Study on the surface energy balance and development ofatmospheric boundary layer over the Shouxian region, China
Tetsuya HIYAMA1, Hiroki TANAKA1, Koh YAMAMOTO2,Atsushi HIGUCHI3, Taro SHINODA1, Hatsuki FUJINAMI1,Shoichiro IKEDA4, Satoshi ENDO2,Nakako KOBAYASHI2, Kenichi IKEDA2,and Kenji NAKAMURA1
1: Hydrospheric Atmospheric Research Center (HyARC), Nagoya University, Japan
2: Graduate School of Environmental Studies, Nagoya University, Japan
3: Center for Environmental Remote Sensing (CEReS), Chiba University, Japan
4: Graduate School of Natural Science and Technology, Okayama University, JapanTel: +81-52-789-3478,

Fax: +81-52-789-3436

E-mail: hiyama@hyarc.nagoya-u.ac.jp

Abstract
As one of the research topics on the LAPS project, we firstly focused on thesurface energy balance over the Shouxian area, using data obtained in the intensive
observation period (IOP) of 2004. Then we revealed diurnal and seasonal variations inthe interaction between the surface energy balance and the atmospheric boundary layer(ABL) development processes. In 2004, IOP at Shouxian was conducted from May 24
to Jul 16, 2004. The surface energy balance was evaluated from the measurements ofsurface shortwave & longwave radiation balances, and those of turbulent heat fluxes
and heat storage rates of air and water body. ABL developments were individuallyobserved using a 1290 MHz Wind Profiler Radar (WPR; type L-28) produced by the
Sumitomo Electric Industries, Japan. The surface atmospheric condition was relatively
dry in the beginning of IOP and changed to humid in the middle of June. The land coveralso changed from wheat, bare soil, and to rice paddy fields, simultaneously with theatmospheric conditions.
The analyses of surface energy balance revealed that the turbulent heat fluxes
obtained at 30-m high (middle part of the surface layer) were representative of theregional surface energy balance. Then we estimated diurnal change of ABL (or mixedlayer; hereafter ML) and its height (zi, cal) using a "slab-type ML model" with theobserved surface buoyancy (sum of the sensible and latent heat) fluxes. On the contrary,we determined ABL (or more exactly ML) height (zi, obs) using vertical profile ofreflectivity, which was obtained from the WPR. The ML heights (zi, cal) derived from the"slab-type ML model" were compared with those (zi, obs) obtained from the reflectivity
using the WPR.
Consequently, we derived important two results from the analyses.
1) The estimated ML heights (zi, cal) with roughly determined buoyancy fluxes included
significant error (as shown in Fig. 1a). Thus, for the application of "slab-type MLmodel", we should carefully evaluate surface energy balance from precise
measurements.
2) Even if the surface energy balance was achieved (i.e., when the determined value ofbuoyancy flux was excellent and regionally represented value), zi, cal did not always
correspond with observed ML height (zi, obs). In this case, previous day's residual
layer and/or synoptic subsidence affected for the ML height (as shown in Fig. 1b).
b)

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Figure 1 Diurnal changes in the WPR observed ML heights (zi, obs; line with closed circles) and estimated MLheights (zi, cal; line with vertical bars) using a "slab-type ML model". The vertical bars attached for the zi, cal indicate
the possible ML height range changing with the entrainment parameters (from 0.1 to 0.4) of the slab-type ML model.
Left figure (a) was obtained in 20 June 2004, when the hourly surface energy balances were almost failed. Right
figure (b) was in 28 June 2004, when the surface energy balance was excellent but with significant atmosphericsubsidence.