Difference between revisions of "Sigma-theta"
From Glossary of Meteorology
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<div class="definition"><div class="short_definition">where ''s<sub>a</sub>'' = (1/''n'')Σ<sub>''i''</sub>sin''θ<sub>i</sub>'' and ''c<sub>a</sub>'' = (1/''n'')Σ<sub>''i''</sub>cos''θ<sub>i</sub>'' are computed from a sequence of ''n'' wind angle (''θ<sub>i</sub>'') measurements.</div></div><br/> | <div class="definition"><div class="short_definition">where ''s<sub>a</sub>'' = (1/''n'')Σ<sub>''i''</sub>sin''θ<sub>i</sub>'' and ''c<sub>a</sub>'' = (1/''n'')Σ<sub>''i''</sub>cos''θ<sub>i</sub>'' are computed from a sequence of ''n'' wind angle (''θ<sub>i</sub>'') measurements.</div></div><br/> | ||
| − | <p>Wikipedia, The Free Encyclopedia, 2018: Yarmartino method. Accessed | + | <p>Wikipedia, The Free Encyclopedia, 2018: Yarmartino method. Accessed 8 May 2018. Wikipedia, https://en.wikipedia.org/wiki/Yamartino_method.</p><br/> |
<p>''Term edited 8 May 2018.''</p> | <p>''Term edited 8 May 2018.''</p> | ||
Revision as of 07:17, 8 May 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,
(Used in meteorology, symbol σθ.) 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 with the Yamartino method (see Wikipedia 2018). Sigma-theta is used as a proxy to characterize the dispersion capabilities of the lower troposphere with different stability categories. The Yarmartino method is given by:
where sa = (1/n)Σisinθi and ca = (1/n)Σicosθi are computed from a sequence of n wind angle (θi) measurements.
Wikipedia, The Free Encyclopedia, 2018: Yarmartino method. Accessed 8 May 2018. Wikipedia, https://en.wikipedia.org/wiki/Yamartino_method.
Term edited 8 May 2018.
