[gradsusr] Confusiong about WEASDSFC, GFS

[Christopher Gilroy]

Hey Stephen,

Thanks for your response I figured that out after the fact. I appreciate
the help you've given me with this the past few days. One last question I
have to throw out there, what would your thoughts be on having a "dynamic"
ratio based on vertical temperatures? Do you think it'd be wildly
inaccurate or? I seen Ryan Maue make a comment one time about it causing
confusing and/or being great for certain areas but terrible for other areas.

On Tue, Sep 29, 2015 at 9:07 AM, Stephen McMillan <smcmillan at planalytics.com
> wrote:

> Chris,
>
> If you want to convert amounts in mm to in, you need to divide by 25.4,
> not 2.54 (or, multiply by the 0.03937 you had in your example).    To go
> the other way (in to mm), multiply in. amounts by 25.4.
>
> However, if you are converting mm to in. and using a 10:1 snow-liquid
> ratio, then simply dividing the weasdsfc amounts by 2.54 should achieve the
> same result as dividing by 25.4 (multiplying by 0.03937) then multiplying
> result by 10.  Result would be in inches.
>
> Stephen Mc
>
>
>
> On Tue, Sep 29, 2015 at 8:41 AM, Christopher Gilroy <
> chris.gilroy at gmail.com> wrote:
>
>> Alright, I have two primary questions, and if the answers are yes to
>> both, the follow-up makes no sense to me.
>>
>> 1.) weasdsfc is water equivalent based in mm, correct?
>> 2.) weasdsfc has no "default" liquid:water ratio, correct? A meteorology
>> friend of mine said 'typically' 10:1 is a good standard, so I'm unsure if
>> the model is based around that or not?
>>
>> I'm fairly certain I'm correct on #1. I'm unsure on the other 2 though,
>> but here's my current situation. If I use the expression below:
>>
>> 'd
>> const((sum(maskout(weasdsfc-weasdsfc(t-1),weasdsfc-weasdsfc(t-1)),t=2,t='%i%')/2.54),
>> 0, -u)'
>>
>> I get an identical looking map as another well known sites 10:1 snow
>> accum, in inchs. The confusion part of that equation should be converting
>> (/2.54) IN to MM, no?
>>
>> Now, if on the other hand I do the (if I'm understanding this right)
>> "correct" calculation to convert mm to in:
>>
>> 'd const((sum(maskout(weasdsfc-weasdsfc(t-1),weasdsfc-
>> weasdsfc(t-1)),t=2,t='%i%')*0.039370), 0, -u)'
>>
>> I get very, very, very little snow plotted.
>>
>> Now, I am using the sflux files instead of the pgrb2.0p25 files, which I
>> thought the flux files maybe used different units or something but they
>> don't, weasdsfc is still [kg/m^2] which should mean (unless my
>> expression is more of a hack than I would have imagine) I should be getting
>> the opposite outputs of what each expression is actually producing?
>>
>> I don't know if I'm missing a parenthesis group somewhere and I'm somehow
>> getting an inches, 10:1 snow accum plot with my code by "accident" or what?
>> :-/
>>
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>
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-- 
-Chris A. Gilroy
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