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Transitions in the wintertime near‐surface temperature inversion at Dome C, Antarctica
Author(s) -
Baas Peter,
van de Wiel Bas J. H.,
van Meijgaard Erik,
Vig Etienne,
Genthon Christophe,
van der Linden Steven J. A.,
de Roode Stephan R.
Publication year - 2019
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.3450
Subject(s) - inversion (geology) , geostrophic wind , geology , thermal wind , wind speed , turbulence , inversion temperature , wind direction , boundary layer , atmospheric sciences , climatology , geodesy , meteorology , mechanics , physics , wind profile power law , geomorphology , oceanography , structural basin , daytime
In this work we study the dynamics of the surface‐based temperature inversion over the Antarctic Plateau during the polar winter. Using 6 years of observations from the French–Italian Antarctic station Concordia at Dome C, we investigate sudden regime transitions in the strength of the near‐surface temperature inversion. Here we define “near‐surface” as being within the domain of the 45‐m measuring tower. In particular, we consider the strongly nonlinear relation between the 10‐m inversion strength ( T 10m – T s ) and the 10‐m wind speed. To this end, all individual events for which the 10‐m inversion strength increases or decreases continuously by more than 15 K in time are considered. Composite time series and vertical profiles of wind and temperature reveal specific characteristics of the transition from weak to very strong inversions and vice versa. In contrast to midlatitudes, the largest variations in temperature are not found at the surface but at a height of 10 m. A similar analysis was performed on results from an atmospheric single‐column model (SCM). Overall, the SCM results reproduce the observed characteristics of the transitions in the near‐surface inversion remarkably well. Using model output, the underlying mechanisms of the regime transitions are identified. The nonlinear relation between inversion strength and wind speed at a given level is explained by variations in the geostrophic wind speed, changes in the depth of the turbulent layer and the vertical divergence of turbulent fluxes. Moreover, the transitions between different boundary layer regimes cannot be explained without considering the contribution of subsidence heating.