Volume 16, No. 3, March 2016, Pages 729-737 PDF(1.53 MB)
Boundary Layer Characteristics over a High Altitude Station, Mauna Loa Observatory
Nimmi C.P. Sharma1, John E. Barnes2
1 Department of Physics and Engineering Physics, Central Connecticut State University, New Britain, CT, USA
2 NOAA/Mauna Loa Observatory, Hilo, Hawaii, USA
- The unique boundary layer at Mauna Loa Observatory (3400 m) is examined.
- A radiation wind flows upslope during the daytime and downslope during the nighttime.
- The CLidar aerosol profiling method, finds three distinct zones above the observatory.
- After sunset, a counter flow region forms above the downslope surface flow.
- A transition at 4000 m caps a less convectively stable region with a more stable one.
The unique boundary layer at Mauna Loa Observatory (3396 meters) is examined with a combination of radiosondes launched from the observatory and a novel aerosol profiling technique called CLidar or camera lidar. This boundary layer is influenced by a combination of radiation winds, due to the heating and cooling of the surrounding lava, and off-island winds. Typically an upslope surface wind forms after sunrise as the ground heats up. The reverse occurs after sunset as the ground cools and a temperature inversion, tens of meters thick forms. Aerosol increases for the first 90 to 160 meters and then decreases to free tropospheric levels. The 90 to 160 m aerosol peak indicates the vicinity of the upslope/downslope interface in the air flow. An upper transition is seen in the aerosol gradient at about 600 meters above the observatory (4000 m Above Sea Level). This transition is also seen in radiosonde potential temperature data. The sondes indicate that the air above the nighttime downslope surface region usually has an upslope component. Some of this counter-flowing air can be entrained in the downslope air, possibly influencing the sampling of aerosols and trace gases at the observatory.
Boundary layer; Aerosol; Lidar; CLidar; High altitude station.