NASA algorithm

The NASA algorithm by [Gloersen and Cavalieri, 1986] is a further development of an earlier version of the same algorithm [Cavalieri and Gloersen, 1984]. It uses the satellite data to calculate two ratios: the polarization ratio (PR) and the spectral gradient ratio (GR):

where , and are the brightness temperatures in the 37V, 19V and 19H channels, respectively. These ratios are supposed to be largely independent of physical temperature [Cavalieri and Gloersen, 1984]. A typical PR-GR plot is shown in Figure 1.

  
Figure 1 The geometry of NASA algorithm (from [Gloersen and Cavalieri, 1986])