Evaluating the impact of assimilating CALIOP-derived aerosol extinction profiles on a global mass transport model

Abstract

Coupled two/three‐dimensional variational (2D/3DVAR) assimilation of aerosol physical properties retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS), Multi‐angle Imaging Spectroradiometer (MISR) and Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite‐borne instruments is described for the U. S. Navy Aerosol Analysis and Prediction System (NAAPS) global aerosol mass transport model. Coupled 2D/3DVAR assimilation for NAAPS is evaluated for 48‐hr forecast cycles, computed four times daily in six‐hour intervals, versus stand‐alone 2DVAR assimilation of MODIS and MISR aerosol optical depths (AOD). Both systems are validated against AERONET ground‐based sun photometer measurements of AOD. Despite a narrow nadir viewing swath and more than 2700 km of equatorial separation between orbits, satellite lidar data assimilation elicits a positive model response. Improvements in analysis and forecast AOD absolute errors are found over both land and maritime AERONET sites. The primary impact to the model from 3DVAR assimilation is the redistribution of aerosol mass into the boundary layer, though the process is sensitive to parameterization of vertical error correlation lengths.

An improved method for retrieving nighttime aerosol optical thickness from the VIIRS Day/Night Band

“…In particular, studies have shown notable improvements in aerosol forecasting through the assimilation of satellite aerosol products, mostly from daytime observations (e.g., Zhang et al, 2008aZhang et al, , 2011Zhang et al, , 2014Yumimoto et al, 2008;Uno et al, 2008;Benedetti et al, 2009;Schutgens et al, 2010;Sekiyama et al, 2010). To capture the diurnal cycle, the aerosol modeling community requires nighttime satellite aerosol data hav-ing broad spatial coverage and high temporal resolution to further advance aerosol, visibility, and air quality forecasts (e.g., Zhang et al, 2011Zhang et al, , 2014.…”

Evaluating nighttime CALIOP 0.532 μm aerosol optical depth and extinction coefficient retrievals

“…Zhang et al (2011) report mean global 0.550 µm AOD error at 12-h relative to AERONET near 0.075. However, this considers only the sunlit sector of the model at 12-h, where validation data are available, but with no assimilation having occurred at initialisation.…”

“…The vertical profile for aerosol particle electro-optical scattering, in particular, is a unique and highly synergistic satellite measurement, since passive aerosol-focused remote sensors alone are limited at best in observing vertically resolved information with reasonably high resolution. CALIOP profiling has, thus, benefitted a number of aerosol research initiatives, including global particle transport studies (e.g., Uno et al, 2009), surface emission estimates and injection scenario characterisation (e.g., Bessagnet et al, 2008;Amiridis et al, 2010), pyrocumulonimbus plume identification and dispersion (Fromm et al, 2010), volcanic plume monitoring (e.g., Carn et al, 2009;Campbell et al, 2012a), coupled two/three-dimensional variational (2D/3DVAR) data assimilation for global mass transport forecasting (e.g., Campbell et al, 2010;Zhang et al, 2011), four-dimensional ensemble Kalman filter data assimilation (e.g., Sekiyama et al, 2010), and transport model validation (e.g., Uno et al, 2008;Yumimoto et al, 2008).…”

Preliminary investigations toward nighttime aerosol optical depth retrievals from the VIIRS Day/Night Band

“…Recent advances in aerosol climate studies (e.g., Kaufman et al, 2002;Zhang et al, 2005a, b) and aerosol and visibility forecasting (e.g., Zhang et al, 2008aZhang et al, , 2011Benedetti et al, 2009;Sekiyama et al, 2010) have responded to the growing demand for nighttime aerosol retrievals from satellite observations. For example, by using multisensor aerosol products from the Moderate Resolution Imaging Spectroradiometer (MODIS), the Multi-angle Imaging Spectroradiometer (MISR), and the Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP), Zhang et al (2011) show improvements in aerosol forecasts using combined 2-D/3-D VAR aerosol assimilation.…”

“…For example, by using multisensor aerosol products from the Moderate Resolution Imaging Spectroradiometer (MODIS), the Multi-angle Imaging Spectroradiometer (MISR), and the Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP), Zhang et al (2011) show improvements in aerosol forecasts using combined 2-D/3-D VAR aerosol assimilation. Their study shows that higher forecast errors, measured by comparing modeled and AERONET aerosol optical depth (τ ) data, occur at the 12 and 36 h forecast ranges, possibly due in part to a lack of nighttime observations.…”