<div dir="ltr"><div><div><div><div><div>You could either...<br><br></div>(1) Knowing the geometry of earth, set up a math problem and solve for the areas of a sphere bounded by such latitudinal/longitudinal coordinates to find the areas of those three regions (I would use spherical coordinates)<br>
<br></div>OR<br><br></div>(2) -Create a flat field of ones (e.g., 'define ones = tmp2m/tmp2m')<br></div> -Use the atot function (grads 2.0.2+ only) to compute the sum of the ones field over your area, which I think should give you the area of each region<br>
<br>Then weight each areal average by the area and compute the final weighted average.<br><br></div>I've never tried this, so I'm not 100% sure it will work and be accurate. I would play around with the atot function first to see if it really does give you the areas of the regions.<br>
<div><br>Jeff Duda<br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Sep 17, 2013 at 11:45 AM, Ivan Toman <span dir="ltr"><<a href="mailto:ivtoman@inet.hr" target="_blank">ivtoman@inet.hr</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello,<br>
<br>
If I want to find average value over a lat/lon range, I would do:<br>
<br>
ave(variable,lat=20,lat=21),lon=70,lon=71)<br>
<br>
<br>
However, if I want to do average over multiple areas, for example:<br>
<br>
Area 1: lat=20,lat=21 ; lon=60,lon=61<br>
Area 2: lat=30,lat=31 ; lon=70,lon=71<br>
Area 3: lat=40,lat=41 ; lon=80,lon=81<br>
<br>
how can I solve this problem? I can't simply find three area averages,<br>
sum them together and divide by three, because areas are not the same sizes.<br>
<br>
Thanks for any hint.<br>
<br>
Regards,<br>
Ivan Toman<br>
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</blockquote></div><br><br clear="all"><br>-- <br>Jeff Duda<br>Graduate research assistant<br>University of Oklahoma School of Meteorology<br>Center for Analysis and Prediction of Storms<br>
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