Cloud-Aerosol Transport System (CATS) 1064 nm calibration  and validation

Pauly, Rebecca M.; Yorks, John E.; Hlavka, Dennis L.; McGill, Matthew J.; Amiridis, Vassilis; Palm, Stephen P.; Rodier, Sharon; Vaughan, Mark; Selmer, Patrick A.; Kupchock, Andrew; Baars, Holger; Gialitaki, Anna

doi:10.5194/amt-12-6241-2019

Cited by 44 publications

(35 citation statements)

References 65 publications

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“…The HSRL-2 employs the HSRL technique (Shipley et al, 1983) to measure calibrated, unattenuated backscatter and aerosol extinction profiles and also has a higher signalto-noise ratio than the space-based lidars, so it can extensively sample the complete aerosol vertical structure of the aerosol. These mitigate the well-documented low signal-tonoise issue with the space-based Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) (Kacenelenbogen et al, 2011;Liu et al, 2015;Lu et al, 2018;Pauly et al, 2019;Rajapakshe et al, 2017).…”

Section: Instrument (Platform)mentioning

confidence: 97%

Modeling the smoky troposphere of the southeast Atlantic: a comparison to ORACLES airborne observations from September of 2016

et al. 2020

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Abstract. In the southeast Atlantic, well-defined smoke plumes from Africa advect over marine boundary layer cloud decks; both are most extensive around September, when most of the smoke resides in the free troposphere. A framework is put forth for evaluating the performance of a range of global and regional atmospheric composition models against observations made during the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) airborne mission in September 2016. A strength of the comparison is a focus on the spatial distribution of a wider range of aerosol composition and optical properties than has been done previously. The sparse airborne observations are aggregated into approximately 2∘ grid boxes and into three vertical layers: 3–6 km, the layer from cloud top to 3 km, and the cloud-topped marine boundary layer. Simulated aerosol extensive properties suggest that the flight-day observations are reasonably representative of the regional monthly average, with systematic deviations of 30 % or less. Evaluation against observations indicates that all models have strengths and weaknesses, and there is no single model that is superior to all the others in all metrics evaluated. Whereas all six models typically place the top of the smoke layer within 0–500 m of the airborne lidar observations, the models tend to place the smoke layer bottom 300–1400 m lower than the observations. A spatial pattern emerges, in which most models underestimate the mean of most smoke quantities (black carbon, extinction, carbon monoxide) on the diagonal corridor between 16∘ S, 6∘ E, and 10∘ S, 0∘ E, in the 3–6 km layer, and overestimate them further south, closer to the coast, where less aerosol is present. Model representations of the above-cloud aerosol optical depth differ more widely. Most models overestimate the organic aerosol mass concentrations relative to those of black carbon, and with less skill, indicating model uncertainties in secondary organic aerosol processes. Regional-mean free-tropospheric model ambient single scattering albedos vary widely, between 0.83 and 0.93 compared with in situ dry measurements centered at 0.86, despite minimal impact of humidification on particulate scattering. The modeled ratios of the particulate extinction to the sum of the black carbon and organic aerosol mass concentrations (a mass extinction efficiency proxy) are typically too low and vary too little spatially, with significant inter-model differences. Most models overestimate the carbonaceous mass within the offshore boundary layer. Overall, the diversity in the model biases suggests that different model processes are responsible. The wide range of model optical properties requires further scrutiny because of their importance for radiative effect estimates.

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Section: Instrument (Platform)mentioning

confidence: 97%

Modeling the smoky troposphere of the southeast Atlantic: a comparison to ORACLES airborne observations from September of 2016

et al. 2020

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“…Between February 2015 and November 2017, the CATS lidar reported profiles at a vertical resolution of 60 m every 350 m along-track, with an average repeat cycle of nearly 3 d (Yorks et al, 2016). CATS Level 2 Operational layer files (L2O files; Palm et al, 2016) describe altitudes where cloud layers were detected within profiles of backscatter coefficients measured at 1064 nm by the CATS lidar (Pauly et al, 2019), averaged 5 km along-track. We considered all such files over the CATS operation period and inspected each 5 km profile within.…”

Section: Cats Cloud Datamentioning

confidence: 99%

“…Overshooting convection can lead to the injection of ice crystals into the stratosphere (Dauhut et al, 2018;Lee et al, 2019). Stratospheric cooling triggered by gravity waves (Pfister et al, 2010) could also lead to so-called cloud in situ formation (Pan and Munchak, 2011). The ratio of stratospheric clouds that are formed in situ has not been estimated yet.…”

mentioning

confidence: 99%

The diurnal cycle of the clouds extending above the tropical tropopause observed by spaceborne lidar

2020

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Abstract. The presence of clouds above the tropopause over tropical convection centers has so far been documented by spaceborne instruments that are either sun-synchronous or insensitive to thin cloud layers. Here we document, for the first time through direct observation by spaceborne lidar, how the tropical cloud fraction evolves above the tropopause throughout the day. After confirming previous studies that found such clouds most frequently above convection centers, we show that stratospheric clouds and their vertical extent above the tropopause follow a diurnal rhythm linked to convective activity. The diurnal cycle of the stratospheric clouds displays two maxima: one in the early night (19:00–20:00 LT) and a later one (00:00–01:00 LT). Stratospheric clouds extend up to 0.5–1 km above the tropopause during nighttime, when they are the most frequent. The frequency and the vertical extent of stratospheric clouds is very limited during daytime, and when present they are found very close to the tropopause. Results are similar over the major convection centers (Africa, South America and the Warm Pool), with more clouds above land in DJF (December–January–February) and less above the ocean and in JJA (June–July–August).

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“…Operating from February 2015 until October 2017, CATS data contains observations of each of the outflow patterns identified in Garstang et al 13 The most intriguing are observations of the westerly transport of aerosols out over the Indian Ocean and over Australia. The detection sensitivity of CATS at 1064 nm has enabled observations of the diffuse aerosol plumes transported off the African subcontinent over those regions, providing direct measurement of the transport predicted by Garstang et al 13 Moreover, unlike other spaceborne lidar sensors, the CATS 1064 nm data is directly calibrated at 1064 nm 44,45 , thereby augmenting the available data record with additional wavelength information.…”

Section: The Cloud-aerosol Transport Systemmentioning

confidence: 99%

Observation and quantification of aerosol outflow from southern Africa using spaceborne lidar

et al. 2020

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Biomass burning in Africa provides a prolific source of aerosols that are transported from the source region to distant areas, as far away as South America and Australia. Models have long predicted the primary outflow and transport routes. Over time, field studies have validated the basic production and dynamics that underlie these transport patterns. In more recent years, the advancement of spaceborne active remote-sensing techniques has allowed for more detailed verification of the models and, importantly,verification of the vertical distribution of the aerosols in the transport regions, particularly with respect to westerly transport over the Atlantic Ocean. The Cloud-Aerosol Transport System (CATS) lidar on the International Space Station has detection sensitivity that provides observations that support long-held theories of aerosol transport from the African subcontinent over the remote Indian Ocean and as far downstream as Australia.

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Cloud-Aerosol Transport System (CATS) 1064 nm calibration and validation

Cited by 44 publications

References 65 publications

Modeling the smoky troposphere of the southeast Atlantic: a comparison to ORACLES airborne observations from September of 2016

Modeling the smoky troposphere of the southeast Atlantic: a comparison to ORACLES airborne observations from September of 2016

The diurnal cycle of the clouds extending above the tropical tropopause observed by spaceborne lidar

Observation and quantification of aerosol outflow from southern Africa using spaceborne lidar

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