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<p class="MsoNormal">Dear Sirs,<o:p></o:p></p>
<p class="MsoNormal">Please I am estimating evapotranspiration (<b><span style="font-size:13.5pt;font-family:"Arial",sans-serif;color:black;background:white">i.evapo.pt</span></b>) from satellite imagery using GRASS 7.0.2. However, I have the following concerns
that I will be glad if you could help me solve:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><em><span style="font-family:"Calibri",sans-serif;font-style:normal"><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></span></em><![endif]>I used the relation <b><span style="font-size:13.5pt;font-family:"Arial",sans-serif;color:black;background:white">i.evapo.pt</span></b><span class="apple-converted-space"><span style="font-size:13.5pt;font-family:"Arial",sans-serif;color:black;background:white"> </span></span><span style="font-size:13.5pt;font-family:"Arial",sans-serif;color:black;background:white">[-<b>z</b>]<span class="apple-converted-space"> </span><b>net_radiation</b>=<em><span style="font-family:"Arial",sans-serif">name</span></em><span class="apple-converted-space"> </span><b>soil_heatflux</b>=<em><span style="font-family:"Arial",sans-serif">name</span></em><span class="apple-converted-space"> </span><b>air_temperature</b>=<em><span style="font-family:"Arial",sans-serif">name</span></em><span class="apple-converted-space"> </span><b>atmospheric_pressure</b>=<em><span style="font-family:"Arial",sans-serif">name</span></em><span class="apple-converted-space"> </span><b>priestley_taylor_coeff</b>=<em><span style="font-family:"Arial",sans-serif">float</span></em><span class="apple-converted-space"> </span><b>output</b>=<em><span style="font-family:"Arial",sans-serif">name</span></em></span><em><span style="font-family:"Calibri",sans-serif;font-style:normal"><o:p></o:p></span></em></p>
<p class="MsoListParagraph">I have image file of the <b><span style="font-size:13.5pt;font-family:"Arial",sans-serif;color:black;background:white">net_radiation, soil_heatflux, air_temperature (</span></b>Which I assume is the same as the surface temperature)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph">The <b><span style="font-size:13.5pt;font-family:"Arial",sans-serif;color:black;background:white">priestley_taylor_coeff c</span></b>onstant 1.26 is used.<o:p></o:p></p>
<p class="MsoListParagraph"><b><span style="font-size:13.5pt;font-family:"Arial",sans-serif;color:black;background:white"><o:p> </o:p></span></b></p>
<p class="MsoListParagraph">However, I don’t know how to compute or derive a map for the
<b><span style="font-size:13.5pt;font-family:"Arial",sans-serif;color:black;background:white">atmospheric_pressure<o:p></o:p></span></b></p>
<p class="MsoListParagraph">Can you help me out with it? <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>I also computing the sensible heat flux ( i.eb.hsebal01) <o:p>
</o:p></p>
<p class="MsoListParagraph">I have successfully obtained all of the other parameters except the
<b><span style="font-size:13.5pt;font-family:"Arial",sans-serif;color:black;background:white">aerodynresistance.</span></b><o:p></o:p></p>
<p class="MsoListParagraph">I will be glad if you can direct me on how to obtain this also
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> Thank you,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best regards<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Benjamin Ghansah<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif">-----------------------------------------------------------<br>
International Water Management Institute</span></b><span style="font-size:9.0pt;font-family:"Arial",sans-serif"><br>
<b>PMB CT 112</b><br>
<b>Cantonments,<br>
Accra</b><br>
<b>Ghana</b> <br>
<b>General Tel: +233 302 784753/4</b> </span><o:p></o:p></p>
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