High spectral resolution solar absorption measurements of ethylene in a forest fire smoke plume using HITRAN parameters: Tropospheric vertical profile retrieval

Abstract. Multi-angle polarimetric (MAP) imaging of Earth scenes can be used for the retrieval of microphysical and optical parameters of aerosols and clouds. The Airborne Hyper-Angular Rainbow Polarimeter (AirHARP) is an aircraft MAP instrument with a hyper-angular imaging capability of 60 along-track viewing angles at 670 nm and 20 along-track viewing angles at other wavelengths – 440, 550, and 870 nm – across the full 114∘ (94∘) along-track (cross-track) field of view. Here we report the retrieval of aerosol properties using the Generalized Retrieval of Aerosols and Surface Properties (GRASP) algorithm applied to AirHARP observations collected during the NASA Aerosol Characterization from Polarimeter and Lidar (ACEPOL) campaign in October–November 2017. The retrieved aerosol properties include spherical fraction (SF), aerosol column concentration in multiple size distribution modes, and, with sufficient aerosol loading, complex aerosol refractive index. From these primary retrievals, we derive aerosol optical depth (AOD), Angstrom exponent (AE), and single scattering albedo (SSA). AODs retrieved from AirHARP measurements are compared with the High Spectral Resolution LiDAR-2 (HSRL2) AOD measurements at 532 nm and validated with measurements from collocated Aerosol Robotic NETwork (AERONET) stations. A good agreement with HSRL2 (ρ=0.940, |BIAS|=0.062, mean absolute error (MAE) = 0.122) and AERONET AOD (0.010≤MAE≤0.015, 0.002≤|BIAS|≤0.009) measurements is observed for the collocated points. There was a mismatch between the HSRL2- and AirHARP-retrieved AOD for the pixels close to the forest fire smoke source and to the edges of the plume due to spatial mismatch in the sampling. This resulted in a higher BIAS and MAE for the HSRL2 AOD comparison. For the case of AERONET AOD comparison, two different approaches are used in the GRASP retrievals, and the simplified aerosol component-based GRASP/Models kernel which retrieves fewer number of aerosol parameter performed well compared to a more generous GRASP/Five mode approach in the low aerosol loading cases. Forest fire smoke intercepted during ACEPOL provided a situation with homogenous plume and sufficient aerosol loading to retrieve the real part of the refractive index (RRI) of 1.55 and the imaginary part of the refractive index (IRI) of 0.024. The derived SSAs for this case are 0.87, 0.86, 0.84, and 0.81 at wavelengths of 440, 550, 670, and 870 nm, respectively. Finer particles with an average AE of 1.53, a volume median radius of 0.157 µm, and a standard deviation (SD) of 0.55 for fine mode is observed for the same smoke plume. These results serve as a proxy for the scale and detail of aerosol retrievals that are anticipated from future space mission data, as HARP CubeSat (mission begins 2020) and HARP2 (aboard the NASA PACE mission with launch in 2023) are near duplicates of AirHARP and are expected to provide the same level of aerosol characterization.

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Simulations of microphysical, radiative, and dynamical processes in a continental-scale forest fire smoke plume

Journal of Geophysical Research Atmospheres ◽

10.1029/91jd01956 ◽

1991 ◽

Vol 96 (D12) ◽

pp. 22379 ◽

Cited By ~ 104

Author(s):

Douglas L. Westphal ◽

Owen B. Toon

Keyword(s):

Forest Fire ◽

Dynamical Processes ◽

Smoke Plume ◽

Continental Scale ◽

Fire Smoke

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Feasibility of forest-fire smoke detection using lidar

International Journal of Wildland Fire ◽

10.1071/wf02048 ◽

2003 ◽

Vol 12 (2) ◽

pp. 159 ◽

Cited By ~ 25

Author(s):

Andrei B. Utkin ◽

Armando Fernandes ◽

Fernando Simões ◽

Alexander Lavrov ◽

Rui Vilar

Keyword(s):

Forest Fire ◽

Forest Fires ◽

Fire Detection ◽

High Repetition Rate ◽

Smoke Detection ◽

Smoke Plume ◽

Smoke Plumes ◽

Lidar Measurements ◽

Fire Smoke ◽

532 Nm

The feasibility and fundamentals of forest fire detection by smoke sensing with single-wavelength lidar are discussed with reference to results of 532-nm lidar measurements of smoke plumes from experimental forest fires in Portugal within the scope of the Gestosa 2001 project. The investigations included tracing smoke-plume evolution, estimating forest-fire alarm promptness, and smoke-plume location by azimuth rastering of the lidar optical axis. The possibility of locating a smoke plume whose source is out of line of sight and detection under extremely unfavourable visibility conditions was also demonstrated. The eye hazard problem is addressed and three possibilities of providing eye-safety conditions without loss of lidar sensitivity (namely, using a low energy-per-pulse and high repetition-rate laser, an expanded laser beam, or eye-safe radiation) are discussed.

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Transport of Canadian forest fire smoke over the UK as observed by lidar

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-11375-2018 ◽

2018 ◽

Vol 18 (15) ◽

pp. 11375-11388 ◽

Cited By ~ 8

Author(s):

Geraint Vaughan ◽

Adam P. Draude ◽

Hugo M. A. Ricketts ◽

David M. Schultz ◽

Mariana Adam ◽

...

Keyword(s):

Forest Fire ◽

Forest Fires ◽

Western Europe ◽

Geographic Area ◽

Thin Layers ◽

Smoke Plume ◽

Fire Smoke ◽

Range Transport ◽

Lidar Ratio ◽

The Uk

Abstract. Layers of aerosol at heights between 2 and 11 km were observed with Raman lidars in the UK between 23 and 31 May 2016. A network of these lidars, supported by ceilometer observations, is used to map the extent of the aerosol and its optical properties. Space-borne lidar profiles show that the aerosol originated from forest fires over western Canada around 17 May, and indeed the aerosol properties – weak volume depolarisation (<5 %) and a lidar ratio at 355 nm in the range 35–65 sr – were consistent with long-range transport of forest fire smoke. The event was unusual in its persistence – the smoke plume was drawn into an atmospheric block that kept it above north-western Europe for 9 days. Lidar observations show how the smoke layers became optically thinner during this period, but the lidar ratio and aerosol depolarisation showed little change. The results demonstrate the value of a dense network of observations for tracking forest fire smoke, and show how the dispersion of smoke in the free troposphere leads to the emergence of discrete thin layers in the far field. They also show how atmospheric blocking can keep a smoke plume in the same geographic area for over a week.

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