Global estimates of 500 m daily aerodynamic roughness length from MODIS data

2022 ◽  
Vol 183 ◽  
pp. 336-351
Author(s):  
Zhong Peng ◽  
Ronglin Tang ◽  
Yazhen Jiang ◽  
Meng Liu ◽  
Zhao-Liang Li
Keyword(s):  
Roughness Length ◽  
Aerodynamic Roughness Length ◽  
Modis Data ◽  
Global Estimates ◽  
Aerodynamic Roughness

scholarly journals Comparison of satellite microwave backscattering (ASCAT) and visible/near-infrared reflectances (PARASOL) for the estimation of aeolian aerodynamic roughness length in arid and semi-arid regions

2012 ◽  
Vol 5 (2) ◽  
pp. 2933-2957
Author(s):  
C. Prigent ◽  
C. Jiménez ◽  
J. Catherinot
Keyword(s):  
Arid Regions ◽  
Near Infrared ◽  
Roughness Length ◽  
Aerodynamic Roughness Length ◽  
Sources Of Information ◽  
Transport Models ◽  
Dust Transport ◽  
Infrared Observations ◽  
Aerodynamic Roughness ◽  
Semi Arid

Abstract. Previous studies examined the possibility to estimate the aeolian aerodynamic roughness length from satellites, either from visible/near-infrared observations or from microwave backscattering measurements. Here we compare the potential of the two approaches and propose to merge the two sources of information to benefit from their complementary aspects, i.e. the high spatial resolution of the visible/near-infrared (PARASOL part of the A-Train) and the independence from atmospheric contamination of the active microwaves (ASCAT on board MetOp). A global map of the aeolian aerodynamic roughness length at 6 km resolution is derived, for arid and semi-arid regions. It shows very good consistency with the existing information on the properties of these surfaces. The dataset is available to the community, for use in atmospheric dust transport models.

scholarly journals Aerodynamic roughness length estimation from very high-resolution imaging LIDAR observations over the Heihe basin in China

2010 ◽  
Vol 14 (12) ◽  
pp. 2661-2669 ◽  
Author(s):  
J. Colin ◽  
R. Faivre
Keyword(s):  
Remote Sensing ◽  
Surface Roughness ◽  
Land Cover ◽  
River Basin ◽  
Land Surface ◽  
Surface Density ◽  
Roughness Length ◽  
Aerodynamic Roughness Length ◽  
Passive Remote Sensing ◽  
Aerodynamic Roughness

Abstract. Roughness length of land surfaces is an essential variable for the parameterisation of momentum and heat exchanges. The growing interest in the estimation of the surface turbulent flux parameterisation from passive remote sensing leads to an increasing development of models, and the common use of simple semi-empirical formulations to estimate surface roughness. Over complex surface land cover, these approaches would benefit from the combined use of passive remote sensing and land surface structure measurements from Light Detection And Ranging (LIDAR) techniques. Following early studies based on LIDAR profile data, this paper explores the use of imaging LIDAR measurements for the estimation of the aerodynamic roughness length over a heterogeneous landscape of the Heihe river basin, a typical inland river basin in the northwest of China. The point cloud obtained from multiple flight passes over an irrigated farmland area were used to separate the land surface topography and the vegetation canopy into a Digital Elevation Model (DEM) and a Digital Surface Model (DSM) respectively. These two models were then incorporated in two approaches: (i) a strictly geometrical approach based on the calculation of the plan surface density and the frontal surface density to derive a geometrical surface roughness; (ii) a more aerodynamic approach where both the DEM and DSM are introduced in a Computational Fluid Dynamics model (CFD). The inversion of the resulting 3-D wind field leads to a fine representation of the aerodynamic surface roughness. Examples of the use of these three approaches are presented for various wind directions together with a cross-comparison of results on heterogeneous land cover and complex roughness element structures.

Field studies of aerodynamic roughness length

1993 ◽  
Vol 25 (1) ◽  
pp. 39-48 ◽  
Author(s):  
D.G. Blumberg ◽  
R. Greeley
Keyword(s):  
Roughness Length ◽  
Field Studies ◽  
Aerodynamic Roughness Length ◽  
Aerodynamic Roughness

Field And Wind-Tunnel Studies Of Aerodynamic Roughness Length

2002 ◽  
Vol 104 (1) ◽  
pp. 151-163 ◽  
Author(s):  
Xue Xian ◽  
Wang Tao ◽  
Sun Qingwei ◽  
Zhang Weimin
Keyword(s):  
Wind Tunnel ◽  
Roughness Length ◽  
Aerodynamic Roughness Length ◽  
Aerodynamic Roughness

scholarly journals Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping

2021 ◽  
Author(s):  
Armin Dachauer ◽  
Richard Hann ◽  
Andrew J. Hodson
Keyword(s):  
Wind Direction ◽  
Roughness Length ◽  
Flow Direction ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Aerodynamic Roughness Length ◽  
Tidewater Glaciers ◽  
Ice Melt ◽  
Order Of Magnitude ◽  
Aerodynamic Roughness

Abstract. The aerodynamic roughness length (z0) is an important parameter in the bulk approach for calculating turbulent fluxes and their contribution to ice melt. However, for heavily crevassed tidewater glaciers z0 estimations are rare or only generalized. This study used unmanned aerial vehicles (UAVs) to map inaccessible tidewater glacier front areas. The high-resolution images were used in a structure-from-motion photogrammetry approach to build digital elevation models (DEMs). These DEMs were applied to five different models (split across transect and raster methods) to estimate z0 values of the mapped area. The results point out that the range of z0 values across a glacier is large, with up to three (locally even four) orders of magnitude. The division of the mapped area into sub-grids (50 m x 50 m), each producing one z0 value, best accounts for the high spatial variability of z0 across the glacier. The z0 estimations from the transect method are in general higher (up to one order of magnitude) than the raster method estimations. Furthermore, wind direction (values parallel to the ice flow direction are larger than perpendicular) and the chosen sub-grid size turned out to have a large impact on the z0 values, again presenting a range of up to one order of magnitude each. On average, z0 values between 0.08 m and 0.88 m for a down-glacier wind direction were found. The UAV approach proved to be an ideal tool to provide distributed z0 estimations of crevassed glaciers, which can be incorporated by models to improve the prediction of turbulent heat fluxes and ice melt rates.

Experimental Investigation of the Aerodynamic Roughness Length for Flexible Plants

2019 ◽  
Vol 172 (3) ◽  
pp. 397-416 ◽  
Author(s):  
Liqiang Kang ◽  
Junjie Zhang ◽  
Xueyong Zou ◽  
Hong Cheng ◽  
Chunlai Zhang ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Roughness Length ◽  
Aerodynamic Roughness Length ◽  
Aerodynamic Roughness
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