Computations of mean areal time series for use in calibration and ESP have traditionally been made using the appropriate preprocessing software (MAP, PXPP, MAT etc.). The preprocessors have traditionally taken point time series as input and have provided facilities for estimation of missing data, and for consistency checking and correction in addition to the mean areal computations. The IDMA tool has been designed to run in conjunction with the preprocessors in an iterative fashion. It performs the consistency checking function, leaving the estimation, correction and mean areal computations to the preprocessors.
Note: Throughout the IDMA tool, the correction factor is the actual value that is applied to the raw data by the preprocessor. This slightly departs from the current manual approach used within the preprocessors where the user may have to manually compute a correction to a correction factor and then multiply the two to obtain a new value.
The estimated data flag in IDMA is displayed if any value in the month has been estimated. The flag does not mean that the whole month is estimated, just tha there is at least on value in the month that is estimated.
The steps that the user needs to go through to use IDMA in conjunction with a particular preprocessor are:
To calculate correction factors, the user must first choose the period of record that will serve as the base. In the other words, this is the period to which other periods will be corrected. Often, this base period is the most recent period. The user may enter a correction factor, have the IDMA tool to compute the correction factor or change the computed correction factor. After all break points and correction factors are determined, the user needs to save all breaks points and correction factors to the input card file for the preprocessor. The IDMA tool also provides an option for automated detection of potential break points. The user may use this option as an initial consideration or reference.
The user may view the station history information and point information during consistency checking. The station history information shows the station moves, dates for the data values, the accumulated data values and the accumulated base values. This information is shown for each station currently being displayed on the double mass plot. The point information shows the station moves, the date of the particular point, the particular accumulated data value for the point, the accumulated base value for that point and whether the station data value is estimated or not. In addition, the user may draw a reference line along the mass curve to identify if any corrections are necessary and assess if the corrected data are acceptable after corrections.
In summary, the GUI-based IDMA tool provides the user the following capabilities and features:
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Page last modified: August 24, 2006