scPDSI

This project didn't modified any sub function in original scPDSCI.cpp, except ET module. This repository is trying to replace ET module with Penman Evapotranspiration. The result is exactly same as the original ones.

Linux diff is used to make sure the result of original version and this one is exactly the same.

mkdir build
cd build
cmake ..
make

Debug\scPDSI.exe -idata\example -odata potentials & diff -r data ..\scPDSI-org\data > diff.txt & subl diff.txt

Updates

• 27 July, 2018 (ET module works now)

  If you need scPDSI_penman, just put weekly_PET or monthly_PETin the input directory. weekly_PET(monthly_PET) is in the same unit and format as weekly_P (monthly_P). When having no PET input, the result is the same as original.

  I only checked the weekly outputs with the original one. Using original PET from potentials file as weekly_PET input, 1 and 2 week output are exactly same as original. For other scales, the difference may be due to that, when saving PET into txt, the accuracy is loss in some extent. This need to further check in the future.

---

Document for original scPDSI V2.0.

Calculates the Palmer Drought Severity Index for a given station.

1.1 Four input files for weekly PDSI calculations:

• weekly_T and weekly_P
  Weekly temperature and precipitation files; each line starts with the year and is followed by 52 data entries. It is important to note that only 52 weeks are on each line, even though 52 weeks is only 364 days. This data must be gathered in such a way that the kth week of the year always represents the same calendar interval. For example, the first week should always represent Jan 1 through Jan 7.

• wk_T_normal
  The average weekly temperature for each week of the year. One line, 52 data entries.

• parameter contains two numbers specific to each station:

  • Su (in inches) the underlying soil water capacity, and
  • TLA: the negative of the tangent of the latitude of the station.

1.2 Four input files for monthly PDSI calculations:

• monthly_T and monthly_P
  Monthly temperature and precipitation files; each line starts with the year and is followed by 12 data entries.

• mon_T_normal
  The average monthly temperature for each week of the year. One line, 12 data entries.

• parameter
  same as above.

1.3. Extra notes on input files

The format of these files matches the format of the original FORTRAN program. There is no precise need for this format to be used.

The program is able to calculate the weekly PDSI, the original monthly PDSI and the monthly self-calibrating PDSI if all the data is in the same directory.

It is possible to use the filename T_normal in place of either mon_T_normal or wk_T_normal. For example, the program will try to open mon_T_normal first, and then T_normal. If T_normal is opened, it will check to make sure it is the right format by counting the number of entries in the file. This was done to allow the program to work on the exact same input data as the original FORTRAN program, allowing comparisons.

2.1 Output Files

There are two formats of output, table and column, which are selected by command line options. The table output files end with .tbl and the column output files end with .clm. The table files list a whole year's worth of resultsing values on each line while the column files list the year and week followed by the resulting value on each line.

file	description
PDSI.tbl and/or PDSI.clm	The Palmer Drought Severity Index values
PHDI.tbl and/or PHDI.clm	The Palmer Hydrological Drought Index values.
WPLM.tbl and/or WPLM.clm	The "Weighted" Palmer Index. An average of either X1 and X3, or X1 and X2 weighted by the probability of the current spell ending. For more information, see how the WPLM is calculated in the pdsi::write() function.
ZIND.tbl and/or ZIND.clm	The Z Index, or the moisture anomaly

2.2 Other possible output files, depending on certain flags

file	description
WB.tbl	The water ballance coefficients (Alpha, Beta, Gamma, & Delta) for each week/month.
bigTable.tbl	Z, % Prob(end), X1, X2, and X3 for every week/month.
potentials	P, PE, PR, PRO, PL, and P - PE for every week/month.
dvalue	The moisture departure, d, for every week/month.