Mandatory level

From Glossary of Meteorology
(Redirected from Mandatory levels)

mandatory level

(Or mandatory surface.) One of several constant-pressure levels in the atmosphere for which a complete evaluation of data derived from upper-air observations is required.

Currently the mandatory pressure levels are 1000 mb, 925 mb, 850 mb, 700 mb, 500 mb, 400 mb, 300 mb, 250 mb, 200 mb, 150 mb, 100 mb, 70 mb, 50 mb, 30 mb, 20 mb, 10 mb, 7 mb, 5 mb, 3 mb, 2 mb, and 1 mb. The radiosonde code has specific blocks reserved for these data. To have a more complete vertical picture, significant levels of radiosonde observations are also evaluated. Until just after World War II, mandatory levels were defined by values of height above sea level.

term edited 9Sept2014

Copyright 2022 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact 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.