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  • 1
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    Online Resource
    Vertical wind retrieved by airborne lidar and analysis of island induced gravity waves in combination with numerical models and in situ particle measurements
    Copernicus GmbH ; 2016
    In:  Atmospheric Chemistry and Physics Vol. 16, No. 7 ( 2016-04-14), p. 4675-4692
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 16, No. 7 ( 2016-04-14), p. 4675-4692
    Abstract: Abstract. This study presents the analysis of island induced gravity waves observed by an airborne Doppler wind lidar (DWL) during SALTRACE. First, the instrumental corrections required for the retrieval of high spatial resolution vertical wind measurements from an airborne DWL are presented and the measurement accuracy estimated by means of two different methods. The estimated systematic error is below −0.05 m s−1 for the selected case of study, while the random error lies between 0.1 and 0.16 m s−1 depending on the estimation method. Then, the presented method is applied to two measurement flights during which the presence of island induced gravity waves was detected. The first case corresponds to a research flight conducted on 17 June 2013 in the Cabo Verde islands region, while the second case corresponds to a measurement flight on 26 June 2013 in the Barbados region. The presence of trapped lee waves predicted by the calculated Scorer parameter profiles was confirmed by the lidar and in situ observations. The DWL measurements are used in combination with in situ wind and particle number density measurements, large-eddy simulations (LES), and wavelet analysis to determine the main characteristics of the observed island induced trapped waves.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    URL: Article
    DOI: 10.5194/acp-16-4675-2016
    DOI: 10.5194/acp-16-4675-2016-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2016
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  • 2
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    Saharan dust long-range transport across the Atlantic studied by an airborne Doppler wind lidar and the MACC model
    Copernicus GmbH ; 2016
    In:  Atmospheric Chemistry and Physics Vol. 16, No. 18 ( 2016-09-20), p. 11581-11600
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 16, No. 18 ( 2016-09-20), p. 11581-11600
    Abstract: Abstract. A huge amount of dust is transported every year from north Africa into the Caribbean region. This paper presents an investigation of this long-range transport process based on airborne Doppler wind lidar (DWL) measurements conducted during the SALTRACE campaign (June–July 2013), as well as an evaluation of the ability of the MACC (Monitoring Atmospheric Composition and Climate) global aerosol model to reproduce it and its associated features. Although both the modeled winds from MACC and the measurements from the DWL show a generally good agreement, some differences, particularly in the African easterly jet (AEJ) intensity, were noted. The observed differences between modeled and measured wind jet speeds are between 5 and 10 m s−1. The vertical aerosol distribution within the Saharan dust plume and the marine boundary layer is investigated during the June–July 2013 period based on the MACC aerosol model results and the CALIOP satellite lidar measurements. While the modeled Saharan dust plume extent shows a good agreement with the measurements, a systematic underestimation of the marine boundary layer extinction is observed. Additionally, three selected case studies covering different aspects of the Saharan dust long-range transport along the west African coast, over the North Atlantic Ocean and the Caribbean are presented. For the first time, DWL measurements are used to investigate the Saharan dust long-range transport. Simultaneous wind and backscatter measurements from the DWL are used, in combination with the MACC model, to analyze different features associated with the long-range transport, including an African easterly wave trough, the AEJ and the intertropical convergence zone.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    DOI: 10.5194/acp-16-11581-2016
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2016
    detail.hit.zdb_id: 2092549-9
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  • 3
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    Long-term (1999–2019) variability of stratospheric aerosol over Mauna Loa, Hawaii, as seen by two co-located lidars and satellite measurements
    Copernicus GmbH ; 2020
    In:  Atmospheric Chemistry and Physics Vol. 20, No. 11 ( 2020-06-10), p. 6821-6839
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 20, No. 11 ( 2020-06-10), p. 6821-6839
    Abstract: Abstract. As part of the Network for the Detection of Atmospheric Composition Change (NDACC), ground-based measurements obtained from the Jet Propulsion Laboratory (JPL) stratospheric ozone lidar and the NOAA stratospheric aerosol lidar at Mauna Loa, Hawaii, over the past 2 decades were used to investigate the impact of volcanic eruptions and pyrocumulonimbus (PyroCb) smoke plumes on the stratospheric aerosol load above Hawaii since 1999. Measurements at 355 and 532 nm conducted by these two lidars revealed a color ratio of 0.5 for background aerosols and small volcanic plumes and 0.8 for a PyroCb plume recorded on September 2017. Measurements of the Nabro plume by the JPL lidar in 2011–2012 showed a lidar ratio of (64±12.7) sr at 355 nm around the center of the plume. The new Global Space-based Stratospheric Aerosol Climatology (GloSSAC), Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) Level 3 and Stratospheric Aerosol and Gas Experiment III on the International Space Station (SAGE III-ISS) stratospheric aerosol datasets were compared to the ground-based lidar datasets. The intercomparison revealed a generally good agreement, with vertical profiles of extinction coefficient within 50 % discrepancy between 17 and 23 km above sea level (a.s.l.) and 25 % above 23 km a.s.l. The stratospheric aerosol depth derived from all of these datasets shows good agreement, with the largest discrepancy (20 %) being observed between the new CALIOP Level 3 and the other datasets. All datasets consistently reveal a relatively quiescent period between 1999 and 2006, followed by an active period of multiple eruptions (e.g., Nabro) until early 2012. Another quiescent period, with slightly higher aerosol background, lasted until mid-2017, when a combination of extensive wildfires and multiple volcanic eruptions caused a significant increase in stratospheric aerosol loading. This loading maximized at the very end of the time period considered (fall 2019) as a result of the Raikoke eruption, the plume of which ascended to 26 km altitude in less than 3 months.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    DOI: 10.5194/acp-20-6821-2020
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2020
    detail.hit.zdb_id: 2092549-9
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  • 4
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    Evaluation of a method for converting Stratospheric Aerosol and Gas Experiment (SAGE) extinction coefficients to backscatter coefficients for intercomparison with lidar observations
    Copernicus GmbH ; 2020
    In:  Atmospheric Measurement Techniques Vol. 13, No. 8 ( 2020-08-13), p. 4261-4276
    Details
    In: Atmospheric Measurement Techniques, Copernicus GmbH, Vol. 13, No. 8 ( 2020-08-13), p. 4261-4276
    Abstract: Abstract. Aerosol backscatter coefficients were calculated using multiwavelength aerosol extinction products from the SAGE II and III/ISS instruments (SAGE: Stratospheric Aerosol and Gas Experiment). The conversion methodology is presented, followed by an evaluation of the conversion algorithm's robustness. The SAGE-based backscatter products were compared to backscatter coefficients derived from ground-based lidar at three sites (Table Mountain Facility, Mauna Loa, and Observatoire de Haute-Provence). Further, the SAGE-derived lidar ratios were compared to values from previous balloon and theoretical studies. This evaluation includes the major eruption of Mt. Pinatubo in 1991, followed by the atmospherically quiescent period beginning in the late 1990s. Recommendations are made regarding the use of this method for evaluation of aerosol extinction profiles collected using the occultation method.
    Type of Medium: Online Resource
    ISSN: 1867-8548
    URL: Article
    DOI: 10.5194/amt-13-4261-2020
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2020
    detail.hit.zdb_id: 2505596-3
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  • 5
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    The impact of aerosol fluorescence on long-term water vapor monitoring by Raman lidar and evaluation of a potential correction method
    Copernicus GmbH ; 2022
    In:  Atmospheric Measurement Techniques Vol. 15, No. 14 ( 2022-07-22), p. 4241-4256
    Details
    In: Atmospheric Measurement Techniques, Copernicus GmbH, Vol. 15, No. 14 ( 2022-07-22), p. 4241-4256
    Abstract: Abstract. The impact of aerosol fluorescence on the measurement of water vapor by UV (355 nm emission) Raman lidar in the upper troposphere and lower stratosphere (UTLS) is investigated using the long-term records of three high-performance Raman lidars contributing to the Network for the Detection of Atmospheric Composition Change (NDACC). Comparisons with co-located radiosondes and aerosol backscatter profiles indicate that laser-induced aerosol fluorescence in smoke layers injected into the stratosphere by pyrocumulus events can introduce very large and chronic wet biases above 15 km, thus impacting on the ability of these systems to accurately estimate long-term water vapor trends in the UTLS. In order to mitigate the fluorescence contamination, a correction method based on the addition of an aerosol fluorescence channel was developed and tested on the water vapor Raman lidar TMWAL located at the JPL Table Mountain Facility in California. The results of this experiment, conducted between 27 August and 4 November 2021 and involving 22 co-located lidar and radiosonde profiles, suggest that the proposed correction method is able to effectively reduce the fluorescence-induced wet bias. After correction, the average difference between the lidar and co-located radiosonde water vapor measurements was reduced to 5 %, consistent with the difference observed during periods of negligible aerosol fluorescence interference. The present results provide confidence that after a correction is applied, long-term water vapor trends can be reasonably well estimated in the upper troposphere, but they also call for further refinements or use of alternate Raman lidar approaches (e.g., 308 nm or 532 nm emission) to confidently detect long-term trends in the lower stratosphere. These findings may have important implications for NDACC's water vapor measurement strategy in the years to come.
    Type of Medium: Online Resource
    ISSN: 1867-8548
    URL: Article
    DOI: 10.5194/amt-15-4241-2022
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2022
    detail.hit.zdb_id: 2505596-3
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  • 6
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    Observed versus simulated mountain waves over Scandinavia – improvement of vertical winds, energy and momentum fluxes by enhanced model resolution?
    Copernicus GmbH ; 2017
    In:  Atmospheric Chemistry and Physics Vol. 17, No. 6 ( 2017-03-24), p. 4031-4052
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 17, No. 6 ( 2017-03-24), p. 4031-4052
    Abstract: Abstract. Two mountain wave events, which occurred over northern Scandinavia in December 2013 are analysed by means of airborne observations and global and mesoscale numerical simulations with horizontal mesh sizes of 16, 7.2, 2.4 and 0.8 km. During both events westerly cross-mountain flow induced upward-propagating mountain waves with different wave characteristics due to differing atmospheric background conditions. While wave breaking occurred at altitudes between 25 and 30 km during the first event due to weak stratospheric winds, waves propagated to altitudes above 30 km and interfacial waves formed in the troposphere at a stratospheric intrusion layer during the second event. Global and mesoscale simulations with 16 and 7.2 km grid sizes were not able to simulate the amplitudes and wavelengths of the mountain waves correctly due to unresolved mountain peaks. In simulations with 2.4 and 0.8 km horizontal resolution, mountain waves with horizontal wavelengths larger than 15 km were resolved, but exhibited too small amplitudes and too high energy and momentum fluxes. Simulated fluxes could be reduced by either increasing the vertical model grid resolution or by enhancing turbulent diffusion in the model, which is comparable to an improved representation of small-scale nonlinear wave effects.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    DOI: 10.5194/acp-17-4031-2017
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2017
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  • 7
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    COVID‐19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere
    American Geophysical Union (AGU) ; 2021
    In:  Geophysical Research Letters Vol. 48, No. 5 ( 2021-03-16)
    Details
    In: Geophysical Research Letters, American Geophysical Union (AGU), Vol. 48, No. 5 ( 2021-03-16)
    Abstract: In spring and summer 2020, stations in the northern extratropics report on average 7% (4 nmol/mol) less tropospheric ozone than normal Such low tropospheric ozone, over several months, and at so many sites, has not been observed in any previous year since at least 2000 Most of the reduction in tropospheric ozone in 2020 is likely due to emissions reductions related to the COVID‐19 pandemic
    Type of Medium: Online Resource
    ISSN: 0094-8276 , 1944-8007
    URL: Article
    DOI: 10.1029/2020GL091987
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2021
    detail.hit.zdb_id: 2021599-X
    detail.hit.zdb_id: 7403-2
    SSG: 16,13
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  • 8
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    Dust Transport Across the Atlantic Studied by Airborne Doppler Wind Lidar During the Saltrace Experiment in 2013
    EDP Sciences ; 2016
    In:  EPJ Web of Conferences Vol. 119 ( 2016), p. 18008-
    Details
    In: EPJ Web of Conferences, EDP Sciences, Vol. 119 ( 2016), p. 18008-
    Type of Medium: Online Resource
    ISSN: 2100-014X
    URL: Article
    DOI: 10.1051/epjconf/201611918008
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2016
    detail.hit.zdb_id: 2595425-8
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  • 9
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    Upgrade and automation of the JPL Table Mountain Facility tropospheric ozone lidar (TMTOL) for near-ground ozone profiling and satellite validation
    Copernicus GmbH ; 2019
    In:  Atmospheric Measurement Techniques Vol. 12, No. 1 ( 2019-01-28), p. 569-583
    Details
    In: Atmospheric Measurement Techniques, Copernicus GmbH, Vol. 12, No. 1 ( 2019-01-28), p. 569-583
    Abstract: Abstract. As part of international efforts to monitor air quality, several satellite missions such as the Tropospheric Monitoring Instrument (TROPOMI) were deployed and others, like Tropospheric Emissions: Monitoring Pollution (TEMPO), are planned for the near future. In support of the validation of these missions, major upgrades to the tropospheric ozone lidar located at the Jet Propulsion Laboratory Table Mountain Facility (TMF) were recently performed. These modifications include the full automation of the system, which now allows unattended measurements during frequent satellite overpasses, and a new receiver that extends the measurement capabilities of the system down to 100 m above surface. The automation led to the systematic operation of the lidar during daily TROPOMI overpasses, providing more than 139 reference profiles since January 2018. Ozone profiles retrieved using the new lidar receiver were compared to ozonesonde profiles obtained from a co-located tethered balloon. An agreement of about 5 % with the ozonesonde down to an altitude range of 100 m a.g.l. was observed. Furthermore, the stability of the receiver configuration was investigated. Comparisons between the lowest point retrieved by the lidar and a co-located surface ozone photometer showed no sign of drift over a 2-month test period and an agreement better than 10 %. Finally, measurements from a 24 h intensive measurement period during a stratospheric intrusion event showed good agreement with two free-flying ozonesondes. These comparisons revealed localized differences between sonde and lidar, possibly owing to the differing vertical resolutions (between 52 and 380 m for lidar and about 100 m for the sonde).
    Type of Medium: Online Resource
    ISSN: 1867-8548
    URL: Article
    DOI: 10.5194/amt-12-569-2019
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2019
    detail.hit.zdb_id: 2505596-3
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  • 10
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    Monitoring volcanic ash in the atmosphere
    SPIE-Intl Soc Optical Eng ; 2013
    In:  SPIE Newsroom ( 2013-06-17)
    Details
    In: SPIE Newsroom, SPIE-Intl Soc Optical Eng, ( 2013-06-17)
    Type of Medium: Online Resource
    ISSN: 1818-2259
    URL: Article
    DOI: 10.1117/2.1201306.004865
    Language: Unknown
    Publisher: SPIE-Intl Soc Optical Eng
    Publication Date: 2013
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