Observations of Neutral Profiles of Wind Speed and Specific Humidity Above a Gently Rolling Landsurface

Abstract

Analyses were made of wind speed and specific humidity profiles under neutral conditions obtained by radiosoundings over the gently rolling terrain of the Little Washita Basin, Oklahoma. Inspection of the wind speed profiles showed that the regional (scale of 1 to 10km) roughness of this basin was z0=0.45 f 0.21m, while the displacement height, do, was found to be 8.9m. The logarithmic layer of wind speed was observed to occupy the range, (38f43)z.<(z-d0)<(297+147)z0 or (0.15+0.10)h where hi is the height of the bottom of the capping inversion. This result is comparable with those of previous investigations for the lower limit of the range; however, this result also suggests that over this terrain hi is the relevant length scale for the upper limit. Evaporation values at the regional scale were computed by combining the wind speed profiles with the specific humidity profiles. Comparison with surface flux measurements at Bowen ratio ground stations supports the idea that profiles in the neutral atmospheric surface layer aloft at around 100m above the ground are conditioned by upwind surface characteristics at the meso-7 scale.

Measurements of Aerodynamic Roughness, Bowen Ratio, and Atmospheric Surface Layer Height by Eddy Covariance and Tethersonde Systems Simultaneously over a Heterogeneous Rice Paddy

“…1). The upper limit of the ISL, or the top of the ISL, over the PDA was close to those observed in a few nearby sites in the same basin (Tsai and Tsuang 2005) and lower than in other locations (Brutsaert and Sugita 1990;Parlange and Brutsaert 1990;Brutsaert and Parlange 1992;Parlange and Katul 1995;Asanuma et al 2000). Note that at about 100 m AGL (the lowest height of the rim of the basin), wind shear was commonly observed in the basin (Tsai and Tsuang 2005), which caused discontinuous vertical structures of the temperature, humidity, and wind vector profiles at the height.…”

Surface flux and atmospheric boundary layer observations from the LAPS project over the middle stream of the Huaihe River basin in China

“…Simultaneous observations of the WPR and the surface flux measurements have not yet been reported for the Asian monsoon region, although many individual surface or ABL observations have been recorded under the Global Energy and Water Cycle Experiment (GEWEX) Asian Monsoon Experiment (GAME) and GAME-related projects (e.g. Hiyama et al, 1999Hiyama et al, , 2003Ohta et al, 1999Ohta et al, , 2001Sugita et al, 1999;Asanuma et al, 2000;Reddy et al, 2001;Tanaka et al, 2001;Toda et al, 2002;Komatsu et al, 2003;Choi et al, 2004;Gao et al, 2004;Gao, 2005;Shinoda et al, 2005). The simultaneous observations reported here will fill this gap.…”

Flux‐gradient relationship of water vapor in the surface layer obtained from CASES‐99 experiment

“…For understanding water vapor flux in the surface layer, it is necessary to obtain the flux‐gradient relationship of water vapor Φ q . This relationship links the vertical gradient and flux of water vapor to atmospheric stability and has been used to obtain the vertical flux from a mean profile [ Beljaars , 1982; Asanuma et al , 2000; Gieske , 2003] and vice versa [ Gryning et al , 2007]. Numerical models for weather and climate also employ concepts of surface layer physics that involve the flux‐gradient relationship [ Garratt , 1993; Pielke , 2001].…”