Pulsed airborne lidar measurements of atmospheric optical depth using the Oxygen A-band at 765 nm

Abstract A study of air quality was performed using a compact, aircraft aerosol lidar designed in the Science Directorate at NASA Langley Research Center and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) retrievals. Five flights of lidar measurements conducted in the Hampton–Norfolk–Virginia Beach, Virginia, region showed complex regional aerosol distributions. Comparisons with MODIS AOD at 10 km × 10 km and 5 km × 5 km resolutions show good agreement, with correlation R2 values of 0.82 and 0.88, respectively. Linear regressions of particulate matter with a diameter of less than 2.5 μm (PM2.5) and AOD within the ranges of 5–40 μg m−3 and 0.05–0.7, respectively, result in R2 values of ∼0.64 and ∼0.82 for MODIS and the Compact Aerosol Lidar, respectively. The linear regressions reflect approximately 51 μg m−3 to 1 AOD. These relationships are in agreement with previous findings for air pollution aerosols in the eastern United States and in northern Italy. However, large vertical variation is seen case by case, with planetary boundary layer heights ranging between 0.7 and 2 km and uncertainties ranging between 0.1 and 0.4 km. The results of the case studies suggest that AOD can be used as an indicator of surface measurements of PM2.5 but with larger uncertainties associated with small aerosol loading (AOD < 0.3).

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Investigating emission sources and transport of aerosols in Siberia using airborne and spaceborne LIDAR measurements

10.5194/acp-2020-195 ◽

2020 ◽

Author(s):

Antonin Zabukovec ◽

Gerard Ancellet ◽

Iwan E. Penner ◽

Mikhail Arshinov ◽

Valery Kozlov ◽

...

Keyword(s):

Optical Depth ◽

Forest Fire ◽

Airborne Lidar ◽

Aerosol Layer ◽

Gas Flaring ◽

Fire Plumes ◽

Lidar Measurements ◽

Lidar Ratio ◽

Aerosol Types ◽

Aerosol Type

Abstract. Airborne backscatter lidar measurements at 532 nm were carried out over Siberia in July 2013 and June 2017. The Russian Tu-134 flew over major Siberian cities (Novosibirsk, Tomsk, Krasnoyarsk, Yakutsk), the gas flaring fields of the Ob valley and Siberian Taiga in order to sample several kinds of Siberian aerosol sources. Aerosol types are derived using the Lagrangian FLEXible PARTicle dispersion model (FLEXPART) simulations, Moderate Resolution Imaging Spectrometer (MODIS) Aerosol Optical Depth (AOD), Infrared Atmospheric Sounding Interferometer (IASI) CO total column and AOD at 10 μm. Forest fire detection is based on NASA Fire Information for Resource Management System (FIRMS) from MODIS and the Visible Infrared Imaging Radiometer Suite (VIIRS) observations and airborne in-situ measurements when available. Six aerosol type could be identified in this work: (i) Dusty aerosol mixture (ii) Ob valley industrial emission (iii) fresh boreal forest fire plumes (iv) aged forest fire plumes (v) pollution over the Tomsk/Novosibirsk region (vi) long range transport of Chinese pollution over Yakutsk. The backscatter to extinction ratio and then the corresponding lidar ratio (LR) were derived for each of these 6 identified aerosol type, using an iterative method based on the Fernald forward inversion constrained by the 10 km MODIS collection 6 AOD distribution closed to the airborne lidar observation. The LR analysis showed that the lowest LR range was obtained for the Dusty Mix case (26–40 sr) and the highest for the urban and industrial pollution from the Tomsk/Novosibirsk area (71–90 sr). The comparison is good with previous estimate of LR according to the aerosol classification. The range of lidar ratio obtained for gas flaring emission (43–60 sr) was lower than the high values encountered in the Tomsk/Novosibirk urban area and has never been characterized using lidar observations. Airborne lidar backscatter ratio vertical structure, aerosol types and integrated LR derived from the airborne data analysis were compared to nearby CALIOP overpasses. These comparisons showed three main differences with the CALIOP LR and aerosol type classification over Siberia: (i) CALIOP aerosol layer can be classified as Elevated smoke instead of Polluted continental and vice versa, but with little influence on the LR value (ii) aging and transport of aerosol layers effect on the CALIOP LR value is not always properly accounted for even when the CALIOP classification is correct (iii) the lack of discrimination between fresh and old fire plume leads to an overestimation of the optical depth for the fresh fires in the CALIOP AOD over the fire source region.

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Validation of ash optical depth and layer height retrieved from passive satellite sensors using EARLINET and airborne lidar data: The case of the Eyjafjallajökull eruption

10.5194/acp-2015-1041 ◽

2016 ◽

Author(s):

D. Balis ◽

M. E. Koukouli ◽

N. Siomos ◽

S. Dimopoulos ◽

L. Mona ◽

...

Keyword(s):

Optical Depth ◽

Volcanic Ash ◽

Volcanic Eruptions ◽

Airborne Lidar ◽

Lidar Data ◽

Atmospheric Measurements ◽

Layer Height ◽

Lidar Measurements ◽

Satellite Retrievals ◽

Ash Plume

Abstract. The vulnerability of the European airspace to volcanic eruptions was brought to the attention of the public and the scientific community by the 2010 eruptions of the Icelandic volcano Eyjafjallajökull. As a consequence of this event ash concentration thresholds replaced the ‘zero-tolerance to ash’ rule, drastically changing the requirements on satellite ash retrievals. In response to that, ESA funded several projects aiming at creating an optimal End-to-End System for Volcanic Ash Plume Monitoring and Prediction. Two of them, namely the SACS-2 and SMASH projects, developed and improved dedicated satellite-derived ash plume and sulphur dioxide level assessments. These estimates were extensively validated using ground-based and aircraft lidar measurements. The validation of volcanic ash levels and height extracted from the GOME-2 and IASI instruments on board the MetOp-A satellite is presented in this work. EARLINET lidar measurements are compared to different satellite retrievals for two eruptive episodes in April and May 2010. Comparisons were made between satellite retrievals and aircraft lidar data obtained with UK's BAe-146-301 Atmospheric Research Aircraft (managed by the Facility for Airborne Atmospheric Measurements, FAAM) over the United Kingdom and the surrounding regions. The validation results are promising for most satellite products and are within the estimated uncertainties of each of the comparative datasets, but more collocation scenes are needed to perform a comprehensive statistical analysis. The satellite estimates and the validation data sets are better correlated for high ash optical depth values, with correlation coefficients greater than 0.8. The IASI data show a better consistency concerning the ash optical depth and ash layer height when compared with the lidar data.

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High-Resolution Satellite Image Based Aerosol Optical Depth Retrieval Method: Validation Through EARLINET and NASA MPLNET Lidar Measurements and NASA AERONET Sunphotometer Data

2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) ◽

10.1109/piers-spring46901.2019.9017776 ◽

2019 ◽

Author(s):

S. Lolli ◽

G. Vivone ◽

L. Alparone ◽

A. Garzelli ◽

M. Bilal ◽

...

Keyword(s):

High Resolution ◽

Aerosol Optical Depth ◽

Method Validation ◽

Optical Depth ◽

Satellite Image ◽

Retrieval Method ◽

Lidar Measurements ◽

High Resolution Satellite Image

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Application and Validation of a Model for Terrain Slope Estimation Using Space-Borne LiDAR Waveform Data

Remote Sensing ◽

10.3390/rs10111691 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1691 ◽

Cited By ~ 1

Author(s):

Xuebo Yang ◽

Cheng Wang ◽

Sheng Nie ◽

Xiaohuan Xi ◽

Zhenyue Hu ◽

...

Keyword(s):

Surface Characteristics ◽

Airborne Lidar ◽

Estimation Accuracy ◽

Estimation Model ◽

Large Area ◽

Waveform Data ◽

Terrain Slope ◽

Lidar Measurements ◽

Slope Estimation ◽

Study Sites

The terrain slope is one of the most important surface characteristics for quantifying the Earth surface processes. Space-borne LiDAR sensors have produced high-accuracy and large-area terrain measurement within the footprint. However, rigorous procedures are required to accurately estimate the terrain slope especially within the large footprint since the estimated slope is likely affected by footprint size, shape, orientation, and terrain aspect. Therefore, based on multiple available datasets, we explored the performance of a proposed terrain slope estimation model over several study sites and various footprint shapes. The terrain slopes were derived from the ICESAT/GLAS waveform data by the proposed method and five other methods in this study. Compared with five other methods, the proposed method considered the influence of footprint shape, orientation, and terrain aspect on the terrain slope estimation. Validation against the airborne LiDAR measurements showed that the proposed method performed better than five other methods (R2 = 0.829, increased by ~0.07, RMSE = 3.596°, reduced by ~0.6°, n = 858). In addition, more statistics indicated that the proposed method significantly improved the terrain slope estimation accuracy in high-relief region (RMSE = 5.180°, reduced by ~1.8°, n = 218) or in the footprint with a great eccentricity (RMSE = 3.421°, reduced by ~1.1°, n = 313). Therefore, from these experiments, we concluded that this terrain slope estimation approach was beneficial for different terrains and various footprint shapes in practice and the improvement of estimated accuracy was distinctly related with the terrain slope and footprint eccentricity.

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The interdependence of continental warm cloud properties derived from unexploited solar background signals in ground-based lidar measurements

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-8389-2014 ◽

2014 ◽

Vol 14 (16) ◽

pp. 8389-8401 ◽

Cited By ~ 7

Author(s):

J. C. Chiu ◽

J. A. Holmes ◽

R. J. Hogan ◽

E. J. O'Connor

Keyword(s):

Optical Depth ◽

Effective Radius ◽

Liquid Water Path ◽

Cloud Optical Depth ◽

Cloud Properties ◽

Warm Cloud ◽

Lidar Measurements ◽

Atmospheric Radiation Measurement ◽

Ground Based Lidar ◽

Geometric Thickness

Abstract. We have extensively analysed the interdependence between cloud optical depth, droplet effective radius, liquid water path (LWP) and geometric thickness for stratiform warm clouds using ground-based observations. In particular, this analysis uses cloud optical depths retrieved from untapped solar background signals that are previously unwanted and need to be removed in most lidar applications. Combining these new optical depth retrievals with radar and microwave observations at the Atmospheric Radiation Measurement (ARM) Climate Research Facility in Oklahoma during 2005–2007, we have found that LWP and geometric thickness increase and follow a power-law relationship with cloud optical depth regardless of the presence of drizzle; LWP and geometric thickness in drizzling clouds can be generally 20–40% and at least 10% higher than those in non-drizzling clouds, respectively. In contrast, droplet effective radius shows a negative correlation with optical depth in drizzling clouds and a positive correlation in non-drizzling clouds, where, for large optical depths, it asymptotes to 10 μm. This asymptotic behaviour in non-drizzling clouds is found in both the droplet effective radius and optical depth, making it possible to use simple thresholds of optical depth, droplet size, or a combination of these two variables for drizzle delineation. This paper demonstrates a new way to enhance ground-based cloud observations and drizzle delineations using existing lidar networks.

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Aerosol optical depth derived from lidar measurements during VELETA-2002 campaign

10.1117/12.511073 ◽

2004 ◽

Author(s):

Francisco Molero ◽

Manuel Pujadas ◽

Jose M. Fernandez ◽

Maria P. Utrillas ◽

Jose A. Martinez-Lozano ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Lidar Measurements

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The interdependence of continental warm cloud properties derived from unexploited solar background signal in ground-based lidar measurements

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-8963-2014 ◽

2014 ◽

Vol 14 (7) ◽

pp. 8963-8996

Author(s):

J. C. Chiu ◽

J. A. Holmes ◽

R. J. Hogan ◽

E. J. O'Connor

Keyword(s):

Optical Depth ◽

Effective Radius ◽

Liquid Water Path ◽

Background Signal ◽

Cloud Optical Depth ◽

Cloud Properties ◽

Lidar Measurements ◽

Atmospheric Radiation Measurement ◽

Ground Based Lidar ◽

Geometric Thickness

Abstract. We have extensively analysed the interdependence between cloud optical depth, droplet effective radius, liquid water path (LWP) and geometric thickness for stratiform warm clouds using ground-based observations. In particular, this analysis uses cloud optical depths retrieved from untapped solar background signal that is previously unwanted and needs to be removed in most lidar applications. Combining these new optical depth retrievals with radar and microwave observations at the Atmospheric Radiation Measurement (ARM) Climate Research Facility in Oklahoma during 2005–2007, we have found that LWP and geometric thickness increase and follow a power-law relationship with cloud optical depth regardless of the presence of drizzle; LWP and geometric thickness in drizzling clouds can be generally 20–40% and at least 10% higher than those in non-drizzling clouds, respectively. In contrast, droplet effective radius shows a negative correlation with optical depth in drizzling clouds, while it increases with optical depth and reaches an asymptote of 10 μm in non-drizzling clouds. This asymptotic behaviour in non-drizzling clouds is found in both droplet effective radius and optical depth, making it possible to use simple thresholds of optical depth, droplet size, or a combination of these two variables for drizzle delineation. This paper demonstrates a new way to enhance ground-based cloud observations and drizzle delineations using existing lidar networks.

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Exploring the Twilight Zone: A Multi-Sensor Approach

EPJ Web of Conferences ◽

10.1051/epjconf/202023707015 ◽

2020 ◽

Vol 237 ◽

pp. 07015

Author(s):

Jonatan da Silva ◽

Fernando G. Morais ◽

Marco A. Franco ◽

Fábio J. S. Lopes ◽

Gregori de A. Arruda ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Vertical Profile ◽

Sao Paulo ◽

Twilight Zone ◽

Upward Movement ◽

São Paulo ◽

Turbulence Measurements ◽

Lidar Measurements ◽

Satellite Instruments

This study shows a set of analysis of measurements from ground-based and satellite instruments to characterize the twilight zone (TLZ) between clouds and aerosols in São Paulo, Brazil. In the vicinity of clouds turbulence measurements showed an intense upward movement of aerosol layers, while sunphotometer results showed an increase in aerosol optical depth, and lidar measurements showed an increase in the backscatter vertical profile signal.

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Monitoring tropical forest carbon stocks and emissions using Planet satellite data

Scientific Reports ◽

10.1038/s41598-019-54386-6 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 18

Author(s):

Ovidiu Csillik ◽

Pramukta Kumar ◽

Joseph Mascaro ◽

Tara O’Shea ◽

Gregory P. Asner

Keyword(s):

Climate Change ◽

Large Scale ◽

Cost Effective ◽

Carbon Stocks ◽

Airborne Lidar ◽

Aboveground Carbon ◽

Lidar Measurements ◽

High Resolution Map ◽

Aboveground Carbon Density ◽

Planet Satellite

AbstractTropical forests are crucial for mitigating climate change, but many forests continue to be driven from carbon sinks to sources through human activities. To support more sustainable forest uses, we need to measure and monitor carbon stocks and emissions at high spatial and temporal resolution. We developed the first large-scale very high-resolution map of aboveground carbon stocks and emissions for the country of Peru by combining 6.7 million hectares of airborne LiDAR measurements of top-of-canopy height with thousands of Planet Dove satellite images into a random forest machine learning regression workflow, obtaining an R2 of 0.70 and RMSE of 25.38 Mg C ha−1 for the nationwide estimation of aboveground carbon density (ACD). The diverse ecosystems of Peru harbor 6.928 Pg C, of which only 2.9 Pg C are found in protected areas or their buffers. We found significant carbon emissions between 2012 and 2017 in areas aggressively affected by oil palm and cacao plantations, agricultural and urban expansions or illegal gold mining. Creating such a cost-effective and spatially explicit indicators of aboveground carbon stocks and emissions for tropical countries will serve as a transformative tool to quantify the climate change mitigation services that forests provide.

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