Inter-Comparison of Operational Wave Forecasting Systems using in-situ data: Experience and Relevance for GlobWave

Transcription

1 Inter-Comparison of Operational Wave Forecasting Systems using in-situ data: Experience and Relevance for GlobWave Jean-Raymond Bidlot European Centre for Medium range Weather Forecasts Reading, UK Slide 1

2 Co-authors: Jean-Raymond Bidlot, European Centre for Medium range Weather Forecasts (ECMWF), Adrian Hines, the Met Office, UK, (MO), Paul Wittmann, Fleet Numerical Meteorology and Oceanography Centre, USA, (FNMOC), Manon Faucher, Meteorological Service of Canada, Canada, (MSC), Arun Chawla, National Centers for Environmental Prediction, USA, (NCEP), Jean Michel Lefèvre, Météo France, France, (MF), Thomas Bruns, Deutscher Wetterdienst, Germany, (DWD), Tom Durrant, Bureau of Meteorology, Australia, (BoM), Fabrice Ardhuin, Service Hydrographique et Océanographique de la Marine, France, (SHOM) Nadao Kohno, Japan Meteorological Agency, Japan, (JMA), Sanwook Park, Korea Meteorological Administration, Republic of Korea, (KMA), Marta Gomez, Puertos del Estado, Spain (PRTOS). Slide

3 History : Following WISE 1995, a routine inter-comparison of wave model forecasts was started. It was intended to provide a mechanism for benchmarking wave forecast products. Since the early 9 s, more in-situ wave observations have become available and could be used for verification. The JCOMM Expert Team on Wind Waves and Storm Surges (ETWS) following ETWS-1(3) endorsed the expansion of the project. At ETWS- (7), it was agreed to continue and expand this activity. Status report was presented at the 1 th Int. workshop on wave hindcasting and forecasting, Hawaii, November 7. Slide 3

4 Participants : 1995: European Centre for Medium range Weather Forecasts (ECMWF), global model. The Met Office, UK, (MO), global model. Fleet Numerical Meteorology and Oceanography Centre, USA, (FNMOC), global model. Meteorological Service of Canada, Canada, (MSC), limited area models (N Pac. & N Atl.). 1996: National Centers for Environmental Prediction, USA, (NCEP), global model. 1: Météo France, France (MF), global model 4: Deutscher Wetterdienst, Germany, (DWD), global model and limited area models (N Sea & Med.). 6: Bureau of Meteorology, Australia, (BoM), global model. Service Hydrographique et Océanographique de la Marine, France, (SHOM), global model & N Atl.. Japan Meteorological Agency, Japan, (JMA), global model. 7: Korea Meteorological Administration, Republic of Korea, (KMA), global model. Puetos del Estado, Spain (PRTOS), limited area models (N Atl. & Med.). Slide 4

5 Methodology: Each month, model data (analysis and forecasts) are exchanged via ftp for a set of prescribed locations (if possible) where wave and wind observations are potentially available. A simple ASCII format is used. The data sets are combined at ECMWF and quality controlled(*) in-situ observations of wind speed and direction, wave height and wave period are added to the data set. The combined data sets are made available to all participants. Summary plots and tables are also produced at ECMWF (an external web site will soon become available). Monthly reports are also uploaded on the JCOMM web pages. (*) Bidlot et al., Wea. Forecasting 17 and Saetra and Bidlot 4 Wea. and Forecasting 19 Slide 5

6 In-situ observations from buoys and platforms: W E 4 E 6 E 8 E 1 E 1 E 14 E 16 E W 14 W 1 W 1 W 8 W 6 W 9 7 N 7 N N 6 N 5 N 5 N 4 N 4 N 3 N 3 N N N 1 N 1 N 1 S 1 S S S 3 S 3 S 4 S 4 S W E 4 E 6 E 8 E 1 E 1 E 14 E 16 E W 14 W 1 W 1 W 8 W 6 W Locations where wind and wave data were collocated with ECMWF model. Sources: mostly via the WMO GTS, but also from the South African Weather Service, and recently from BoM, Puertos del Estado, Oceanor, SHOM, KMA, and BSH (Germany). Essential quality control and processing of the data done at ECMWF. Slide 6

7 Latest results based on a list of common buoy locations: some examples: Analysed Forecast significant (t= t+7) wave height and and averaged buoy data at at buoy avg obs ECMWF UKMO FNMOC AES NCEP METFR DWD AUSBM SHOM JMA KMA PRTOS MARCH 9 Forecast (t= Analysed t+7) peak Tp period and averaged and averaged buoy data buoy at data 461 at buoy avg obs ECMWF UKMO FNMOC AES NCEP METFR DWD AUSBM SHOM JMA KMA PRTOS MARCH 9 Looking at time series can be interesting, but Statistics are needed to analyse all the data Slide 7

8 Latest results based on common list of buoy locations global model, except MétéoFrance and KMA scatter diagrams for the analysis NB: some of FNMOC and SHOM data were not available for January to March 9, hence they are not shown here. Slide 8

9 Scatter Index (normalised standard deviation of difference Latest results based on common list of buoy locations: scores plots for January to March 9 S.I. S.I. S.I. BIAS (m) BIAS (m/s) BIAS (sec.) Hs common data only, fc from and 1Z for 91 to SIGNIFICANT WAVE HEIGHT SCATTER INDEX at all 13 buoys ECMWF METOF FNMOC MSC NCEP METFR DW D AUSBM SHOM JMA KMA PRTOS 1m WIND SPEED SCATTER INDEX at all 1 buoys ECMWF METOF FNMOC MSC NCEP METFR DW D AUSBM SHOM JMA KMA PRTOS Wind speed common data only, fc from and 1Z for 91 to SIGNIFICANT WAVE HEIGHT BIAS at all 13 buoys ECMWF METOF FNMOC MSC NCEP METFR DW D AUSBM SHOM JMA KMA PRTOS common data only, fc from and 1Z for 91 to m WIND SPEED BIAS at all 1 buoys ECMWF METOF FNMOC MSC NCEP METFR DW D AUSBM SHOM JMA KMA PRTOS common data only, fc from and 1Z for 91 to PEAK PERIOD SCATTER INDEX at all 96 buoys ECMWF METOF FNMOC MSC NCEP METFR DW D AUSBM SHOM JMA KMA PRTOS Tp common data only, fc from and 1Z for 91 to 93 PEAK PERIOD BIAS at all 96 buoys ECMWF METOF FNMOC MSC NCEP METFR DW D AUSBM SHOM JMA KMA PRTOS common data only, fc from and 1Z for 91 to 93 Slide 9

10 Wave height scatter index and bias time series fc d+3 3 month running average Analysis Slide 1

11 Peak period scatter index and bias time series fc d+3 3 month running average Analysis Slide 11

12 E(f) (m s) E(f) (m s) Extension: wave spectra? Normalised -D spectrum for ey8s 145 AN alpha=.1 1:Z on at xxxxx ( 9., ) at depth. m Hs= m, fm=.85 Hz, fp=.67 Hz Qp= 1.156, Dir. Spread = -nan Normalised -D spectrum for ey8s 145 AN alpha= 1. 1:Z on at xxxxx ( 9., ) at depth. m Hs= 16. m, fm=.79 Hz, fp=.67 Hz Qp= 1.3, Dir. Spread = -nan Normalised -D spectrum for ey8s 145 AN alpha=.1 :Z on at xxxxx ( 9., ) at depth. m Hs= 8.3 m, fm=.96 Hz, fp=.74 Hz Qp=.968, Dir. Spread =.647 Normalised -D spectrum for ey8s 145 AN alpha= 1. :Z on at xxxxx ( 9., ) at depth. m Hs= 1.41 m, fm=.97 Hz, fp=.9 Hz Qp=.853, Dir. Spread = -nan ey8s: Hs= m, fm=.85 Hz, fp=.67 Hz U1=43.7 m/s, u*= 3.17 m/s, windsea direction = 95 ey8s: Hs= 16. m, fm=.79 Hz, fp=.67 Hz U1=43.7 m/s, u*= 3.18 m/s, windsea direction = 99 buoy: Hs=. m, fm=. Hz, fp=. Hz wind speed =. m/s, wind direction (ocean. convention) = ey8s: Hs= 8.3 m, fm=.96 Hz, fp=.74 Hz U1=3.3 m/s, u*= 1.66 m/s, windsea direction = 7 ey8s: Hs= 1.41 m, fm=.97 Hz, fp=.9 Hz U1=3.3 m/s, u*=.6 m/s, windsea direction = 6 buoy: Hs=. m, fm=. Hz, fp=. Hz wind speed =. m/s, wind direction (ocean. convention) = 4 3 ey8s ey8s xxxxx 1 8 ey8s ey8s xxxxx Frequency (Hz) Frequency (Hz) Slide 1

13 Extension: wave spectra : we will start to gather data at selected locations Method of analysis, yet undecided: As done at ECMWF From Hanson et al. 8: Pacific Hindcast Performance of Three Numerical Wave Model. JOAT. In latest WW3 software (NCEP) Slide 13

14 Extension: comparison with altimeter Hs? Model hindcast with future operational cycle, new parametrisation for swell damping Bias computed on 3ºx3º grid boc Model hindcast with current operational cycle Slide 14

15 STD (m) Extension: comparison with altimeter Hs? Comparison model first guess with altimeter wave height since 3: Slide 15

16 High Resolution Diagnostic Data set (HRDDS) Extension: field comparison? Slide 16

17 Extension: field comparison: scores as in atm. forecasting Slide 17

18 Comments: In-situ data from buoys and platforms are not uniform This has become quite apparent when collocating with Altimeter wave height observations. This was discusses during the JCOMM Technical Workshop on Wave Measurements from Buoys (October 8, New York) A pilot project for the measurements of waves from buoys (PP-WET) for the inter-comparison and evaluation of wave spectral measurements from moored buoys was proposed and approved by DBCP (Data Buoy Cooperation Panel). Next meeting on 11-1 May at Scripps to review work plan and progress. Slide 18

19 Assessment of the systematic differences in wave observations from moorings. Jean-Raymond Bidlot European Centre for Medium Range Weather Forecasts, Reading, U.K. Tom Durrant Bureau of Meteorology Research Centre, Ocean and Marine Forecasting Group, Melbourne, Australia. Pierre Queffeulou IFREMER, Laboratoire d Océanographie Spatiale, Brest, France JCOMM Technical Workshop on Wave Measurements from Buoys - 3 October 8, New York, United States Slide 19

20 Jun-1987 Jun-1988 Jun-1989 Jun-199 Jun-1991 Jun-199 Jun-1993 Jun-1994 Jun-1995 Jun-1996 Jun-1997 Jun-1998 Jun-1999 Jun- Jun-1 Jun- Jun-3 Jun-4 Jun-5 Jun-6 Jun-1987 Jun-1988 Jun-1989 Jun-199 Jun-1991 Jun-199 Jun-1993 Jun-1994 Jun-1995 Jun-1996 Jun-1997 Jun-1998 Jun-1999 Jun- Jun-1 Jun- Jun-3 Jun-4 Jun-5 Jun-6 Wave Height Bias (model-buoy) (m) Wave Mean Period Bias (model-buoy) (s) Motivations: problem with wave data in ERA-4.4 Comparison with buoy data 3 month running average Comparison with buoy data 3 month running average. Hs bias ERA-4 (e4 1) ops (od 1) 1.5 Tz bias ERA-4 (e4 1) ops (od 1) months Dec months Dec May 1993 May 1993 Between Dec and May 1993 low quality ERS-1 altimeter data were wrongly assimilated. Between Dec and May 1993 low quality ERS-1 altimeter data were wrongly assimilated. Note: this problem was originally spotted by KNMI. This emphasises the need for in-house monitoring tools. Slide

21 Jun-1987 Jun-1988 Jun-1989 Jun-199 Jun-1991 Jun-199 Jun-1993 Jun-1994 Jun-1995 Jun-1996 Jun-1997 Jun-1998 Jun-1999 Jun- Jun-1 Jun- Jun-3 Jun-4 Jun-5 Jun-6 Number of collocations with model Wave data for reanalysis verification: in-situ Buoy reporting wave observations have a relatively limited geographical coverage. They are used for verification only. Number of collocations between ENVISAT altimeter and buoys to W 14 W 1 W 1 W 8 W 6 W 4 W W E 4 E 6 E 8 E 1 E 1 E 14 E N 6 N 5 N 5 N 9 4 N 4 N 75 3 N 3 N N N 6 1 N 1 N 45 6 N 5 N 5 N 15 4 N 3 N 3 N 1 N 1 N 1 N 9 1 S 1 S S 3 S 3 S 4 S Number of collocations between ERS-1 altimeter and buoys to W 16 W 14 W 14 W 1 W 6 N 4 N N S 4 S 1 W 1 W S S Number of collocations between ERS- altimeter and buoys 3 S 3 S 1 W 8 W 16 W 8 W 6 W 6 W 4 W 4 W W W E E 4 E 4 E 6 E 6 E 8 E 8 E 1 E 4 S E 4 E 1 E 1 E 1 S 1 S 14 E 1 E 14 E 16 W 14 W 6 N N 135 N 15 S 4 S W 1 W 8 W 6 W 6 N 5 N 5 N 3 N 3 N 1 N 1 N 1 S 1 S 3 S 3 S 16 W 14 W 14 W 1 W 1 W 1 W 1 W 8 W to W 6 W 6 W 4 W 4 W W W E 4 E 6 E 6 E 8 E 8 E 1 E 1 E 1 E 14 E 1 E 14 E 4 N N S 4 S W W E 4 E 6 E 8 E 1 E months 1 E 14 E Comparison with buoy data 3 month collocation period The number of wave buoys available on the GTS has steadily increased over the years. 4 S 3 15 Slide 1

22 Collocation altimeter-buoy-model: Collocation between altimeter and buoy is done using a maximum collocation distance (1km) and time window (3hrs). but also model hindcast values at both Altimeter and buoy locations are used to estimate the uniformity of the wave field (Relative collocation error RCE< 5%, mean wave direction within 45º. Slide

23 model wave heights model wave heights mod 1 ERS- OPR wave heights are slightly biased low when compared to buoys 11-7 w Using in-situ CORR ith CORRECTED wave COEF =.946 alt. data SI = from SYMMETRIC SLOPE =.86 data.164 era5 w ave LDWR LF3F for the interim LF3J LF3N ENTRIES: 3FYT LF4B LF4C LF5U 9 reanalysis : TFBLK GTS wave heights Comparison of an w ave heights (era5 w ave) w ith GTS observations Comparison RMSE =.558 of an BIAS w ave = heights (era5 w ave) ERS OPR wave heights are still biased low when LDWR compared to buoys 5 1 ENTRIES = MODEL MEAN =. STDEV = BUOY 1 MEAN 3 4= STDEV 7 8 = to LSQ FIT: SLOPE GTS wave =.866 heights INTR = -.9 Comparison RMSE =.519 of an BIAS w ave = heights (era5 w ave) wcorr ith GTS COEF observations. =.963 SI =.137 SYMMETRIC SLOPE = GTS wave heights Buoy wave heights Comparison of corrected altimeter with gts wave heights for 1 ERS- 15. km, 5 % max RCE and 45. degrees max in mean wave 9 dir Corrected alt. wave heights 13 ERS-1 ENTRIES: FYT A35 46A LF3F LF3J LF3N LF4C LF5U TFGRS TFGRV TFGSK TFKGR Slide TFSRT TFSTD ZSWAV ENTRIES 9 = MODEL MEAN =.14 STDEV = 1.17 BUOY 8 MEAN =.45 STDEV = 1.84 LSQ 7 FIT: SLOPE =.839 INTR =.85 RMSE =.498 BIAS = CORR 6 COEF =.956 SI =.159 SYMMETRIC 5 SLOPE =.874 ENVISAT wave heights are slightly LDWR LF3F biased high when LF3J LF3N LF4B 4451 compared LF4C to buoys ENTRIES 9 = MODEL MEAN =.36 STDEV = BUOY 8 MEAN =.45 STDEV = LSQ 7 to FIT: SLOPE =.95 INTR =.8 RMSE =.3 BIAS = CORR COEF =.971 SI =.16 SYMMETRIC 5 SLOPE = GTS wave heights 4 Buoy wave heights Comparison of corrected altimeter with gts wave heights for km, 5 % max RCE and 45. degrees max in mean wave dir Corrected alt. wave heights11 ENTRIES: FYT LF5U TFBLK TFGRS TFGRV Corrected altimeter wave heights Comparison of an w ave heights (era5 w ave) w ith CORRECTED alt. data from era5 w ave GTS wave heights Comparison of an w ave heights (era5 w ave) w ith GTS observations TFGSK TFKGR TFSRT TFSTD ZSWAV ENTRIES: GTS wave heights Buoy wave heights Comparison of corrected altimeter with gts wave heights for 15. km, 5 % max RCE and 45. degrees max in mean wave dir Corrected alt. wave heights 11 ENVISAT to ENTRIES: MOD BUO LSQ RMS COR SYM FYT 411 ENT MOD BUO LSQ RMS COR SYM FYT 411 ENT MOD BUO LSQ RMS COR SYM

24 BIAS (m) Wave data for the interim reanalysis : Using a non-parametric bias estimation technique, we have determined the relative bias with respect to the buoys. Satellite Altimeter wave height bias as determined from in-situ data ERS-1 (OPR) ERS- (OPR) ENVISAT (NRT) Jason-1 (NRT) Wave height (m) Slide 4

25 Discrepancies in wave observations: GTS NDBC MEDS W 14 W 1 W 1 W 8 W 6 W 4 W W E 4 E 6 E 8 E 1 E 1 E 14 E 7 N 7 N 6 N 6 N 5 N 5 N 4 N 4 N 3 N 3 N N N 1 N 1 N 1 S 1 S S S 3 S 3 S 4 S 4 S W 14 W 1 W 1 W 8 W 6 W 4 W W E 4 E 6 E 8 E 1 E 1 E 14 E List data providers Slide 5

26 Gridded alt. wave heights Discrepancies in wave observations: ENVISAT 3711_69318 ALL All data buoy wave heights ENTRIES: FYT ZSWAV LDWR LF3F LF3J LF3N LF4B LF4C LF4H LF5U TFBLK TFSRT TFSTD ENTRIES = 1358 ALTM MEAN =.46 STDEV = 1.7 BUOY MEAN =.35 STDEV = LSQ FIT: SLOPE =.94 INTR =.4 RMSE =.313 BIAS =.13 CORR COEF =.974SI =.15 SYMMETRIC SLOPE = 1.6 Comparison of gridded altimeter with buoy wave heights for 1. km, 5 % max RCE and 45. degrees max in mean wave dir Slide 6

27 Discrepancies in wave observations: Gridded alt. wave heights8 ENVISAT 3711_69318 NDBC_above_3N NDBC buoy wave heights ENTRIES: ENTRIES = 411 ALTM MEAN =.4 STDEV = 1.1 BUOY MEAN =.4 STDEV = 1.98 LSQ FIT: SLOPE =.91 INTR =.7 RMSE =.83 BIAS =.1 CORR COEF =.977 SI =.118 SYMMETRIC SLOPE =.989 Comparison of gridded altimeter with buoy wave heights for 1. km, 5 % max RCE and 45. degrees max in mean wave dir Note: NDBC for locations north of 3N Slide 7

28 Gridded alt. wave heights Discrepancies in wave observations: ENVISAT 3711_69318 MEDS MEDS buoy wave heights ENTRIES: ENTRIES = 177 ALTM MEAN =.63 STDEV = 1.19 BUOY MEAN =.39 STDEV = LSQ FIT: SLOPE = 1.3 INTR =.36 RMSE =.343 BIAS =.43 CORR COEF =.98 SI =.11 SYMMETRIC SLOPE = 1.87 Comparison of gridded altimeter with buoy wave heights for 1. km, 5 % max RCE and 45. degrees max in mean wave dir Slide 8

29 Gridded alt. wave heights Discrepancies in wave observations: ENVISAT 3711_69318 EUROPE European buoys buoy wave heights ENTRIES: ENTRIES = 437 ALTM MEAN =.93 STDEV = BUOY MEAN =.89 STDEV = LSQ FIT: SLOPE =.959 INTR =.157 RMSE =.8 BIAS =.38 CORR COEF =.983 SI =.96 SYMMETRIC SLOPE = 1.5 Comparison of gridded altimeter with buoy wave heights for 1. km, 5 % max RCE and 45. degrees max in mean wave dir Slide 9

30 Discrepancies in wave observations: Gridded alt. wave heights7 ENVISAT 3711_69318 UK_PLATFORMS UK platforms buoy wave heights ENTRIES: ENTRIES = 15 ALTM MEAN =.41 STDEV = 1.59 BUOY MEAN =.16 STDEV = 1.9 LSQ FIT: SLOPE =.949 INTR =.367 RMSE =.39 BIAS =.57 CORR COEF =.974 SI =.136 SYMMETRIC SLOPE = 1.83 Comparison of gridded altimeter with buoy wave heights for 1. km, 5 % max RCE and 45. degrees max in mean wave dir Slide 3

31 Discrepancies in wave observations: Gridded alt. wave heights1 ENVISAT 3711_69318 NORWAY Norwegian data buoy wave heights ENTRIES: FYT LDWR LF3F LF3J LF3N LF4B LF4C LF4H LF5U ENTRIES = 163 ALTM MEAN =.73 STDEV = BUOY MEAN =.54 STDEV = 1.41 LSQ FIT: SLOPE =.936 INTR =.354 RMSE =.451 BIAS =.191 CORR COEF =.957 SI =.161 SYMMETRIC SLOPE = 1.53 Comparison of gridded altimeter with buoy wave heights for 1. km, 5 % max RCE and 45. degrees max in mean wave dir Slide 31

32 Discrepancies in wave observations: ENVISAT wave heights compared to in-situ data (July 3 to September 6) Bias (m) symmetric slope all data NDBC NDBC north of 3N European buoys Indian buoys GoMoos & Scripps buoys MEDS buoys UK platforms Norwegian platforms Bias: altimeter Hs in-situ Hs Symmetric slope: ratio of variance altimeter to variance in-situ Slide 3

33 Discrepancies in wave observations: Jason-1 wave heights compared to in-situ data (October 3 to September 6) Bias (m) symmetric slope all data NDBC NDBC north of 3N European buoys Indian buoys GoMoos & Scripps buoys MEDS buoys UK platforms Norwegian platforms Bias: altimeter Hs in-situ Hs Symmetric slope: ratio of variance altimeter to variance in-situ Slide 33

34 Discrepancies in wave observations: ERS- wave heights compared to in-situ data (June 1996 to June 3) Bias (m) symmetric slope all data NDBC NDBC north of 3N European buoys Japanese buoys MEDS buoys UK platforms Norwegian platforms Bias: altimeter Hs in-situ Hs Symmetric slope: ratio of variance altimeter to variance in-situ Slide 34

35 Discrepancies in wave observations: ERS- wave heights compared to in-situ data (June 1996 to December 1998) Bias (m) symmetric slope all data NDBC NDBC north of 3N European buoys Japanese buoys MEDS buoys UK platforms Norwegian platforms Bias: altimeter Hs in-situ Hs Symmetric slope: ratio of variance altimeter to variance in-situ Slide 35

36 Discrepancies in wave observations: ERS- wave heights compared to in-situ data (January 1999 to June 3) Bias (m) symmetric slope all data NDBC NDBC north of 3N European buoys Japanese buoys MEDS buoys UK platforms Norwegian platforms Bias: altimeter Hs in-situ Hs Symmetric slope: ratio of variance altimeter to variance in-situ Slide 36

37 Jan-1994 Jan-1994 Jan-1995 Jan-1995 Jan-1996 Jan-1996 Jan-1997 Jan-1997 Jan-1998 Jan-1998 Jan-1999 Jan-1999 Jan- Jan- Jan-1 Jan-1 Jan- Jan- Jan-3 Jan-3 Jan-4 Jan-4 Jan-5 Jan-5 Jan-6 Jan-6 Wave Wave Height Height Bias symmetric (model-buoy) slope (m) Discrepancies in wave observations: against re-analysis (ERA interim).4 Comparison of of ERA interim with with buoy data 33 month month running running average average UK UK platforms platforms Norwegian Norwegian platforms platforms European European buoys buoys NDBC NDBC (north (north of of 3N) 3N) MEDS MEDS months months Slide 37

38 Discrepancies in wave observations: others Jason H s Bias=-.1 R=.983 RMS=.7 SI=.11 N=345 BIAS (altmiter - buoy) (m) Durrant et al., 8 using ENVISAT and Jason (a) 1 1 (b) Jason Jason H s Bias=.75 R=.979 RMS=.413 SI=.117 N= Buoy H s NDBC Buoy H s MEDS 16 FIG..Buoys usedin this study. Buoys from the NDBC aremarkedwith squaresandthosefrom the MEDSnetwork aremarkedwith triangles Bias as found bu Durrant et al. 8 ENVISAT Jason-1 ENVISAT Envisat H s (c) Buoy H s NDBC Bias=.36 R=.986 RMS=.19 SI=.16 N= Envisat H s (d) Buoy H s MEDS Bias=.8 R=.989 RMS=.355 SI=.87 N= NDBC buoys MEDS buoys From Durrant et al., 8: Validation of Jason-1 and Envisat Remotely-Sensed Wave Heights. Accepted for publication in JAOT. FIG. 3. Scatterplots of co-locatedh s observationsfor Jason-1and Envisat for both the NDBC andmeds buoy networks separately. Panelson the top (a andb) show Jason-1datawhil e those on the bottom (c and d) show Envisat data. Panelson the left (a and c) show co-locationswith NDBC buoys only, thoseon the right (b and d) show co-locationswith MEDS buoys only. The numberof co-locationsin each.5 m bin have have beencontoured ENVISAT data from April 3 to April 6. Jason-1 data from January to March 6. Slide 38

39 Discrepancies in wave observations: others Queffeulou P., 6 using TOPEX, ENVISAT and Jason-1 TOPEX MEDS NDBC Similar results reported for other satellites. From: Queffeulou P., 6: Altimeter wave height validation - an update, OSTST meeting, Venice, Italy, March 16-18, 6. ( Slide 39

40 Discrepancies in wave observations: others Cotton et al., 4 using ENVISAT and ERS- (FD) NDBC WAM ENVISAT Ku ENVISAT S MEDS Using multiple regressions, They found systematic differences between the different buoy networks. Europe ERS- From: Cotton, P. D., P. G. Challenor and J.M. Lefèvre, 4, Calibration of ENVISAT and ERS- wind and wave data through comparison with in-situ data and wave model analysis fields. ENVISAT ERS Symposium, ESA SP57, Salzburg, Austria Slide 4

41 Discrepancies in wave observations: others Challenor et al., 1 using Geosat, TOPEX and ERS-1& (FD) Using the combined, calibrated (against NDBC) altimeter data set, Collocate with other networks: slope with respect to Alt NDBC UKMO JMA MEDS From: P. G. Challenor and P. D. Cotton, 1, The joint calibration of altimeter and in situ wave heights in "Advances in the Applications of Marine Climatology - The Dynamic Part of the WMO Guide to the Applications of Marine Climatology WMO/TD-No. 181, WMO Geneva. Slide 41