C o p e r n i c u s L a n d M o n i t o r i n g S e r v i c e

Transcription

1 C o p e r n i c u s L a n d M o n i t o r i n g S e r v i c e Integration into existing Snow and Ice Services and draft product specifications Annett BARTSCH b.geos Copernicus High Resolution Snow and Ice Product - User consultation workshop EEA, Brussels,

2 A v a i l a b l e S & I E O s e r v i c e s f o r E u r o p e ESA GlobSnow GlobSnow 2 CCI+ Snow 2021 ESA SEOM S1-4Sci Snow S3-4Sci Snow FP7 Cryo FP7 Sen3App Cop Global 2020 ESA GlobGlacier CCI Glaciers CCI Glaciers Phase 2 Cop C3S 312a/b 2021 Snow Snow, glaciers, lake ice Snow, lake ice Glaciers

3 A v a i l a b l e S & I E O s e r v i c e s f o r E u r o p e Snow Presence of snow within grid cell 1km (H-SAF) Snow cover area per grid cell 500 m (Global ) Snow water equivalent 5km (Global ) Snow status (wet/dry) 500 m (Global ) Glaciers Glacier extent (glacier presence) 10 m (C3S) Permanent snow line on glaciers demonstrated with Sentinel-2 Lakes Lake ice presence 250 m (Global ) Snow cover on lake ice 250 m (Global ) Lake ice fraction per lake freeze and break-up timing 3

4 S t a t u s s u m m a r y Pan-European NRT services available but limited too coarse resolution for snow and lake ice services The potential of Sentinel-1 and Sentinel-2 for snow extent mapping has been demonstrated on regional level - higher spatial resolution is possible SWE improvement impeded by technical limitations Glacier extent monitoring operational Snow covered glacier area has been demonstrated feasible, available regionally Users request higher spatial resolution, consistently over entire Europe

5 G a i n b y h i g h r e s o l u t i o n s e r v i c e s HR service detail Snow spatial variability of snow melt information lacking in current services fractional information at coarse resolution is impacted by vegetation cover, the effect can be partially reduced by using higher spatial resolution Lake and river ice Rivers have not been addressed so far due to lack of spatial resolution Current service detail (dashed - lake ice) 7

6 P a r a m e t e r s t o b e c o v e r e d FSC1 Fractional snow cover FSC2 Permanent snow line LI1 Presence of ice on lakes and rivers (including snow/no snow), Fraction of ice cover per lake LI2 Freeze and break-up timing

7 G e n e r a l Combination of Sentinel-1 and 2 for best results Appropriate cloud masking Adequate quality assurance/control

8 F r a c t i o n a l s n o w c o v e r s p e c i f i c a t i o n s

9 F r a c t i o n a l s n o w c o v e r s p e c i f i c a t i o n s Each pixel represents the situation in a single day. The main information is the Fractional Snow Cover to be given in a scale of 0 100, where 0 equals NoSnow, and 100 means 100 % of snow cover. Anything in between describes the snow fractions. In case no data on snow cover is available due to the cloud cover or polar night then value Cloud or Polar Night will be assigned.

10 F r a c t i o n a l s n o w c o v e r s p e c i f i c a t i o n s Input data sources Mandatory: Optical satellite data from Sentinel-2 Microwave satellite data from Sentinel-1 S2 & S Optional: Other optical satellite data (e.g. sat- 8)

11 F r a c t i o n a l s n o w c o v e r s p e c i f i c a t i o n s Spatial resolution Threshold: 100 m Target: 20 m Update frequency Daily Snow Cover layer Temporal aggregation according to user needs Coverage Europe- EEA39

12 F r a c t i o n a l s n o w c o v e r s p e c i f i c a t i o n s Data type : Raster layer Delivery time: maximum 6 h Delivery format : NetCDF (preferred by the meteorological community and by the climate modellers) Metadata: INSPIRE compliant Archive & Data accessibility Low level: Efficient bulk data access High level: Web interface Time coverage: In high mountain areas: all year Remaining regions: all potential days with snow cover

13 F r a c t i o n a l s n o w c o v e r s p e c i f i c a t i o n s Methodology The chosen methodology should be based on a retrieval approach that has been established for a continental scale, not a regionally tuned one. The approach is expected to be widely accepted, used and peer reviewed at this stage Required DEM (same as the one used to correct the data is needed for S&I processing, needs to be available. High quality water mask: EU-Hydro inland water and river polygons Forest mask (TCD tree cover density) Output products DEM Forest mask (TCD) Snow parameter

14 F r a c t i o n a l s n o w c o v e r s p e c i f i c a t i o n s Steps Intermediate: For each S2 image S2 FSC for a certain acquisition time Final: FSC S2 + wet/dry snow (using S1) combined FSC for a certain day Based on single combined FSC files above eventually also: Composites (i.e. weekly, monthly, ), including maximum FSC Yearly snow cover duration Yearly permanent snow line on glaciers

15 F r a c t i o n a l s n o w c o v e r s p e c i f i c a t i o n s Result from user consultation January 2018 Product ID Update frequency Accuracy (threshold) Accuracy (target) Timeliness (after overpass) Auxiliary information (Uncertainty) FSC1 Daily RMSE 20 RMSE 10 6h (ideal) <12h <24h hydro FSC2 Annual permanent snow line Pixel wise uncertainty information (sd of FSE %)

16 F r a c t i o n a l s n o w c o v e r s p e c i f i c a t i o n s Validation At selected spots (e.g. by local teams): E.g. Time leaps/vhr/uav/webcams Meteorological stations (e.g. Synop stations, snow transects) Challenges Snow/ Cloud discrimination Zero snow cover reporting

17 F r a c t i o n a l s n o w c o v e r s p e c i f i c a t i o n s Confidence map to be published together with the primary layers. Confidence map represents a single layer where each pixel is assigned a number describing the confidence with which a pixel was assigned the value of FSC correctly.

18 L a k e a n d r i v e r i c e s p e c i f i c a t i o n s

19 L a k e a n d r i v e r i c e s p e c i f i c a t i o n s each pixel represents the situation in a single day Primary information is pixelwise ice/snow/open water Secondary information is the Fractional Ice Cover of a lake or river to be given in a scale of 0 100, where 0 equals No Ice, and 100 means 100 % of ice cover. Anything in between describes the lake or river fractions. In case no data on lake and river ice is available due to the cloud cover or polar night then value Cloud or Polar Night will be assigned. Minimum lake size: 1ha Minimum river size: > 50 m width, appropriate segmentation 21

20 L a k e a n d r i v e r i c e s p e c i f i c a t i o n s Input data sources Mandatory: Optical satellite data from Sentinel-2 Microwave satellite data from Sentinel-1 Optional: Other optical satellite data (e.g. sat- 8) S2 & S

21 L a k e a n d r i v e r i c e s p e c i f i c a t i o n s Spatial resolution Threshold: 100 m Target: 20 m Update frequency Daily: lake/river ice layers Annually: Freeze up/break up date of a river/lake Coverage Europe- EEA39

22 L a k e a n d r i v e r i c e s p e c i f i c a t i o n s Data type : Raster layer Delivery time: maximum 6 h Delivery format : NetCDF CF (preferred by the meteorological community and by the climate modellers) Metadata: INSPIRE compliant Archive & Data accessibility Low level: Efficient bulk data access High level: Web interface Time coverage: all potential days with ice cover

23 L a k e a n d r i v e r i c e s p e c i f i c a t i o n s Methodology The chosen methodology should be based on a retrieval approach that has been established for a continental scale, not a regionally tuned one. The approach is expected to be widely accepted, used and peer reviewed at this stage Required High quality water mask: EU-Hydro inland water and river polygons Output products Ice/Snow/open water (pixel wise) Ice fraction per lake / river segment

24 L a k e a n d r i v e r i c e s p e c i f i c a t i o n s Steps Intermediate: For each S2 image (at 20m) S2 ice class for a certain acquisition time Ice class S2 + ice/no ice using S1 combined ice class for a certain day Final: Lake/River ice fraction per day (LI1) Based on single combined LI1 files above eventually also: Day of breakup and day of refreeze (LI2)

25 L a k e a n d r i v e r i c e s p e c i f i c a t i o n s Result from user consultation January 2018 Product ID Update frequency Accuracy (threshold) Accuracy (target) Timeliness Auxiliary information (Uncertainty) LI1 Daily 75% of the lake is correctly classified 85% 6h (ideal) <12h LI2 Annual Freeze up / break up date (potentially added to the service in the future)

26 L a k e a n d r i v e r i c e s p e c i f i c a t i o n s Input data Lake and river outline mask (e.g. EU-Hydro River Network) lake Ice in situ observation VHR optical Challenges Snow/ Cloud discrimination Water quality- the clarity of water affects data retrieval Water turbidity- the turbidity of water affects data retrieval

27 L a k e a n d r i v e r i c e s p e c i f i c a t i o n s Confidence map to be published together with the primary layers Confidence map represents a single layer where each pixel is assigned a number describing the confidence with which a pixel was assigned the value of ice type correctly.

28 S u m m a r y The new S&I service will complement existing services and cover additional parameters provide improved services with respect to spatial resolution and higher level products enable across-boarder applications, especially in the field of weather forecasting and hydrological services enable new applications of S&I services due to the higher detail (e.g. pixels information can be associated with roads) will make use of potential of the Copernicus missions (S1 and S2), not exploited so far for S&I services pan-european