Hi! I was wondering if someone could elaborate on the ‘estimated_oxygen_concentration’ variable and how it is used in the processing of the DOSTA oxygen variable? Is it used when temp/sal/pressure from the co-located CTD is not available? Is this in the documentation somewhere?
Thank you!
Hi Kristen,
Despite the name, that variable is actually the temperature-corrected L1 data product (produced onboard the instrument) in units of umol L-1 that is then used to produce the L2 temp and salinity corrected data. However, it’s listed in preload as a deprecated parameter (PD940) which was to be replaced by PD950: uncorrected_do, which is again confusingly named. I’m looking into why that replacement was never done (I think it was part of a cleanup of redundant parameters that was never completed), but hopefully that helps with your data analysis.
I’ll let you know if I find out anything more.
Thanks,
Mike Vardaro
Hey Kristen,
As @mvardaro noted, it is the oxygen concentration computed onboard the sensor using internally stored calibration coefficients and the optode thermistor temperature. OOI also recalculates the same value from the raw phase measurements and the optode thermistor temperature with the calibration coefficients loaded into our database, calling it dosta_abcdjm_cspp_tc_oxygen. You can use the two values as a quick check of the OOI algorithm and uploaded calibration coefficients; they should be essentially identical to each other. The later value, dosta_abcdjm_cspp_tc_oxygen, is then used as the input for the pressure and salinity corrected dissolved oxygen (umol kg-1) using data from a co-located CTD.
Cheers,
Chris