Remote sensing data
Overview of remote sensing data that may be useful for hydrological analysis
Spectrometer
| Institute | Satellite | Sensor | channels | launched | resolution | Notes |
|---|---|---|---|---|---|---|
| ESA | ENVISAT | MERIS | 15 | March 2002 | 260x290m | Visible and Near Infrared spectrum (390 to 1040 nm), cloud cover, water bodies, frequency 3 days (higher at the poles) |
| NASA | TIROS-N | AVHRR | 4 | 1.09x1.09km | http://www.nsof.class.noaa.gov. Can be used for cloud cover (Bendix et al.), surface temperature (ref), delineation of water bodies (Zhou et al., 2000) | |
| NOAA | NOAA-7 | AVHRR | 5 | |||
| NOAA | NOAA-15 | AVHRR | 6 | May 1998 | ||
| NOAA | NOAA-16 | AVHRR | 6 | Sep 2000 | ||
| NOAA | NOAA-17 | AVHRR | 6 | Jun 2002 | ||
| NOAA | NOAA-18 | AVHRR | 6 | May 2005 | ||
| Eumetsat | METOP | AVHRR | ? | cloud cover, surface temperature | ||
| ESA | MSG-1 & 2 (Meteosat-8 & 9) | SEVIRI | 12 | 2002 | Spinning Enhanced Visible and Infrared Imager. [Africa and Europe] @ 15 minutes. 8 channels can be used for monitoring the earth surface. Channel 12 is a high resolution visible (hrv) channel. Resolution: 3 km at the sub-satellite point (5 – 6 km over Europe). Channel 12 has a resolution of 1 km at the sub-satellite point (1.5 – 2 km over Europe). Can be used for precipitation (see e.g. Thies et al. doi:10.1029/2008JD010464) | |
| NASA | TRMM | ?? | 25x25km (0.25°) | rainfall | ||
| NASA | AQUA | AMSR-E | May 2002 | 6.25 - 25 km | Wind speed, water vapor, cloud liquid water, Snow water equivalent,Surface Soil Moisture (daily). [More details]. | |
| NASA | TERRA | ASTER | 15 | 1999 | 15-90m | temperature, reflectance, elevation, land use. On demand; some images exist for the Andes |
| NASA | TERRA/AQUA | MODIS | 36 | 1999/2002 | see notes | http://www.landcover.org, spatial resolution: 250 m (bands 1-2) 500 m (bands 3-7) 1000 m (bands 8-36), temporal resolution 1 to 2 days, visible and near infrared (400 to 14400 nm) |
radar
| Institute | Satellite | Sensor | launched | resolution | Notes |
|---|---|---|---|---|---|
| ESA | ENVISAT | ASAR | March 2002 | 30m | APG HH and HV -> delineation of water bodies |
| ESA | ENVISAT | Altimeter | March 2002 | 400m | altitude (only 1 dimension) |
| MDA | RADARSAT-1 | ASAR | November 1995 | 10m | commercial (Canadian private company) |
| MDA | RADARSAT-2 | ASAR | December 2007 | 3m | commercial (Canadian private company) |
| ASI | COSMO-SkyMed | SAR | June 2007 | Constellation of 4 satellites |
other
One that has not gone up yet: SWOT
Data aquisition
ESA
ESA is a very big engine and it is tricky to find what you are actually looking for or what you need but there is lots:
The following link is a shortcut to ESA's 'Resources' page that includes upcoming workshops, the ESA library, data samples and archives, and probably most useful for anyone working with ESA data, there are ESA-tailored software tools that run free-of-charge on Windows, linux and also MacOS (although mac versions are usually appearing a bit later than the other two!): http://earth.esa.int/resources/ P.S. I attended an ESA Land Training course in Lisbon in September 2007 on Flooding/Soil moisture and Forests and have lots of lecture notes on ASAR, ALOS and how to use these data with the BEST, BEAM and POLSARPRO packages (I have actually worked with an ALOS quadpol for tree height and soil moisture retrieval: amazing data!). If you want any of these notes or some help, just email me (guy.schumann@bristol.ac.uk) and I'll try to help!
There is a useful tool from the ESA website to search for available images (does ENVISAT and others):
To access online (last 7-10 days) data and submit CAT-1 (free data) proposals for projects:
http://earth.esa.int/dataproducts/accessingeodata/
To answer third party mission (from non-ESA satellites) calls: http://eopi.esa.int/esa/esa?type=10&cmd=aolist, and go to the 'TPM' link to the left of the page,
and AO (Announcement of Opportunities) calls: http://eopi.esa.int/esa/esa?type=10&cmd=aolist
ESA conferences and workshops
Anyone interested in this year's (2008) ESA summer school in August (4-14) at the ESRIN centre in Italy? Topic: Data assimilation, monitoring and modelling the Earth System. Have a look at: http://envisat.esa.int/envschool/
Detailed info on satellites
meteosat
The channels of SEVERI on board meteosat-8 (spectral band / μm)
(from http://las.physik.uni-oldenburg.de/eProceedings/vol05_1/05_1_de-ruyter1.pdf)
| Channel | min | max | description |
|---|---|---|---|
| 1 | 0.635 | 0.56 | 0.71 visual |
| 2 | 0.81 | 0.74 | 0.88 visual |
| 3 | 1.64 | 1.50 | 1.78 near infrared |
| 4 | 3.90 | 3.48 | 4.36 infrared |
| 5 | 6.25 | 5.35 | 7.15 infrared (water vapour absorption) |
| 6 | 7.35 | 6.85 | 7.85 infrared (water vapour absorption) |
| 7 | 8.70 | 8.30 | 9.1 infrared |
| 8 | 9.66 | 9.38 | 9.94 infrared (ozone absorption) |
| 9 | 10.80 | 9.80 | 11.80 infrared |
| 10 | 12.00 | 11.00 | 13.00 infrared |
| 11 | 13.40 | 12.40 | 14.40 infrared (CO2 absorption) |
| 12 | 0.75 | 0.60 | 0.90 high resolution visual broadband (hrv) |
Processing
Envisat altimeter
Some information that may make life easier when dealing with ESA's altimeter N1 files:
- ESA's Basic Radar Altimeter Toolbox provides a set of tools and an interface for extracting data from the original N1 files. The interface is broken on recent linux versions due to obsolete dependencies but the command line tools work.
- The XY extraction utility (BratCreateZFXY) does not seem capable of extracting the original data directly. It requires a predefined raster size and automatically interpolates before exporting.
- BratCreateYFX extracts the measurements in the original resolution. However it only includes one dimension so you have to add the other one manually as a dataset. Something like this in the parameter file:
# longitude
X=lon
X_NAME=X
X_TYPE=Longitude
X_UNIT=degrees_east
X_TITLE=X
# latitude
FIELD=lat
FIELD_NAME=Y
FIELD_TYPE=Data
FIELD_UNIT=count
FIELD_TITLE=Y
# data of interest follow
FIELD=alt_cog_ellip
FIELD_NAME=alt_cog_ellip
FIELD_TYPE=Data
FIELD_UNIT=mm
FIELD_TITLE=alt_cog_ellip
- Extracting many fields from many files is much easier using the command line tools and a batch script.
downscaling techniques
statistical
singular vector decomposition
Bretherton CS, Smith C, Wallace JM. 1992. An intercomparison of methods for finding coupled patterns in climate data. Journal of Wilks DS. 1995. Statistical Methods in the Atmospheric Sciences. Climate 5: 541–560