Continuous Daily Observation of the Marine Atmospheric Boundary Layer over the Kuroshio by a Helicopter Shuttle Service

Abstract

This paper describes a new initiative in which in situ observations of the marine atmospheric boundary layer (MABL) are made by a helicopter shuttle connecting six islands south of Tokyo. This observation method aims to make frequent measurements of temperature and moisture in the MABL across an ocean front, where direct measurements of the MABL have been limited. An onboard observation system to meet flight regulations was developed. Observed temperature and moisture as a function of pressure at 1-s intervals provided vertical profiles up to the 900-hPa level above each of the islands, from 24 December 2010 to 6 April 2011, with the exception of an accidental power down in mid-February 2011. The observed values are validated by intercomparison with surface measurements from weather stations, atmospheric soundings, and mesoscale weather analysis provided by the Japan Meteorological Agency. Temperature and moisture values obtained using the system described here at the surface are significantly correlated with those from the weather station. The meridional changes revealed by the observed vertical profiles depict rich MABL structures, such as a cold-air intrusion and a strong near-surface inversion, that are not captured by the mesoscale weather analysis. However, this discrepancy is probably due to insufficient treatment in the mesoscale numerical model rather than observational errors. Additional intercomparisons indicate no influence from either artificial mixing by the helicopter rotor or by dynamic pressure caused by the fastmoving helicopter when obtaining the vertical profiles. Following these validations, the continuation of the initiative will allow for examining the influence of the ocean front on the overlying MABL on a synoptic time scale.

A Correction Method for UAV Helicopter Airborne Temperature and Humidity Sensor

“…However, the vertical resolution of the temperature and humidity profiles retrieved form satellite data is more than 1 km [12,13] so that the satellite profiles are not able to capture local and subtle structure which is crucial for high precision numerical prediction. Several researches have been implemented to obtain these high precision profiles, such as shipboard atmospheric soundings [14][15][16][17] and airborne measurements [18][19][20]. But, airborne and shipborne measurements cost much, and they cannot reach the specific zone where the oceanographic phenomena are both difficult to be seized and of great importance.…”

Detecting the structure of marine atmospheric boundary layer over the Northern South China Sea by shipboard GPS sondes

“…Atmospheric soundings are one of the most effective ways to observe the vertical structure of the atmosphere, including the vertical heating/moisture profiles and the features of mixing layer or inversion layer which are essential to the development of convective systems (Liu and Ding, ; Rappenglück et al , ; Tanimoto et al , ). Over ocean, although more difficult and expensive in deployment, atmospheric soundings can be still a feasible way to detect the vertical structure of MABL (Sweet et al , ; Hashizume et al , ; Tokinaga et al , ; Yu et al , ).…”