scholarly journals Novel aerosol extinction coefficients and lidar ratios over the ocean from CALIPSO-CloudSat: Evaluation and global statistics

2018 ◽  
Author(s):  
David Painemal ◽  
Marian Clayton ◽  
Richard Ferrare ◽  
Sharon Burton ◽  
Damien Josset ◽  
...  
Keyword(s):  
Marine Boundary Layer ◽  
High Spectral Resolution ◽  
Homogeneous Layer ◽  
Aerosol Extinction ◽  
Negative Bias ◽  
Extinction Coefficients ◽  
Global Comparison ◽  
Aerosol Classification ◽  
Global Statistics ◽  
Lidar Equation

Abstract. Aerosol extinction coefficients (σa) and lidar ratios (LR) are retrieved over the ocean from CALIOP attenuated backscatter profiles by solving the lidar equation constrained with aerosol optical depths (AOD) derived by applying the Synergized Optical Depth of Aerosols (SODA) algorithm to ocean surface returns measured by CALIOP and CloudSat’s Cloud Profiling Radar. σa and LR are retrieved for two independent scenarios that require somewhat different assumptions: a) a single homogeneous atmospheric layer (1L) for which the LR is constant with height, and b) a vertically homogeneous layer with a constant LR overlying a marine boundary layer with a homogenous LR fixed at 25 sr (2-layer method, 2L). These new retrievals differ from the standard CALIPSO version 4.1 (V4) product, as the CALIOP-SODA method does not rely on an aerosol classification scheme to select LR. CALIOP-SODA σa and LR are evaluated using airborne high spectral resolution lidar (HSRL) observations over the northwest Atlantic. CALIOP-SODA LR (1L and 2L) positively correlates with its HSRL counterpart (linear correlation coefficient r > 0.67), with a negative bias smaller than 13.2 %, and a good agreement for σa (r ≥ 0.78) with a small negative bias (≤|−9.2 %|). Furthermore, a global comparison of optical depths derived by CALIOP SODA and CALIPSO V4 reveals substantial differences over regions dominated by dust and smoke, in qualitative agreement with previously reported discrepancies between MODIS and CALIPSO AOD. Global maps of CALIOP-SODA LR feature high values over littoral zones, consistent with expectations of continental aerosol transport offshore. In addition, seasonal transitions associated with biomass burning during June to October over the southeast Atlantic are well reproduced by CALIOP-SODA LR.

scholarly journals Novel aerosol extinction coefficients and lidar ratios over the ocean from CALIPSO–CloudSat: evaluation and global statistics

2019 ◽  
Vol 12 (4) ◽  
pp. 2201-2217 ◽  
Author(s):  
David Painemal ◽  
Marian Clayton ◽  
Richard Ferrare ◽  
Sharon Burton ◽  
Damien Josset ◽  
...  
Keyword(s):  
Marine Boundary Layer ◽  
High Spectral Resolution ◽  
Homogeneous Layer ◽  
Orthogonal Polarization ◽  
Aerosol Extinction ◽  
Negative Bias ◽  
Extinction Coefficients ◽  
Global Comparison ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Lidar Equation

Abstract. Aerosol extinction coefficients (σa) and lidar ratios (LRs) are retrieved over the ocean from CALIPSO's Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) attenuated backscatter profiles by solving the lidar equation constrained with aerosol optical depths (AODs) derived by applying the Synergized Optical Depth of Aerosols (SODA) algorithm to ocean surface returns measured by CALIOP and CloudSat's Cloud Profiling Radar. σa and LR are retrieved for two independent scenarios that require somewhat different assumptions: (a) a single homogeneous atmospheric layer (1L) for which the LR is constant with height and (b) a vertically homogeneous layer with a constant LR overlying a marine boundary layer with a homogenous LR fixed at 25 sr (two-layer method, 2L). These new retrievals differ from the standard CALIPSO version 4.1 (V4) product, as the CALIOP–SODA method does not rely on an aerosol classification scheme to select LR. CALIOP–SODA σa and LR are evaluated using airborne high-spectral-resolution lidar (HSRL) observations over the northwest Atlantic. CALIOP–SODA LR (1L and 2L) positively correlates with its HSRL counterpart (linear correlation coefficient r>0.67), with a negative bias smaller than 17.4 % and a good agreement for σa (r≥0.78) with a small negative bias (≤|-9.2%|). Furthermore, a global comparison of optical depths derived by CALIOP–SODA and CALIPSO V4 reveals substantial discrepancies over regions dominated by dust and smoke (0.24), whereas Aqua's Moderate resolution Imaging Spectroradiometer (MODIS) and SODA AOD regional differences are within 0.06. Global maps of CALIOP–SODA LR feature high values over littoral zones, consistent with expectations of continental aerosol transport offshore. In addition, seasonal transitions associated with biomass burning from June to October over the southeast Atlantic are well reproduced by CALIOP–SODA LR.

Aeolus aerosol and cloud product

2021 ◽  
Author(s):  
Thomas Flament ◽  
Alain Dabas ◽  
Dimitri Trapon ◽  
Adrien Lacour ◽  
Frithjof Ehlers ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spectral Resolution ◽  
Aerosol Particles ◽  
High Spectral Resolution ◽  
Extinction Coefficients ◽  
Direct Estimation ◽  
Rayleigh Channel ◽  
Aerosol Classification ◽  
Lidar Ratio ◽  
European Satellite

<p>The European Satellite has the first space-borne high-spectral resolution UV lidar onboard called ALADIN. Two detection channels, a broadband (Rayleigh channel) and a narrowband (Mie channel), are implemented. Carefully calibrated, this combination offers the possibility to derive independent estimates of the backscatter and extinction coefficients of clouds andaerosols, leading to a direct estimation of the lidar ratio, useful for aerosol classification.</p><p>The presentation will show how the official processor of the mission works for the retrieval of optical properties of cloud and aerosol particles, with a focus on the currently available products (called L2A). The potential of the L2A processor will be illustrated by results obtained on data acquired since Aeolus launch and by comparisons to ground based lidars in the frame of Cal/Val activities.</p><p>The L2A product will become publicly available during Spring 2021. Thus, this is also an opportunity to introduce a few practical aspects about its usage.</p>

scholarly journals Assessment of NAAPS-RA performance in Maritime Southeast Asia during CAMP<sup>2</sup>Ex

2021 ◽  
Author(s):  
Eva-Lou Edwards ◽  
Jeffrey S. Reid ◽  
Peng Xian ◽  
Sharon P. Burton ◽  
Anthony L. Cook ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Cloud Condensation Nuclei ◽  
Particle Mass ◽  
High Spectral Resolution ◽  
Light Extinction ◽  
Aerosol Extinction ◽  
Hygroscopic Growth ◽  
Extinction Coefficients ◽  
Wide Range ◽  
Aerosol Properties

Abstract. Monitoring and modeling aerosol particle lifecycle in Southeast Asia (SEA) is challenged by high cloud cover, complex meteorology, and the wide range of aerosol species, sources, and transformations found throughout the region. Satellite observations are limited, and there are few in situ observations of aerosol extinction profiles, aerosol properties, and environmental conditions. Therefore, accurate aerosol model outputs are crucial for the region. This work evaluates the Navy Aerosol Analysis and Prediction System Reanalysis (NAAPS-RA) aerosol optical thickness (AOT) and light extinction products using airborne aerosol and meteorological measurements from the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex) in SEA. Modeled AOTs and extinction coefficients were compared to those retrieved with a High Spectral Resolution Lidar (HSRL-2). Correlations were highest for AOT in the mixed layer (AOTML; R2 = 0.83, bias = 0.00, root mean square error [RMSE] = 0.03) compared to total AOT (R2 = 0.68, bias = 0.01, RMSE = 0.14), although the correlations between the observations and 1° × 1° degree NAAPS-RA outputs were weaker in regions with strong gradients in aerosol properties, such as near areas of active convection. Correlations between simulated and retrieved aerosol extinction coefficients were highest from 145–500 m (R2 = 0.75, bias = 0.01 km−1, RMSE = 0.08 km−1) and decreased with increasing altitude (R2 = 0.69 and 0.26, bias = 0.00 and 0.00 km−1, RMSE = 0.09 and 0.00 km−1 for 500–1500 m and > 1500 m, respectively), which was likely a result of the use of bulk cloud mixing parameterizations. We also investigated the role of possible relative humidity (RH) errors in extinction simulations. Despite negative biases in modeled RH (−4.9, −7.7, and −2.3 % for altitudes < 500 m, 500–1500 m, and > 1500 m, respectively), AOT and extinction agreement with the HSRL-2 did not change significantly at any altitude when RHs from dropsondes were substituted into the model. Improvements may have been stunted due to errors in how NAAPS-RA modeled physics of particle hygroscopic growth, dry particle mass concentrations, and/or dry mass extinction efficiencies, especially when combined with AOT corrections from data assimilation. Specifically, the model overestimated the hygroscopicity of (i) smoke particles from biomass burning in the Maritime Continent (MC), and (ii) anthropogenic emissions transported from East Asia. This work provides insight into how certain environmental and microphysical properties influence AOT and extinction simulations, which can then be interpreted in the context of modeling global concentrations of particle mass and cloud condensation nuclei (CCN).

scholarly journals Aerosol classification from airborne HSRL and comparisons with the CALIPSO vertical feature mask

2013 ◽  
Vol 6 (1) ◽  
pp. 1815-1858 ◽  
Author(s):  
S. P. Burton ◽  
R. A. Ferrare ◽  
M. A. Vaughan ◽  
A. H. Omar ◽  
R. R. Rogers ◽  
...  
Keyword(s):  
High Spectral Resolution ◽  
Dependent Observations ◽  
Aerosol Retrieval ◽  
Direct Measurements ◽  
Aerosol Classification ◽  
Lidar Ratio ◽  
Langley Research Center ◽  
High Spectral Resolution Lidar ◽  
Aerosol Types ◽  
Aerosol Type

Abstract. Aerosol classification products from the NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft are compared with coincident V3.01 aerosol classification products from the CALIOP instrument on the CALIPSO satellite. For CALIOP, aerosol classification is a key input to the aerosol retrieval, and must be inferred using aerosol loading-dependent observations and location information. In contrast, HSRL-1 makes direct measurements of aerosol intensive properties, including the lidar ratio, that provide information on aerosol type. In this study, comparisons are made for 109 underflights of the CALIOP orbit track. We find that 62% of the CALIOP marine layers and 54% of the polluted continental layers agree with HSRL-1 classification results. In addition, 80% of the CALIOP desert dust layers are classified as either dust or dusty mix by HSRL-1. However, agreement is less for CALIOP smoke (13%) and polluted dust (35%) layers. Specific case studies are examined, giving insight into the performance of the CALIOP aerosol type algorithm. In particular, we find that the CALIOP polluted dust type is overused due to an attenuation-related depolarization bias. Furthermore, the polluted dust type frequently includes mixtures of dust plus marine aerosol. Finally, we find that CALIOP's identification of internal boundaries between different aerosol types in contact with each other frequently do not reflect the actual transitions between aerosol types accurately. Based on these findings, we give recommendations which may help to improve the CALIOP aerosol type algorithms.

Aerosol classification method based on high spectral resolution lidar

2017 ◽  
Vol 46 (4) ◽  
pp. 411001
Author(s):  
刘秉义 Liu Bingyi ◽  
庄全风 Zhuang Quanfeng ◽  
秦胜光 Qin Shengguang ◽  
吴松华 Wu Songhua ◽  
刘金涛 Liu Jintao
Keyword(s):  
Spectral Resolution ◽  
Classification Method ◽  
High Spectral Resolution ◽  
Aerosol Classification ◽  
High Spectral Resolution Lidar

scholarly journals A study on the aerosol extinction-to-backscatter ratio with combination of micro-pulse LIDAR and MODIS over Hong Kong

2006 ◽  
Vol 6 (11) ◽  
pp. 3243-3256 ◽  
Author(s):  
Q. S. He ◽  
C. C. Li ◽  
J. T. Mao ◽  
A. K. H. Lau ◽  
P. R. Li
Keyword(s):  
Hong Kong ◽  
Aerosol Extinction ◽  
Scattering Coefficients ◽  
Aerosol Scattering ◽  
Microphysical Parameters ◽  
Lidar Measurements ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Lidar Equation ◽  
Micro Pulse Lidar

Abstract. The aerosol extinction-to-backscatter ratio is an important parameter for inverting LIDAR signals in the LIDAR equation. It is a complicated function of the aerosol microphysical characteristics. In this paper, a method to retrieve the column-averaged aerosol extinction-to-backscatter ratio by constraining the aerosol optical depths (AOD) from a Micro-pulse LIDAR (MPL) by the AOD measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) is presented. Both measurements were taken on cloud free days between 1 May 2003 and 30 June 2004 over Hong Kong, a coastal city in south China. Simultaneous measurements of aerosol scattering coefficients with a forward scattering visibility sensor are compared with the LIDAR retrieval of aerosol extinction coefficients. The data are then analyzed to determine seasonal trends of the aetrosol extinction-to-backscatter ratio. In addition, the relationships between the extinction-to-backscatter ratio and wind conditions as well as other aerosol microphysical parameters are presented. The mean aerosol extinction-to-backscatter ratio for the whole period was found to be 29.1±5.8 sr, with a minimum of 18 sr in July 2003 and a maximum of 44 sr in March 2004. The ratio is lower in summer because of the dominance of oceanic aerosols in association with the prevailing southwesterly monsoon. In contrast, relatively larger ratios are noted in spring and winter because of the increased impact of local and regional industrial pollutants associated with the northerly monsoon. The extended LIDAR measurements over Hong Kong provide not only a more accurate retrieval of aerosol extinction coefficient profiles, but also significant substantial information for air pollution and climate studies in the region.

scholarly journals Aerosol classification using airborne High Spectral Resolution Lidar measurements – methodology and examples

2012 ◽  
Vol 5 (1) ◽  
pp. 73-98 ◽  
Author(s):  
S. P. Burton ◽  
R. A. Ferrare ◽  
C. A. Hostetler ◽  
J. W. Hair ◽  
R. R. Rogers ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Color Ratio ◽  
Lidar Measurements ◽  
Aerosol Classification ◽  
Langley Research Center ◽  
High Spectral Resolution Lidar ◽  
Aerosol Types ◽  
532 Nm ◽  
Aerosol Type

Abstract. The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical depth (AOD) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, and spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of AOD and inferences of aerosol types are used to apportion AOD to aerosol type; results of this analysis are shown for several experiments.

scholarly journals Aerosol classification by airborne high spectral resolution lidar observations

2013 ◽  
Vol 13 (5) ◽  
pp. 2487-2505 ◽  
Author(s):  
S. Groß ◽  
M. Esselborn ◽  
B. Weinzierl ◽  
M. Wirth ◽  
A. Fix ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Spectral Resolution ◽  
Classification Scheme ◽  
In Situ Measurements ◽  
High Spectral Resolution ◽  
Data Set ◽  
Aerosol Classification ◽  
High Spectral Resolution Lidar ◽  
Aerosol Types

Abstract. During four aircraft field experiments with the DLR research aircraft Falcon in 1998 (LACE), 2006 (SAMUM-1) and 2008 (SAMUM-2 and EUCAARI), airborne High Spectral Resolution Lidar (HSRL) and in situ measurements of aerosol microphysical and optical properties were performed. Altogether, the properties of six different aerosol types and aerosol mixtures – Saharan mineral dust, Saharan dust mixtures, Canadian biomass burning aerosol, African biomass burning mixture, anthropogenic pollution aerosol, and marine aerosol have been studied. On the basis of this extensive HSRL data set, we present an aerosol classification scheme which is also capable to identify mixtures of different aerosol types. We calculated mixing lines that allowed us to determine the contributing aerosol types. The aerosol classification scheme was supported by backward trajectory analysis and validated with in-situ measurements. Our results demonstrate that the developed aerosol mask is capable to identify complex stratifications with different aerosol types throughout the atmosphere.

Calibration of the Lidar Measurement of Tropospheric Aerosol Extinction Coefficients

1999 ◽  
Vol 38 (Part 1, No. 1A) ◽  
pp. 293-297 ◽  
Author(s):  
Hideki Kinjo ◽  
Hiroaki Kuze ◽  
Yasushi Sakurada ◽  
Nobuo Takeuchi
Keyword(s):  
Lidar Measurement ◽  
Aerosol Extinction ◽  
Extinction Coefficients ◽  
Tropospheric Aerosol

scholarly journals Studying the vertical aerosol extinction coefficient by comparing in situ airborne data and elastic backscatter lidar

2016 ◽  
Vol 16 (7) ◽  
pp. 4539-4554 ◽  
Author(s):  
Bernadette Rosati ◽  
Erik Herrmann ◽  
Silvia Bucci ◽  
Federico Fierli ◽  
Francesco Cairo ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Aerosol Particle ◽  
Index Of Refraction ◽  
Aerosol Extinction ◽  
Hygroscopic Growth ◽  
Dynamic Features ◽  
Extinction Coefficients ◽  
Po Valley ◽  
Ground Station

Abstract. Vertical profiles of aerosol particle optical properties were explored in a case study near the San Pietro Capofiume (SPC) ground station during the PEGASOS Po Valley campaign in the summer of 2012. A Zeppelin NT airship was employed to investigate the effect of the dynamics of the planetary boundary layer at altitudes between ∼  50 and 800 m above ground. Determined properties included the aerosol particle size distribution, the hygroscopic growth factor, the effective index of refraction and the light absorption coefficient. The first three parameters were used to retrieve the light scattering coefficient. Simultaneously, direct measurements of both the scattering and absorption coefficient were carried out at the SPC ground station. Additionally, a single wavelength polarization diversity elastic lidar system provided estimates of aerosol extinction coefficients using the Klett method to accomplish the inversion of the signal, for a vertically resolved comparison between in situ and remote-sensing results. Note, however, that the comparison was for the most part done in the altitude range where the overlap function is incomplete and accordingly uncertainties are larger. First, the airborne results at low altitudes were validated with the ground measurements. Agreement within approximately ±25 and ±20 % was found for the dry scattering and absorption coefficient, respectively. The single scattering albedo, ranged between 0.83 and 0.95, indicating the importance of the absorbing particles in the Po Valley region. A clear layering of the atmosphere was observed during the beginning of the flight (until ∼  10:00 LT – local time) before the mixing layer (ML) was fully developed. Highest extinction coefficients were found at low altitudes, in the new ML, while values in the residual layer, which could be probed at the beginning of the flight at elevated altitudes, were lower. At the end of the flight (after ∼  12:00 LT) the ML was fully developed, resulting in constant extinction coefficients at all altitudes measured on the Zeppelin NT. Lidar estimates captured these dynamic features well and good agreement was found for the extinction coefficients compared to the in situ results, using fixed lidar ratios (LR) between 30 and 70 sr for the altitudes probed with the Zeppelin. These LR are consistent with values for continental aerosol particles that can be expected in this region.

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