Mixed-layer depth

From Glossary of Meteorology

mixed-layer depth

(Also called mixed-layer height, mixed-layer top, mixing height.) The thickness, zi, of the mixed layer, defined as the location of a capping temperature inversion or statically stable layer of air.

Often associated with, or measured by, a sharp increase of potential temperature with height, a sharp decrease of water-vapor mixing ratio, a sharp decrease in turbulence intensity, a sharp decrease in pollutant concentration, a change of wind speed to geostrophic, a minimum of turbulent heat flux, and a maximum of signal intensity from remote sensors such as sodars and wind profilers. Quite variable in space and time, the mixed-layer depth typically increases during fair-weather daytime over land from tens of meters shortly after sunrise to 1–4 km before sunset, depending on the location and season.

Copyright 2022 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact [email protected]. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act (17 U.S. Code § 107) or that satisfies the conditions specified in Section 108 of the U.S.Copyright Act (17 USC § 108) does not require AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, require written permission or a license from AMS. Additional details are provided in the AMS Copyright Policy statement.