Abstract 203

Abstract ID: 203

Quantifying direct aerosol effect on subseasonal prediction: climatology versus interactive aerosols in the UFS model

Lead Author: Shan Sun
NOAA Global Systems Laboratory, United States of America

Keywords: Aerosol-radiation interaction, Subseasonal prediction, Unified Forecast System

Abstract: We investigate the aerosol direct and semi-direct effect on subseasonal prediction using NOAA’s fully coupled Unified Forecast System (UFS) model, which includes the atmospheric model FV3 with the Global Forecast System (GFS) physics package V17, MOM6 ocean model, WW3 wave model and CICE6 sea ice model. Three sets of experiments are carried out: (i) UFS with prescribed aerosol climatology from MERRA2, (ii) UFS coupled to interactive aerosols from the GOCART aerosol module, (iii) UFS without aerosols. All experiments are deterministic 32-day hindcasts with monthly initialization over multiple years.

The modeled aerosol optical depth (AOD) in the two experiments considering aerosols is in good agreement with the MODIS satellite observations. The AOD from the experiments with interactive aerosols captured the interannual variability seen in the observations. The estimated radiative forcings from the aerosol radiation interaction in these two sets of experiments are both negative in the order of a few W/m2 compared to the one without aerosols, on the multi-year average. The advantage of interactive aerosols can be seen clearly in the simulated radiative forcing during the extreme events of dust storms and biomass burning. Changes in cloud and precipitation are small between the two sets of experiments with aerosols.

Gregory Frost (NOAA CSL), Georg Grell (NOAA GSL), Li Zhang (CRES, Univ. of Colorado & NOAA GSL), Barry Baker (NOAA ARL), Jessica Meixner (NOAA NCEP EMC), Fanglin Yang (NOAA NCEP EMC), Anning Cheng (Lynker at NOAA NCEP EMC), Lydia Stefanova (Lynker at NOAA NCEP EMC), and Jiande Wang (Lynker at NOAA NCEP EMC)