Numerical Study of Near‐Surface Jet in the Atmospheric Surface Layer over an Oceanic Temperature Front

We use unmanned aerial vehicles to interrogate the surface layer processes during a solar eclipse and gain a comprehensive look at the changes made to the atmospheric surface layer as a result of the rapid change of insolation. Measurements of the atmospheric surface layer structure made by the unmanned systems are connected to surface measurements to provide a holistic view of the impact of the eclipse on the near-surface behaviour, large-scale turbulent structures and small-scale turbulent dynamics. Different regimes of atmospheric surface layer behaviour were identified, with the most significant impact including the formation of a stable layer just after totality and evidence of Kelvin–Helmholtz waves appearing at the interface between this layer and the residual layer forming above it. The decrease in surface heating caused a commensurate decrease in buoyant turbulent production, which resulted in a rapid decay of the turbulence in the atmospheric surface layer both within the stable layer and in the mixed layer forming above it. Significant changes in the wind direction were imposed by the decrease in insolation, with evidence supporting the formation of a nocturnal jet, as well as backing of the wind vector within the stable layer.

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Measurement-Based Numerical Study of the Effects of Realistic Land Topography and Stratification on the Coastal Marine Atmospheric Surface Layer

Boundary-Layer Meteorology ◽

10.1007/s10546-018-00423-2 ◽

2019 ◽

Vol 171 (2) ◽

pp. 289-314 ◽

Cited By ~ 3

Author(s):

Zixuan Yang ◽

Antoni Calderer ◽

Sida He ◽

Fotis Sotiropoulos ◽

Raghavendra Krishnamurthy ◽

...

Keyword(s):

Surface Layer ◽

Atmospheric Surface Layer ◽

Numerical Study ◽

Coastal Marine

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A numerical study of the vertical dispersion of passive contaminants from a continuous source in the atmospheric surface layer

Atmospheric Environment (1967) ◽

10.1016/0004-6981(80)90288-7 ◽

1980 ◽

Vol 14 (2) ◽

pp. 267-269 ◽

Cited By ~ 3

Author(s):

Thomas W. Horst

Keyword(s):

Surface Layer ◽

Atmospheric Surface Layer ◽

Numerical Study ◽

Vertical Dispersion ◽

Continuous Source

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Daily cycle of the surface layer and energy balance on the high Antarctic Plateau

Antarctic Science ◽

10.1017/s095410200500252x ◽

2005 ◽

Vol 17 (1) ◽

pp. 121-133 ◽

Cited By ~ 31

Author(s):

DIRK VAN AS ◽

MICHIEL VAN DEN BROEKE ◽

RODERIK VAN DE WAL

Keyword(s):

Heat Flux ◽

Surface Layer ◽

Energy Balance ◽

Wind Speed ◽

Atmospheric Surface Layer ◽

Specific Humidity ◽

Inertial Oscillation ◽

Sensible Heat ◽

Daily Cycle ◽

Near Surface

This paper focuses on the daily cycle of the surface energy balance and the atmospheric surface layer during a detailed meteorological experiment performed near Kohnen base in Dronning Maud Land, East Antarctica, in January and February 2002. Temperature, specific humidity, wind speed and the turbulent scales of these quantities, exhibit a strong daily cycle. The sensible heat flux cycle has a mean amplitude of ∼8 W m−2, while the latent heat flux has an amplitude of less than 2 W m−2, which is small compared to the amplitude of net radiation (∼ 35 W m−2) and sub-surface heat (∼ 25 W m−2). Between ∼ 9 and 16 h GMT convection occurs due to a slightly unstable atmospheric surface layer. At the end of the afternoon, the wind speed decreases abruptly and the mixed layer is no longer supported by the sensible heat input; the stratification becomes stable. At night a large near-surface wind shear is measured due to the presence of a nocturnal jet, which is likely to be katabatically driven, but can also be the result of an inertial oscillation. No strong daily cycle in wind direction is recorded, since both the katabatic forcing at night and the daytime forcing by the large-scale pressure gradient were directed approximately downslope during the period of measurement.

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Toward the Assimilation of the Atmospheric Surface Layer Using Numerical Weather Prediction and Radar Clutter Observations

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-12-0320.1 ◽

2013 ◽

Vol 52 (10) ◽

pp. 2345-2355 ◽

Cited By ~ 12

Author(s):

Ali Karimian ◽

Caglar Yardim ◽

Tracy Haack ◽

Peter Gerstoft ◽

William S. Hodgkiss ◽

...

Keyword(s):

Surface Layer ◽

Relative Humidity ◽

Numerical Weather Prediction ◽

Atmospheric Surface Layer ◽

Weather Prediction ◽

Propagation Model ◽

Near Surface ◽

Radar Clutter ◽

Numerical Weather ◽

Evaporation Duct

AbstractRadio wave propagation on low-altitude paths over the ocean above 2 GHz is significantly affected by negative refractivity gradients in the atmospheric surface layer, which form what is often referred to as an evaporation duct (ED). Refractivity from clutter (RFC) is an inversion approach for the estimation of the refractivity profile from radar clutter, and RFC-ED refers to its implementation for the case of evaporation ducts. An approach for fusing RFC-ED output with evaporation duct characterization that is based on ensemble forecasts from a numerical weather prediction (NWP) model is examined here. Three conditions of air–sea temperature difference (ASTD) are examined. Synthetic radar clutter observations are generated using the Advanced Propagation Model. The impacts of ASTD on the evaporation duct refractivity profile, atmospheric parameter inversion, and propagation factor distributions are studied. Relative humidity at a reference height and ASTD are identified as state variables. Probability densities from NWP ensembles, RFC-ED, and joint inversions are compared. It is demonstrated that characterization of the near-surface atmosphere by combining RFC-ED and NWP reduces the estimation uncertainty of ASTD and relative humidity in an evaporation duct, with respect to using either method alone.

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