A Study of Thermal Wind in the Vicinity of a Jet Stream

[摘要]  Wind and temperature data from a specially instrumented B-29 aircraft, operating near 400 and 300 mb, are used to test the thermal wind equation in the vicinity of a middle-latitude jet stream. Analyses of the data at the two levels are presented with respect to both the small and large-scale distribution of wind and temperature. The geostrophic wind shear between the two levels is calculated for horizonal temperature gradient computed over varying distances, and these are compared with the vertical shear obtained from aircraft-measured winds at the mid-point of each interval over which the temperature gradient is measured. The flow patterns at the two levels are considered in determining the ageostrophic components of the wind due to curved flow, and these corrections are applied in the final comparisons of calculated and aircraft-measured shear. A method using averaged winds at the lower level of the layer suggests that this may be a more representative reference than “spot winds” for approximating the wind above when using the thermal wind relation.

[学科分类] 大气科学