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<body class='hmmessage'><div dir='ltr'><span id="result_box" lang="en"><span class="hps">Dear All</span><span>,</span><br><br><span class="hps">I have a problem</span> <span class="hps">with the calculation</span> <span class="hps">of the area</span><span> (million km2).</span><br><br><span class="hps">I have a file</span> <span class="hps">of</span> <span class="hps">sea ice</span> <span class="hps atn">(</span><span>ice concentration</span> <span class="hps">data from</span> <span class="hps">0-100</span><span>%</span><span>)</span> <span class="hps">and</span> <span class="hps">I need to create</span> <span class="hps">a time series</span> <span class="hps">with a total</span> <span class="hps">extension</span> <span class="hps">of</span> <span class="hps">sea ice</span> <span class="hps">in the</span> <span class="hps">arctic</span> <span class="hps">and</span> <span class="hps">antartica</span> <span class="hps">(million</span> <span class="hps">km2</span><span>)</span><span>.</span> <span class="hps">For this calculation</span><span>,</span> <span class="hps">usually</span> <span class="hps">consider only</span> <span class="hps">areas with</span> <span class="hps">ice concentration</span> <span class="hps">equal to or</span> <span class="hps">above 15</span><span>%,</span> <span class="hps">so I used</span> <span class="hps">the function</span> <span class="hps">maskout</span><span>.</span><br><br><span class="hps">The</span><span>.</span> <span class="hps">gs</span> <span class="hps">is running</span> <span class="hps">but the values</span> <span class="hps">for the</span> <span class="hps">Arctic</span> <span class="hps">are wrong</span><span>,</span> <span class="hps">can someone help me</span><span>?</span> <span class="hps">Some other method to</span> <span class="hps">calculate the area</span> <span class="hps atn">(</span><span>million</span> <span class="hps">km2</span><span>)</span><br><br><span class="hps">these data are from</span> <span class="hps">satellite.</span></span><br><br><br>'sdfopen <a href="http://X172.16.9.158.108.11.23.58.nc" target="_blank">X172.16.9.158.108.11.23.58.nc</a>'<br>
*calculate area (million km2)<br>'dx=2*3.1416*6371*cos(lat*3.1416/180)/360.0*cdiff(lon,x)/2 '<br><div>'dy=2*3.1416*6371/360.0*cdiff(<wbr>lat,y)/2'<br>'area=(dx*dy)' <br>'fracao=area*(icec/100)'<br></div>
<div><br>say 'calcula a area'<br><br>'set lon 0 360'<br>'set lat -90 90'<br>'set t 1 last'<br><br>
'define ones = const(const(maskout(icec,icec-<wbr>15),1),0,-u)' <br>'set x 1'<br>'set y 1'<br></div><div><br>
</div>'define xx=tloop(asum(ones*area,lon=0,lon=360,lat=-90,lat=0))'<br><div>'d xx'<br><br>'ltrend xx a b c'<br>'set ccolor 2'<br>'d a';'d b'<br>trend=subwrd(result,4)<br> say 'trend='trend<br>
' d c'<br>rmse=subwrd(result,4)<br> say 'rmse='rmse<br><br>'draw title Antarctic Sea Ice obs incl.'trend' rmse. 'rmse' '<br><br><br>regards<br></div><br><br><br><br><br><font style="" face="Verdana">Fernanda</font> </div></body>
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