Review: the atmospheric boundary layer

Garratt, J. R.

doi:10.1016/0012-8252(94)90026-4

Cited by 634 publications

(582 citation statements)

References 158 publications

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“…[15] A Campbell Scientific CSAT-3 sonic anemometer and a Licor-7500 CO 2 /H 2 O infrared gas analyzer were used to measure velocity and gas concentrations at 10 Hz for the estimation of latent heat (LE), and sensible heat fluxes (H) through standard eddy correlation methods [e.g., Brutsaert, 1982;Garratt, 1992]. The two instruments were placed at 10 m height above the ground.…”

Section: Tower Setupmentioning

confidence: 99%

“…Recent efforts [Baldocchi et al, 2004;Kurc and Small, 2004;Williams and Albertson, 2004] compared spatially aggregate ET estimates in grasslands and shrublands from micrometerological observations [e.g., Brutsaert, 1982;Garratt, 1992], and estimated the relationships between ET and q for the two contrasting ecosystems. However, in heterogeneous ecosystems with various land cover components, micrometeorological observations need to be carefully interpreted.…”

Section: Introductionmentioning

confidence: 99%

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Soil moisture and vegetation controls on evapotranspiration in a heterogeneous Mediterranean ecosystem on Sardinia, Italy

Detto

Montaldo

Albertson

et al. 2006

Water Resources Research

199

241

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[1] Micrometeorological measurements of evapotranspiration (ET) can be difficult to interpret and use for validating model calculations in the presence of land cover heterogeneity. Land surface fluxes, soil moisture (q), and surface temperatures (T s ) data were collected by an eddy correlation-based tower located at the Orroli (Sardinia) experimental field (covered by woody vegetation, grass, and bare soil) from April 2003 to July 2004. Two Quickbird high-resolution images (summer 2003 and spring 2004) were acquired for depicting the contrasting land cover components. A procedure is presented for estimating ET in heterogeneous ecosystems as the residual term of the energy balance using T s observations, a two-dimensional footprint model, and the Quickbird images. Two variations on the procedure are successfully implemented: a proposed two-source random model (2SR), which treats the heat sources of each land cover component separately but computes the bulk heat transfer coefficient as spatially homogeneous, and a common two-source tile model. For 2SR, new relationships between the interfacial transfer coefficient and the roughness Reynolds number are estimated for the two bare soil-woody vegetation and grass-woody vegetation composite surfaces. The ET versus q relationships for each land cover component were also estimated, showing that that the woody vegetation has a strong tolerance to long droughts, transpiring at rates close to potential for even the driest conditions. Instead, the grass is much less tolerant to q deficits, and the switch from grass to bare soil following the rainy season had a significant impact on ET.

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Section: Tower Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Soil moisture and vegetation controls on evapotranspiration in a heterogeneous Mediterranean ecosystem on Sardinia, Italy

Detto

Montaldo

Albertson

et al. 2006

Water Resources Research

199

241

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“…Further, the turbulent heat fluxes are modified due to a rapid decrease of the roughness length. Typical mean values over snow, given, e.g., by Stull [1988], Garratt [1992], and K6nig [1985], vary between 10 -3 m over snow-covered farmland, 10 -4 m for the Antarctic region, and 10 -5 m over snow-covered flat or rolling ground.Due to the altered albedo the net radiation and, consequently, the surface temperature are reduced, leading to a smaller amount of outgoing long wave radiation, an increased sensible heat flux into the snow, and causing a cooling of the overlying lower atmosphere. The small thermal conductivity of snow additionally prevents an efficient heat conduction from the underlying snow layers and the soil.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Snow cover model for global climate simulations

Loth¹,

Graf²,

Oberhuber³

1993

J. Geophys. Res.

149

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Because of the high sensitivity of the climate system to anomalies of the snow cover, appropriate models of the latter are required. In this paper a one-dimensional multilayer model of a snow cover is presented combining relatively accurate model physics with minimal computer time. The model is based on the balance of mass and energy, including the important internal processes such as the diffusion of temperature and water vapor, melting and freezing, the extinction of short wave radiation, and the retention of liquid water. In order to keep the possibility of using the model on a global scale, no local parameterizations are employed. An efficient numerical scheme makes the model suitable for long-term climate studies. Integrations for Potsdam (52øN, 13øE) with standard synoptic measurements over a period of six winters demonstrate good correspondence between the model results and the observed values. The most serious problem remaining is the choice of a satisfactory criterion to distinguish between snowfall and rain which strongly affects the simulation of snow depth and water equivalent. In addition, snow on sea ice, causing a net cooling of air and keeping the sea ice warm and thin, affects the climate at high latitudes [Ledley, 1991]. On the other hand, variations of the snow cover might indicate climate changes due to the ability to integrate atmospheric disturbances [Flohn, 1974].In comparison with the bare soil, various physical parameters are significantly altered by a snow cover. The surface albedo rises suddenly from 10 to 25% to values of 75 to 90% for freshly fallen snow, reducing the short wave radiation absorbed by the surface. Further, the turbulent heat fluxes are modified due to a rapid decrease of the roughness length. Typical mean values over snow, given, e.g., by Stull [1988], Garratt [1992], and K6nig [1985], vary between 10 -3 m over snow-covered farmland, 10 -4 m for the Antarctic region, and 10 -5 m over snow-covered flat or rolling ground.Due to the altered albedo the net radiation and, consequently, the surface temperature are reduced, leading to a smaller amount of outgoing long wave radiation, an increased sensible heat flux into the snow, and causing a cooling of the overlying lower atmosphere. The small thermal conductivity of snow additionally prevents an efficient heat conduction from the underlying snow layers and the soil. In spring the increase of the air and soil temperature is delayed, as compared with snow-free areas, since energy is used for the melting of snow. In the case of nonfrozen soil Copyright 1993 by the American Geophysical Union. Paper number 93JD00324.0148-0227/93/93 JD-00324505.00 the soil temperature is decreased both directly and by inducing evaporation when melting water penetrates into the soil. The higher amount of soil moisture may contribute to cloud formation and, therefore, have another effect on the air temperature.The snow cover, however, is undergoing internal changes due to aging processes. The typical "life cycle" of a snow cover is shown in Figur...

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“…In the second layer above the surface layer, the so-called 'macrowind' U macro is defined from (Garratt, 1992):…”

Section: Surface Wind Speed Interpolation Using a Simplified Boundarymentioning

confidence: 99%

Wind speed interpolation in the vicinity of the Panama Canal

Cheng

Georgakakos

2011

Meteorological Applications

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ABSTRACT:A simplified boundary layer (SBL) model formulation is tested against the mesoscale meteorological model MM5 with respect to the 2 km interpolation of hourly surface wind station data for stations in the close vicinity of the Panama Canal. The required short computation time for the real time interpolation of the wind during air pollution incidents involving crossing cargo ships makes the use of simplified wind models an alternative to the full implementation of mesoscale models. The SBL model does take into consideration the land cover of the ground surface, which exhibits substantial variability in the study region. The SBL model produces features of wind speed that are similar to those of the MM5 simulation along the better-observed Canal centreline. The presence of orographic features makes the applicability of the simplified formulation reasonable only near the Canal where the terrain has small undulations. The simulated wind fields show that the dry season (January to April) is more spatially and temporally coherent than the wet season and that it also has higher wind speeds than the wet season. The evening hours have higher wind speeds than the morning hours in both seasons. The simulated wind exhibits higher average wind speeds and higher frequencies of exceeding 5 m s −1 within the Gatun Lake on the Caribbean side of the Isthmus and the entrance/exit of the Canal on the Caribbean and Pacific coasts. These results are useful for the development of effective disaster mitigation strategies for air pollution events in the region.

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Review: the atmospheric boundary layer

Cited by 634 publications

References 158 publications

Soil moisture and vegetation controls on evapotranspiration in a heterogeneous Mediterranean ecosystem on Sardinia, Italy

Soil moisture and vegetation controls on evapotranspiration in a heterogeneous Mediterranean ecosystem on Sardinia, Italy

Snow cover model for global climate simulations

Wind speed interpolation in the vicinity of the Panama Canal

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