Threshold Analysis
Description
This tool determines the frequency a user-specified threshold value is met. This threshold value can be a specific value or a percentile.
Input
Input File
Select the input data by clicking on "Browse" and navigating to the proper file.
Start Row
This input is the row number where the 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.
Data Column Number
This input is the column number where the 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.
Input Error Bars
Place a check in the box to include +/- error bars in the conversion. It is expected that this error encompasses only one column and is symmetrical about the value (i.e., an error value of 1.5 means +/- 1.5).
Error Column Number
If "Input Error Bars" is checked, then this field will be enabled. This input is the column number where the +/- error bars 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.
Data Format
Select whether the input data are daily or monthly.
Input Data Format
If input data are daily:
If input data are monthly:
Each "/" is a tab (i.e., data should be tab-delimited). Missing Data should be denoted as "-99".
Threshold Details
Critical Value
Enter the critical value that will be used to calculate the frequency in which the threshold is exceeded. This critical value can be either a specific number or a percentile. All percentiles are calculated relative to the entire period of record input into HOB Tools. Note also this analysis is done on values that are either "Above" or "Below" the critical value. If "Above" is selected, then the threshold will determine the frequency when daily or monthly value is above the specified critical value.
Count Threshold 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.
Count Threshold 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.
Only Count Days Between First and Last Occurrence
Select this option to have HOB Tools only count the number of Julian days between the first and last occurrence the threshold is met. This is helpful to calculate the length of the warm, cold, and growing seasons. The start and end Julian dates are also reported in the output file.
Include Persistent Daily Spells >=
Select this option to have HOB Tools only count events that meet the threhold for a user-specified number of days (entered in the box; default is 6). Each event is then summed over the month or range to determine an index that takes into account how many spells occurred and their length.
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.