The Three-Dimensional Structure of Transatlantic African Dust Transport: A New Perspective from CALIPSO LIDAR Measurements

Dong Liu,Jun Zhou,Yingjian Wang,Zhien Wang

doi:10.1155/2012/850704

Abstract

The lack of information on the vertical distribution of dust, in turn, results in large uncertainties when attempting to evaluate the impacts of dust on climate processes. We analyzed over two years of LIDAR measurements from NASA’s CALIPSO and CloudSat satellites to document the vertical pathways of transatlantic transport of Saharan dust. Our analysis overcomes the limitations of quantitative dust detections with passive satellite measurements over land and low clouds and provides the fine vertical resolved structures. The results show the strong seasonal shift in dust source regions and transportation pathways due to the meteorological and thermodynamical conditions, which also control the dust vertical distribution as well as the depth of the dust layer. The dust layer top descending rates of 35 m/degree in summer, 25 m/degree in autumn and spring, and 10 m/degree in winter are found, respectively, while the dust is being transported across the Atlantic. Comparison with the model simulation highlights the potentials of dust observations using CALIPSO LIDAR. The observed seasonal dependence of these pathways gives new insights into the transport of the Saharan dust and provides important guidance for simulations of the production and transport of the global dust aerosol.

Highlights

Mineral dust is mainly generated from the continents and can be transported both horizontally and vertically into the atmosphere and affect vast area on the earth
Mineral dust plays an important role in the climate system processes by affecting radiation, modifying cloud and precipitation processes, and modulating a variety of marine biogeochemical processes
To overcome the limitations of quantitative dust detections with passive satellite measurements over the land and low clouds, we use multiyear combined CALIPSO and CloudSat data to show three-dimensional dust distributions over the source regions and their transport pathways across the Atlantic

Summary

Introduction

Mineral dust is mainly generated from the continents and can be transported both horizontally and vertically into the atmosphere and affect vast area on the earth. Our limited understanding results from the inherent inability of passive sensors to provide vertically resolved measurements over large scales. Distribution of dust, in turn, results in large uncertainties when attempting to evaluate the impacts of dust on climate processes [1, 4]. Multiyear polarization LIDAR measurements from CALIPSO satellite provide new insights into the vertical distribution of dust on a global scale [14, 21]. An approach was developed to provide vertical extinction and mass mixing ratio distribution based on CALIPSO LIDAR measurements. With these data we show a 3D view of across Atlantic dust transport and discuss their associations with largescale dynamics.

Dataset and Methodology

Results and Discussions

Summary