Mean Structure of the Nocturnal Drainage Flow in a Deep Valley

Abstract

Wind and temperature data collected by an instrumented tethered balloon and a Doppler lidar in a deep valley are used to investigate the mean properties of the nocturnal drainage flow down the valley on four nights when the wind at ridgetop had an up-valley component. We examine the vertical structure of temperature and the vertical and horizontal structure of the drainage wind. An empirical description of the wind field is derived and used to estimate the mass flux resulting from the drainage flow. Mean properties of the flow are presented and relationships among some of the parameters are examined.