Reconstruction of the surface-layer vertical structure from measurements of wind, temperature and humidity at two levels

Abstract The major sources of atmospheric moisture over the Red Sea are analyzed using ERA-Interim for the 1979–2013 period. The vertical structure of moisture transports across the coastlines has been computed separately for the western and eastern coasts of the Red Sea. The vertical structure of the moisture transport from the Red Sea to the continents is dominated by a breeze-like circulation in the near-surface layer and the Arabian high above 850 hPa. The lower-layer, breeze-like circulation is acting to export the moisture to the northwest of Africa and to the Arabian Peninsula and contributes about 80% of the moisture exports from the Red Sea, dominating over the transport in the upper layer, where the moisture is advected to the Arabian Peninsula in the northern part of the sea and to the African continent in the southern part. Integrated moisture divergence over the Red Sea decreased from the early 1980s to 1997 and then increased until the 2010s. Associated changes in the moisture export were provided primarily by the increasing intensity of the breeze-associated transports. The transports above the boundary layer, while being strong across the western and the eastern coasts, have a smaller effect on the net moisture export. The interannual variability of the moisture export in the near-surface layer was found to be closely correlated with the variability in sea surface temperature, especially in summer. Implications of the observed changes in the moisture advection for the hydrological cycle of the Middle East are discussed.

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Temperature and humidity spectra in the atmospheric surface layer

Boundary-Layer Meteorology ◽

10.1007/bf00736184 ◽

1973 ◽

Vol 3 (3) ◽

pp. 329-347 ◽

Cited By ~ 33

Author(s):

Ann-Sofi Smedman-Högström

Keyword(s):

Surface Layer ◽

Atmospheric Surface Layer ◽

Temperature And Humidity

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Variability of the Structure Parameters of Temperature and Humidity Observed in the Atmospheric Surface Layer Under Unstable Conditions

Boundary-Layer Meteorology ◽

10.1007/s10546-013-9882-2 ◽

2013 ◽

Vol 150 (3) ◽

pp. 399-422 ◽

Cited By ~ 7

Author(s):

Miranda Braam ◽

Arnold F. Moene ◽

Frank Beyrich

Keyword(s):

Surface Layer ◽

Atmospheric Surface Layer ◽

Structure Parameters ◽

Temperature And Humidity

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Moisture and dynamical interactions maintaining decoupled Arctic mixed-phase stratocumulus in the presence of a humidity inversion

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-10127-2011 ◽

2011 ◽

Vol 11 (19) ◽

pp. 10127-10148 ◽

Cited By ~ 89

Author(s):

A. Solomon ◽

M. D. Shupe ◽

P. O. G. Persson ◽

H. Morrison

Keyword(s):

Surface Layer ◽

Water Vapor ◽

Mixed Layer ◽

Liquid Water ◽

Cloud Layer ◽

Mixed Phase ◽

Specific Humidity ◽

Cloud Liquid Water ◽

Temperature And Humidity ◽

Entrainment Zone

Abstract. Observations suggest that processes maintaining subtropical and Arctic stratocumulus differ, due to the different environments in which they occur. For example, specific humidity inversions (specific humidity increasing with height) are frequently observed to occur near cloud top coincident with temperature inversions in the Arctic, while they do not occur in the subtropics. In this study we use nested LES simulations of decoupled Arctic Mixed-Phase Stratocumulus (AMPS) clouds observed during the DOE Atmospheric Radiation Measurement Program's Indirect and SemiDirect Aerosol Campaign (ISDAC) to analyze budgets of water components, potential temperature, and turbulent kinetic energy. These analyses quantify the processes that maintain decoupled AMPS, including the role of humidity inversions. Key structural features include a shallow upper entrainment zone at cloud top that is located within the temperature and humidity inversions, a mixed layer driven by cloud-top cooling that extends from the base of the upper entrainment zone to below cloud base, and a lower entrainment zone at the base of the mixed layer. The surface layer below the lower entrainment zone is decoupled from the cloud mixed-layer system. Budget results show that cloud liquid water is maintained in the upper entrainment zone near cloud top (within a temperature and humidity inversion) due to a down gradient transport of water vapor by turbulent fluxes into the cloud layer from above and direct condensation forced by radiative cooling. Liquid water is generated in the updraft portions of the mixed-layer eddies below cloud top by buoyant destabilization. These processes cause at least 20% of the cloud liquid water to extend into the inversion. The redistribution of water vapor from the top of the humidity inversion to its base maintains the cloud layer, while the mixed layer-entrainment zone system is continually losing total water. In this decoupled system, the humidity inversion is the only source of water vapor for the cloud system, since water vapor from the surface layer is not efficiently transported into the mixed layer. Sedimentation of ice is the dominant sink of moisture from the mixed layer.

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