[NARCCAP-discuss] High observed vs. modeled errors for precipitation

[Obeysekera, Jayantha]

Hi Kelli,
I am not surprised.
We have had similar findings in Florida.  I believe your only choice may be to "bias-correct" the NARCCAP data before they are used in hydrological models.  I personally do not think that is the right way to use RCM data but there appears to be no other choice.
Obey
________________________________________
From: narccap-discuss-bounces at mailman.ucar.edu [narccap-discuss-bounces at mailman.ucar.edu] on behalf of Kelli Walters [waltersk at onid.orst.edu]
Sent: Tuesday, August 27, 2013 8:17 PM
To: narccap-discuss at mailman.ucar.edu
Subject: [NARCCAP-discuss] High observed vs. modeled errors for precipitation

Hello,

I am evaluating which NARCCAP model runs best fit my observed data to
determine which ones I should use as climate projections in a
hydrologic model. I am comparing the past data set (1970-2000) from
the models to observed data for temperature (max and min) and
precipitation. For temperature, the models seem to accurately reflect
the observations, with Nash-Sutcliffe efficiencies around 0.5 (r2 of
0.5-0.6) for daily comparison and in the range of 0.6-0.9 (r2 of about
0.85) for monthly averages.

However, for precipitation, my errors have been much larger. I am
getting Nash-Sutcliffe efficiencies of around -0.4 to -1 (r2 of 0.02
and smaller) for both daily values and monthly averages. What I am
wondering is: are these error values normal or in the same range as
other people are getting for precipitation?

Do you have any papers or references that give these error metrics for
precipitation when comparing the modeled data to observations? I have
been looking for literature to back up what I am finding, but I can't
seem to find what values are considered "acceptable" for precipitation
error. Any help or sources you can provide on this would be much
appreciated.

Thank you,
Kelli


--
KELLI WALTERS, EIT
M.S. Candidate
Civil Engineering | Water Resources
Oregon State University
waltersk at onid.orst.edu





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