Compute Precipitation Percentages
Description
This tool transforms monthly precipitation data into a form of percentage relative to the modern period, which can be useful to place a historical event into perspective with the modern period. Please note that this tool is extremely sensitive to missing values in the input datasets because those will bias the percentiles or percent of normal values. HOB Tools completely skips calculations when a missing value is involved. This includes calculations performed during a specified range. For example, if percentages from December through February are being calculated and only January and February have data for the 1872-1873 period, then HOB Tools will skip the percentage calculation for 1872-1873 and output a value of “-99” for 1873.
Historical Precipitation Input
Historical Input File
Select the historical precipitation data to analyze by clicking on "Browse" and navigating to the proper file.
Input Data Format
Year / Month / Data
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 historical and modern records must be in the same units. The precipitation data can also be in the form of day counts instead of amounts.
Historical Start Row
This input is the row number where the main historical 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.
Historical Precipitation Column Number
This input is the column number where the historical 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.
Modern Precipitation Input
Modern Input File
Select the modern precipitation data to analyze by clicking on "Browse" and navigating to the proper file.
Input Data Format
Year / Month / Data
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 historical and modern records must be in the same units. The precipitation data can also be in the form of day counts instead of amounts.
Modern Start Row
This input is the row number where the main modern 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.
Modern Precipitation Column Number
This input is the column number where the modern 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.
Computation Type
Percentiles
Select this option to transform each monthly precipitation value into a percentile relative to the modern record (cf., Mock and Bartlein 1995; Mock and Brunelle-Daines 1999).
Percent of Normal
Select this option to transform each monthly precipitation value into a percentage relative to normal.
Compute By Month
This computation type is selected by default, and will perform the analysis by months that are checked by the user. If "Jan" and "Feb" are checked, then the analysis will be run twice--once for January data and once for February data.
Compute By Range
Selecting this computation type will enable the "Start Month" and "End Month" fields, which will allow for the analysis to be performed across a range of months (e.g., seasonal, annual). For example, to analyze Northern Hemispheric winter, select "December" as the start month and "February" as the end month.
Precipitation 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.