Remote Sensing of Ocean Winds

Transcription

1 Remote Sensing of Ocean Winds Stephen Frasier Dept. of Electrical and Computer Engineering Offshore Wind Energy IGERT Seminar 3/5/2015

2 Remote Sensing of Wind For wind energy applications: Wind Profilers Radar: UHF frequency Sodar: audible Lidar: IR 2

3 Remote Sensing of Wind For wind energy applications: Wind Profilers Radar: UHF frequency Sodar: audible Lidar: IR Problematic over ocean 3

4 Remote Sensing of Wind For wind energy applications: Wind Profilers Radar: UHF frequency Sodar: audible Lidar: IR Problematic over ocean Platform required: buoy, mooring 4

5 Remote Sensing of Wind For wind energy applications: Wind Profilers Radar: UHF frequency Sodar: audible Lidar: IR Problematic over ocean Platform required: buoy, mooring Data retrieval, power constraints 5

6 Remote Sensing of Wind For wind energy applications: Wind Profilers Radar: UHF frequency Sodar: audible Lidar: IR Problematic over ocean Platform required: buoy, mooring Data retrieval, power constraints motion compensation, maintenance (salt) 6

7 Motivation Why measure global ocean winds? Input to global circulation models (GCMS) Numerical weather prediction (NWP) Wind and wave forecasting (shipping) Wind energy forecasting/climatology 7

8 Motivation How do we measure from space or aircraft? Radar scatterometers (active) Radiometers (passive) Measure sea-surface signature of wind Day/Night/All-weather operation 8

9 ISS Rapidscat Mission NASA's latest wind scatterometer deployed on the international space station (9/2014) 9

10 EU's Advanced Scatterometer 10

11 A Brief History NASA missions RadScat onskylab (1973) demonstration SASS on SeaSAT-A (1978) failed at 100 days NSCAT on ADEOS-1 ( ) solar panel failure SeaWinds on QuikSCAT ( ) rescue mission SeaWinds on ADEOS-2 ( ) solar panel failure RapidScat on ISS (2014- ) stopgap mission 11

12 A Brief History NASA missions RadScat onskylab (1973) demonstration SASS on SeaSAT-A (1978) failed at 100 days NSCAT on ADEOS-1 ( ) solar panel failure SeaWinds on QuikSCAT ( ) rescue mission SeaWinds on ADEOS-2 ( ) solar panel failure RapidScat on ISS (2014- ) stopgap mission ESA missions ERS-1 ( ), ERS-2 ( ) Envisat ( ) EUMetSat operational satellites ASCAT on METOP-A (2006- ), METOP-B (2013- ) OSCAT ( ): India 12

13 A Brief History NASA missions RadScat onskylab (1973) demonstration SASS on SeaSAT-A (1978) failed at 100 days NSCAT on ADEOS-1 ( ) solar panel failure SeaWinds on QuikSCAT ( ) rescue mission SeaWinds on ADEOS-2 ( ) solar panel failure RapidScat on ISS (2014- ) stopgap mission ESA missions ERS-1 ( ), ERS-2 ( ) Envisat ( ) EUMetSat operational satellites ASCAT on METOP-A (2006- ), METOP-B (2013- ) Other agency missions OSCAT ( ): India HY-2A (2011-): China 13

14 Radar echo from surface roughness Bragg Scattering Incident microwave radiation in resonance with short waves (dominant for 30 < < 70 ) B /(2sin( ~ 2cm (Ku-band) ; ~ 5cm (C-band) 14

15 Radar echo from surface roughness Courtesy Z.Jelenak 15

16 Radar echo from surface roughness Courtesy Z.Jelenak 16

17 Radar echo from surface roughness Courtesy Z.Jelenak 17

18 Radar echo from surface roughness Courtesy Z.Jelenak 18

19 Dependence on Wind and Incidence Angle Most sensitivity to wind at moderate incidence angles Courtesy Z.Jelenak 19

20 Dependence on Wind and Azimuth Angle Most sensitivity to wind dir. at moderate wind speeds 30m/s 25m/s 20m/s 15m/s 10m/s 5m/s 20 Z.Jelenak

21 Current Scatterometer Designs Fixed fan beam C-band (5 cm) VV-pol Sampling km Static antenna ASCAT, double swath Rotating pencil beam Ku-band (2 cm) Dual polarization Sampling km Rotating antenna Seawinds Courtesy Z.Jelenak 21

22 Near Real-Time Products 22

23 Microwave Radiometry Blackbody Radiation 23

24 Microwave Radiometry Blackbody Radiation Microwaves over here 24

25 Microwave Radiometry Blackbody Radiation Greybody Radiation P = k(et)b e = emissivity T = Temperature et = T B Brightness Temperature Microwaves over here 25

26 Microwave Radiative Transfer T B Observations: Surface properties Atmospheric properties Copyright 1996 Japan Association of Remote Sensing All rights reserved 26

27 Dependence on Wind Speed and Rain 27

28 Dependence on Wind Speed and Rain foam roughness 28

29 Ocean Wind Climatology from Satellite Liu et al., Wind power at sea as observed from space, ch 14 in Muyeen, S.M. (ed.), Wind Power, Intech, Vienna,

30 Ocean Wind Climatology from Satellite 30

31 Global Scatterometer Missions Launch Date 10/06 08 C-band /99 Ku-band QuikSCAT USA EPS SG Europe HY-2A China Combined C- and Ku-band Operating FY-3E with 2FS China Operational Series with 2FS India Approved Extended sw 24feb11 31

32 A Future Scatterometer Design Cyclone Global Navigation Satellite System (CYGNSS) 32

33 Scatterometry Issues Poor sensitivity in high winds Investigation polarizations Contamination by rain Attenuation through atm. Add'l surface roughening by drops and/or downdrafts Spatial smoothing Extreme events smaller than resolution 33

34 What do we do? Obtain scatterometer measurements in high-wind (and rain) regimes Hurricanes (typ. Aug-Oct) Based from Tampa, St. Croix, or Barbados High-latitude winter storms (Jan-Feb) Based from Anchorage, St. Johns, Halifax How does it work? 34

35 Developed at NASA/UMass (C.T. Swift) Sold/maintained by Prosensing, Inc. Nicknamed the Smurf 35

36 Hurricane Reconnaisance 53 rd Weather Reconnaisance Squadron Based at Keesler AFB in Biloxi, Mississippi Provide operational reconnaisance for National Hurricane Center (NHC) in Miami, FL. Fly specialized (W)C-130 aircraft These are the guys on the TV show Hurricane Hunters NOAA Aircraft Operations Center Based at McDill AFB in Tampa, FL Do research reconnaisance for developing new observing techniques or studying storm structure. Fly specialized (W)P-3 aircraft. Periodically tasked by NHC for operational storm fixes. 36

37 Research Aircraft: Lockheed WP-3D 37

38 Research Aircraft: Lockheed WP-3D LF Weather Radar Microwave Radiometer SFMR Tail Doppler Radar 38

39 NOAA has 2 WP-3Ds: N43RF Miss Piggy 39

40 In the cockpit... Rabbit's foot 40

41 In the cockpit... Fuzzy dice Rabbit's foot 41

42 Aircraft Measurements Flight-level winds pressure Wind, temperature, humidity profiles via GPS dropsonde Winds & precipitation aloft via tail Doppler radar Surface-level winds via microwave radiometer & dropsonde Sea surface temperature Expendable bathythermographs Our measurements: Radar signature of sea-surface Precipitation between aircraft and sea-surface 42

43 Expendables XBT: expendable bathythermograph 43

44 Our Radar Imaging Wind & Rain Airborne Profiler 44

45 Our digs on the P-3 Radar electronics in the back Data recording up front 45

46 Tasked Mission on 10/17/

47 Tasked Mission on 10/17/

48 Tasked Mission on 10/17/2014 Eyewall 48

49 Tasked Mission on 10/17/ Leg 1 49

50 Radar view from the eye... 50

51 View from 8 kft just inside the eye... 51

52 Tasked Mission on 10/17/2014 High-Winds Research 52

53 Tasked Mission on 10/17/2014 I threw up about here... 53

54 Sample NRCS Observations 54

55 The End 55

56 Eye Transect of Hurricane Rita (Cat 5) 56