PNNL

Abstract

This study investigates the seasonal variation of dust aerosol vertical distribution using polarized Micropulse lidar (MPL) measurements at the Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) observatory from January 2013 to September 2017. The reliable long-term MPL backscatter retrievals at the ARM NSA site are given in this study for the first time, which are compared with the co-located High Spectral Resolution Lidar (HSRL) measurements. The high-quality backscattering coefficient retrievals are used to derive the particle depolarization ratio (PDR) at the wavelength of 532 nm, which is used to identify the presence of dust aerosols. The seasonality of vertical profiles of dust backscatter coefficients and PDRs, and the seasonality of dust aerosol optical depth (DAOD) show that aerosol loading has a maximum in late winter and early spring but minimum in late summer and early autumn. For the vertical distributions, dust aerosol occurs in the entire troposphere in spring and winter and in the low and middle troposphere in summer and autumn. The seasonality of dust aerosols vertical distribution has important implication to the Arctic climate through the aerosol-cloud-radiation interactions, especially through mixed-phase cloud processes.