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<p><font size="2">Hi!
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<br /></font><font size="2">Could you please tell me how to calculate total column from the verticle distribution of NOx at the following z levels?
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<br /><font size="2">zdef 20 levels 994.600 983.800 970.300 950.950 925.300 893.350 855.100 810.550 759.700 702.550 639.100 569.350 492.850 412.300 337.150 275.500 228.250 190.000</font></font>
<p><font size="2">Sachin Ghude
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