Relations between land surface properties: Altitude, slope and curvature

2005 ◽  
pp. 13-45 ◽  
Author(s):  
I. S. Evans ◽  
N. J. Cox
Keyword(s):  
Surface Properties ◽  
Land Surface

GCM sensitivity experiments with locally modified land surface properties over tropical South America

2006 ◽  
Vol 26 (7-8) ◽  
pp. 729-749 ◽  
Author(s):  
Čedo Branković ◽  
Franco Molteni ◽  
Pedro Viterbo
Keyword(s):  
South America ◽  
Surface Properties ◽  
Land Surface ◽  
Sensitivity Experiments ◽  
Tropical South America

scholarly journals BIDIRECTIONAL REFLECTANCE MODELING OF THE GEOSTATIONARY SENSOR HIMAWARI-8/AHI USING A KERNEL-DRIVEN BRDF MODEL

2016 ◽  
Vol III-7 ◽  
pp. 3-8 ◽  
Author(s):  
M. Matsuoka ◽  
M. Takagi ◽  
S. Akatsuka ◽  
R. Honda ◽  
A. Nonomura ◽  
...  
Keyword(s):  
Surface Properties ◽  
Land Surface ◽  
Goodness Of Fit ◽  
Near Infrared ◽  
Temporal Frequency ◽  
Atmospheric Correction ◽  
Time Of Day ◽  
Coefficient Of Determination ◽  
Near Infrared Reflectance ◽  
Bidirectional Reflectance

Himawari-8/AHI is a new geostationary sensor that can observe the land surface with high temporal frequency. Bidirectional reflectance derived by the Advanced Himawari Imager (AHI) includes information regarding land surface properties such as albedo, vegetation condition, and forest structure. This information can be extracted by modeling bidirectional reflectance using a bidirectional reflectance distribution function (BRDF). In this study, a kernel-driven BRDF model was applied to the red and near infrared reflectance observed over 8 hours during daytime to express intraday changes in reflectance. We compared the goodness of fit for six combinations of model kernels. The Ross-Thin and Ross-Thick kernels were selected as the best volume kernels for the red and near infrared bands, respectively. For the geometric kernel, the Li-sparse-Reciprocal and Li-Dense kernels displayed similar goodness of fit. The coefficient of determination and regression residuals showed a strong dependency on the azimuth angle of land surface slopes and the time of day that observations were made. Atmospheric correction and model adjustment of the terrain were the main issues encountered. These results will help to improve the BRDF model and to extract surface properties from bidirectional reflectance.

scholarly journals Intraurban Temperature Variability in Baltimore

2017 ◽  
Vol 56 (1) ◽  
pp. 159-171 ◽  
Author(s):  
Anna A. Scott ◽  
Ben Zaitchik ◽  
Darryn W. Waugh ◽  
Katie O’Meara
Keyword(s):  
Surface Properties ◽  
Land Surface ◽  
Low Cost ◽  
Canopy Cover ◽  
Tree Canopy ◽  
Temperate Climate ◽  
Weather Station ◽  
Underserved Area ◽  
Air Temperatures ◽  
Tree Canopy Cover

AbstractHow much does minimum daily air temperature vary within neighborhoods exhibiting high land surface temperature (LST), and does this variability affect agreement with the nearest weather station? To answer these questions, a low-cost sensor network of 135 “iButton” thermometers was deployed for summer 2015 in Baltimore, Maryland (a midsized American city with a temperate climate), focusing on an underserved area that exhibits high LST from satellite imagery. The sensors were evaluated against commercial and NOAA/NWS stations and showed good agreement for daily minimum temperatures. Variability within the study site was small: mean minimum daily temperatures have a spatial standard deviation of 0.9°C, much smaller than the same measure for satellite-derived LST. The sensor-measured temperatures agree well with the NWS weather station in downtown Baltimore, with a mean difference for all measurements in time and space of 0.00°C; this agreement with the station is not found to be correlated with any meteorological variables with the exception of radiation. Surface properties are found to be important in determining spatial variability: vegetated or green spaces are observed to be 0.5°C cooler than areas dominated by impervious surfaces, and the presence of green space is found to be a more significant predictor of temperature than surface properties such as elevation. Other surface properties—albedo, tree-canopy cover, and distance to the nearest park—are not found to correlate significantly with air temperatures.

scholarly journals Pasture degradation modifies the water and carbon cycles of the Tibetan highlands

2014 ◽  
Vol 11 (6) ◽  
pp. 8861-8923 ◽  
Author(s):  
W. Babel ◽  
T. Biermann ◽  
H. Coners ◽  
E. Falge ◽  
E. Seeber ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Surface Properties ◽  
Land Surface ◽  
Carbon Allocation ◽  
Carbon Sink ◽  
Plant Cover ◽  
The Tibetan Plateau ◽  
Onset Of Convection ◽  
Pasture Degradation ◽  
Kobresia Pygmaea

Abstract. The Tibetan Plateau has a significant role with regard to atmospheric circulation and the monsoon in particular. Changes between a closed plant cover and open bare soil are one of the striking effects of land use degradation observed with unsustainable range management or climate change, but experiments coupling changes of surface properties and processes with atmospheric feedbacks are rare and have not been undertaken in the world's two largest alpine ecosystems, the alpine steppe and the Kobresia pygmaea pastures of the Tibetan plateau. We coupled measurements of micro-lysimeter, chamber, 13C labeling, and eddy-covariance and combined the observations with land surface and atmospheric models, adapted to the highland conditions. This allowed us to analyze how three degradation stages affect the water and carbon cycle of pastures on the landscape scale within the core region of the Kobresia pygmaea ecosystem. The study revealed that increasing degradation of the Kobresia turf affects carbon allocation and strongly reduces the carbon uptake, compromising the function of Kobresia pastures as a carbon sink. Pasture degradation leads to a shift from transpiration to evaporation while the total sum of evapotranspiration remains unaffected. The results show an earlier onset of convection and cloud generation, likely triggered by enhanced evaporation. Consequently, precipitation starts earlier and clouds decrease the incoming solar radiation. In summary, the changes in surface properties by pasture degradation found on the highland have a~significant influence on larger scales.

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