scholarly journals The effect of misleading surface temperature estimations on the sensible heat fluxes at a high Arctic site – the Arctic turbulence experiment 2006 on Svalbard (ARCTEX-2006)

2009 ◽  
Vol 9 (4) ◽  
pp. 16913-16939 ◽  
Author(s):  
J. Lüers ◽  
J. Bareiss
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Temperature Profile ◽  
Sensible Heat Flux ◽  
Transport Processes ◽  
The Arctic ◽  
Accurate Estimation ◽  
Physical Parameters ◽  
Turbulent Heat ◽  
Sensible Heat

Abstract. The observed rapid climate warming in the Arctic requires improvements in permafrost and carbon cycle monitoring, accomplished by setting up long-term observation sites with high-quality in-situ measurements of turbulent heat, water and carbon fluxes as well as soil physical parameters in an Arctic landscape. But accurate quantification and well adapted parameterizations of turbulent fluxes in polar environments presents fundamental problems in soil-snow-ice-vegetation-atmosphere interaction studies. One of these problems is the accurate estimation of the surface or aerodynamic temperature T(0) required to force most of the bulk aerodynamic formula currently used. Results from the Arctic-Turbulence-Experiment (ARCTEX-2006) performed on Svalbard during the winter/spring transition 2006 helped to better understand the physical exchange and transport processes of energy. The existence of an untypical temperature profile close to the surface in the Arctic spring at Svalbard could be proven to be one of the major issues hindering estimation of the appropriate surface temperature. Thus, it is essential to adjust the set-up of measurement systems carefully when applying flux-gradient methods that are commonly used to force atmosphere-ocean/land-ice models. The results of a comparison of different sensible heat-flux parameterizations with direct measurements indicate that only the use of a hydrodynamic three-layer temperature-profile model achieves enough accuracy for heat flux calculations as it reliably reproduces the temporal variability of the surface temperature.

scholarly journals The effect of misleading surface temperature estimations on the sensible heat fluxes at a high Arctic site – the Arctic Turbulence Experiment 2006 on Svalbard (ARCTEX-2006)

2010 ◽  
Vol 10 (1) ◽  
pp. 157-168 ◽  
Author(s):  
J. Lüers ◽  
J. Bareiss
Keyword(s):  
Surface Temperature ◽  
Temperature Profile ◽  
Sensible Heat Flux ◽  
Gradient Methods ◽  
Transport Processes ◽  
The Arctic ◽  
Accurate Estimation ◽  
Physical Parameters ◽  
Turbulent Heat ◽  
Sensible Heat

Abstract. The observed rapid climate warming in the Arctic requires improvements in permafrost and carbon cycle monitoring, accomplished by setting up long-term observation sites with high-quality in-situ measurements of turbulent heat, water and carbon fluxes as well as soil physical parameters in Arctic landscapes. But accurate quantification and well adapted parameterizations of turbulent fluxes in polar environments presents fundamental problems in soil-snow-ice-vegetation-atmosphere interaction studies. One of these problems is the accurate estimation of the surface or aerodynamic temperature T(0) required to force most of the bulk aerodynamic formulae currently used. Results from the Arctic-Turbulence-Experiment (ARCTEX-2006) performed on Svalbard during the winter/spring transition 2006 helped to better understand the physical exchange and transport processes of energy. The existence of an atypical temperature profile close to the surface in the Arctic spring at Svalbard could be proven to be one of the major issues hindering estimation of the appropriate surface temperature. Thus, it is essential to adjust the set-up of measurement systems carefully when applying flux-gradient methods that are commonly used to force atmosphere-ocean/land-ice models. The results of a comparison of different sensible heat-flux parameterizations with direct measurements indicate that the use of a hydrodynamic three-layer temperature-profile model achieves the best fit and reproduces the temporal variability of the surface temperature better than other approaches.

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 Parameterization of Urban Sensible Heat Flux from Remotely Sensed Surface Temperature: Effects of Surface Structure

2019 ◽  
Vol 11 (11) ◽  
pp. 1347 ◽  
Author(s):  
Jinxin Yang ◽  
Massimo Menenti ◽  
E. Scott Krayenhoff ◽  
Zhifeng Wu ◽  
Qian Shi ◽  
...  
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Sensible Heat Flux ◽  
Effective Resistance ◽  
Three Dimensions ◽  
Sensible Heat ◽  
Wall Surface ◽  
Surface Temperatures ◽  
Flux Parameterization ◽  
The Impact

Sensible heat exchange has important consequences for urban meteorology and related applications. Directional radiometric surface temperatures of urban canopies observed by remote sensing platforms have the potential to inform estimations of urban sensible heat flux. An imaging radiometer viewing the surface from nadir cannot capture the complete urban surface temperature, which is defined as the mean surface temperature over all urban facets in three dimensions, which includes building wall surface temperatures and requires an estimation of urban sensible heat flux. In this study, a numerical microclimate model, Temperatures of Urban Facets in 3-D (TUF-3D), was used to model sensible heat flux as well as radiometric and complete surface temperatures. Model data were applied to parameterize an effective resistance for the calculation of urban sensible heat flux from the radiometric (nadir view) surface temperature. The results showed that sensible heat flux was overestimated during daytime when the radiometric surface temperature was used without the effective resistance that accounts for the impact of wall surface temperature on heat flux. Parameterization of this additional resistance enabled reasonably accurate estimates of urban sensible heat flux from the radiometric surface temperature.

scholarly journals Evaluation of functional properties of various types of vegetation cover using remotely sensed data analysis

2010 ◽  
Vol 4 (Special Issue 2) ◽  
pp. S49-S58 ◽  
Author(s):  
J. Brom ◽  
J. Procházka ◽  
A. Rejšková
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Land Surface ◽  
Hydrological Cycle ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Remotely Sensed Data ◽  
Mean Values

The dissipation of solar energy and consequently the formation of the hydrological cycle are largely dependent on the structural and optical characteristics of the land surface. In our study, we selected seven units with different types of vegetation in the Mlýnský and Horský catchments (South-Eastern part of the Šumava Mountains, Czech Republic) for the assessment of the differences in their functioning expressed through the surface temperature, humidity, and energy dissipation. For our analyses, we used Landsat 5 TM satellite data from June 25<SUP>th</SUP>, 2008. The results showed that the microclimatic characteristics and energy fluxes varied in different units according to their vegetation characteristics. A cluster analysis of the mean values was used to divide the vegetation units into groups according to their functional characteristics. The mown meadows were characterised by the highest surface temperature and sensible heat flux and the lowest humidity and latent heat flux. On the contrary, the lowest surface temperature and sensible heat flux and the highest humidity and latent heat flux were found in the forest. Our results showed that the climatic and energetic features of the land surface are related to the type of vegetation. We state that the spatial distribution of different vegetation units and the amount of biomass are crucial variables influencing the functioning of the landscape.

Sensible Heat Flux-Radiometric Surface Temperature Relationship for Eight Semiarid Areas

1994 ◽  
Vol 33 (9) ◽  
pp. 1110-1117 ◽  
Author(s):  
J. B. Stewart ◽  
W. P. Kustas ◽  
K. S. Humes ◽  
W. D. Nichols ◽  
M. S. Moran ◽  
...  
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Sensible Heat Flux ◽  
Temperature Relationship ◽  
Sensible Heat ◽  
Semiarid Areas

Climate and Vegetation in the Middle East: Interannual Variability and Drought Feedbacks

2007 ◽  
Vol 20 (15) ◽  
pp. 3924-3941 ◽  
Author(s):  
Benjamin F. Zaitchik ◽  
Jason P. Evans ◽  
Roland A. Geerken ◽  
Ronald B. Smith
Keyword(s):  
Heat Flux ◽  
Interannual Variability ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Vegetation Index ◽  
Climate Model ◽  
Sensible Heat Flux ◽  
Radiation Balance ◽  
Turbulent Heat ◽  
Sensible Heat

Abstract The Euphrates Plain (EP) experiences large interannual variability in vegetation cover, especially in areas of marginal rain-fed agriculture. Vegetation in this region is primarily limited by available soil moisture, as determined by winter precipitation, spring precipitation, and air temperature. Satellite analyses indicate that the springtime normalized difference vegetation index (NDVI) is negatively correlated with surface albedo, and that interannual variability in albedo in the EP produces an estimated forcing on the radiation balance that peaks at 16.0 W m−2 in May. Simulations with a regional climate model indicate that surface energy fluxes during a drought year (1999) differed substantially from those during a year with normal precipitation (2003). These differences were geographically specific, with the EP exhibiting increased albedo and decreased sensible heat flux while the neighboring Zagros Plateau region showed no albedo effect, a large increase in sensible heat flux, and an offsetting reduction in latent heat flux. In both the EP and the Zagros there was a potential for positive feedbacks on temperature and drought in late spring, though the most likely feedback mechanisms differed between the two regions: in the EP surface brightening leads to cooling and reduced turbulent heat flux, while in the Zagros region reduced latent heat flux leads to warming and a deepening of the planetary boundary layer.

Sensible Heat Flux in Near-Neutral Conditions over the Sea

2012 ◽  
Vol 42 (7) ◽  
pp. 1134-1142 ◽  
Author(s):  
L. Mahrt ◽  
Dean Vickers ◽  
Edgar L Andreas ◽  
Djamal Khelif
Keyword(s):  
Heat Flux ◽  
Wind Speed ◽  
Surface Temperature ◽  
Sensible Heat Flux ◽  
Sea Surface ◽  
Sensible Heat ◽  
Stable Conditions ◽  
Weakly Stable ◽  
Weak Winds ◽  
Neutral Conditions

Abstract The variation of the sea surface sensible heat flux is investigated using data from the Gulf of Tehuantepec Experiment (GOTEX) and from eight additional aircraft datasets representing a variety of surface conditions. This analysis focuses on near-neutral conditions because these conditions are common over the sea and are normally neglected, partly because of uncertain reliability of measurements of the small air–sea temperature difference. For all of the datasets, upward heat flux is observed for slightly stable conditions. The frequency of this “countergradient” heat flux increases with increasing wind speed and is possibly related to sea spray or microscale variations of surface temperature on the wave scale. Upward area-averaged sensible heat flux for slightly stable conditions can also be generated by mesoscale heterogeneity of the sea surface temperature (SST). Significant measurement errors cannot be ruled out. The countergradient heat flux for weakly stable conditions is least systematic for weaker winds, even though it occurs with weak winds in all of the datasets. In an effort to reduce offset errors and different SST processing and calibration procedures among field programs, the authors adjusted the SST in each field program to minimize the countergradient flux for weak winds. With or without this adjustment for the combined dataset, the extent of the upward heat flux for weakly stable conditions increases with increasing wind speed.

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