Observations of cold air pooling in a narrow mountain valley

The evolution of vertical temperature and winds in a narrow valley in the Diablo Range of California was observed during two short field campaigns conducted as part of a field course at San José State University. Measurements were made with an array of instrumentation that included radiosonde, sodar, and micrometeorological towers. The instruments were deployed along a cross section of the valley. Observations from HOBO temperature data loggers placed in the cross-section showed that a cold pool developed in the valley with a temperature gradient of 0.1 K m-1. The vertical profile of the wind obtained from the Sodar indicated decoupling of regional winds from the surface during the cold pool buildup. Turbulence kinetic energy on the valley floor varied from 1 to 1.5 m2 s-2 during the day and decreased to 0.1 to 0.25 m2 s-2 during the nighttime. This presentation will discuss the observations made during two nights and will present cooling rates and inversion destruction for each case.