Sentinel-1 Colocation

The colocation activity is an important part of the work for the Sentinel-1 Mission Performance Center.

This page deals with the massive colocations realized between Sentinel-1 products (L1 or L2) and different reference datasets.

 

FTP link to netCDF colocalisation files

 download-button-blue-300x133

 

Here is the list of reference dataset used:

 
average delay between SAR availability on MPC ftp and coloc file availability spatial window (km) temporal window (min)
model
WW3 (IOWAGA) 0.5° 3h global SAR data driven 65 90
Arpege High Resolution 0.1° 1h Europe (MeteoFrance) SAR data driven 35  30
ECMWF forecast Global 0.125° 3h SAR data driven 20 90
in situ
Coriolis network(IFREMER) 12h  5 60
NDBC network (NOAA) 12h  5 60
CDIP network (Scripps) 1 month  5 60 
MEDS  network (Canada) not available yet  5 60
ECMWF collection (ECMWF)  6 months  5 60
scatterometer
metop-A ascat (KNMI netCDF) 25km 48h 25 360
metop-B ascat(KNMI netCDF) 25km 48h 25 360
oceansat-2 oscat(KNMI netCDF) 25km satellite down 25 360
coriolis windsat not available yet 25 360
ISS rapidscat (JPL/PODAAC)  12.5km not available yet 25 360
altimeter
 Cryosat-2 L2p GDR (Globwave)  48h 25 360

Colocation parameters

  • The default method of colocation is closest neighbour.
  • For Level1 SAR data, the resolution is lowered to 1km in order to enhance processing performances.

Colocation netCDF files content

 
collocation with Satellites and models moored buoys
level  Level1 Level2 Level1 and Level2
SAR data  all variables at 1km resolution (ex: sigma0, incidence_angle,...)  all variables L2 resolution (ex: oswHs,oswWindSpeed, oswNrcs,...) all SAR variables at original resolution on a 5x5 pixels box centered on the buoy position.
ancillary data  defined variables depending of the data resampled on SAR positions (ex: wind_speed_selection for scatterometer matchup, Hs for WW3 model,...) measured buoy parameters at the nearest time step.
miscellanous
  •  distance to pixel field
  • mean time difference between the two measurement

Colocation files naming

Satellites and models Buoys
example 20150219T030000_WW3_s1a-wv1-ocn-vv-20150219t030204-20150219t032548-004686-005CAB-093.nc  s1a-s1-slc-hh-20141016t143858-20141016t143923-002856-0033a4-001.tiff_sentinel1A_ndbcnrt_matchups.nc
rule

yyyymmddTHHMMSS_A_sat-inc-type-pol-yyyymmddtHHMMSS-yyyymmddtHHMMSS-cycle-datatakeid-imagetteNbre.ext

  • first date: date of thr ancillary product
  • A: name of the ancillary product
  • last part: copy of the measurement filename
  • Sentinel-1 measurement filename
  • satellite
  • buoy network