Snow water equivalent (SWE) indicates the amount of accumulated snow on land surfaces; in other words the amount of water contained within the snowpack. The SWE product time series covers the period from 1979 to 2018. Northern Hemisphere SWE products are available at daily temporal resolution with alpine areas masked.
The product is based on data from the Scanning Multichannel Microwave Radiometer (SMMR) operated on National Aeronautics and Space Administration’s (NASA) Nimbus-7 satellite, the Special Sensor Microwave / Imager (SSM/I) and the Special Sensor Microwave Imager / Sounder (SSMI/S) carried onboard the Defense Meteorological Satellite Program (DMSP) 5D- and F-series satellites. The satellite bands provide spatial resolutions between 15 and 69 km. The retrieval methodology combines satellite passive microwave radiometer (PMR) measurements with ground-based synoptic weather station observations by Bayesian non-linear iterative assimilation. A background snow-depth field from re-gridded surface snow-depth observations and a passive microwave emission model are required components of the retrieval scheme.
The dataset was aimed to serve the needs of users working on climate research and monitoring activities, including the detection of variability and trends, climate modelling, and aspects of hydrology and meteorology.
The Finnish Meteorological Institute is responsible for the SWE product development and generation. For the period from 1979 to May 1987, the products are available every second day. From October 1987 till May 2018, the products are available daily. Products are only generated for the Northern Hemisphere winter seasons, usually from beginning of October till the middle of May. A limited number of SWE products are available for days in June and September; products are not available for the months July and August as there is usually no snow information reported on synoptic weather stations, which is required as input for the SWE retrieval. Because of known limitations in alpine terrain, a complex-terrain mask is applied based on the sub-grid variability in elevation determined from a high-resolution digital elevation model. All land ice and large lakes are also masked; retrievals are not produced for coastal regions of Greenland.
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Public data: access to these data is available to both registered and non-registered users.
Use of these data is covered by the following licence: http://artefacts.ceda.ac.uk/licences/specific_licences/esacci_snow_terms_and_conditions.pdf. When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record.
Data were produced by the project team and supplied for archiving at the Centre for Environmental Data Analysis (CEDA).
Data are as provided by the data producer. The statistical standard deviation of snow water equivalent is added as uncertainty layer in each product.
Data are netCDF formatted.
|Title||ESA Snow Climate Change Initiative (snow_cci): SWE|
|Abstract||The snow_cci SWE product has been based on the ESA GlobSnow SWE retrieval approach (Takala et al. 2011). The retrieval is based on passive microwave radiometer (PMR) data considering the change of brightness temperature due to different snow depth, snow density, grain size and more. The retrieval algorithm handles data from the sensors SMMR, SSM/I, SSMIS, AMSR-E and AMSR-2. The retrieval methodology combines the satellite passive microwave radiometer (PMR) measurements with ground-based synoptic weather station observations by Bayesian non-linear iterative assimilation. A background snow-depth field from re-gridded surface snow-depth observations and a passive microwave emission model are required components of the retrieval scheme. Improvements to the GlobSnow algorithm implemented for snow_cci version 1 include the utilisation of an advanced emission model with an improved forest transmissivity module and treatment of sub-grid lake ice. Because of the importance of the weather station snow-depth observations on the SWE retrieval, there is improved screening for consistency through the time series. Snow_cci SWE version 1products are based on SMMR, SSM/I and SSMIS PMR data for non-alpine regions of the Northern Hemisphere.|
- long_name: Coordinate reference system definition
- var_id: spatial_ref
- names: Coordinate reference system definition
- units: mm
- long_name: Snow Water Equivalent
- var_id: swe
- names: Snow Water Equivalent
- var_id: lat_bnds
- var_id: lon_bnds
- units: mm
- long_name: statistical standard deviation of estimate
- var_id: swe_std
- names: statistical standard deviation of estimate
- units: degree_north
- standard_name: latitude
- var_id: lat
- long_name: WGS84 latitude coordinates, center of pixel
- names: latitude, WGS84 latitude coordinates, center of pixel
- units: degree_east
- standard_name: longitude
- var_id: lon
- long_name: WGS84 longitude coordinates, center of pixel
- names: longitude, WGS84 longitude coordinates, center of pixel
- long_name: time
- standard_name: time
- var_id: time
- names: time