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Trends in daily wintertime temperatures in the northern stratosphere
Author(s) -
Pawson Steven,
Naujokat Barbara
Publication year - 1997
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/97gl00352
Subject(s) - stratosphere , atmospheric sciences , climatology , maxima , environmental science , physics , geology , art , performance art , art history
Long‐term changes in the extrema reached in 31 years of daily northern stratospheric temperatures ( T ' are discussed. The lowest T reached at any location on any day ( T min ' show trends of −1.90 and −1.85 K/decade at 50 hPa and 30 hPa. Increases in the maxima ( T max ' are twice as large at 30 hPa as at 50 hPa. The trends are superimposed on a low‐frequency variability of T min with clear peaks between 1975/1976 and 1986/1987 and after 1991/1992. Before the middle 1970s no very low T min were observed; this is very likely an observational constraint since T =192 K this may be the lowest detectable value in the earliest years. A more robust measure of the coldness of the lower stratosphere is the area with T < 195 K at 50 hPa, which is relevant for PSC formation. It increased considerably over the 31 years owing largely to the persistence of cold days.