LABLE

Lower Atmospheric Boundary Layer Experiment

17 September 2012 - 13 November 2012

Lead Scientist: David Turner

Observatory: SGP

Boundary layer turbulence is an important process that is parameterized in most atmospheric numerical models. Turbulence redistributes energy and mass within the boundary layer. Many different characteristics can impact the character of turbulence in the boundary layer, including different surface types, horizontal wind speed and direction, and the vertical temperature structure of the atmosphere. However, there have been few studies that have investigated how the vertical turbulence profile changes over short horizontal distances. We will deploy 4 instruments at the SGP Central Facility to investigate how the turbulence profiles may change over short horizontal distances. This study will primarily be sensitive to the surface conditions upwind of these instruments, and thus should help to better characterize the SGP site in general. These four instruments include 2 Doppler wind lidars (one from Halo Photonic that is virtually identical to the one ARM has deployed, and one from Leosphere), a sodar, and a laser scintillometer. While the primary purpose of this experiment is to characterize how different the vertical turbulence profiles are at different locations at the SGP CF and how this may depend on wind direction and other variables, there are two other objectives to this experiment. The first is that, by deploying a Doppler lidar co-located with the Raman lidar, we will be able to derive water vapor fluxes at the top of the boundary layer. [It is believed that this cannot be done with the current ARM Doppler lidar because of the ~350 m separation between the two systems; however, this experiment will allow us to investigate this.] The second objective is to carefully compare vertical motions observed by multiple Doppler lidars (of different vendors), the 915 MHz profiler, and the sodar.