SMAP 70km released

Date Added: 
Friday, March 30, 2018

SMAP 70km Salinity Product Available Now

A new SMAP salinity product is now available. This new product samples the SMAP observations to a spatial resolution of 70 km. For most oceanographic applications, it is recommended that the new 70-km product be used.

As is the case for the 40-km resolution product, the 70-km product is resampled onto a 0.25° fixed Earth grid using a Backus-Gilbert type optimum interpolation (OI). In the case of the 70-km product, the target cell of the OI is a circular footprint with a diameter of 70 km. Compared to the 40-km product, the 70-km is spatially smoother and less noisy. A quantitative statistical comparison of the 40km and 70km Level 2C products for June 2015 is given below:

SMAP 40km

Bias Standard Deviation
Tb Measured – Tb Modeled (h-pol) -0.000639 0.498
Tb Measured – Tb Modeled (v-pol) -0.0130 0.440
SSS SMAP – SSS HYCOM 0.00884 0.920

SMAP 70km

Bias Standard Deviation
Tb Measured – Tb Modeled (h-pol) -0.00674 0.268
Tb Measured – Tb Modeled (v-pol) -0.0113 0.263
SSS SMAP – SSS HYCOM 0.00593 0.559

The noise in the Level 2C salinity is strongly reduced from 0.92 psu (40 km) to 0.56 psu (70 km) when compared to HYCOM. This noise reduction and smoothing is still visible in the 8-day and monthly averages

The new RSS SMAP 70km salinity is produced concurrently with the RSS SMAP 40km salinity. As with the SMAP 40km salinity, we produce 3 products with different temporal sampling: Level 2-C swath data, Level 3 8-day running mean, and Level 3 monthly averages. They are available for download here:

SMAP 70km L2C
SMAP 70km L3 8 Day Running
SMAP 70km L3 Monthly