AOSC Seminar
October 26, 2017

IMPROVING CONSTRAINTS ON AEROSOLS IN THE UNITED STATES USING GROUND BASED OBSERVATIONS, SATELLITE RETRIEVALS, RADAR, AND A CHEMICAL TRANSPORT MODEL


Aishwarya Raman
ESSIC, UMD
Abstract:  

Knowledge of emissions and distributions of aerosols are critical for Earth’s radiative budget, air quality, human health, and precipitation. However, the lack of sufficient direct measurements of aerosol composition and other limitations of current polar orbiting satellites elevate the complexities involved in predictive capability for aerosols. To this end, this talk will focus oncurrent capabilities for: 1) dust storm monitoring in the southwest, 2) improving constraints on black carbon (BC) aerosol by indirectly augmenting the observing system of BC using Carbon monoxide (CO) and Nitrogen oxides (NOX). For dust monitoring, we use aerosol retrievals from MODIS, CALIPSO, and OMI UVAI in combination with a coupled community weather chemistry model (WRF-Chem) and radar reflectivities to understand how convective dust storms affect the long term variability of aerosols in the North American Monsoon (NAM) region. We model the dust pathways and regional air quality impacts of haboobs in Arizona using convective scale WRF-Chem simulations and we show here results from a prototype framework for the July 5, 2011 haboob. Our results clearly point to the future need for high resolution, dynamic dust source datasets and synergistic use of aerosol retrievals from multiple satellites to improve dust source detection and model simulations of haboobs. To improve aerosol forecasts, we also use a probabilistic framework called ‘ANalog Ensemble approach (AnEn)’ to determine probabilistic distributions of Aerosol Optical Depth (AOD) using historical model simulations and MODIS L2 AOD retrievals. We find that the AnEn approach is more computationally efficient than conventional ensemble simulations. The analog estimates show promise in capturing the mean variability of AOD and show implications for improving real time PM2.5 forecasting using satellite retrievals. For BC, the issue of monitoring is further complicated by the complex nature of physical and chemical properties of BC. In order to augment the constraints on BC observation system, we use ‘local’ variations of BC/CO and BC/NOX ratios. We also demonstrate the utility of these ratios in evaluating the emission inventories by comparing these estimates with global and National Emission Inventory (NEI). The ratio based approach to understand the characteristics of aerosols is also explored using the satellite retrievals of AOD, CO, and NOXand preliminary results from this study will also be shown. Looking forward, we anticipate more challenges in monitoring aerosols due to climate change and increasing fuel consumptiondemands. This calls for a commitment in developing sufficient scientific constraints in improving observational coverage and predictive capability for these aerosols.