Estimate Precipitation
Description
Undercount is a typical bias associated with older precipitation records (Mock 1991, 2000). Thus, a better reconstruction may be obtained by summing precipitation amounts or days based on a threshold (e.g., ≥0.10 inches). This "threshold data" series can be developed using the Compute Precipitation Totals tool. This tool compares a reconstruction of precipitation based on "all data" to the one based on "threshold data" in a user-defined period when the data are higher quality and then derives a conservative estimate of precipitation based on "all data" during the lower quality period (e.g., Burnette and Stahle 2013a). This estimation can be performed at monthly, seasonal, or annual resolution.
Discussion of the Output Data
When the tool is run, a test is first performed on the estimation method by splitting the period of time between the derivation start and end dates in half. The adjustment values are then derived on the last half of the period and output under "Initial Derived Differences". Those derived adjustment values are then used to estimate the "All Data” time series during the first half of the period to determine the accuracy of the estimation technique. The results are output under "Verification of Initial Derived Differences". The tool then derives the differences using the entire period between the derivation start and end dates, and those are output under "Final Derived Differences". Low average errors during the verification period and low differences between the initial and final derived difference values are ideal. All these results are reported in a separate output file with the word "Statistics" appended to the end of the filename. The tool then adds the appropriate differences to the "Threshold Data” time series to create a new "All Data” time series during the user-defined period of adjustment. If monthly data are input, then each month is processed and estimated separately. Once the end of the adjustment period is reached, HOB Tools appends the rest of the "All Data” time series to the end of the newly estimated dataset.
Input
All Data Precipitation File
Select the precipitation data computed using all amounts by clicking on "Browse" and navigating to the proper file.
All Data Start Row
This input is the row number where the main data to be processed begin in the "All Data" input file selected above. An example of how row numbers are entered is shown in Figure 2 located in the Running HOB Tools topic.
Threshold Precipitation File
Select the precipitation data computed using a threshold by clicking on "Browse" and navigating to the proper file.
Threshold Data Start Row
This input is the row number where the main data to be processed begin in the "Threshold Data" input file selected above. An example of how row numbers are entered is shown in Figure 2 located in the Running HOB Tools topic.
Precipitation Data Type
Select the format of the precipitation data. Amounts are selected by default.
Estimate Input
Input Data Format
If precipitation data are monthly:
If precipitation data are seasonal or annual:
Each "/" is a tab (i.e., data should be tab-delimited). Missing Data should be denoted as "-99". Precipitation amounts can be in any units, but both "All Data" and "Threshold Data" files must be in the same units. The precipitation data can also be in the form of day counts instead of amounts.
Start Adjustment
Enter the year and, if necessary, the month when HOB Tools should begin adjusting the "All Data" series. If "Year / Data" is selected under "Input Data Format", then the month field will be disabled.
End Adjustment
Enter the year and, if necessary, the month when HOB Tools should stop adjusting the "All Data" series. If "Year / Data" is selected under "Input Data Format", then the month field will be disabled.
Start Derivation
Enter the year and, if necessary, the month when HOB Tools should begin deriving adjustment values between the "All Data" and "Threshold Data" series. If "Year / Data" is selected under "Input Data Format", then the month field will be disabled.
End Derivation
Enter the year and, if necessary, the month when HOB Tools should end deriving adjustment values between the "All Data" and "Threshold Data" series. If "Year / Data" is selected under "Input Data Format", then the month field will be disabled.
Output
Output File
Select the file where the numerical results will be stored.
Output File Header
Information entered here will be output in the first line of the output file.