PODAAC

time-latitude diagram of the Aquarius L3 1.3.7 bias with respect to Argo

We computed the bias as the difference between 1x1deg Aquarius daily SSS and the shallowest valid Argo salinity (in the upper 10m) binned daily on the same 1x1 deg grid.

The temporal variations of the bias display apparent seasonal dependencies. In the mid-latitudes westerly wind bands, AQ salinity is biased fresh during local winter (higher roughness), but it is too salty during local summer (lower roughness).

Noting that biases are weaker in the 30S-30N band, it points (I guess) at remaining problems with the reflected component.

senyagrodsky

Senya's plot shows that V1.3.7 has very good results in the mid-latitudes between 40N and 40S. The large Southern Hemisphere low SSS anomaly from April-August 2012 is due to slight errors in the galactic reflection correction, likely due to the roughness correction that computes the diffusion of the specular reflection. There is progress on fixing this in the next version to be released later in 2013. The conspicuous variations northward of 40N are likely to be a similar artifact. The positive result of this is that these errors are now localized in space and time and their influence on the sensor calibration is minimized in the new V1.3.7 calibration scheme.

Lagerloef