The quantification of the first direct aerosol cloud interaction mechanism requires simultaneous observations of
cloud water drop properties as well as aerosol properties below the cloud. The simultaneous measurement of both
these properties is very difficult from space borne systems and efforts to develop ground remote sensing
measurements are critical. To measure the cloud properties, we make use of an approach which combines a
Microwave radiometer and a MFRSR radiometer for simultaneous Cloud Optical Depth (COD) and Liquid Water
Path (LWP). From these measurements, effective droplet diameter can be estimated assuming the homogeneity of
the cloud. In using the diffuse flux, we confirm that for COD > 2 and solar zenith angles < 60, the standard MFRSR
correction can be applied with errors < 1%. In addition, we develop a method whereby regional retrieval of
Microphysical properties from multispectral extinction measurements can be made based on NN based methods
trained on full sky scans. Also, we discuss the uncertainty in the inferred COD due to various input parameters in the
formation of Look-Up-Tables and present preliminary data sets for evaluation. Finally, we discuss methods to
extract useful aerosol information during partly cloudy conditions that can be used to better define the state of the
aerosol prior to cloud interaction.
In this paper, the simulations of the Weather Research and Forecast (WRF) and Community Multiscale Air Quality
(CMAQ) Models applied to the New York City (NYC) area are assessed with the aid of vertical profiling and column
integrated remote sensing measurements. First, we find that when turbulent mixing processes are dominant, the WRFderived
planetary boundary layer (PBL) height exhibits a strong linear correlation (R>0.85) with lidar-derived PBL
height. In these comparisons, we estimate the PBL height from the lidar measurements using a Wavelet Covariance
Transform (WCT) approach that is modified to better isolate the convective layer from the residual layer (RL).
Furthermore, the WRF-Lidar PBL height comparisons are made using different PBL parameterization schemes,
including the Asymmetric Convective Model-version2 (ACM2) and the Modified Blackadar (BLK) scheme (which are
both runs using hindcast data), as well as the Mellor-Yamada-Janjic (MYJ) scheme run in forecast mode. Our findings
show that the correlations for these runs are high (>0.8), but the hindcast runs exhibit smaller overall dispersion (≈0.1)
than the forecast runs. We also apply continuous 24-hour/7-day vertical ceilometer measurements to assess WRFCMAQ
model forecasts of surface PM2.5 (particulate matter has aerodynamic diameter <2.5μm). Strong overestimations
in the surface PM2.5 mass that are observed in the summer prior to sunrise are particularly shown to be strongly
connected to underestimations of the PBL height and less to enhanced emissions. This interpretation is consistent with
observations that TEOM (Tapered Element Oscillating MicroBalance) PM2.5 measurements are better correlated to pathintegrated
CMAQ PM2.5 than the near-surface measurements during these periods.
In the standard MODIS Collection 5 aerosol retrieval algorithm, estimates of the surface albedo between the VIS
and MIR channels must be made. Unfortunately, the operational model used is not suitable for urban areas and
efforts to modify the required VIS-MIR surface spectral ratios for urban areas are needed to remove aerosol retrieval
biases. To address these issues, we use results based on the ASRVN product to provide regionally tuned surface
reflection ratios Using these values removes retrieval bias and improves resolution to 1.5 km. In addition, we note
explore the relationships for multiple urban sites and illustrate a general correspondence between the surface
reflection ratiosn and biases in AOD retrieval. Further validations of the surface reflection differences in urban
areas are illustrated using high resolution LANDSAT 7 imagery for vegetation / urban boundaries.
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