scholarly journals Comparisons of LASE, aircraft, and satellite measurements of aerosol optical properties and water vapor during TARFOX

2000 ◽  
Vol 105 (D8) ◽  
pp. 9935-9947 ◽  
Author(s):  
R. Ferrare ◽  
S. Ismail ◽  
E. Browell ◽  
V. Brackett ◽  
S. Kooi ◽  
...  
Keyword(s):  
Optical Properties ◽  
Water Vapor ◽  
Satellite Measurements ◽  
Aerosol Optical Properties

Aerosol optical properties and precipitable water vapor column in the atmosphere of Norway

2015 ◽  
Vol 54 (6) ◽  
pp. 1505 ◽  
Author(s):  
Dennis Muyimbwa ◽  
Øyvind Frette ◽  
Jakob J. Stamnes ◽  
Taddeo Ssenyonga ◽  
Yi-Chun Chen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Water Vapor ◽  
Precipitable Water ◽  
Precipitable Water Vapor ◽  
Aerosol Optical Properties

Comparison of aerosol optical properties and water vapor among ground and airborne lidars and Sun photometers during TARFOX

2000 ◽  
Vol 105 (D8) ◽  
pp. 9917-9933 ◽  
Author(s):  
R. Ferrare ◽  
S. Ismail ◽  
E. Browell ◽  
V. Brackett ◽  
M. Clayton ◽  
...  
Keyword(s):  
Optical Properties ◽  
Water Vapor ◽  
Aerosol Optical Properties

scholarly journals Effect of altitude on aerosol optical properties

2006 ◽  
Vol 2 (SPS5) ◽  
pp. 111-114
Author(s):  
Aziza Bounhir ◽  
Zouhair Benkhaldoun ◽  
El Arbi Siher ◽  
L. Masmoudi
Keyword(s):  
Optical Properties ◽  
North America ◽  
Site Selection ◽  
Selection Process ◽  
Santa Cruz ◽  
Satellite Measurements ◽  
Aerosol Optical Properties ◽  
Low Altitude ◽  
Aerosol Index ◽  
Aerosol Properties

AbstractThe ELT project is currently under way in Europe and North America. Astronomical sites depend critically on sky transparency and on aerosol loadings. A quantitative survey of aerosol optical properties at candidate ELT sites is an essential part of the site selection process. There are basically two methods to characterize aerosol properties: ground based measurements and satellite measurements. In this paper we will establish a full climatology of two sites very close to each other, but at a difference of 2300m in altitude: Izaña and Santa Cruz located in the Canary Islands. Both have sun photometers from the AERONET network. We also use the aerosol index determined from TOMS satellite data to determine how aerosol optical properties vary with altitude. We establish a correlation between the TOMS index and the aerosol optical thickness in both sites. Aerosol optical properties show very good correlation between Izaña and Santa Cruz. As a result we establish a set of relationships helpful to characterize sites at elevated altitude from data of neighbouring sites at low altitude.

Enhanced water vapor in Asian dust layer: Entrainment processes and implication for aerosol optical properties

2006 ◽  
Vol 40 (13) ◽  
pp. 2409-2421 ◽  
Author(s):  
Soon-Chang Yoon ◽  
Sang-Woo Kim ◽  
Jiyoung Kim ◽  
Byung-Ju Sohn ◽  
Anne Jefferson ◽  
...  
Keyword(s):  
Optical Properties ◽  
Water Vapor ◽  
Asian Dust ◽  
Aerosol Optical Properties ◽  
Dust Layer

scholarly journals Ultraviolet radiation modelling from ground-based and satellite measurements on Reunion Island, southern tropics

2018 ◽  
Vol 18 (1) ◽  
pp. 227-246 ◽  
Author(s):  
Kévin Lamy ◽  
Thierry Portafaix ◽  
Colette Brogniez ◽  
Sophie Godin-Beekmann ◽  
Hassan Bencherif ◽  
...  
Keyword(s):  
Optical Properties ◽  
Total Ozone ◽  
Reunion Island ◽  
Satellite Measurements ◽  
Aerosol Optical Properties ◽  
Total Ozone Column ◽  
Clear Sky ◽  
Réunion Island ◽  
The Tropics ◽  
Ozone Column

Abstract. Surface ultraviolet radiation (SUR) is not an increasing concern after the implementation of the Montreal Protocol and the recovery of the ozone layer (Morgenstern et al., 2008). However, large uncertainties remain in the prediction of future changes of SUR (Bais et al., 2015). Several studies pointed out that UV-B impacts the biosphere (Erickson et al., 2015), especially the aquatic system, which plays a central part in the biogeochemical cycle (Hader et al., 2007). It can affect phytoplankton productivity (Smith and Cullen, 1995). This influence can result in either positive or negative feedback on climate (Zepp et al., 2007). Global circulation model simulations predict an acceleration of the Brewer-Dobson circulation over the next century (Butchart, 2014), which would lead to a decrease in ozone levels in the tropics and an enhancement at higher latitudes (Hegglin and Shepherd, 2009). Reunion Island is located in the tropics (21° S, 55° E), in a part of the world where the amount of ozone in the ozone column is naturally low. In addition, this island is mountainous and the marine atmosphere is often clean with low aerosol concentrations. Thus, measurements show much higher SUR than at other sites at the same latitude or at midlatitudes. Ground-based measurements of SUR have been taken on Reunion Island by a Bentham DTMc300 spectroradiometer since 2009. This instrument is affiliated with the Network for the Detection of Atmospheric Composition Change (NDACC). In order to quantify the future evolution of SUR in the tropics, it is necessary to validate a model against present observations. This study is designed to be a preliminary parametric and sensitivity study of SUR modelling in the tropics. We developed a local parameterisation using the Tropospheric Ultraviolet and Visible Model (TUV; Madronich, 1993) and compared the output of TUV to multiple years of Bentham spectral measurements. This comparison started in early 2009 and continued until 2016. Only clear-sky SUR was modelled, so we needed to sort out the clear-sky measurements. We used two methods to detect cloudy conditions: the first was based on an observer's hourly report on the sky cover, while the second was based on applying Long and Ackerman (2000)'s algorithm to broadband pyranometer data to obtain the cloud fraction and then discriminating clear-sky windows on SUR measurements. Long et al. (2006)'s algorithm, with the co-located pyranometer data, gave better results for clear-sky filtering than the observer's report. Multiple model inputs were tested to evaluate the model sensitivity to different parameters such as total ozone column, aerosol optical properties, extraterrestrial spectrum or ozone cross section. For total column ozone, we used ground-based measurements from the SAOZ (Système d'Analyse par Observation Zénithale) spectrometer and satellite measurements from the OMI and SBUV instruments, while ozone profiles were derived from radio-soundings and the MLS ozone product. Aerosol optical properties came from a local aerosol climatology established using a Cimel photometer. Since the mean difference between various inputs of total ozone column was small, the corresponding response on UVI modelling was also quite small, at about 1 %. The radiative amplification factor of total ozone column on UVI was also compared for observations and the model. Finally, we were able to estimate UVI on Reunion Island with, at best, a mean relative difference of about 0.5 %, compared to clear-sky observations.

scholarly journals Development of on-site self-calibration and retrieval methods for sky-radiometer observations of precipitable water vapor

2019 ◽  
Author(s):  
Masahiro Momoi ◽  
Rei Kudo ◽  
Kazuma Aoki ◽  
Tatsuhiro Mori ◽  
Kazuhiko Miura ◽  
...  
Keyword(s):  
Optical Properties ◽  
Water Vapor ◽  
Solar Irradiance ◽  
Precipitable Water ◽  
Dry Season ◽  
Calibration Constant ◽  
Aerosol Optical Properties ◽  
Vapor Channel ◽  
Long Term Observation

Abstract. The Prede sky-radiometer, whose aerosol channels are calibrated by on-site measurements (the Improved Langley method), has been used for continuous long-term observation of aerosol properties. However, continuous long-term observation of precipitable water vapor (PWV) by sky-radiometer remain challenge, because the water vapor channel is generally calibrated by the standard Langley method at limited observation sites (e.g., the Mauna Loa Observatory). In this study, we developed SKYMAP, a new onsite self-calibration method for the water vapor channel of the Prede sky-radiometer using diffuse radiances normalized by direct solar irradiance. The SKYMAP algorithm consists of three steps. First, aerosol optical and microphysical properties are retrieved using direct solar irradiances and the normalized diffuse radiances at aerosol channels. The aerosol optical properties at the water vapor channel are interpolated from those at aerosol channels. Second, the transmittance of PWV is retrieved using the diffuse radiance normalized to the direct solar irradiance at the water vapor channel, which does not need the calibration constant. Third, the calibration constant at the water vapor channel is estimated from the transmittance of PWV and aerosol optical properties. Intensive sensitivity tests of SKYMAP using simulated data of the sky-radiometer showed that the calibration constant is retrieved reasonably well for PWV < 2 cm, indicating that SKYMAP can calibrate the water vapor channel on-site in dry conditions. Then SKYMAP was applied to actual measurements in the dry season at two sites (Tsukuba and Chiba, Japan). Because the SKYMAP algorithm is useful for clear-sky and low PWV (< 2 cm) conditions, the water vapor channel was calibrated for the dry season. After determining the calibration constant, PWV is able to be retrieved using direct solar irradiances for the whole year. The retrieved PWV values correspond well to those derived from a Global Navigation Satellite System (GNSS)/Global Positioning System (GPS) receiver, a microwave radiometer, and a AERONET sun-sky radiometer at both sites (correlation coefficient γ > 0.96), indicating that the Prede sky-radiometer provides both aerosol and PWV data based on its unique on-site calibration methods.

scholarly journals Investigating Wavelength-Dependent Aerosol Optical Properties Using Water Vapor Slant Column Retrievals from CLARS over the Los Angeles Basin

2016 ◽  
Author(s):  
Zhao-Cheng Zeng ◽  
Qiong Zhang ◽  
Jack S. Margolis ◽  
Run-Lie Shia ◽  
Sally Newman ◽  
...  
Keyword(s):  
Optical Properties ◽  
Water Vapor ◽  
Los Angeles ◽  
Near Infrared ◽  
Wavelength Dependence ◽  
Single Scattering ◽  
Aerosol Optical Properties ◽  
Absorption Bands ◽  
Novel Approach ◽  
Aerosol Scattering

Abstract. In this study, we propose a novel approach to constrain the optical properties of atmospheric aerosol in a complex urban environment using water vapor (H2O) slant column measurements in the near infrared. This approach is demonstrated using measurements from the California Laboratory for Atmospheric Remote Sensing Fourier Transform Spectrometer (CLARS-FTS) on the top of Mt. Wilson, California, and a two-stream-exact single scattering (2S-ESS) radiative transfer (RT) model. From the spectral measurements, we retrieve H2O slant column density (SCD) using 15 different absorption bands between 4000 and 8000 cm−1. Due to the wavelength dependence of aerosol scattering, large variations in H2O SCD retrievals are observed as a function of wavelength. Moreover, the variations are found to be correlated with aerosol optical depths (AOD) measured at the AERONET-Caltech station. Simulation results from the RT model reproduce this correlation and show that the aerosol scattering is the primary contributor to the variations in the wavelength dependence of the H2O SCD retrievals. The evidence from both measurements and simulations suggest that wavelength-dependent aerosol optical properties can be constrained using H2O retrievals from multiple bands.

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