[NARCCAP-discuss] extremely small precipitation value

[Seth McGinnis]

Hi Jianhua,

All of the RCMs can put out very small precipitation values; those are the
values in the files, not a problem reading them into R.  The theoretical lower
limit is zero, so you should treat negative values as zero. (We have plans to
set them to zero in the published data at some point in the future.)

Whether you should use a trace threshold and ignore values below that level
depends on how you are using the data.  The conventional trace value used in
meteorological observations is 0.01 inches per time period.

Cheers,

--Seth


On Mon, 11 Feb 2013 15:58:14 -0700
 "Jianhua Huang" <jh.eco.cas at gmail.com> wrote:
>Hi all:
>
> 
>
>I am using the precipitation (pr) data from rcm3-cgcm3 model. Some values
>are very close to zero, for example 3*10^(-23),  and there are even some
>negative values (like -3*10^(-21)). Should I treat these values as zero? I
>don't know whether this problem is caused by the software I used to process
>the data (I am using the ncdf4 package in R). Anybody knows the theoretical
>smallest output from the rcm3-cgcm3 model, so that I can treat all values
>less than this value as zero?
>
> 
>
>Thanks
>
> 
>
>Jianhua 
>
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