[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[IDV #WYC-198714]: IDV 4.1u1: Vertical cross section plots conforming to variable surface elevation



> 
> On Dec 4, 2013, at 10:55 AM, Unidata IDV Support 
> <address@hidden<mailto:address@hidden>> wrote:
> 
> One question is, what does the IDV use to determine the vertical coordinate 
> of each grid point in the field that it is contouring? If it is the value of 
> sigma (between 0 and 1, with 1 at the bottom and 0 at the top of the domain), 
> then where does sigma = 1 begin on the plot's vertical scale? (Should it be 
> same as z = 0 for the topographic profile?) And why wouldn't the bottom edge 
> of the plot be a straight, horizontal line (corresponding to the same value 
> of sigma)? (In my plot, the bottom of the vertical cross section is mostly a 
> straight, horizontal line, but it indents upward in distinct, rectangular 
> steps to stay above the highest terrain.)
> 
> 
 
   
Dave,
     I checked with John about the coordinate transfer in the WRF output. The 
CDM library uses the formula: 
pressure formula", "pressure(x,y,z) = P(x,y,z) + PB(x,y,z), and height(x,y,z) = 
(PH(x,y,z) + PHB(x,y,z)) / 9.81")

And I checked the data value of PH and PHB, not seeing many area with the value 
of 0. 

     Another information from MMM WRF support is that we can not compare the 
terrain height with the model first level height. And they think the output is 
correct. 

     So I guess there is not much can be explored from the IDV side. You can 
verify the first level value of the PH and PHB in the IDV.


Yuan

Ticket Details
===================
Ticket ID: WYC-198714
Department: Support IDV
Priority: Emergency
Status: Closed


NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.