Reliable methods to estimate local sensible and la- tent heat flux at a point using micro-meteorological or turbulence data are available (e.g., Brutsaert. 1982).
Journal of the MeteorologicalSociety of Japan, Vol. 78, No. 6, pp. 719-730, 2000
Observations
of Neutral Above
Profiles
of Wind
a Gently
Rolling
By Jun Terrestrial Environment
and
Specific
Humidity
Landsurface
Asanuma
Research Center, University of Tsukuba, Tsukuba, Japan Nelson
SIMEPAR-Parana
Speed
719
L. Dias
Meteorological System, Centeo Politecnico da UFPR, PR Brazil William
P. Kustas
Hydrology Laboratory, Agricultural Research Service, US Department of Agriculture, Maryland, USA and Wilfried
Brutsaert)
School of Civil and Environmental Engineering, Cornell University, New York, USA (Manuscript
received 4 June 1999, in revised form 28 July 2000) 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.(>-0.0059 0.28+(-)0.75 0.28+(0.0059-0)0.75
where (0-z0/L. For strictly neutral conditions, 1m (=0 is required in (2), which is simultaneously equivalent to L=0 with Hv=0 or u*=oc. As mentioned, such strictly neutral conditions occur very rarely in the real atmosphere. Rather, for practical purposes, it is usually permissible to take a certain range of L as "practically neutral", where L is large enough so that the stability correction term, Wm(1), is negligibly small compared to the logarithmic term, In ((z-d0) /z0) in (2). If the permissible error caused by taking a profile as neutral is defined as In z
profiles.
Vol. 78, No. 6
the
north
in degrees.
Table
2. Criteria
over
the
of atmospheric
lowest
neutrality.
50m.
for -0.0059>C>-15.025 for (
