NWRFC CHPS Forcing Study Goal of Forcings Study Compare the current operational process with the calibration Mean Areal Precipitation (MAP). Create a historical grid or Local Analysis of Record (LAOR) for use in the evaluation process and bias assessments. Develop a method to produce an unbiased grid MAP, representing the volumes used in the calibration phase. Consider methods that can be employed in future calibration activities that use historical grids in lieu of point data. 1HIC Meeting - 2/2010

NWRFC CHPS Forcing Study Rationale for Gridded Data Forcings CAT-I decision to retire the OFS Preprocessors. Data sets (becoming) readily available in gridded form. Preparation to use new/advanced modeling systems, ie., distributed modeling. Aligns hydrology with agency direction in data assimilation, verification, and research programs. 2HIC Meeting - 2/2010

3 NWRFC CHPS Forcing Study Steps of Study Procedure 1.Generate quality and consistent hourly point precipitation from the point data network used in the calibration process + OHD provided special MAP program + Post point data to a new database 2.Create 6-hour and 24-hour aggregates from hourly point data (output from MAP program). 3.Use auto_mpe_dailyQC to generate historical 6 and 24 hour grids for the calibration period of 1949 to Employ an instance of a CHPS stand alone system to compare calibration (OFS point) MAPS and new generated historical MAPX (MPE). 5.Use CHPS and Excel to generate statistics for analysis. HIC Meeting - 2/2010

4 NWRFC CHPS Forcing Study Sample of Grids Produced by MPE dailyQC

NWRFC CHPS Forcing Study 5HIC Meeting - 2/2010 OHD MAP Program Database Tables Database Tables MPE Auto_dailyQC 55 Years 6 and 24 Grids CHPS Excel Evaluation Schematic of Process 1 hr Precip calibration sites 6 and 24 hr Precip values Grids MAP and MAPX

NWRFC CHPS Forcing Study Issues MAP fails to accurately disaggregate the 6-hour data to 1-hourly values. Values are lumped in a single 1-hr data point. Address multiple time zones. For an RFC that crosses multiple time zones, data must be loaded taking actual time into account. MAP program renders 6-hour MAP in local time. Supplied MPE 6 hour data in local time. Adjustments must be made in CHPS so MAP and MAPX represent the same period. CHPS limited to 20 years of data for historical calculation. The full 55 years of grids split into multiple groups. CHPS generates historical time series with output used by Excel for analysis and scatter plot generation. 6HIC Meeting - 2/2010

NWRFC CHPS Forcing Study Sites Include in Evaluation 7HIC Meeting - 2/2010

NWRFC CHPS Forcing Study 8HIC Meeting - 2/2010 Site-ZoneR2R2 BiasMAE DWRI1U DWRI1L HHWM8U HHWM8L PLDI1U PLDI1L SAKW1G SAKW1U SAKW1L WFBM8U WFBM8L TOPI DARM8U DARM8L BONM8U BONM8L

NWRFC CHPS Forcing Study 9HIC Meeting - 2/2010 Typical Comparison

NWRFC CHPS Forcing Study 10HIC Meeting - 2/2010 Typical Comparison

NWRFC CHPS Forcing Study 11HIC Meeting - 2/2010 Bitterroot Basin Has Issues

NWRFC CHPS Forcing Study Results The majority of sites analyzed exhibited R 2 >.80 over the 55 years. Considerable scatter for all sites and also need to look at categories. Bitterroot basin has the weakest relationship. Bias between sites is not consistent. Bias for a site is not consistent from month to month. Analysis using only shows a minor improvement in the relationships. Process is very simple and easy to update. 12HIC Meeting - 2/2010

NWRFC CHPS Forcing Study Future Develop QC points for Western Oregon. Needed for final LAOR grid. Develop method to disaggregate values from MAP that were not time distributed. Analysis runs (today) on 6-hour data. Analysis using simulations and runoff to determine impacts of this solution. Automate the bias correction process. 13HIC Meeting - 2/2010