“Data Screening” Window

“Data Screening” Window

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The "Data Screening" window is the initial window following the "Title Screen" from which you may load and screen the data that you would like to analyze.  This window is divided into three panels titled ‘Load Data’, ‘Data Screening’, and ‘Index Analysis’.  After the data input file is selected, you can choose the resolution of the data, the analysis and data types, the beginning year (in the case of extreme value analysis or beginning month (if a specific period of the year is to be analyzed), duration, and the and the data units.  If you would like to screen the data further according to a range of values for a particular climate index, this can also be performed by selecting the desired index, the appropriate lag between the index and the data, and the upper and/or lower limits of the index.

An analysis cannot be initiated before an input file has been selected.  By clicking on the ‘Browse’ button, the user can select the location of the input file.  The only input file types that are currently allowed in Hydro-FIT are Microsoft Excel files having the extensions ‘.xls’ or ‘.xlsx’ and netCDF files having the extension ‘.nc’.  Once an input file is selected, the path and filename of the input file will be displayed in the box near the top of the window.  Most of the menus, buttons, and textboxes in the "Data Screening" window will become enabled after the input file is selected; the options that remain disabled depend on selections throughout the window.

The ‘Data Resolution’ drop-down menu allows the user to select the desired resolution of the data to be analyzed.  There are only two data resolutions currently supported in Hydro-FIT:  daily and monthly. The user must ensure that the ‘Data (Daily)’ or ‘Data (Monthly)’ worksheets exist, in the case of an input file in the format of an Excel spreadsheet, when selecting a daily or monthly resolution, respectively; otherwise, Hydro-FIT will display an error message.  Likewise, if the resolution of the netCDF file is inconsistent with the selected resolution, an error will result.

The ‘Analysis Type’ drop-down menu allows the user to choose whether to perform an annual daily or monthly extreme value analysis {‘Peak Annual (Daily)’ or ‘Peak Annual (Monthly)’} or a monthly frequency analysis using all data from a specific period of the year {‘All Data (Monthly)’}.  Different options in the ‘Data Screening’ panel will become enabled or disabled depending on the analysis type that is chosen.

The user can choose the data type from seven different types that are listed in the ‘Data Type’ drop-down menu.  Available data types include ‘Rainfall’, ‘Streamflow’, ‘Storm Number’, ‘Pressure’, ‘Temperature’, ‘Wind’, and ‘Indices’.  The data type that is chosen will determine whether Hydro-FIT computes cumulative annual totals (rainfall and storm number) or annual averages (streamflow, pressure, temperature, wind, and indices) of the data.  For example, rainfall data are computed as cumulative totals while stream flow data are computed as average flows.  It is very important that the correct data type is selected; otherwise, the results may not be as expected.  The data type, along with the specified data units, also determines the y-axis label for several graphs in the ‘Site Analysis’ window.

The option that allows the user to indicate whether there are leap days included in the data is only available when the input file is a netCDF (‘.nc’) file and contains daily data.  By clicking ‘Yes’, the user indicates that data are provided for February 29 of each leap year; by clicking ‘No’, the use indicates that data for February 29 of each leap year are not provided in the data set.  Choosing the wrong option will cause discrepancies in the results.

The final option in the ‘Load Data’ panel is the ability to specify a value that represents an undefined data value in the input file. Undefined data values are typically represented by the number -999, but if a different number is used, the user must enter that number here; otherwise, the results that are shown in the ‘Site Analysis’ window may not be correct.

The first two options in the ‘Data Screening’ panel will be active if the user has chosen ‘Peak Annual (Daily)’ or ‘Peak Annual (Monthly)’ from the ‘Analysis Type’ drop-down menu. The user must enter a beginning year and a duration in years in order to proceed with the extreme value analysis. If a beginning year that is less than the initial year of the data is entered, Hydro-FIT will begin with the initial year of the data set. If a duration greater than the duration of the data is entered, Hydro-FIT will analyze the entire dataset.

The next two options in the ‘Data Screening’ panel will be active if the user has chosen ‘All Data (Monthly)’ from the ‘Analysis Type’ drop-down menu. This option indicates that the user would like to perform a full frequency analysis on all data in the input file for a specific period of the year(s). In order to specify the desired period, the user must choose a beginning month and a duration in months. The duration can be any value that does not exceed 60 months. The program will analyze the data by summing or averaging (depending on the data type) the data over the number of months indicated, beginning with the specified initial month of each year. If the desired duration is greater than 12 months, the period for each year will overlap with the period(s) of other year(s).

When analyzing a site’s data, the validity of the data for each year will be determined.  This means that there should not be any undefined data values within the range of data that is used for each year.  In the case of an extreme value analysis {analysis type = ‘Peak Annual (Daily)’ or ‘Peak Annual (Monthly)’}, a year is considered valid if all daily or monthly values, respectively, are valid during that year.  In the case of a regular frequency analysis {analysis type = ‘All Data (Monthly)’}, a year is considered valid if all data, beginning with the ‘Beginning Month’ specified for that year and extending through the specified duration, are defined values (not equal to the ‘No Data’ value and/or -999).  If one value is invalid, the entire year is considered invalid.  Hydro-FIT determines the number of valid years for each site, and if that number is less than the specified value given for ‘Minimum Data (yrs)’, the site is not used in the frequency analysis.  A minimum data value less than five is not allowed as this is not sufficient to perform many of the statistical calculations in Hydro-FIT.

The user may or may not specify the units of the data. The given units will be displayed within the y-axis labels of various plots accessible through the ‘Site Analysis’ window.

The ‘Index Analysis’ panel allows the user to choose particular years to be used in the frequency analysis by specifying a range of values for any one of 39 different global climate indices. The features used to conduct an index analysis can be enabled by clicking the checkbox next to ‘Index Analysis’.  The desired global climate index can be selected from this drop-down menu. Clicking the ‘Information’ button will open a window that displays a description of the global climate index that is currently selected in the drop-down box. The lag (in units of months) between the input file data values and the values of the selected global climate index should be entered here.  If no lag is desired, the user should enter ‘0’ or leave this space empty.The ‘Graph’ button is used to determine if any of the 39 global climate indices included in Hydro-FIT correlate with the data for the chosen period of the year using the specified lag; index limits have no effect on the correlation results.  The upper and lower limits of the range of the selected global climate index are entered here.  All years during which the average value of the selected global climate index during the months included in the frequency analysis (while also taking into account the desired lag) exceeds the upper limit and/or is less than the lower limit will not be included in the frequency analysis.  If no upper limit and/or lower limit is desired, the user should leave the corresponding space(s) empty.

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