scholarly journals The Formation of Drainage Wind on a Snow-Dome

1965 ◽  
Vol 5 (42) ◽  
pp. 833-841 ◽  
Author(s):  
J.A. Businger ◽  
K. Ramana Rao
Keyword(s):  
Heat Flux ◽  
Temperature Profile ◽  
Energy Budget ◽  
Air Flow ◽  
Sensible Heat Flux ◽  
Wind Component ◽  
Sensible Heat ◽  
Snow Surface ◽  
Direct Measurements ◽  
The Mean

Abstract Direct measurements of the horizontal divergence of the air flow close to the snow surface have been made. The mean vertical wind component has been derived from these observations. The temperature profile has been analyzed near the center of the snow-dome and a method to determine the sensible heat flux independent from the energy budget has been developed.

scholarly journals The Formation of Drainage Wind on a Snow-Dome

1965 ◽  
Vol 5 (42) ◽  
pp. 833-841
Author(s):  
J.A. Businger ◽  
K. Ramana Rao
Keyword(s):  
Heat Flux ◽  
Temperature Profile ◽  
Energy Budget ◽  
Air Flow ◽  
Sensible Heat Flux ◽  
Wind Component ◽  
Sensible Heat ◽  
Snow Surface ◽  
Direct Measurements ◽  
The Mean

AbstractDirect measurements of the horizontal divergence of the air flow close to the snow surface have been made. The mean vertical wind component has been derived from these observations. The temperature profile has been analyzed near the center of the snow-dome and a method to determine the sensible heat flux independent from the energy budget has been developed.

scholarly journals Observation of sensible and latent heat flux profiles with lidar

2020 ◽  
Vol 13 (6) ◽  
pp. 3221-3233 ◽  
Author(s):  
Andreas Behrendt ◽  
Volker Wulfmeyer ◽  
Christoph Senff ◽  
Shravan Kumar Muppa ◽  
Florian Späth ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Sensible Heat Flux ◽  
Ground Level ◽  
Sensible Heat ◽  
Flux Divergence ◽  
Convective Boundary ◽  
The Mean

Abstract. We present the first measurement of the sensible heat flux (H) profile in the convective boundary layer (CBL) derived from the covariance of collocated vertical-pointing temperature rotational Raman lidar and Doppler wind lidar measurements. The uncertainties of the H measurements due to instrumental noise and limited sampling are also derived and discussed. Simultaneous measurements of the latent heat flux profile (L) and other turbulent variables were obtained with the combination of water-vapor differential absorption lidar (WVDIAL) and Doppler lidar. The case study uses a measurement example from the HOPE (HD(CP)2 Observational Prototype Experiment) campaign, which took place in western Germany in 2013 and presents a cloud-free well-developed quasi-stationary CBL. The mean boundary layer height zi was at 1230 m above ground level. The results show – as expected – positive values of H in the middle of the CBL. A maximum of (182±32) W m−2, with the second number for the noise uncertainty, is found at 0.5 zi. At about 0.7 zi, H changes sign to negative values above. The entrainment flux was (-62±27) W m−2. The mean sensible heat flux divergence in the observed part of the CBL above 0.3 zi was −0.28 W m−3, which corresponds to a warming of 0.83 K h−1. The L profile shows a slight positive mean flux divergence of 0.12 W m−3 and an entrainment flux of (214±36) W m−2. The combination of H and L profiles in combination with variance and other turbulent parameters is very valuable for the evaluation of large-eddy simulation (LES) results and the further improvement and validation of turbulence parameterization schemes.

scholarly journals Meridional Sea-Ice Transport and its Impact on Climate

1990 ◽  
Vol 14 ◽  
pp. 141-143 ◽  
Author(s):  
Tamara Shapiro Ledley
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Energy Exchange ◽  
Sensible Heat Flux ◽  
Polar Regions ◽  
Sensible Heat ◽  
The Mean ◽  
Ice Edge ◽  
Energy Convergence ◽  
Ice Model

Sea ice is an important factor in controlling the ocean–atmosphere energy exchange in polar regions, and has an important impact on climate. This is because sea ice insulates the relatively warm ocean from the cold winter atmosphere, and has a higher surface albedo than the ocean. In this study the effect of sea-ice transport on the energy exchange between the atmosphere and ocean, and thus on climate, is examined using a coupled energy-balance climate–thermodynamic sea-ice model. Transport of sea ice produces a thinning of the zonally annually-averaged sea ice in the poleward-most zones, and an extension of the ice edge equatorward. Thinning of the poleward-most ice produces an increase in the annual sensible heat flux from the ocean to the atmosphere, which produces an increase in the mean annual atmospheric temperatures. Sensible heat flux is decreased in the zones that contain the ice edge. However, warming in the poleward-most zones produces an increased meridional energy convergence at the ice edge that offsets the decrease in the sensible heat flux to the atmosphere, resulting in a net warming.

scholarly journals Spatio-Temporal Trends of Surface Energy Budget in Tibet from Satellite Remote Sensing Observations and Reanalysis Data

2021 ◽  
Vol 13 (2) ◽  
pp. 256
Author(s):  
Usman Mazhar ◽  
Shuanggen Jin ◽  
Wentao Duan ◽  
Muhammad Bilal ◽  
Md. Arfan Ali ◽  
...  
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Energy Budget ◽  
Sensible Heat Flux ◽  
Reanalysis Data ◽  
The Tibetan Plateau ◽  
Sensible Heat ◽  
Spatio Temporal

Being the highest and largest land mass of the earth, the Tibetan Plateau has a strong impact on the Asian climate especially on the Asian monsoon. With high downward solar radiation, the Tibetan Plateau is a climate sensitive region and the main water source for many rivers in South and East Asia. Although many studies have analyzed energy fluxes in the Tibetan Plateau, a long-term detailed spatio-temporal variability of all energy budget parameters is not clear for understanding the dynamics of the regional climate change. In this paper, satellite remote sensing and reanalysis data are used to quantify spatio-temporal trends of energy budget parameters, net radiation, latent heat flux, and sensible heat flux over the Tibetan Plateau from 2001 to 2019. The validity of both data sources is analyzed from in situ ground measurements of the FluxNet micrometeorological tower network, which verifies that both datasets are valid and reliable. It is found that the trend of net radiation shows a slight increase. The latent heat flux increases continuously, while the sensible heat flux decreases continuously throughout the study period over the Tibetan Plateau. Varying energy fluxes in the Tibetan plateau will affect the regional hydrological cycle. Satellite LE product observation is limited to certain land covers. Thus, for larger spatial areas, reanalysis data is a more appropriate choice. Normalized difference vegetation index proves a useful indicator to explain the latent heat flux trend. Despite the reduction of sensible heat, the atmospheric temperature increases continuously resulting in the warming of the Tibetan Plateau. The opposite trend of sensible heat flux and air temperature is an interesting and explainable phenomenon. It is also concluded that the surface evaporative cooling is not the indicator of atmospheric cooling/warming. In the future, more work shall be done to explain the mechanism which involves the complete heat cycle in the Tibetan Plateau.

scholarly journals Atmospheric Flow Development and Associated Changes in Turbulent Sensible Heat Flux over a Patchy Mountain Snow Cover

2015 ◽  
Vol 16 (3) ◽  
pp. 1315-1340 ◽  
Author(s):  
Rebecca Mott ◽  
Megan Daniels ◽  
Michael Lehning
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Energy Balance ◽  
Snow Cover ◽  
Sensible Heat Flux ◽  
Ambient Air ◽  
Small Scale ◽  
Sensible Heat ◽  
Katabatic Winds ◽  
The Mean

Abstract In this study, the small-scale boundary layer dynamics and the energy balance over a fractional snow cover are numerically investigated. The atmospheric boundary layer flows over a patchy snow cover were calculated with an atmospheric model (Advanced Regional Prediction System) on a very high spatial resolution of 5 m. The numerical results revealed that the development of local flow patterns and the relative importance of boundary layer processes depend on the snow patch size distribution and the synoptic wind forcing. Energy balance calculations for quiescent wind situations demonstrated that well-developed katabatic winds exerted a major control on the energy balance over the patchy snow cover, leading to a maximum in the mean downward sensible heat flux over snow for high snow-cover fractions. This implies that if katabatic winds develop, total melt of snow patches may decrease for low snow-cover fractions despite an increasing ambient air temperature, which would not be predicted by most hydrological models. In contrast, stronger synoptic winds increased the effect of heat advection on the catchment’s melt behavior by enhancing the mean sensible heat flux over snow for lower snow-cover fractions. A sensitivity analysis to grid resolution suggested that the grid size is a critical factor for modeling the energy balance of a patchy snow cover. The comparison of simulation results from coarse (50 m) and fine (5 m) horizontal resolutions revealed a difference in the spatially averaged turbulent heat flux over snow of 40%–70% for synoptic cases and 95% for quiescent cases.

scholarly journals ESTUDO DO CALOR SENSÍVEL E LATENTE OBTIDOS POR INTERMÉDIO DA RAZÃO DE BOWEN EM UMA CULTURA DE SOJA IRRIGADA.

Irriga ◽  
2007 ◽  
Vol 12 (3) ◽  
pp. 281-296 ◽  
Author(s):  
Edemo João Fernandes
Keyword(s):  
Heat Flux ◽  
Latent Heat ◽  
Sensible Heat Flux ◽  
Bowen Ratio ◽  
Vertical Displacement ◽  
Heat Fluxes ◽  
Sensible Heat ◽  
Soybean Crop ◽  
The Mean ◽  
Soil Water Conditions

ESTUDO DO CALOR SENSÍVEL E LATENTE OBTIDOS POR INTERMÉDIO DA RAZÃO DE BOWEN EM UMA CULTURA DE SOJA IRRIGADA.  Edemo João FernandesDepartamento de Engenharia Rural, Universidade Estadual Paulista, Campus de Jaboticabal, SP,[email protected]  1 RESUMO O experimento teve por objetivo estudar as variações dos fluxos de calor sensível e latente sobre uma cultura de soja irrigada, obtidos com a utilização da razão de Bowen. Foi construída uma estação micrometeorológica, com deslocamento vertical dos sensores para manter o mesmo nível de medidas acima da cobertura vegetal. A estação foi instalada na parte central da parcela, distante130 mda margem principal da direção dos ventos predominantes. Os fluxos foram calculados em função dos gradientes verticais de temperaturas determinadas a 0,15 e1,15 mde altura acima da cultura de soja. Em condições de bom suprimento de água e com a cultura cobrindo totalmente o solo o fluxo de calor latente é o maior consumidor da energia disponível na vegetação. O fluxo de calor sensível foi maior no início do desenvolvimento da cultura, quando o índice de área foliar foi menor. A cobertura vegetal é preponderante no consumo da energia disponível na vegetação em forma de calor latente. UNITERMOS: fluxos de calor, radiação líquida, temperatura do ar.  FERNANDES, E. J. F. STUDY OF SENSIBLE AND LATENT HEAT OBTAINED BY BOWEN RATIO FROM IRRIGATED SOYBEAN CROP  2 ABSTRACT                                       The goal of this experiment was to study the latent and sensible heat variation determined by Bowen ratio from an irrigated soybean crop. A micrometeorological station with vertical displacement was constructed to maintain the same level of all measures over the canopy. The station was installed in the center of the crop, and it was over130 maway from the main edge of the predominant wind direction. Fluxes were calculated by vertical temperature gradient determined at 0.15 and1.15 mover the canopy. The latent heat flux was the mean energy consumer when the canopy covered the soil totally, and there were good soil water conditions. The sensible heat flux was greater when the soil was not totally covered by the canopy. The canopy was essential on the amount of latent heat dissipated by the crop. KEYWORDS: heat fluxes, net radiation, air temperature.

scholarly journals The annual surface energy budget of a high-arctic permafrost site on Svalbard, Norway

2009 ◽  
Vol 3 (2) ◽  
pp. 245-263 ◽  
Author(s):  
S. Westermann ◽  
J. Lüers ◽  
M. Langer ◽  
K. Piel ◽  
J. Boike
Keyword(s):  
Heat Flux ◽  
Surface Energy ◽  
Latent Heat ◽  
Energy Budget ◽  
Sensible Heat Flux ◽  
Surface Energy Budget ◽  
Wave Radiation ◽  
Sensible Heat ◽  
Near Surface ◽  
Ground Heat Flux

Abstract. Independent measurements of radiation, sensible and latent heat fluxes and the ground heat flux are used to describe the annual cycle of the surface energy budget at a high-arctic permafrost site on Svalbard. During summer, the net short-wave radiation is the dominant energy source, while well developed turbulent processes and the heat flux in the ground lead to a cooling of the surface. About 15% of the net radiation is consumed by the seasonal thawing of the active layer in July and August. The Bowen ratio is found to vary between 0.25 and 2, depending on water content of the uppermost soil layer. During the polar night in winter, the net long-wave radiation is the dominant energy loss channel for the surface, which is mainly compensated by the sensible heat flux and, to a lesser extent, by the ground heat flux, which originates from the refreezing of the active layer. The average annual sensible heat flux of −6.9 Wm−2 is composed of strong positive fluxes in July and August, while negative fluxes dominate during the rest of the year. With 6.8 Wm−2, the latent heat flux more or less compensates the sensible heat flux in the annual average. Strong evaporation occurs during the snow melt period and particularly during the snow-free period in summer and fall. When the ground is covered by snow, latent heat fluxes through sublimation of snow are recorded, but are insignificant for the average surface energy budget. The near-surface atmospheric stratification is found to be predominantly unstable to neutral, when the ground is snow-free, and stable to neutral for snow-covered ground. Due to long-lasting near-surface inversions in winter, an average temperature difference of approximately 3 K exists between the air temperature at 10 m height and the surface temperature of the snow. As such comprehensive data sets are sparse for the Arctic, they are of great value to improve process understanding and support modeling efforts on the present-day and future arctic climate and permafrost conditions.

scholarly journals Meridional Sea-Ice Transport and its Impact on Climate

1990 ◽  
Vol 14 ◽  
pp. 141-143
Author(s):  
Tamara Shapiro Ledley
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Energy Exchange ◽  
Sensible Heat Flux ◽  
Polar Regions ◽  
Sensible Heat ◽  
The Mean ◽  
Ice Edge ◽  
Energy Convergence ◽  
Ice Model

Sea ice is an important factor in controlling the ocean–atmosphere energy exchange in polar regions, and has an important impact on climate. This is because sea ice insulates the relatively warm ocean from the cold winter atmosphere, and has a higher surface albedo than the ocean. In this study the effect of sea-ice transport on the energy exchange between the atmosphere and ocean, and thus on climate, is examined using a coupled energy-balance climate–thermodynamic sea-ice model.Transport of sea ice produces a thinning of the zonally annually-averaged sea ice in the poleward-most zones, and an extension of the ice edge equatorward. Thinning of the poleward-most ice produces an increase in the annual sensible heat flux from the ocean to the atmosphere, which produces an increase in the mean annual atmospheric temperatures. Sensible heat flux is decreased in the zones that contain the ice edge. However, warming in the poleward-most zones produces an increased meridional energy convergence at the ice edge that offsets the decrease in the sensible heat flux to the atmosphere, resulting in a net warming.

scholarly journals The influence of long-term changes in canopy structure on rainfall interception loss: a case study in Speulderbos, the Netherlands

2018 ◽  
Vol 22 (7) ◽  
pp. 3701-3719 ◽  
Author(s):  
César Cisneros Vaca ◽  
Christiaan van der Tol ◽  
Chandra Prasad Ghimire
Keyword(s):  
Heat Flux ◽  
The Netherlands ◽  
Energy Budget ◽  
Sensible Heat Flux ◽  
Canopy Structure ◽  
Negative Energy ◽  
Sensible Heat ◽  
Net Radiation ◽  
Growing Seasons ◽  
Interception Loss

Abstract. The evaporation of intercepted water by forests is a significant contributor to both the water and energy budget of the Earth. In many studies, a discrepancy in the water and energy budget is found: the energy that is needed for evaporation is larger than the available energy supplied by net radiation. In this study, we analyse the water and energy budget of a mature Douglas fir stand in the Netherlands, for the two growing seasons of 2015 and 2016. Based on the wet-canopy water balance equation for these two growing seasons, derived interception losses were estimated to be 37 and 39 % of gross rainfall, respectively. We further scrutinized eddy-covariance energy balance data from these two consecutive growing seasons and found the average evaporation rate during wet-canopy conditions was 0.20 mm h−1. The source of energy for this wet-canopy evaporation was net radiation (35 %), a negative sensible heat flux (45 %), and a negative energy storage change (15 %). This confirms that the energy for wet-canopy evaporation is extracted from the atmosphere as well as the biomass. Moreover, the measured interception loss at the forest was similar to that measured at the same site years before (I = 38 %), when the forest was younger (29 years old, vs. 55 years old in 2015). At that time, the forest was denser and had a higher canopy storage capacity (2.4 mm then vs. 1.90 mm in 2015), but the aerodynamic conductance was lower (0.065 m s−1 then vs. 0.105 m s−1 in 2015), and therefore past evaporation rates were lower than evaporation rates found in the present study (0.077 mm h−1 vs. 0.20 mm h−1 in 2015). Our findings emphasize the importance of quantifying downward sensible heat flux and heat release from canopy biomass in tall forest in order to improve the quantification of evaporative fluxes in wet canopies.

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