<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: arial,helvetica,sans-serif; font-size: 12pt; color: #000000'>Hello Claudio,<div><br></div><div>To calculate the prevailing wind direction for a day, you should average the hourly u and v components, then find the direction of this average wind vector. It's not a good idea to average the hourly wind directions because very weak winds would get the same weighting as stronger winds. On the other hand, for daily average wind speed, you should average the hourly wind speeds.</div><div><br></div><div>Best regards,</div><div><br></div><div><div><span name="x"></span>Eric L. Altshuler<br>Research Scientist<br>Center for Ocean-Land-Atmosphere Studies<br>4041 Powder Mill Road, Suite 302<br>Calverton, MD 20705-3106<br>USA<br><br>E-mail: ela@cola.iges.org<br>Phone: (301) 902-1257<br>Fax: (301) 595-9793<span name="x"></span><br></div><br><hr id="zwchr"><b>From: </b>"claudiomet" <claudiomet@gmail.com><br><b>To: </b>"GrADS Users Forum" <gradsusr@gradsusr.org><br><b>Sent: </b>Thursday, May 30, 2013 9:47:50 PM<br><b>Subject: </b>Re: [gradsusr] Get direction of max wind in hourly time serie of a point<br><br><div dir="ltr"><div><div><div>Thanks Martin !<br><br></div>I will try the method !<br></div>Concening with the direction no problem, the dataset includes speed in degrees<br></div><div>(It's a WRF output post-processed with ARWpost specifying the wind as u,v vectors and speed and direction) <br>
</div>Thanks again !<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/5/30 Martin V. Mathew <span dir="ltr"><<a href="mailto:vmartinmathew@gmail.com" target="_blank">vmartinmathew@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Hi</div><div>I think you can try following two steps to obtain the direction of maximum wind. </div>
<div><br></div><div>First you have to find the hour of the day in which have maximum wind speed (use mag and maxloc commands). </div>
<a href="http://www.iges.org/grads/gadoc/gadocindex.html" target="_blank">http://www.iges.org/grads/gadoc/gadocindex.html</a><br><div><br></div><div>After identifying the particular hour use trigonometric function <b style="font-family:'Times New Roman'">atan2() </b><span style="font-family:'Times New Roman'">to obtain the angle. </span></div>
<div> <a href="http://www.iges.org/grads/gadoc/functionsatt.html" target="_blank">http://www.iges.org/grads/gadoc/functionsatt.html</a></div><div><br></div><div>Regards</div><div>Martin</div></div><div class="gmail_extra">
<br><br><div class="gmail_quote"><div><div class="h5">On 29 May 2013 21:42, claudiomet <span dir="ltr"><<a href="mailto:claudiomet@gmail.com" target="_blank">claudiomet@gmail.com</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div class="h5">
Greetings users.<br>
<br>
I'm writing a script to extract data of a single point in ascii file<br>
(my data set is hourly and I'm extracting daily vaues of max temp, min<br>
temp, max wind, max rel hum, etc... solved).<br>
<br>
But my problem is that I need to obtain the direction of the wind at<br>
the hour of the max wind intensity and the prevailing wind of the day<br>
¿How can I do this?<br>
<br>
Thanks in advance !<br>
<br></div></div>
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</font></span></blockquote></div><span class="HOEnZb"><font color="#888888"><br><br clear="all"><div><br></div>-- <br>Martin V. Mathew<br>Research scholar<br>Centre for Oceans, Rivers, Atmosphere and Land Sciences (CORAL)<br>
IIT Kharagpur<br>India.<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br><div dir="ltr"><span style="font-family:arial narrow,sans-serif"><span style="color:"><span style="font-family:tahoma,sans-serif"><font><font><span style="font-family:arial,helvetica,sans-serif"><b>Claudio Cortes N.</b><br>
Project Engineer R&D<br>Environmental Area<br><b>MICOMO S.A.</b><br><b>Tel: <a>+56 (2) 22400516</a> <br>Cel: <a>+56 (9) 65871064</a></b><br>
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Antonio Rabat Sur 6165, Vitacura</span></font><br><img height="56" width="200" dfsrc="https://lh3.googleusercontent.com/-bz9I034u53s/UPW8vY7EN6I/AAAAAAAAAfk/wkh3xiZ_-rk/h101/firma.png" src="https://lh3.googleusercontent.com/-bz9I034u53s/UPW8vY7EN6I/AAAAAAAAAfk/wkh3xiZ_-rk/h101/firma.png"></font></span></span></span></div>
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