Viviana Vladutescu

Aerosol particles exert important influences on climate and climate change by scattering and ab-sorbing solar radiation and by influencing the properties of clouds. The aerosol life cycle deter-mines the spatial and temporal distribution of atmospheric particles and their chemical, microphysi-cal, and optical properties, which in turn determines the earth radiation budget. In this paper, we investigate the performance of the atmospheric model CMAQ 4.71 (Community Multiscale Air Quality) currently used by the Department of Environmental Conservation (DEC) to provide re-gional pollution forecasts and analysis. We focus on the use of remote sensing tools to better un-derstand the modifications of the optical properties of aerosols as a function of relative humidity, size-distributed composition and sulphate content. In doing this, a novel technique is used to calcu-late the comparison of optical parameters, such as extinction, backscatter and aerosol optical depth. This, in turn, is us...

A scanning Fabry Perot Imager design is proposed based on combinations of Fabry Perot etalons and/or broadband interference filters that can in principle be used as a hyperspectral sensors from geostationary spaceborne platforms. In a single stage etalon design, a number of interference filters are required that can be rotated in front of the ethalon to eliminate overlapping orders. A

Understanding of chemical, physical, and radiative processes of atmospheric aerosols emissions, transport, aging, and removal is of major importance in studies of climate change, visibility, and air quality affecting human health and welfare. This paper presents aerosol optical properties retrieved with a Multifilter Rotating Shadowband Radiometer (MFRSR) and the source attribution based on the NOAA HYSPLIT model and in situ aerosol chemical composition analysis during the Aerosol Life Cycle IOP at Brookhaven National Laboratory, Long Island, NY, during July, 2011. The MFRSR is calibrated using two different techniques. These techniques, which are based directly on observation data, are used to determine the aerosol optical depths (AODs). The instrument calibration constants are validated internally against each other as well as against a technique based on top-of-atmosphere solar spectral irradiance convolved with the MFRSR filter response. In addition, the aerosol optical paramete...

ABSTRACT In this paper, we compare the open-path FTIR to the differential optical absorption spectroscopy (DOAS) approach in the Mid-Infrared region for the continuous retrieval of trace gases. After consideration of FTIR capabilities and results, we explore the potential for a compact quantum cascade laser (QCL) based DOAS system to continuously monitor ambient concentration levels of Ozone and Ammonia. Based on absorption spectra obtained from the HITRAN2000 database and processed within the GENSPECT environment, we find the optimal window for simultaneous retrieval of Ozone and Ammonia to be between 1045 (cm-1) and 1047 (cm-1). We further show that for a QCL-based transmitter with 0.1cm-1 spectral resolution and 10mW power and using nitrogen cooled MCT detector (D* ~ 1010 W-1m Hz1/2) in the receiver, it is possible to detect total path ambient concentrations of ozone and ammonia to within 10% accuracy using suitable targets of opportunity such as an building. Details of the optimal frequency sweeping methodology, optical path length, shot averaging, and SNR considerations are considered for comparison of the QCL-based standoff DOAS performance to more conventional open-path FTIR sensors.

In this paper, we present results showing the usefulness of multi-wavelength lidar measurements to study the interaction of aerosols in the PBL with long range advected aerosol plumes. In particular, our measurements are used to determine the plume angstrom exponent, which allows us to differentiate smoke events from dust events, as well as partitioning the total aerosol optical depth obtained

In this paper, we explore the possibility of determining the nature and variability of urban aerosol hygroscopic properties using multi-wavelength Raman lidar measurements at 355nm, as well as backscatter measurements at 532nm and 1064nm. The addition of these longer wavelength channels allow us to more accurately validate the homogeneity of the aerosol layer as well as provide additional multiwavelength information that can be used to validate and modify the aerosol models underlying the hygroscopic trends observed in the Raman channel. In support of our hygroscopic measurements, we also discuss our calibration procedures for both the aerosol and water vapor profiles. The calibration algorithm we ultimately use for the water vapor measurements are twilight measurements where water vapor radiosonde data from the OKX station in NYS, are combined with total water vapor obtained from a GPS MET station. These sondes are then time correlated with independent near surface RH measurements to address any bias issues that may occur due to imperfect calibration due to lidar overlap issues and SNR limitations in seeing the water vapor at high altitudes. In particular, we investigate the possibility of using ratio optical scatter measurements which eliminate the inherent problem of variable particle number and illustrate the sensitivity of different hygroscopic aerosols to these measurements.

With the dramatically climate changing we are facing today atmospheric monitoring is of major importance. Several atmospheric monitoring instruments are used for measuring atmospheric composition, optical coefficients, PM2.5, aerosol optical depth, size distribution, PBL height and many other parameters. However an inexpensive method of determining these parameters is by use of models and one model that depicts the aerosol dynamics in the atmosphere is the Community Multi-scale Air Quality (CMAQ) model. Our paper is focused on converting CMAQ retrieval outputs into optical coefficients that can then be comparing the lidar, AERONET and TEOM measurements performed at City College of the City University of New York . Differences between the full approach and parameterized methods such as the MALM formula used in AIR-NOW are observed and comparisons with AERONET show the full modeling is in general superior to the MALM formula.

ABSTRACT In this paper, we explore the possibility of determining thenature and variability of urban aerosol hygroscopic properties using multi-wavelength Raman lidar measurements at 355nm, as well as backscatter measurements at 532nm and 1064nm.. The addition of these longer wavelength channels allow us to more accurately validate the homogeneity of the aerosol layer as well as provide additional multiwavelength information that can be used to validate and modify the aerosol models underlying the hygroscopic trends observed in the Raman channel. In support of our hygroscopic measurements, we also discuss our calibration procedures for both the aerosol and water vapor profiles. The calibration algorithm we ultimately use for the water vapor measurements are twilight measurements where water vapor radiosonde data from the OKX station in NYS, are combined with total water vapor obtained from a GPS MET station. These sondes are then time correlated with independent near surface RH measurements to address any bias issues that may occur due to imperfect calibration due to lidar overlap issues and SNR limitations in seeing the water vapor at high altitudes.. In particular, we investigate the possibility of using ratio optical scatter measurments which eliminate the inherent problem of variable particle number and illustrate the sensitivity of different hygroscopic aerosols to these measurements. We find that the use of combine backscatter color ratios between 355 and 1064 together with the conventional extinction to backscatter ratio at 355nm should be able to improve retrieval of hygroscopic properties.

In this paper, we implement and compare two complementary methods for the measurement of low cloud optical depth with a Raman-Mie lidar over the metropolitan area of New York City. The first approach, based on the method of S. Young, determines the cloud optical depth by regressing the elastic signal against a molecular reference signal above and below the cloud.

Between 1900 and 1970, the emission of principal pollutants such as particulate matter, increased significantly across the globe. Particulate Matter less than 2.5 microns in diameter have been shown to have health effects, not only to human health, but also to the entire global ...