Difference between revisions of "Sigma-theta"

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(Used in [[meteorology]], symbol ''&#x003b8;<sub>&#x003c3;</sub>''.) The [[standard deviation]] of horizontal [[wind direction]] used primarily in [[air pollution]] applications. Sigma-theta can either be computed directly from measured wind direction or wit the [[Yamartino method]]. Sigma-theta is used as a proxy to characterize the [[dispersion]] capabilities of the lower [[troposphere]] in the [[Pasquill-Gifford categories]]. The Yarmartino method is given by:</div><br/> <div class="paragraph"><div class="display-formula"><blockquote>[[File:sigma-theta-atmos.gif|link=|left|sigma-theta-atmos]]</blockquote></div></div><br/>
 
(Used in [[meteorology]], symbol ''&#x003b8;<sub>&#x003c3;</sub>''.) The [[standard deviation]] of horizontal [[wind direction]] used primarily in [[air pollution]] applications. Sigma-theta can either be computed directly from measured wind direction or wit the [[Yamartino method]]. Sigma-theta is used as a proxy to characterize the [[dispersion]] capabilities of the lower [[troposphere]] in the [[Pasquill-Gifford categories]]. The Yarmartino method is given by:</div><br/> <div class="paragraph"><div class="display-formula"><blockquote>[[File:sigma-theta-atmos.gif|link=|left|sigma-theta-atmos]]</blockquote></div></div><br/>
  
where ''s<sub>a</sub>'' = (1/''n'')&#x3A3;<sub>''i''</sub>sin''&#x003b8;<sub>i</sub>'' and ''c<sub>a</sub>'' = (1/''n'')&#x3A3;<sub>''i''</sub>cos''&#x003b8;<sub>i</sub>'' are computed from a sequence of ''n'' wind angle (''&#x003b8;<sub>i</sub>'') measurements.<br/>
+
<p>where ''s<sub>a</sub>'' = (1/''n'')&#x3A3;<sub>''i''</sub>sin''&#x003b8;<sub>i</sub>'' and ''c<sub>a</sub>'' = (1/''n'')&#x3A3;<sub>''i''</sub>cos''&#x003b8;<sub>i</sub>'' are computed from a sequence of ''n'' wind angle (''&#x003b8;<sub>i</sub>'') measurements.<br/></p>
  
 
<p>''Term edited 9 April 2018.''</p>
 
<p>''Term edited 9 April 2018.''</p>

Revision as of 09:39, 9 April 2018



sigma-theta

(Used in physical oceanography, symbol σθ.) The density ρ (<1000 kg m−3) that a parcel of water of salinity S and temperature T would have if it were raised adiabatically to the sea surface, where its temperature would change from T to potential temperature θ due to adiabatic decompression. In symbols,

sigma-theta-ocean

(Used in meteorology, symbol θσ.) The standard deviation of horizontal wind direction used primarily in air pollution applications. Sigma-theta can either be computed directly from measured wind direction or wit the Yamartino method. Sigma-theta is used as a proxy to characterize the dispersion capabilities of the lower troposphere in the Pasquill-Gifford categories. The Yarmartino method is given by:


sigma-theta-atmos


where sa = (1/nisinθi and ca = (1/nicosθi are computed from a sequence of n wind angle (θi) measurements.

Term edited 9 April 2018.