<div dir="ltr">On Wed, May 21, 2014 at 6:48 PM, Júlio Barboza Chiquetto <span dir="ltr"><<a href="mailto:julio22@gmail.com" target="_blank">julio22@gmail.com</a>></span> wrote:<br><div class="gmail_extra"><div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr"><div><div>Hello dear users,<br></div>I have a tropospheric ozone time series in micrograms/m3, but I need to display it in ppm. I know it's a simple issue, but I don't have much experience in writing formulas in GrADS and I was wondering if other users might have already needed a script that does this unit conversion when displaying a variable.<br>
</div></div></blockquote><div><br></div><div>Consult the wikipedia to learn about the part-per notation:</div><div><br></div><div> <a href="http://en.wikipedia.org/wiki/Parts-per_notation">http://en.wikipedia.org/wiki/Parts-per_notation</a></div>
<div> </div><div>Notice that ppm (parts per million) implies mass mixing ratio (ppmv is used for volume mixing ratio). All you have to do is to divide your ozone density time series by the air density which in principle depends on pressure and temperature:</div>
<div><br></div><div> rho = p / (RT) </div><div><br></div><div>If you express the air density in micrograms/m3 as your ozone density you will have your mixing ratio in Kg/Kg. Mutiply it by 1,000,000 to have ppm. <br>
</div><div><br></div><div> Arlindo</div><div><br></div></div>-- <br><font face="'comic sans ms', sans-serif" size="6" color="#006600"><span style="font-family:Helvetica;font-size:12px"></span><span></span><span></span>Arlindo da Silva</font><br>
<font size="4"><i><a href="mailto:dasilva@alum.mit.edu" target="_blank">dasilva@alum.mit.edu</a></i></font>
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