The Turbulent Transfer Model Applied to Geodolite Measurements

1984 ◽  
Vol 38 (2) ◽  
pp. 79-90
Author(s):  
C. S. Fraser
Keyword(s):  
Long Range ◽  
Meteorological Parameters ◽  
Sensible Heat Flux ◽  
Reduction Technique ◽  
Transfer Model ◽  
Turbulent Transfer ◽  
Sensible Heat ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Wave Path

This paper reports on an application of the Turbulent Transfer Model (TTM) for the atmospheric reduction of long-range geodolite EDM measurements. To apply the TTM, additional meteorological parameters must be determined. For this application, the sensible heat flux, which is central to the modeling of the vertical temperature gradient, has been empirically modeled. The atmospheric reduction obtained with the TTM is compared to both the distance corrected for refraction by the standard reduction technique, and the “true” distance which has been determined using temperatures measured along the wave path by an aircraft. The results indicate that the TTM can yield a significant improvement in accuracy over the standard reduction for long-range electrooptical EDM. To attain this improvement only a few additional, and mainly qualitative field observations need to be recorded.

Vegetation pattern of Istanbul from the Landsat data and the relationship with meteorological parameters

1994 ◽  
Vol 12 (6) ◽  
pp. 574-584
Author(s):  
Zafer Aslan ◽  
Krishnaier Natarajan ◽  
Mehmet Tankut
Keyword(s):  
Heat Flux ◽  
Relative Humidity ◽  
Momentum Flux ◽  
Meteorological Parameters ◽  
Sensible Heat Flux ◽  
Vegetation Pattern ◽  
Rainfall Rate ◽  
Landsat Data ◽  
Sensible Heat ◽  
Static Energy

Abstract. This paper discusses the preliminary results of a study on the vegetation pattern and its relationship with meteorological parameters in and around Istanbul. The study covers an area of over 6800 km2 consisting of urban and suburban centers, and uses the visible and near-infrared bands of Landsat. The spatial variation of the Normalized Difference Vegetation Index (NDVI) and meteorological parameters such as sensible heat flux, momentum flux, relative humidity, moist static energy, rainfall rate and temperature have been investigated based on observations in ten stations in the European (Thracian) and Anatolian parts of Istanbul. NDVI values have been evaluated from the Landsat data for a single day, viz. 24 October 1986, using ERDAS in ten different classes. The simultaneous spatial variations of sensible heat and momentum fluxes have been computed from the wind and temperature profiles using the Monin-Obukhov similarity theory. The static energy variations are based on the surface meteorological observations. There is very good correlation between NDVI and rainfall rate. Good correlation also exists between: NDVI and relative humidity; NDVI, sensible heat flux and relative humidity; NDVI, momentum flux and emissivity; and NDVI, sensible heat flux and emissivity. The study suggests that the momentum flux has only marginal impact on NDVI. Due to rapid urbanization,the coastal belt is characterized by reduced NDVI compared to the interior areas, suggesting that thermodynamic discontinuities considerably influence the vegetation pattern. This study is useful for the investigation of small-scale circulation models, especially in urban and suburban areas where differential heating leads to the formation of heat islands. In the long run, such studies on a global scale are vital to gain accurate, timely information on the distribution of vegetation on the earth's surface. This may lead to an understanding of how changes in land cover affect phenomena as diverse as the atmospheric CO2 concentrations, the hydrological cycle and the energy balance at the surface-atmosphere interface.

scholarly journals Response of the Energy Balance on the Margin of the Greenland Ice Sheet to Temperature Changes

1990 ◽  
Vol 36 (123) ◽  
pp. 217-221 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Ole B. Olesen
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Air Temperature ◽  
Sensible Heat Flux ◽  
Ice Sheet ◽  
Temperature Response ◽  
Greenland Ice Sheet ◽  
Energy Balance Model ◽  
Balance Model ◽  
Sensible Heat

AbstractDaily ice ablation on two outlet glaciers from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), is related to air temperature by a linear regression equation. Analysis of this ablation-temperature equation with the help of a simple energy-balance model shows that sensible-heat flux has the greatest temperature response and accounts for about one-half of the temperature response of ablation. Net radiation accounts for about one-quarter of the temperature response of ablation, and latent-heat flux and errors account for the remainder. The temperature response of sensible-heat flux at QQamanârssûp sermia is greater than at Nordbogletscher mainly due to higher average wind speeds. The association of high winds with high temperatures during Föhn events further increases sensible-heat flux. The energy-balance model shows that ablation from a snow surface is only about half that from an ice surface at the same air temperature.

Components of the energy balance of the ground surface and their effect on the thermics of the substrata of the vegetation oasis at Henryk Arctowski Station, King George Island, South Shetland Islands

Polar Record ◽  
2000 ◽  
Vol 36 (196) ◽  
pp. 3-18 ◽  
Author(s):  
P. Prosek ◽  
M. Janouch ◽  
K. Láska
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Soil Temperature ◽  
Sensible Heat Flux ◽  
Ground Surface ◽  
South Shetland Islands ◽  
Radiation Balance ◽  
Sensible Heat ◽  
King George Island ◽  
Shetland Islands

AbstractThis article presents the results of measurements of the components of ground-surface energy balance (radiation balance, sensible heat flux, latent heat flux, and ground heat flux) taken during the 1994/95 summer season at Poland's Henryk Arctowski Station, King George Island, South Shetland Islands (62°09'42”S, 58°28'10”W). This was the first time that these complex measurements had been taken in the central part of the South Shetlands archipelago. The results are evaluated at the level of daily and seasonal fluctuations. The consequences of energy balance on the temperature conditions of the soil substrata are highlighted. The verification of the degree of influence of a subset of energy-balance components on soil temperature allowed analysis of the relationships among soil temperature, radiation balance, and sensible heat flux. This analysis leads to the conclusion that there is a rapid reaction of the soil temperature to the radiation balance and sensible heat flux to a depth of 5 cm. The boundary atmosphere and soil substrate represent the basic components of the ecotops of the Antarctic vegetation oasis, so these results are interpreted in pedological or botanical studies in the search for environmental influences on the vegetation.

scholarly journals Influence of Subfacet Heterogeneity and Material Properties on the Urban Surface Energy Budget

2014 ◽  
Vol 53 (9) ◽  
pp. 2114-2129 ◽  
Author(s):  
Prathap Ramamurthy ◽  
Elie Bou-Zeid ◽  
James A. Smith ◽  
Zhihua Wang ◽  
Mary L. Baeck ◽  
...  
Keyword(s):  
Surface Energy ◽  
Energy Budget ◽  
Material Properties ◽  
Sensible Heat Flux ◽  
Role Reversal ◽  
Surface Energy Budget ◽  
Urban Surface ◽  
Urban Site ◽  
Peak Time ◽  
Sensible Heat

AbstractUrban facets—the walls, roofs, and ground in built-up terrain—are often conceptualized as homogeneous surfaces, despite the obvious variability in the composition and material properties of the urban fabric at the subfacet scale. This study focuses on understanding the influence of this subfacet heterogeneity, and the associated influence of different material properties, on the urban surface energy budget. The Princeton Urban Canopy Model, which was developed with the ability to capture subfacet variability, is evaluated at sites of various building densities and then applied to simulate the energy exchanges of each subfacet with the atmosphere over a densely built site. The analyses show that, although all impervious built surfaces convert most of the incoming energy into sensible heat rather than latent heat, sensible heat fluxes from asphalt pavements and dark rooftops are 2 times as high as those from concrete surfaces and light-colored roofs. Another important characteristic of urban areas—the shift in the peak time of sensible heat flux in comparison with rural areas—is here shown to be mainly linked to concrete’s high heat storage capacity as well as to radiative trapping in the urban canyon. The results also illustrate that the vegetated pervious soil surfaces that dot the urban landscape play a dual role: during wet periods they redistribute much of the available energy into evaporative fluxes but when moisture stressed they behave more like an impervious surface. This role reversal, along with the direct evaporation of water stored over impervious surfaces, significantly reduces the overall Bowen ratio of the urban site after rain events.

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