Challenges and Advances related to TC Rainfall Forecast. WOO Wang-chun Hong Kong Observatory IWTCLP-III, Jeju, Korea 10 Dec 2014

Transcription

1 Challenges and Advances related to TC Rainfall Forecast WOO Wang-chun Hong Kong Observatory IWTCLP-III, Jeju, Korea 10 Dec 2014

2 Working Group Composition Member Wallace HOGSETT Affiliations Weather Analytics, Inc. (formerly National Oceanic and Atmospheric Administration, NOAA) M. MOHAPATRA Indian Meteorological Department (IMD) Kazuhiko NAGATA Peter OTTO QI Liangbo VO Van Hoa WOO Wang-chun XU Yinglong Japan Meteorological Agency (JMA) Bureau of Meteorology, Australia (BoM) Shanghai Meteorological Bureau, China Meteorological Administration (SMB/CMA) National Hydro-Meteorological Service, Viet Nam (NHMS) Hong Kong Observatory (HKO) China Meteorological Administration (CMA)

3 Outline Introduction Progresses in the Past 4 Years Observations Quantitative Precipitation Estimation (QPE) Quantitative Precipitation Forecast (QPF) Hydrological Forecast Notable Case Studies 2010: Kompasu & Lionrock 2011: Talas; Irene 2012: Sandy 2013: Oswald; Fitow; & Phailin 2014: Rammasun Recommendations

4 Introduction TC Rainfall Crucial to water supplies & agriculture Contributes 5-10% of rainfall for TC basins 25% over southern China coast Up to 40% in certain coast of Australia BUT, too much causes problems!

5 Multi-Hazard Transmission Line Street trees Traffic accident Casualty Severe convection Strong wind Typhoon Infrastructure damage Street Billboards Strom surge Green house Farmland Traffic accident Electrocution Inundation Basement flooding Heavy Rain Water logging Plant disease High waves Overflowing River banks destroyed Marine accident Image Courtesy: Shanghai Meteorological Bureau

6 Factors affecting TC Rainfall Intensity and size of TC Speed of movement Distance from TC center Interaction with environmental flow Orographic Enhancements Climate Change Urbanization

7 PROGRESSES IN THE PAST 4 YEARS

8 Observations In-situ measurements Rain gauges Remote Sensing Radar Doppler radar Dual-polarization radar Phased array (experimental) Airborne (experimental) Mosaics Satellite Tropical Rainfall Measuring Mission (TRMM) MTSAT FY-2F rapid-scan Himawari-8 (coming soon) Others Public mobile phone network (emerging)

9 Observations Rain Gauges IMD now maintains 1,300 rain gauges, planned to expand to 1,000 AWS and 5,000 automatic rain gauges by phases. NHMS (Viet Nam) expanded the observation network, now have 20 AWS and 150 rain gauges.

10 Observations Rain Gauges HKO established the Community Weather Information Network (Co-WIN).

11 QPE Quantitative Precipitation Estimation (QPE) Radar-based, i.e. Z=aR b Satellite-derived rainfall, e.g. TRMM Rain-gauge-based, e.g. Barnes analysis Blended, e.g. co-kriging analysis

12 QPE CMA s integrated system CMA s QPE, integrated: radar network FY-2/3 Over 40,000 rain gauges 24-h precipitation estimation of Super Typhoon Rammasun from 00UTC July 20 to 00UTC July

13 QPE JMA s R/A Radar/Raingauge- Analyzed Precipitation (R/A) Hourly rainfall Updated every 30 mins Spatial resolution of 1km Quality Control (QC) Improved noise reduction algorithm Eliminate bright bands referencing NWP model An example of R/A: 1700 UTC 15 Sep (Typhoon MAN-YI)

14 QPE TRMM verified by BoM Verified TRMM Multi-satellite Precipitation Analysis 3B42, and found that: Generally good, but Overestimated TC rainfall at low rain rate Underestimated TC rainfall at high rain rate Skills better on ocean than over land Unable to account for orographic enhancement during landfall

15 QPE Rain Index in IMD Rain Index (RI) Based on Meteosat-7 Raingauge and satellite based merged rainfall analysis during TC, Phailin period (8-14 October 2014)

16 QPE Co-Kriging Useful for QPE based on radar and rain gauge data Also useful for QC 0 0 co-kriging estimate: K( x ) ( x ) G ( x ) R N 0 i 0 i j 0 j i=1 j=1 M R j R j R j R j G i G R j R j R i j R j K(x 0 ) 2 seek to minimize: E K( x0) G( x0) 2 R j R j R j R j G i h G i N 0 0 subject to constraints: ( x ) 1 & ( x ) 0 i 0 j 0 i=1 j=1 M R j R j R j R j Solution: N M 0 0 ( x ) ( x, x ) ( x ) ( x, x ) ( x ) ( x, x ), for n 1,, N i 0 GG n i j 0 GR n j G 0 GG n 0 0 i=1 j=1 N M 0 0 ( x ) ( x, x ) ( x ) ( x, x ) ( x ) ( x, x ), for m 1,, M i 0 RG m i j 0 RR m j R 0 RG m 0 0 i=1 j=1

17 QPE Co-kriging Co- Kriging Barnes Kriging Radar QPE

18 QPF Methods NWP models Global Models Regional Models TC models, e.g. HWRF Advection-based (radar-based) models Statistical models Analog

19 QPF - etrap Ensemble Tropical Rainfall Potential (etrap)

20 QPF CMA s nowcasting system Rapid data assimilation and nowcasting system Targeted to land-falling TC Operation since D-VAR Assimilates radar data, surface and sounding etc. Horizontal resolution of 10 km 8 runs per day The 24h accumulated precipitation forecast of Rammasun from 06UTC July 18 to 06UTC July

21 QPF extreme precipitation index and precipitation grade forecast 24-h extreme precipitation index forecast of Super Typhoon Rammasun CMA Ensemble Prediction Toolkit 24-h precipitation grade forecast of Rammasun from 00UTC July 18 to 00UTC July Statistical-dynamical model based on ECMWF

22 QPF CMA s GRAPES-TYM Based on CMA s GRAPES-Meso 15 km resolution 72-hour forecast Track, intensity, wind and precipitation To be upgraded to 10 km in 2015, 3-5 km in 2016

23 QPF SWIRLS: TC module and public location-specific nowcast TC module in HKO s SWIRLS nowcasting system Location-specific Rainfall Nowcast Service for the Public Supports notifications

24 QPF Analog Forecast System By HKO

25 QPF - JMA LFM Local Forecast Model (LFM) Since Aug km horizontal resolution hourly forecast up to 9 hours Since Oct 2013

26 QPF JMA s VSRF Very Short Range Forecasting of Precipitation (VSRF)

27 QPF JMA s Precipitation Nowcast 1 hour f/c 250 m resolution Once every 5 mins

28 QPF - HRWF In addition to WRF, IMD also runs HWRF Fig.10.Rainfall forecast of HWRF model based on 00 UTC of valid upto 126hr

29 QPF Poor Man Ensemble (PME) in BoM Ensemble prediction (medium range) derived from a poor-man s ensemble of different models: Access-G, JMA, NCEP, ECMWF & CMC

30 Hydrological Forecasts In IMD, use of hydro-meteorological models, based on QPE, QPF In JMA, use of Soil Water Index (SWI) and Runoff Index (RI) for warnings and advisories In NHMS (Viet Nam), use hydrological models based on observation, QPE and models.

31 NOTABLE CASE STUDIES

32 Case Kompasu & Lionrock (2010) IR cloud image at 09UTC, Aug. 31, 2010 Rainfall in Shanghai during (a) UTC and (b) UTC on September 1, 2010 (adapted from Qi and Cao, 2013)

33 Case Kompasu & Lionrock (2010) E-W direction convergence line (left) and radar echo band (right) at 10UTC, September 1, 2010 (adapted from Qi and Cao, 2013)

34 Case: Fitow (2013)

35 Case Talas (2011) Source: JMA and Ministry of Land, Infrastructure, Transport and Tourism

36 Case Talas (2011)

37 Case Talas (2011)

38 Case Irene (2011) Rainfall forecasts for Hurricane Irene. Three one-day forecasts are combined to create total forecast. Figure courtesy of the NOAA Weather Prediction Center

39 Case Sandy (2012) Observed rainfall associated with Sandy. Figures courtesy of the NOAA Weather Prediction Center. Observed snowfall associated with Sandy. Figures courtesy of the NOAA Weather Prediction Center.

40 Case: Oswald (2013)

41 Case: Oswald (2013) B Observed Deterministic NWP output for the 24 hours to 00 UTC on the 27 Jan 2013 (from 12 UTC runs on 25 Jan). The cities of Brisbane (Bris) and Bundaberg (Bun) are also shown.

42 Case: Oswald (2013)

43 Case: Phailin (2013)

44 Case: Rammasun (2014) Affected 11 million people. 62 killed and 21 went missing. Economic loss amounted to several US billion. Evacuated 180,000 people within 25 km radius of landfall site

45 Lessons and Inspirations from Notable Cases TC Kompasu & Lionrock (2011) Fitow (2013) Talas (2011) Irene (2011) Sandy (2012) Oswald (2013) Phailin (2013) Rammasun (2014) Lessons / Inspirations Remote TC Rainfall Emergency Warning for exceptional extreme cases Inland TC Rainfall TC precipitation in the form of Snow Extreme rainfall forecast

46 Summary New ways to observe precipitation emerged. Many QPE and QPF methods/systems developed and became operational Several notable cases reviewed Emergency Warning Remote TC rainfall needs more work Extreme QPF remains a challenge

47 Q&A