Micropulse lidar observations of aerosols over the atmospheric radiation measurement site at Barrow

Abstract

Micropulse lidar (MPL) is a ground-based optical remote sensing system designed to determine the vertical structure of clouds and aerosols in the atmosphere. An MPL has operated at Barrow, Alaska since November 2002. From these data, we seek to determine the altitude of aerosol layers in the free troposphere from lidar backscatter profiles. Layer heights are then fed into the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory Model) model, a back-trajectory model developed by NOAA (National Oceanic and Atmospheric Administration) to compute isentropic back-trajectories. The model is run interactively using the READY interface and can calculate trajectories from multiple heights within a layer. Case analyses are done correlating dates and trajectory coordinates, synoptic weather charts and events reported from satellites and other remote sensing instruments to determine aerosol sources (e.g. forest fire, volcano eruption or dust storm). All the aerosol events detected by the MPL were categorized into five common atmospheric flow patterns identified from the NCEP (National Centers for Environmental Prediction) / NCAR (National Center for Atmospheric Research) reanalysis charts. We conclude that most of the MPL-identified free-tropospheric aerosol layers could be attributed to Siberian/Alaskan forest fires and Asian dust storms.