Mauna Loa Observatory, Hawaii Boundary Layer Observations

Abstract:

The NOAA Mauna Loa Observatory is an atmospheric monitoring station on the North side of Mauna Loa Volcano (4169 m summit) located at an altitude of 3396 m. The bright sun, dark lava surface, and the seven percent grade of the mountain create a surface radiation wind that changes from upslope in the daytime to downslope after sunset. The radiation wind has a magnitude of 2.5-3.0 m/s. The off-island wind interacts with the mountain to create a barrier wind. The radiation wind dominates when the off-island winds are low and opposite is true when the off-island winds are strong. Temperature inversions form at sunset in the first 50 meters above the ground. Aerosol profiles, measured with a unique technique called CLidar or camera lidar, often increase and show a peak between 60 and 160 meters. The aerosol generally decreases to upper tropospheric values with a distinct change in the rate of decrease at 600 m above the ground. At night the region between the aerosol peak and 600 m is often flowing upslope, counter to the downslope surface flow. The source of the air in this counter flow region is not well understood, but appears to come from levels below the station altitude at least occasionally. This possibly would impact the interpretation of some of the air samples taken during this period.