The Temporal Evolution and Spatial Structure of the Local Easterly Wind “Kiyokawa-dashi” in Japan PART II: Numerical Simulations

Abstract

A numerical simulation of the strong southeasterly (SE) ''Kiyokawa-dashi'' wind in Yamagata, Japan on August 30, 2004, is examined and compared to the Coherent Doppler Lidar (CDL) observation. Three-dimensional numerical simulations were performed using a non-hydrostatic meso-scale model developed by the Japan Meteorological Agency. The sensitivity of the numerical simulation was examined with respect to the resolution of the horizontal and vertical grid, surface roughness, and ground surface temperature. For the case of a 1-km grid with 85 vertical layers including realistic surface settings, the observed characteristics of Kiyokawa-dashi were well reproduced: the strong SE wind (10 m s À1 ) was extremely low, about 0.1-0.5 km AGL, and the maximum wind Strong winds appeared at the foot of the final lee slope facing the Shonai Plain and 1 km south of the valley; this result was in good agreement with the CDL observation. On the basis of the stream line analysis, Kiyokawa-dashi was strongly affected by the upper SE wind, i.e., upper air on the eastern side of the mountains blew down to the middle and lower layer on the western side. The strongest wind field located 1 km south of the valley was a¤ected by the mountain at the southwestern end of the valley. It was observed from the sensitivity experiments that the height of the jet-like flow was found to be closely related to the low-level stable layer, and the critical layer was not very important in reinforcing the low-level SE wind. This case of Kiyokawa-dashi was explained on the basis of the hydraulic theory.

A Climatological Study of the Local “Karakkaze” Wind, with a Focus on Temperature Change

“…The islands are thus in an environment that favors the development of strong winds caused by terrain, and many local winds occur in Japan (Yoshino 1975;Kusaka and Fudeyasu 2017). Well-known examples of such local winds include the Karakkaze (Yoshino 1975(Yoshino , 1978Kusaka et al 2011), Matsubori-kaze (Yoshino 1975;Kurose et al 2002), Hirodo-kaze (Yoshino 1975;Fudeyasu et al 2008), Yamaji-kaze (Saito and Ikawa 1991;Saito 1993), and Kiyokawadashi (Yoshino 1975;Ishii et al 2007;Sasaki et al 2010).…”

Transient Downslope Winds under the Influence of Stationary Lee Waves from the Zao Mountain Range

“…Clark et al (1994) described the fine-scale structure of gusts using lidar and simulated windstorms using two-and three-dimensional models to examine impacts of three-dimensionality, surface friction, and horizontal resolution on windstorms. We have also studied the feasibility of a mobile Doppler lidar that was developed at the National Institute of Information and Communication Technology (NICT) for observing local circulation (Ishii et al 2007(Ishii et al , 2008Sasaki et al 2010). In this work, intensive observations were conducted to target the strong downslope winds of the Zao mountain range during the winter monsoon season with a lidar system that was installed at the western corner of Sendai Airport.…”