Open AccessRecent widening of the tropical belt from global tropopause statistics: Sensitivities
Author(s) -
Birner Thomas
Publication year - 2010
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2010jd014664
Subject(s) - tropopause , latitude , climatology , tropics , environmental science , middle latitudes , atmospheric sciences , geography , geology , stratosphere , geodesy , fishery , biology
Several recent studies have shown evidence for a widening of the tropical belt over the past few decades. One line of evidence uses statistics of the tropopause height to distinguish between tropics and extratropics and defines tropical edge latitudes as those latitudes at which the number of days per year with tropopause heights greater than 15 km exceeds a certain threshold (typically 200 days/yr). This definition involves two somewhat arbitrary thresholds. Here the sensitivity of the resulting widening trend of the tropical belt to these thresholds is investigated using four different reanalysis data sets. Widening trends are found to be particularly sensitive to changes in the tropopause height threshold. Ways to objectively determine appropriate thresholds to define tropical edge latitudes based on tropopause statistics are presented. Trend estimates for the width of the tropical belt from different reanalysis data sets are found to be mostly inconsistent with each other despite consistent seasonal and interannual variations.