# Re: Divergence

From: Guilherme Martins <jgmsantos_at_nyahnyahspammersnyahnyah>
Date: Wed Jul 24 2013 - 10:51:22 MDT

Thanks,

Now it's ok.

The unit is *[g kg-1 s-1]*?

*According to:*

u = f->uvel(0,0,:,:) ; m/s
v = f->vvel(0,0,:,:) ; m/s
q = f->umes(0,0,:,:) ; kg/kg
*uq = u*(q*1e3) ; kg/kg -> g/kg*
*vq = v*(q*1e3) ; kg/kg -> g/kg*

dv = uv2dvG(uq,vq) ; divergence - gaussian grid
dv@long_name = "moisture divergence"

Guilherme

2013/7/24 Dennis Shea <shea@ucar.edu>

> I think what you want is
>
> uq = u*q
> vq = v*q
> dv = uv2dvG(uq,vq)
> dv@long_name = "moisture divergence"
>
>
> On 7/24/13 10:00 AM, Guilherme Martins wrote:
>
>> My question is: The values using the function uv2dvG make sense? I
>> multiply
>> "divg" by "humidity specific" because I want humidity divergence.
>>
>> f = addfile("uvq.1000hpa.nc","r") ; gaussian grid
>>
>> u = f->uvel(0,0,:,:) ; m/s
>> v = f->vvel(0,0,:,:) ; m/s
>> q = f->umes(0,0,:,:) ; kg/kg
>> dv = uv2dvG(u,v) ; divergence - gaussian grid
>>
>> divg = dv * q
>>
>> Thanks,
>>
>> Guilherme.
>>
>>
>>
>> 2013/7/24 Dennis Shea <shea@ucar.edu>
>>
>> Not sure what you want.
>>>
>>> The units of divergence are 1/sec
>>> --
>>> Embedded in the long_name ... units are m/s
>>>
>>> float uvel ( time, lev, lat, lon )
>>> long_name : ZONAL WIND (U) (M/Sec
>>> )
>>>
>>> float vvel ( time, lev, lat, lon )
>>> long_name : MERIDIONAL WIND (V) (M/Sec
>>> )
>>>
>>> float umes ( time, lev, lat, lon )
>>> long_name : SPECIFIC HUMIDITY (No Dim
>>> )
>>>
>>> If the largest values of 'umes' are (say) 20 then the
>>> units are g/kg; if the largest values are (say) 0.002
>>> they are kg/kg (ie unitless)
>>>
>>> ====
>>> The code you sent indicates this already
>>>
>>> u = f->uvel(0,0,:,:) ; m/s
>>> v = f->vvel(0,0,:,:) ; m/s
>>> q = f->umes(0,0,:,:) ; kg/kg
>>> dv = uv2dvG(u,v) ; divergence - gaussian grid
>>>
>>>
>>>
>>>
>>>
>>> On 7/24/13 9:10 AM, Guilherme Martins wrote:
>>>
>>> Hi all,
>>>>
>>>> I'm calculating the divergence, but I'm not sure about the units of the
>>>> variables. Can anyone help me?
>>>>
>>>> The files are in attach.
>>>>
>>>> Thanks,
>>>>
>>>> Guilherme.
>>>>
>>>>
>>>>
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>>>>
>>>>
>>>>
>>
>>

```--
*Guilherme Martins*