A combination of the invariant imbedding T-matrix (II-TM) method, the improved geometric-optics method (IGOM),
and the pseudo-spectral time domain (PSTD) method provides advanced modeling capabilities to simulate the singlescattering
properties of ice crystals for the entire size parameter range. The downstream applications of the singlescattering
properties simulated from the new modeling capabilities, and, consequently, the bulk radiative properties
render significant improvements, particularly, in remote sensing implementations involving ice clouds. Furthermore, the
single-scattering properties of individual ice crystals are simulated. In addition, a sensitivity study is performed
regarding the application of the single-scattering properties to remote sensing of ice cloud properties based on
The performance of the Community Radiative Transfer Model (CRTM) under ice cloud conditions is evaluated and
improved with the implementation of MODIS collection 6 ice cloud optical property model based on the use of severely
roughened solid column aggregates and a modified Gamma particle size distribution. New ice cloud bulk scattering
properties (namely, the extinction efficiency, single-scattering albedo, asymmetry factor, and scattering phase function)
suitable for application to the CRTM are calculated by using the most up-to-date ice particle optical property library.
CRTM-based simulations illustrate reasonable accuracy in comparison with the counterparts derived from a combination
of the Discrete Ordinate Radiative Transfer (DISORT) model and the Line-by-line Radiative Transfer Model
(LBLRTM). Furthermore, simulations of the top of the atmosphere brightness temperature with CRTM for the Crosstrack
Infrared Sounder (CrIS) are carried out to further evaluate the updated CRTM ice cloud optical property look-up
The effect of black carbon on the optical properties of polluted mineral dust is studied from a satellite remote-sensing perspective. By including the auxiliary data of surface reflectivity and aerosol mixing weight, the optical properties of mineral dust, or more specifically, the aerosol optical depth (AOD) and single-scattering albedo (SSA), can be retrieved with improved accuracy. Precomputed look-up tables based on the principle of the Deep Blue algorithm are utilized in the retrieval. The mean differences between the retrieved results and the corresponding ground-based measurements are smaller than 1% for both AOD and SSA in the case of pure dust. However, the retrievals can be underestimated by as much as 11.9% for AOD and overestimated by up to 4.1% for SSA in the case of polluted dust with an estimated 10% (in terms of the number-density mixing ratio) of soot aggregates if the black carbon effect on dust aerosols is neglected.
Substantial uncertainties exist in the current knowledge of aerosol-cloud-precipitation relationships and stem from the complicated interactions among the atmospheric constituents. We use a straightforward statistical method, the regression analysis technique, to examine the aerosol-cloud-precipitation relationships from satellite observational data sets, including the aqua moderate resolution imaging spectroradiometer (MODIS) aerosol and cloud products and the tropical rainfall measuring mission (TRMM) precipitation rate. Furthermore, the conventional MODIS aerosol product is combined with the Deep Blue algorithm product to reconstruct a complete global map of aerosol optical depth. Numerical simulations using the latest version of the community earth system model (CESM) are also carried out. Globally, distinct statistically significant relationships between aerosol optical depth, cloud fraction, and precipitation rate are obtained over both land and ocean. Signals agreeing with the first and second indirect effects of aerosols are detected, but other factors are likely contributors. The modeling results are found to generally agree with satellite observations, but the model usually overestimates the aerosol-cloud-precipitation relationship. An increasing trend in cloud fraction with the increase of aerosol optical depth (AOD) over ocean regions is found in the observations, while the reverse is true in the model simulation. It is mostly consistent that the model and observation both show a negative relationship between AOD and precipitation rate over land and a positive relationship over ocean.