Screen Precipitation Data
Description
This tool screens daily precipitation data by analyzing the frequency of days with specific precipitation amounts. Precipitation frequencies are created for every hundredth of an inch from 0.01 to 2.00 inches. The results for every day and for each month are output separately to the output file and displayed in frequency histograms.
Discussion of the Output Data
HOB Tools uses the output file to create frequency histograms of the daily precipitation data (Figs. 1 and 2). These frequency histograms can be plotted for specific months or seasons by choosing the appropriate month or season from the drop-down list box next to “Displayed Plot” and pressing the “Plot” button (Figs. 1 and 2). The title of the frequency histograms is the same as the “Output File Header” specified below.
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Figure 1. An analysis of the precipitation data at Fort Leavenworth suggests that the observers may have been biased toward recording precipitation amounts to the nearest tenth of an inch and undercounting the real light amounts such as 0.01 inches. |
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Figure 2. Precipitation data at Dodge City appear to be more homogenous than the Fort Leavenworth data in Figure 1 given the smoother negative exponential curve of the precipitation frequency histogram. |
A frequency histogram of precipitation amounts arranged in order from low amounts on the left side to high amounts on the right side should show a smooth negative exponential curve with no significant deviation or stair-step appearance if the daily precipitation data are of high-quality (e.g., Fig. 2; Daly et al. 2007).
Input
Precipitation File
Select the precipitation data to analyze by clicking on "Browse" and navigating to the proper file.
Input Data Format
Year / Month / Day / Data
Each "/" is a tab (i.e., data should be tab-delimited). Missing Data should be denoted as "-99". All precipitation data input into this tool must be in units of inches. The Convert Precipitation Units tool can be used to transform any precipitation not in the proper units.
Start Row
This input is the row number where the main data to be processed begin in the 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 Column
This input is the column number where the precipitation data are located in the input file selected above. An example of how column numbers are entered is shown in Figure 2 located in the Running HOB Tools topic.
Date to Start Quality Check
Enter the Year, Month, and Day to start screening of the precipitation data.
Date to End Quality Check
Enter the Year, Month, and Day to end screening of the precipitation data.
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.