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Title: Modulation of Boundary-Layer Stability and the Surface Energy Budget by a Local Flow in Central Alaska

The pre-ALPACA (Alaskan Layered Pollution And Chemical Analysis) 2019 winter campaign took place in Fairbanks, Alaska, in November–December 2019. One objective of the campaign was to study the life-cycle of surface-based temperature inversions and the associated surface energy budget changes. Several instruments, including a 4-component radiometer and sonic anemometer were deployed in the open, snow-covered University of Alaska Fairbanks (UAF) Campus Agricultural Field. A local flow from a connecting valley occurs at this site. This flow is characterized by locally elevated wind speeds (greater than 3 m s$$^{-1}$$-1) under clear-sky conditions and a north-westerly direction. It is notably different to the wind observed at the airport more than 3.5 km to the south-west. The surface energy budget at the UAF Field site exhibits two preferential modes. In the first mode, turbulent sensible heat and net longwave fluxes are close to 0 W m$$^{-2}$$-2, linked to the presence of clouds and generally low winds. In the second, the net longwave flux is around − 50 W m$$^{-2}$$-2and the turbulent sensible heat flux is around 15 W m$$^{-2}$$-2, linked to clear skies and elevated wind speeds. The development of surface-based temperature inversions at the field is hindered compared to the airport because the local flow sustains vertical mixing. In this second more » mode the residual of the surface energy budget is large, possibly due to horizontal temperature advection.

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Publication Date:
Journal Name:
Boundary-Layer Meteorology
Page Range or eLocation-ID:
p. 395-414
Springer Science + Business Media
Sponsoring Org:
National Science Foundation
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