Area-Averaged Sensible Heat Flux and a New Method to Determine Zero-Plane Displacement Length over an Urban Surface using Scintillometry

Manabu Kanda, Ryo Moriwaki, Matthias Roth & Tim Oke

Boundary-Layer Meteorology, 105 (1): 177-193, October 2002

Abstract

Field observations of area-averaged turbulence characteristics were conducted in a densely built-up residential neighbourhood in Tokyo, Japan. In addition to eddy-correlation (EC) sensors a scintillometer was used for the first time in a city. Significant results include: (1) Scintillometer-derived sensible heat fluxes, Q_H, obtained at a height 3.5 times the building height agree well with those using the EC technique; (2) source areas for the scintillometer fluxes are larger than for the EC sensors, so that at low heights over inhomogeneous terrain scintillometry offers advantages; (3) new similarity relationships for dissipation rates are proposed for urban areas; (4) a new technique that uses simultaneous scintillation measurements at two heights to directly estimate area-averaged zero-plane displacement height, z_d, is proposed. z_d estimated in this way depends slightly on atmospheric stability (lower z_d under more unstable conditions).