I am saving a couple of 3d variables monthly and their values at a chosen specific depth daily because writing out the entire 3d variable daily is too expensive. I am attaching a plot below that shows the difference (in %) between: (i) the daily value at the chosen depth averaged over a month (from the daily file); and (ii) the monthly value at the same depth (from the monthly file). The top panel shows this difference for the variables WTT and KPP_SRC_TEMP. For WTT, I am writing the daily value at the shallowest model level and for KPP_SRC_TEMP, the corresponding depth is 40 m. The bottom panel is zooming into the Kuroshio region.
Shouldn't the difference in the plots below be close to zero? I am finding them to be within 0.01% of each other for WTT and 0.001% for KPP_SRC_TEMP. This might not be too large but why is there any difference at all? To be consistent, I would have thought averaging the daily values over a month should be equal to the monthly value to within machine precision.
Shouldn't the difference in the plots below be close to zero? I am finding them to be within 0.01% of each other for WTT and 0.001% for KPP_SRC_TEMP. This might not be too large but why is there any difference at all? To be consistent, I would have thought averaging the daily values over a month should be equal to the monthly value to within machine precision.