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The near 50GHz sea ice emissivity product (OSI-404)

In the context of the first Continuous Development and Operation Phase (CDOP-1), a sea ice emissivity product was introduced in the Ocean and Sea Ice SAF product's portofolio. It is based on satellite SSMIS microwave radiometer data.

The spatial resolution is about 50 km. However it is provided on daily grids where the grid-point spacing is 10km or 25km. All swath data from one day are combined and resampled to the grid using nearest neighbor. The model for computing the emissivities is described in the ATBD. It uses the brightness temperatures at 19v, 37v and 37h measured by the conically scanning SSMIS.

  1. Introduction and FAQ
  2. Algorithms
  3. Validation
  4. Documentation and links

1.Introduction and FAQ

How should I cite this dataset?

This dataset shall be referred to as the The near 50GHz sea ice emissivity product of the EUMETSAT Ocean and Sea Ice Satellite Application Facility (OSI SAF, www.osi-saf.org).

Which satellite sensors are processed?

The brightness temperatures at 19v, 37v and 37h measured by the conically scanning SSMIS.

What is the spatial resolution of this product?

The spatial resolution of the product is about 50km. similar to the 19GHz channel on the SSMIS.

What is the time-span of this product?

One day (24 hours).

There are 4 different layers in the NetCDF file, which one should I use?

The R and S coefficients are input to the emissivity model in equation 1 and 2 of the PUM. Provided with these coefficients it is possible to compute the near 50GHz sea ice emissivity at vertical and horizontal polarisation and a angles between nadir and about 60 degrees. The emissivity at vertical polarisation and at 50 degrees, ev, is compatible with the SSMIS sounding channels 1-5 configuration. The nadir emissivity, e, is compatible with the mid-swath AMSU configuration. The emissivity near the edges of the swath will be lower than the nadir emissivity.

Today's product file is empty or has large data gaps, what happened?

There are two possible reasons for missing data:

  • 1: In case of interrupted data link with the satellite operating centres, no input swath data are available for processing of sea ice drift data inside the time constraints, resulting in an empty grid.
  • 2: The data point values are outside of model range.

What is the legend used for the quicklooks?

Quicklooks for the product can be viewed from this page.

Where can I find the emissivity for Antarctic regions?

The product is global and covers sea ice and ice shelves in the Arctic and the Antarctic.

I do not fancy NetCDF, do you have other formats?

The processing chain is currently only producing NetCDF files. Please let us know (contact) if you need another format.

3. Validation

Validation of OSISAF can be found in the product specific validation report, also referred to in Documentation and links, below.

4. Documentation and links

The following documentation is available, further describing the OSI-404 sea ice emissivity product.
Quicklooks for this dataset can be accessed from this page.