[gradsusr] Visualize Wind Vectors

Thu Oct 21 03:50:09 EDT 2010

Hi Nena,

the time increment must be specified in the ctl file.
The .dat file serves "to organize" the data.

Perhaps this scheme for .dat file can help you

First instant
Station 1 header: id, rlat, rlon, rt, nlev, iflag (=1 if there surface data)
Station 1 data: surface data, upper levels data
Station 2 header: id, rlat, rlon, rt, nlev, iflag (=1 if there surface data)
Station 2 data: surface data, upper levels data
....

Last station header: id, rlat, rlon, rt, nlev, iflag (=1 if there surface data)
Last Station data: surface data, upper levels data
Closure header: id, 0.0, 0.0, 0.0, 0, 1

Second istant
Station 1 header: id, rlat, rlon, rt, nlev, iflag (=1 if there surface data)
Station 1 data: surface data, upper levels data
Station 2 header: id, rlat, rlon, rt, nlev, iflag (=1 if there surface data)
Station 2 data: surface data, upper levels data
....

Last station header: id, rlat, rlon, rt, nlev, iflag (=1 if there surface data)
Last Station data: surface data, upper levels data
Closure header: id, 0.0, 0.0, 0.0, 0, 1

...

Last istant
Station 1 header: id, rlat, rlon, rt, nlev, iflag (=1 if there surface data)
Station 1 data: surface data, upper levels data
Station 2 header: id, rlat, rlon, rt, nlev, iflag (=1 if there surface data)
Station 2 data: surface data, upper levels data
....

Last station header: id, rlat, rlon, rt, nlev, iflag (=1 if there surface data)
Last Station data: surface data, upper levels data
Closure header: id, 0.0, 0.0, 0.0, 0, 1

Bye

Dan

----- Messaggio originale -----
Da: "Nena Carina Española" <nena at asti.dost.gov.ph>
A: "GrADS Users Forum" <gradsusr at gradsusr.org>
Inviato: Giovedì, 21 ottobre 2010 5:31:17
Oggetto: Re: [gradsusr] Visualize Wind Vectors

Hi Arlindo, 

I already saw that recipe and the data used there is annual. Mine's hourly. Can I use it with hourly data? If yes, is there something I need to change in my data to make the recipe work? 

Thanks, 

Nena 

On Thursday, 21 October, 2010 09:48 AM, Arlindo da Silva wrote: 

2010/10/20 Nena Carina Española < nena at asti.dost.gov.ph > 

Hi Daniele, 

Thanks for the help. 

I am still figuring out how to convert my station data into GrADS binary as I am very new to GrADS. I already posted my problem yesterday but nobody has answered it yet. http://gradsusr.org/pipermail/gradsusr/2010-October/011667.html 

I do not know how to create a binary with more than one surface variable. I was able to create a binary for one variable only and most examples I find use only one variable. Now I have three, and data is hourly. Here's a sample: 

Have you seen this Recipe? 

http://cookbooks.opengrads.org/index.php?title=Recipe-005:_Creating_GrADS_binary_station_data_from_ASCII 

Arlindo 

YEAR MO DA HO STNID LATITUDE LONGITUDE PRESSURE DIR SPEED 
2010 09 08 08 98132 20.800283 121.847534 1012.3 160 12 
2010 09 08 08 98133 19.283147 121.463012 1008.5 120 8 
2010 09 08 08 98134 20.454293 121.963806 1009.2 140 12 
2010 09 08 08 98222 17.582765 120.387268 1008.1 220 4 
2010 09 08 08 98223 18.185845 120.58239 1006.6 250 10 
2010 09 08 08 98232 18.360782 121.658935 1009.5 90 4 
2010 09 08 08 98233 17.629364 121.70288 1008.1 0 0 
2010 09 08 08 98324 15.328294 119.980087 1007.2 270 2 
2010 09 08 08 98325 16.051192 120.333195 1007.3 360 4 
2010 09 08 08 98327 16.607768 121.265259 1007.5 190 4 

Thanks again. :-) 

On Friday, 15 October, 2010 05:52 PM, Daniele Gandini wrote: 

Hi Nena.

Here a simple formula to have U and V in m/s from wind speed (velv) and direction (dirv):

 'set gxout barb'
 'd -velv*cos((dirv-90)/180*3.14);-velv*cos(dirv/180*3.14)'

To display these data with OACRES function first you must create a base grid file
with a "dummy" constant value for example and then you can interpolate wind data:

  'vel=oacres(dummy.1,velv.2,4,3,3,1)'
  'd vel'
  'run cbarn.gs '

Good luck. 

Daniele

----- Messaggio originale -----
Da: "Nena Carina Española" <nena at asti.dost.gov.ph> A: "GrADS Users Forum" <gradsusr at gradsusr.org> Inviato: Venerdì, 15 ottobre 2010 5:32:26
Oggetto: [gradsusr] Visualize Wind Vectors

Hello Guys! 

I am trying to create a visualization of the wind vectors. I am not sure where to begin as my data is not split into U and V components. Here's a snippet of the sample data I have. These are from 24 weather stations in the Philippines. Can I also interpolate these scattered data to create a gridded data using the OACRES function? 

	Station ID 	Latitude 	Longitude 	Wind Speed (m/s) 	Wind Direction (degrees) 
	12 	15.721279 	121.522293 	0.8 	204 
	70 	7.135233 	124.814758 	2.21 	148 
	72 	6.960916 	126.212082 	6.34 	286 
	73 	9.282162 	123.244572 	9.6 	20 
	74 	8.997093 	124.883595 	1.54 	85 
	75 	9.217067 	124.713134 	3.84 	89 
Thanks, 

Nena 

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Email: nena at asti.dost.gov.ph 
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-- 
Arlindo da Silva 
dasilva at alum.mit.edu 
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