Near-surface profiles of aerosol number concentration and temperature over the Arctic Ocean

Abstract. Temperature and particle number concentration profiles were measured at small height intervals above open and frozen leads and snow surfaces in the central Arctic. The device used was a gradient pole designed to investigate potential particle sources over the central Arctic Ocean. The collected data were fitted according to basic logarithmic flux-profile relationships to calculate the sensible heat flux and particle deposition velocity. Independent measurements by the eddy covariance technique were conducted at the same location. General agreement was observed between the two methods when logarithmic profiles could be fitted to the gradient pole data. In general, snow surfaces behaved as weak particle sinks with a maximum deposition velocity v_d = 1.3 mm s⁻¹ measured with the gradient pole. The lead surface behaved as a weak particle source before freeze-up with an upward flux F_c = 5.7 × 10⁴ particles m⁻² s⁻¹, and as a relatively strong heat source after freeze-up, with an upward maximum sensible heat flux H = 13.1 W m⁻². Over the frozen lead, however, we were unable to resolve any significant aerosol profiles.