Jacobsen, Sven

Pleskachevsky, Andrey

Tings, Björn

Institute of Transport Research:Publications

Multiparametric Sea State from spaceborne Synthetic Aperture Radar and Sentinel-1 Wave Mode Archive Processing in Scope of ESA Climate Change Initiative CCIGerman Aerospace Center (DLR)Remote Sensing Technology InstituteMaritime Safety and Security Lab BremenAm Fallturm 9 28359 BremenGermanyExample of Sentinel-1 WM archive processing:right half - one-day acquisitions, left half   - all data acquired during Feb. 2021— Sentinel-1 Wave-Mode whole archive 2014-2021 processed (~15 Mio imagettes), validated, delivered to ESA: 8 sea state parameters: wave height (swell’s, wind-sea), periods (mean, cross-zero, wind-sea). Format: ID.nc for each ID-product— Accuracy of 24 cm reached (significant wave height) – comparable to accuracy of altimeter  and  ground truth noise combination of classical approaches with machine learning — Method adopted for  Sentinel-1 modes IW, EW, WV and also for TS-X SMSentinel-1 daily acquisitions (~60 overflights)► IW - Interferometric Wide Swath Mode  - Coastal areasimage ~ 200 km × 250 km, 10 m pixel, 0.2-2 GB/ID-productGRDH: Level-1 Ground Range Detected High-resolution products ►WV - Wave Mode - Ocean~ 20 km × 20 km vignette each 100 km,  ~ 3 m pixel, 2-10 GB/ID-product  SLC: Single Look Complex products ► flight 704 km ► ground speed 6.8 km/s ► C-Band Radar with wavelength of 5.6 cm► EW - Extra Wide  - Ocean, Polar regionsimage ~ 400 km × 400 km, 40 m pixel    GRDH, 0.1-1 GB/ID-product Sentinel-1A (launch 2014), Sentinel-1B (launch 2016) 1. Sensor and data 2. Processing and validation techniques► IW - Interferometric Wide Swath Mode  - Coastal areas~ 200 km × 250 km, 10 m pixel    ►WV - Wave Mode - Ocean~ 20 km × 20 km Vignette each 100 km, ~ 3 m pixelHs = 0.50m     Hs = 3.90m   Hs = 6.50m      calm                 moderate                  strong1 kmActive sensor > ► no sun illumination needed► signal  penetrates the clouds ► Smearing and displacement ofmoving targetscalm                 moderate                  strongSAR – Synthetic Aperture RadarBlack: features of published CWAVE approachBlue:  additional introduced features Total:60 first-order features Subscene-calibrated-pre-filtered-denoisedEmpirical FunctionsI-stage:simple empiricalII-stage:linearregressionII-stage machine learningWind (CMOD, XMOD) 2. Geophysical NRCS, Norm.-variance, skewness, kurtosis, incidence-angle1. Subscene properties and statistics  3. GLCM (grey level co-occurrence matrix)GLCM-mean, variance, entropy, correlation, homogeneity, contrast, dissimilarity, energy 5. Spectral-B  20 parameter by using orthonormal functions+cutoff by ACF (autocorrelation function)  using spectral bins for different wavelengths4. Spectral-A  Goda-parameter, Longuet-Higgins-parameter + 5 additional parametersSAR features  type SAR features first orderSAR features ResultsSea state parameters+Control of results,filtering CMEMS1/12°WW3 NOAA1/2°2018-01-01   00:002018-01-01   00:00Comparison WW3 and CMEMS (at position NDBC 46001)Temporary: 3h output → 10 min interpolated; Spatially: WW3 on 0.5 deg →0.25 degCross-validationCMEMSTuningValidationWW3TuningValidationWW3 & CMEMSTuningValidationBUOYSValidationCMEMSWW3ValidationValidationalidationGround truth: different hindcast models and buoys SAR products, output and total RMSE (all sea state conditions) for 8 sea state parameters: NRT version 3. Accuracy for 8 integrated sea state parameters 4. Sea state fields and Near Real Time processing5. Sentinel-1 Wave Mode Archive Processing in Scope of ESA Climate Change Initiative Example sea state fields estimated from S1 IWimage acquired on 2018-11-02. Isolines show theHs from CMEMS on 2018-11-02 at 18:00 UTC.Sea State SAR imagingS1 WV  wv1 and wv2 tracks   54 products     S1 EW ~ 410 km swath          229 productsS1 IW   ~ 250 km swath         894 productsS1 WV  wv1 and wv2 tracks   54 products     2020-09-01 Sentinel-1  A and B   SAR  S1 SM ~ 80 km swath            10 products          Screenshot of thedemonstrator for NRT servicesat Ground Station Neustrelitz.The demonstrator runs dailyfor Sentinel-1 IW in North andBaltic Seas. The actualprocessing raster is 3 km, thewave-detection layer showswave height (colored) andperiod (in circles: Hs above,Tm2 below). Data for all eightsea state parameters can bedownloaded as google-earthfile (scene ID.kmz). The wind-detection layer shows the windspeed estimated from the SARimage and wind direction.worldwide NDBC 50 km collocation2016-2021Hindcast model2016-2021Andrey Pleskachevsky, Björn Tings, Sven Jacobsen – DLR, Earth Observation Center, Maritime Safety and Security Lab BremenEgbert Schwarz, Detmar Krause, Sergey Voinov – DLR, Earth Observation Center, Maritime Safety and Security Lab NeustrelitzSea StateParameterDescription S1 IWS1 EWS1 WVTS-X SM / SLproducts used > GRDH GRDM SLC MGDREoutput type > Sea state fields(raster)Sea state fields(raster)Along track imagettes 20km×20km each 100 kmSea state fields (raster)SWH (m) Total significant wave height 0.62 0.64 0.25 0.36Tm0 (s) Mean wave period 0.96 0.86 0.62 0.72Tm1 (s) First moment period 0.97 0.85 0.52 0.59Tm2 (s) Second moment period 0.82 0.86 0.45 0.51SW1 (m) Dominant swell wave height 0.68 0.63 0.46 0.33SW2 (m) Secondary swell wave height 0.38 0.44 0.35 0.27SWW (m) Windsea wave height 0.77 0.66 0.41 0.37Tmw (s) Windsea wave period 0.97 0.95 0.62 0.71Hs = 3.40m

Multiparametric Sea State from spaceborne Synthetic Aperture Radar and Sentinel-1 Wave Mode Archive Processing in Scope of ESA Climate Change Initiative CCI

https://elib.dlr.de/146712/1/ESA_LPS_Pleskachevsky_%20DLR_Sea-State_poster.pdf

Multiparametric Sea State from spaceborne Synthetic Aperture Radar and Sentinel-1 Wave Mode Archive Processing in Scope of ESA Climate Change Initiative CCI

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