Spatial Dependence of Stably Stratified Nocturnal Boundary-Layer Regimes in Complex Terrain
Date
2020
Authors
Abraham, Carsten
Monahan, Adam H.
Journal Title
Journal ISSN
Volume Title
Publisher
Boundary-Layer Meteorology
Abstract
The stably stratified atmospheric boundary layer (SBL) has been found in previous studies
to display distinct regimes of behaviour. In particular, a contrast is often drawn between
the weakly (wSBL) and very (vSBL) stable boundary layers. Time series of SBL regime
affiliation obtained from hidden Markov model analyses of data from three different towers
at the Los Alamos National Laboratory are used to investigate the spatial dependence of SBL
regime occupation and SBL transitions. The local topography influences the flow such that
south-west to north-east flow prevails, for which wSBL and vSBL conditions respectively are
more likely to occur. Joint probabilities of shared regime occupation at the three towers (with
and without conditioning on wind direction) are much larger than would be expected from
statistically independent regime sequences at the different locations. Very persistent wSBL
nights (without any transitions to the vSBL) have a higher probability of occurring across
the entire tower network domain than very persistent vSBL nights. Many regime transitions
occur within a narrow time window between the different towers; occurrence probabilities of
such events are much higher than would be expected from statistically independent regime
transitions. Of such events, transitions occurring at exactly the same time across the tower
network occur most often. Many co-occurring turbulence recovery events can be associated
with high-intensity intermittent turbulence events. Our results imply that the scale on which
the SBL regime occupation and transitions are dependent exceeds 10 km in this region of
complex terrain.
Description
Keywords
Clustering, Spatial structure, Spatial variability, Stable boundary layer, Statistics
Citation
Abraham, C., & Monahan, A. H. (2020). Spatial Dependence of Stably Stratified Nocturnal Boundary-Layer Regimes in Complex Terrain. Boundary-Layer Meteorology, 177, 19-47. https://doi.org/10.1007/s10546-020-00532-x.