[gradsusr] Masking out grid boxes for elevation correction

[Roberto Mera]

Sure thing.

I'm putting output from HadRM and NARR onto a common 25 km grid.

I will only be adjusting temperature such that once the adjustment has been calculated, I can do the following: Tavg_dif =  Tavg_model - Tavg_narr + adjust

So, what I need is to be able to make a mask with the adjustment such that it gets computed using 6.5 c/km lapse rate except for over the grid cells over the Cascades and Sierra as I specified below. Over the mountains the lapse rate is 4.5 c/km.

I want to know how I can mask out a couple of boxes of grid points over the mountains. In the past I have been able to mask out the ocean, for example. But in this work it's not necessarily a mask over a certain height (say 2000 meters). Doing so misses most of the Cascades and adds other areas in the high desert that we prefer to leave at 6.5 c/km. Instead we want to do it specifically for the mountain ranges.

Thanks!

Robert

From: gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at gradsusr.org] On Behalf Of Jeff Duda
Sent: Tuesday, February 18, 2014 12:22 PM
To: GrADS Users Forum
Subject: Re: [gradsusr] Masking out grid boxes for elevation correction

Robert,
Can you be a little more precise in what you want to do?  Which two grids are you putting onto a  common 25 km grid? Are you trying to adjust just the temperature?

Jeff Duda

On Tue, Feb 18, 2014 at 8:20 AM, Roberto Mera <RMera at ucsusa.org<mailto:RMera at ucsusa.org>> wrote:
All,


I'm trying to apply an elevation correction to model data by adjusting the lapse rate based on NARR. Basically, I'm looking to use a rate of 4.5 C/km for mountains, otherwise 6.5. where the adjustment is the rate the times the elevation difference.



The location where I'd like to apply the masks are lon -122.5 -121 lat 43.5 45.2 for the Oregon Cascades and lat 46  49 for Washington Cascades and lon -121 -117.9, lat 35.5 - 40.5 for the Sierra.



I'm placing the two grids on a common 25km grid and taking the difference between elevation.



I appreciate the help.

Robert



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--
Jeff Duda
Graduate research assistant
University of Oklahoma School of Meteorology
Center for Analysis and Prediction of Storms
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