calculating dry-wet and wet-wet probabilities for a forecast simulation period

[Jaeger]

Hello All,
As part of the forecast input file, the probability of a wet day
following a dry day in the month in the forecast period is required as
well as the probability of a wet day following a wet day in the month
in the forecast period.

I'm trying to calculate these probabilities based off of a 10-year
daily precipitation data set. Essentially I am tallying the number of
times for either a wet-wet occurrence or a dry-wet occurrence for each
month over the 10-year period and dividing it by (the number of days
in each month minus 1).

I was going to do this for each year and look at the distribution of
these values over the 10 year period. From there I was either going to
take the mean or the median of values. I could also just tally the
number of occurrences for each month over the total number of years
and divide it by( (number of days in the month minus 1)*number of
years in the dataset).

With the understanding that this is more like a likelihood rather than
a probability because the computation is based on a known outcome
rather than an unknown, I am wondering what other folks have done.

I'd be very grateful for any thoughts or input.

Thanks,
Kris

[yongguang zhang]

Hi,

I remember there was a tool (software) from CLIGEN to calculate Pw/w and Pw/d.

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[Naresh Pai]

The pcpStat software can calculate these statistical parameters. You can download the "SWAT Input Preprocessors" at the following link:

http://swatmodel.tamu.edu/software/links-to-related-software

Here is the link to its user manual:

http://www.brc.tamus.edu/swat/manual_pcpSTAT.pdf

[Kristin Jaeger]

This is perfect! Thanks very very much!

I am also now looking for an example of the .cst file. I see the format in the input/output manual and past posts have included links, but they are no longer active.

Any help would be appreciated.

Thanks again for this PCPstat program!

Kristin