I am trying to downscale Reanalysis-II data using WRF. Earlier i was successful in getting a good output precipitation using FNL Data. However now using Reanalysis-II i get a pretty bad output precipitation when compared to TRMM data. Does anyone have good experience with output rain using a coarse resolution data over Tropics ?
My WRF runs under predicts precipitation. The output file comparison is attached in the question.
Any suggestions please.
Hi, I've run the WRF model over this area and it tends to overpredict precipitation (using the GFS model for initial & boundary conditions). In order to try to help you, could you please tell me the physical parameterizations used to run your experiment (cumulus scheme, microphysics, pbl...) and its resolution? I'd also like to know the scale of your comparison plot... is it a daily mean?
I use BMJ scheme for convection, the problem is when I switched from FNL to reananlysis, theoutput RAIN became poor. The physics that I use worked fine for FNL data.
As Bo Huang suggests, it's always a good idea to check and compare other variables. My experience using the BMJ scheme in this area is that it clearly underestimates high precipitation intensities whereas it tends to produce spurious light rain. Thus, for real-time forecasting it wasn't a good choice, but it might work fine for long runs if you are interested in mean values.
Anyway, I don't have experience with Reanalysis-II data. A good idea could be to compare FNL vs Reanalysis-II searching for a bias in fields like SST, 850 hPa wind and temperature, moisture, etc...
You may want to check the paper Brands et al, On the Use of Reanalysis Data for Downscaling, J Climate, 2012. They show that many relevant fields in different reanalyses are virtually uncorrelated over the tropics, i.e., the downscaling results will depend heavily on the chosen reanalysis. This does not help to solve the problem, but might help to understand where it comes from.
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