coast One summer season at a station at east coast

31. Interaction between microphysics of rain formation and environment Campaigns • Operational analysis from NCMRWF (IMD) for large scale • Enhanced soundings (4/day) at three locations around the station synoptic environment • Mesoscale winds from X-band radar • Cloud properties and microphysics from Ka-band radar • Vertical velocity from micro-rain radar • Aerosols from micro-pulsed LIDAR

32. Interaction between microphysics of rain formation and environment Modeling • The data collected will be used to validate a cloud resolving model (CRM) • The CRM will also be used to understand the interaction between the clouds and the environment • Try to develop better parameterization

33. Cloud-Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEX) • A major National experiment is being planned for studying the aerosol-cloud interaction and possible rain enhancement • Will involve cloud microphysics measurements with instrumented aircraft • Ground based c-band or x-band radar measurements • CCN measurements • Three year duration

34. Preamble • Claims – cloud seeding as panacea for drought alleviation • After IITM experiment 30 years ago, NO systematic experiment and data exists. • Positive results in IITM’s experiments are taken as basis for operational experiments • Large changes in aerosol / CCN concentrations during last 30 years • New technology

35. Scientific Issues • Hardly any data on cloud microphysics and its role on growth and decay of clouds exists over India • How aerosols interact with cloud microphysical processes and influence growth and decay of clouds, cloudiness distribution. • Indirect influence of aerosols on climate • Understanding the potential for rain enhancement through cloud seeding (artificial introduction of aerosols!) over India

36. Need for a comprehensive Expt. • An Experiment, however, is not meaningful unless the route through which rain enhancement is understood. • Under different environment, this route could be very different. • Must add data and additional knowledge to other important National programmes, linkages • Interaction between cloud-environment • Aerosol-cloud interaction

37. Proposed experiment for estimation of potential in the enhancement of rainfall in seeded clouds • Seeding conceptual model and physical hypothesis • The objective of hygroscopic seeding is to alter the natural CCN to enhance the formation of the select few cloud droplets that become raindrops while glaciogenic seeding attempts to enhance precipitation formation by increasing ice crystal concentrations and buoyancy effects through the freezing of supercooled water.

38. Measurements of CCN and the natural droplet spectra, ice nuclei and ice formation, are important objectives of the field program. In addition, ice processes also depend on the characteristics of the cloud droplet spectra.

39. Measurements During Cloud Seeding • The effects of hygroscopic seeding are highly dependent on the natural characteristics of clouds and precipitation processes. • Physical measurements are therefore important in order to assess which seeding technique should be used and to evaluate the potential effects from seeding on precipitation. • It is thus important to design airborne flight patterns for data gathering to answer important questions related to the natural characteristics of clouds. • In addition, aircraft measurements of cloud microphysical characteristics will provide a better understanding of the natural processes in clouds.

40. Measurements During Cloud Seeding • The aircraft data are important to build a climatology of microphysical characteristics of clouds in the region to determine the dominant precipitation formation processes in clouds and the effects seeding may have on these processes. • These measurements will also help to validate the model simulations and radar observations.

41. May to October May to October 2007 2008 - 2009 2010 Implementation Plan Phase I Observations Phase II Expt. K band X band radar Aerosol and cloud observations Aerosol and cloud observations Assessment of results Cloud seeding

42. VARIABLE INSTRUMENT RANGE ACCURACY RESOLUTION FREQUENCY Air temperature Rosemount 102DB1CB -50°C to +50°C 0.1°C 0.01°C 1 Hz Air temperature (reverse flow) 0.038" DIA. Bead Thermistor -30°C to +50°C 0.05°C/0.3°C incl DHC 0.01°C < 1 s TC Relative humidity (reverse flow) Thermoset Polymer RH Sensor 0 to 100% RH 2% RH 0.1% RH 5 s TC @ 20°C Barometric pressure MEMS Pressure Sensor 0 to 110000 Pa 100 Pa 10 Pa 20 Hz u wind component (+ North) Extended Kalman Filter (EKF) 0.50 m/s @ 75 m/s TAS 0.01 m/s 5 Hz v wind component (+ East) Extended Kalman Filter (EKF) 0.50 m/s @ 75 m/s TAS 0.01 m/s 5 Hz w wind component (+ Down) Extended Kalman Filter (EKF) 0.50 m/s @ 75 m/s TAS 0.01 m/s 5 Hz INSTRUMENTS

43. Position (Latitude/Longitude) WAAS DGPS 2 m (2 ) < 1 m 5 Hz Altitude WAAS DGPS -300 to 18000 m 5 m (2 ) < 1 m 5 Hz Geometric Altitude King KRA 405 Radar Altimeter 0 to 2000 ft 3% < 500 ft 5% > 500 ft 0.48 ft (0.15 m) Roll Attitude (o) MEMS IMU/GPS/EKF -60 to +60° 0.1° 0.01° 5 Hz Pitch Attitude (o) MEMS IMU/GPS/EKF -60 to +60° 0.2° 0.01° 5 Hz Yaw Attitude (o)/ Heading MEMS IMU/GPS/EKF 0 to 360° 0.1° 0.01° 5 Hz INSTRUMENTS

44. Angle of attack (o) MEMS Pressure Sensor -15 to +15° 0.03° @ 150 m/s 0.001° @ 150 m/s 20 Hz Side-slip (o) MEMS Pressure Sensor -15 to +15° 0.03° @ 150 m/s 0.001° @ 150 m/s 20 Hz True Air Speed MEMS Pressure Sensor 0 to 150 m/s 0.1 m/s 0.01 m/s 20 Hz Video record Sony DCR-DVD 201 Logging, telemetry & event markers ESD DTS (GPS) 1 Hz INSTRUMENTS

45. Cloud droplet spectra DMT CDP 2 to 50 µm 1 to 2 µm, 30 bins 1 Hz Cloud particle spectra DMT CIP 25 to 1550 µm 25 µm, 62 bins 1 Hz Cloud particle image DMT CIP 25 to 1550 µm 25 µm Liquid water content DMT LWC-100 0 to 3 g/m3 0.05 g/m3 0.01 g/m3 1 Hz CDP calculated > 3 g/m3 1 Hz Isokinetic aerosol inlet Brechtel double diffuser inlet 28 lpm 100 m/s Aerosol spectrometer PMS PCASP SPP-200 0.1 to 3 µm 0.02 µm, 30 bins 1 Hz CCN DMT CCN counter 0.5 to 10 µm 0.1 to 1.2 % SS see text 0.5 µm, 20 bins 1 Hz INSTRUMENTS

46. Specifications for the Mobile Dual Polarized Ka-band Doppler Radar

47. Frequency Range 33-37 GHz (Ka Band) Transmitter Type Extended Interactive Klystron/TWT based Minimum measuring range 100 m Maximum measuring range 18 km Range resolution 100 m Sensitivity - 45 dBz at 5 km Transmitter Polarization Both co- and cross-polarization Receiver polarization Both Pulse repetition frequency 2-10 kHz Beam width 0.5° Antenna Steerable Parabolic Antenna with Radome Azimuth steering 360° with ±1° accuracy and 0-4 rpm Vertical Steering -2° to +92° with ±1° accuracy Doppler processing Pulse Pair and FFT Antenna mounting Trailor-mountable Container Shelter for radar system, tower, radar operator, air conditioner etc. Software Custom-built licensed software with all inbuilt algorithms for cloud physics studies Source code to be supplied Computer and control Industrial workstations for operation and control of the radar Power 230 V, 50 cycles/s single phase Calibration BITE and Self calibration Side lobe for cross polarized levels Both -25 dB or better Polarimetric output ZDR, KDP, HV, Z, V, , DP Training and Installation Onsite training and Installation

48. Specifications for the Mobile Dual Polarized X-band Doppler Radar

49. Frequency Range 9.3 – 9.6 GHz (X-Band) Minimum measuring range 1 km Maximum measuring range 80 km Range resolution 1 km Sensitivity 0 dBz at 10 km Polarization Both co- and cross-polarization Receiver polarization Both Pulse repetition frequency 2-10 kHz Beam width 1° Antenna Steerable Parabolic Antenna with Radome Azimuth steering 360° with ±1° accuracy and 0-4 rpm Vertical Steering -2° to +92° with ±1° accuracy Doppler processing Pulse Pair and FFT Antenna mounting Trailor-mountable Container Shelter for radar system, tower, radar operator, air conditioner etc. Software Custom-built licensed software with all inbuilt algorithms. Software source code to be supplied Computer and control Industrial workstations for operation and control of the radar Power 230 V, 50 cycles/s, single phase Calibration BITE and self calibration Side lobe for cross polarized levels Both -25 dB or better Polarimetric outputs ZDR, KDP, HV, Z, V, , DP Training and Installation Onsite training and Installation