The nocturnal boundary layer during the passage of a mesoscale fog front

✍ Scribed by K. -P. Wittich

• Publisher: Springer
• Year: 1990
• Tongue: English
• Weight: 980 KB
• Volume: 51
• Category: Article
• ISSN: 0006-8314
• DOI: 10.1007/bf00119674

✦ Synopsis

The structure of the nocturnal boundary layer affected by an advected fog mass is investigated. For this, measurements of the horizontal wind vector, the temperature, relative humidity and horizontal visibility performed on a radio mast 300 m high are used together with a monostatic SODAR recording.

The shape of the cold fog mass, which roughly resembles that of a density current, is described by the shallow water equations in a first approximation. Ahead of the leading edge of the fog mass, a stream function analysis suggests an upward flow component. In addition, a local circulation pattern exists at the density interface. After the fog front has passed the measuring site, the boundary-layer flow becomes more turbulent and, from the hydrodynamical point of view, critical. In agreement with this, the friction velocity inside the growing fog mass increases with time, as shown by a simple integral method.