# Difference between revisions of "Sigma-theta"

From Glossary of Meteorology

imported>Rbrandt |
imported>Rbrandt |
||

Line 15: | Line 15: | ||

<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

*σ*.) The density_{θ}*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

*σ*.) 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:_{θ}where

*s*= (1/_{a}*n*)Σ_{i}sin*θ*and_{i}*c*= (1/_{a}*n*)Σ_{i}cos*θ*are computed from a sequence of_{i}*n*wind angle (*θ*) measurements._{i}Wikipedia, The Free Encyclopedia, 2018: Yarmartino method. Accessed 8 May 2018. Wikipedia, https://en.wikipedia.org/wiki/Yamartino_method.

*Term edited 8 May 2018.*