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Height‐resolved variability of midlatitude tropospheric water vapor measured by an airborne lidar
Author(s) -
Fischer Lucas,
Kiemle Christoph,
Craig George C.
Publication year - 2012
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 - 10.1029/2011gl050621
Subject(s) - troposphere , atmospheric sciences , environmental science , water vapor , lidar , humidity , relative humidity , middle latitudes , scaling , advection , climatology , meteorology , geology , physics , remote sensing , geometry , mathematics , thermodynamics
Free tropospheric water vapor variability, measured by airborne lidar over Europe during summertime, is analyzed at altitudes from 2 km to 10 km. Horizontal structure functions of specific humidity were computed and show power‐law scaling between about 10 km to 100 km in range. The second‐order structure function shows scaling exponents equivalent to spectral slopes that vary from around 5/3 in the lower troposphere to 2 at upper levels. More specifically humidity smoothness typically increases with height, while intermittency decreases. A classification of the data according to whether the series occurred above or below the level of nearby convective cloud tops gives a separation of the scaling exponents in the two air masses. The results are consistent with a water vapor distribution determined at upper levels by a downscale cascade of variance by advective mixing, but increasingly influenced at lower levels by local injection of humidity by moist convection.