[ecco-support] [EXTERNAL] Difference in sea surface salinity regarding the ECCO v4r3 and v4r4

[Wang, Ou (US 329B)]

Hao,

Thank you for bringing to our attention the sea surface salinity (SSS) difference between ECCO’s v4r4 and v4r3 estimates. We took a closer look at our estimates by comparing the model SSS against observations by the Aquarius satellite (2011-2015). Both v4r4 and v4r3 are different from Aquarius, but, on average, v4r4 is in fact slightly closer to Aquarius than v4r3 is. The mode-data difference is within the expected uncertainties of Aquarius data.

For your reference, the attached figure shows root mean square differences (RMS) of v4r3-Aquarius (top left) and v4r4-Aquarius (top right). Also shown for comparison in bottom left is our formal uncertainty estimate of Aquarius SSS; Values in the top two panels generally being smaller than this error estimate demonstrates the model-data differences being smaller than the error estimate. Bottom right shows the RMS of v4r3-Aquarius minus RMS of v4r4-Aquarius; the largely positive values in in this bottom right panel demonstrates the slightly closer agreement of v4r4 to Aquarius than v4r3 to Aquarius.

Note that our formal data error estimate includes model representation error in addition to instrument noise in the Aquarius data. Model representation error corresponds to differences between model and the real ocean due to limitations in the model, such as spatial resolution, among others.

We hope this comparison is helpful. Please do not hesitate to contact us again if you have further questions.

Ou


From: <ecco-support-bounces at mit.edu> on behalf of 刘浩 <lhao at fio.org.cn>
Reply-To: "ECCO support list, wider membership" <ecco-support at mit.edu>
Date: Thursday, February 6, 2020 at 8:47 AM
To: "ecco-support at mit.edu" <ecco-support at mit.edu>
Subject: [EXTERNAL] [ecco-support] Difference in sea surface salinity regarding the ECCO v4r3 and v4r4


Hi, ECCO producers



I has downloaded salinity data from folders interp_monthly of the ECCO v4r3 and v4r4, and I noticed the two sets of data shows large differences in all individual years(for example, SSS over 2001 is shown in the attachment). I wonder what causes the large differece? Is it because new observation introduced (gliders, moorings)? Or profiles is re-weighted? Or else？





Best,Regrads, HAO LIU


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