Search

Your search keyword '"Romanens, Gonzague"' showing total 33 results
Start Over Author "Romanens, Gonzague"
33 results on '"Romanens, Gonzague"'

1. OZONESONDE QUALITY ASSURANCE : The JOSIE–SHADOZ (2017) Experience

Author

Thompson, Anne M., Smit, Herman G. J., Witte, Jacquelyn C., Stauffer, Ryan M., Johnson, Bryan J., Morris, Gary, von der Gathen, Peter, Van Malderen, Roeland, Davies, Jonathan, Piters, Ankie, Allaart, Marc, Posny, Françoise, Kivi, Rigel, Cullis, Patrick, Anh, Nguyen Thi Hoang, Corrales, Ernesto, Machinini, Tshidi, da Silva, Francisco R., Paiman, George, Thiong’o, Kennedy, Zainal, Zamuna, Brothers, George B., Wolff, Katherine R., Nakano, Tatsumi, Stübi, Rene, Romanens, Gonzague, Coetzee, Gert J. R., Diaz, Jorge A., Mitro, Sukarni, Mohamad, Maznorizan, and Ogino, Shin-Ya

Published
2019

3. Homogenization of the long-term global ozonesonde records

Author

Malderen, Roeland van, Poyraz, D., Smit, Herman G. J., Stauffer, Ryan M., Kois, Bogumil, Gathen, Peter von der, Querel, Richard, Ancellet, Gerard, Godin-Beekmann, Sophie, Díaz Rodríguez, Ana María, Hernández Pérez, José Luis, Jepsen, Nis, Kivi, Rigel, Prats Porta, Natalia, Torres, Carlos, Romanens, Gonzague, Stübi, Rene, Steinbrecht, Wolfgang, Allaart, Marc, Piters, Ankie J. M., Tully, Matt, Klikova, B., Motl, M., Skrivánková, Pavla, Lyall, Norrie, Gill, Michael, Oelsner, Peter, Rizi, V., Iarlori, M., Tarasick, David W., Johnson, B. J., and Thompson, Anne M.

Subjects
Homogenization, Stratospheric ozone, Ozonesondes
Abstract

Póster presentado en: WMO Technical Conference on Meteorological and Environmental Instruments and Methods of Observation celebrada del 10 al 13 de octubre de 2022 en París.

Published
2022

5. Validation of aerosol backscatter profiles from Raman lidar and ceilometer using balloon-borne measurements

Author

Brunamonti, Simone, Martucci, Giovanni, Romanens, Gonzague, Poltera, Yann, Wienhold, Frank G., Hervo, Maxime, Haefele, Alexander, and Navas-Guzmán, Francisco

Abstract

Remote-sensing measurements by light detection and ranging (lidar) instruments are fundamental for the monitoring of altitude-resolved aerosol optical properties. Here we validate vertical profiles of aerosol backscatter coefficient (βaer) measured by two independent lidar systems using co-located balloon-borne measurements performed by Compact Optical Backscatter Aerosol Detector (COBALD) sondes. COBALD provides high-precision in situ measurements of βaer at two wavelengths (455 and 940 nm). The two analyzed lidar systems are the research Raman Lidar for Meteorological Observations (RALMO) and the commercial CHM15K ceilometer (Lufft, Germany). We consider in total 17 RALMO and 31 CHM15K profiles, co-located with simultaneous COBALD soundings performed throughout the years 2014–2019 at the MeteoSwiss observatory of Payerne (Switzerland). The RALMO (355 nm) and CHM15K (1064 nm) measurements are converted to 455 and 940 nm, respectively, using the Ångström exponent profiles retrieved from COBALD data. To account for the different receiver field-of-view (FOV) angles between the two lidars (0.01–0.02∘) and COBALD (6∘), we derive a custom-made correction using Mie-theory scattering simulations. Our analysis shows that both lidar instruments achieve on average a good agreement with COBALD measurements in the boundary layer and free troposphere, up to 6 km altitude. For medium-high-aerosol-content measurements at altitudes below 3 km, the mean ± standard deviation difference in βaer calculated from all considered soundings is −2 % ± 37 % (−0.018 ± 0.237 Mm−1 sr−1 at 455 nm) for RALMO−COBALD and +5 % ± 43 % (+0.009 ± 0.185 Mm−1 sr−1 at 940 mm) for CHM15K−COBALD. Above 3 km altitude, absolute deviations generally decrease, while relative deviations increase due to the prevalence of air masses with low aerosol content. Uncertainties related to the FOV correction and spatial- and temporal-variability effects (associated with the balloon's drift with altitude and different integration times) contribute to the large standard deviations observed at low altitudes. The lack of information on the aerosol size distribution and the high atmospheric variability prevent an accurate quantification of these effects. Nevertheless, the excellent agreement observed in individual profiles, including fine and complex structures in the βaer vertical distribution, shows that under optimal conditions, the discrepancies with the in situ measurements are typically comparable to the estimated statistical uncertainties in the remote-sensing measurements. Therefore, we conclude that βaer profiles measured by the RALMO and CHM15K lidar systems are in good agreement with in situ measurements by COBALD sondes up to 6 km altitude., Atmospheric Chemistry and Physics, 21 (3), ISSN:1680-7375, ISSN:1680-7367

Published
2021

6. COVID-19 crisis reduces free tropospheric ozone across the northern hemisphere

Author

Steinbrecht, Wolfgang, Kubistin, Dagmar, Plass-Dülmer, Christian, Davies, Jonathan, Tarasick, David W., von der Gathen, Peter, Deckelmann, Holger, Jepsen, Nis, Kivi, Rigel, Lyall, Norrie, Palm, Matthias, Notholt, Justus, Kois, Bogumil, Oelsner, Peter, Allaart, Marc, Piters, Ankie, Gill, Michael, Van Malderen, Roeland, Delcloo, Andy W., Sussmann, Ralf, Mahieu, Emmanuel, Servais, Christian, Romanens, Gonzague, Stübi, Rene, Ancellet, Gerard, Godin-Beekmann, Sophie, Yamanouchi, Shoma, Strong, Kimberly, Johnson, Bryan, Cullis, Patrick, Petropavlovskikh, Irina, Hannigan, James W., Hernandez, Jose-Luis, Rodriguez, Ana Diaz, Nakano, Tatsumi, Chouza, Fernando, Leblanc, Thierry, Torres, Carlos, Garcia, Omaira, Röhling, Amelie N., Schneider, Matthias, Blumenstock, Thomas, Tully, Matt, Paton-Walsh, Clare, Jones, Nicholas, Querel, Richard, Strahan, Susan, Stauffer, Ryan M., Thompson, Anne M., Inness, Antje, Engelen, Richard, Chang, Kai-Lan, Cooper, Owen R., Steinbrecht, Wolfgang, Kubistin, Dagmar, Plass-Dülmer, Christian, Davies, Jonathan, Tarasick, David W., von der Gathen, Peter, Deckelmann, Holger, Jepsen, Nis, Kivi, Rigel, Lyall, Norrie, Palm, Matthias, Notholt, Justus, Kois, Bogumil, Oelsner, Peter, Allaart, Marc, Piters, Ankie, Gill, Michael, Van Malderen, Roeland, Delcloo, Andy W., Sussmann, Ralf, Mahieu, Emmanuel, Servais, Christian, Romanens, Gonzague, Stübi, Rene, Ancellet, Gerard, Godin-Beekmann, Sophie, Yamanouchi, Shoma, Strong, Kimberly, Johnson, Bryan, Cullis, Patrick, Petropavlovskikh, Irina, Hannigan, James W., Hernandez, Jose-Luis, Rodriguez, Ana Diaz, Nakano, Tatsumi, Chouza, Fernando, Leblanc, Thierry, Torres, Carlos, Garcia, Omaira, Röhling, Amelie N., Schneider, Matthias, Blumenstock, Thomas, Tully, Matt, Paton-Walsh, Clare, Jones, Nicholas, Querel, Richard, Strahan, Susan, Stauffer, Ryan M., Thompson, Anne M., Inness, Antje, Engelen, Richard, Chang, Kai-Lan, and Cooper, Owen R.

Abstract

Throughout spring and summer 2020, ozone stations in the northern extratropics recorded unusually low ozone in the free troposphere. From April to August, and from 1 to 8 kilometers altitude, ozone was on average 7% (≈4 nmol/mol) below the 2000 to 2020 climatological mean. Such low ozone, over several months, and at so many stations, has not been observed in any previous year since at least 2000. Atmospheric composition analyses from the Copernicus Atmosphere Monitoring Service and simulations from the NASA GMI model indicate that the large 2020 springtime ozone depletion in the Arctic stratosphere contributed less than one quarter of the observed tropospheric anomaly. The observed anomaly is consistent with recent chemistry-climate model simulations, which assume emissions reductions similar to those caused by the COVID-19 crisis. COVID-19 related emissions reductions appear to be the major cause for the observed reduced free tropospheric ozone in 2020.

Published
2021

7. Use of automatic radiosonde launchers to measure temperature and humidity profiles from the GRUAN perspective

Author

Madonna, Fabio, Kivi, Rigel, Dupont, Jean-Charles, Ingleby, Bruce, Fujiwara, Masatomo, Romanens, Gonzague, Hernandez, Miguel, Calbet, Xavier, Rosoldi, Marco, Giunta, Aldo, Karppinen, Tomi, Iwabuchi, Masami, Hoshino, Shunsuke, von Rohden, Christoph, Thorne, Peter William, Madonna, Fabio, Kivi, Rigel, Dupont, Jean-Charles, Ingleby, Bruce, Fujiwara, Masatomo, Romanens, Gonzague, Hernandez, Miguel, Calbet, Xavier, Rosoldi, Marco, Giunta, Aldo, Karppinen, Tomi, Iwabuchi, Masami, Hoshino, Shunsuke, von Rohden, Christoph, and Thorne, Peter William

Abstract

In the last two decades, technological progress has not only seen improvements to the quality of atmospheric upper-air observations but also provided the opportunity to design and implement automated systems able to replace measurement procedures typically performed manually. Radiosoundings, which remain one of the primary data sources for weather and climate applications, are still largely performed around the world manually, although increasingly fully automated upper-air observations are used, from urban areas to the remotest locations, which minimize operating costs and challenges in performing radiosounding launches. This analysis presents a first step to demonstrating the reliability of the automatic radiosonde launchers (ARLs) provided by Vaisala, Meteomodem and Meisei. The metadata and datasets collected by a few existing ARLs operated by the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) certified or candidate sites (Sodankylä, Payerne, Trappes, Potenza) have been investigated and a comparative analysis of the technical performance (i.e. manual versus ARL) is reported. The performance of ARLs is evaluated as being similar or superior to those achieved with the traditional manual launches in terms of percentage of successful launches, balloon burst and ascent speed. For both temperature and relative humidity, the ground-check comparisons showed a negative bias of a few tenths of a degree and % RH, respectively. Two datasets of parallel soundings between manual and ARL-based measurements, using identical sonde models, provided by Sodankylä and Faa'a stations, showed mean differences between the ARL and manual launches smaller than ±0.2 K up to 10 hPa for the temperature profiles. For relative humidity, differences were smaller than 1 % RH for the Sodankylä dataset up to 300 hPa, while they were smaller than 0.7 % RH for Faa'a station. Finally, the observation-minus-background (O–B) mean and root mean square (rms) statistics for Ger

Published
2020

8. COVID‐19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere

Author

Steinbrecht, Wolfgang, primary, Kubistin, Dagmar, additional, Plass‐Dülmer, Christian, additional, Davies, Jonathan, additional, Tarasick, David W., additional, von der Gathen, Peter, additional, Deckelmann, Holger, additional, Jepsen, Nis, additional, Kivi, Rigel, additional, Lyall, Norrie, additional, Palm, Matthias, additional, Notholt, Justus, additional, Kois, Bogumil, additional, Oelsner, Peter, additional, Allaart, Marc, additional, Piters, Ankie, additional, Gill, Michael, additional, Van Malderen, Roeland, additional, Delcloo, Andy W., additional, Sussmann, Ralf, additional, Mahieu, Emmanuel, additional, Servais, Christian, additional, Romanens, Gonzague, additional, Stübi, Rene, additional, Ancellet, Gerard, additional, Godin‐Beekmann, Sophie, additional, Yamanouchi, Shoma, additional, Strong, Kimberly, additional, Johnson, Bryan, additional, Cullis, Patrick, additional, Petropavlovskikh, Irina, additional, Hannigan, James W., additional, Hernandez, Jose‐Luis, additional, Diaz Rodriguez, Ana, additional, Nakano, Tatsumi, additional, Chouza, Fernando, additional, Leblanc, Thierry, additional, Torres, Carlos, additional, Garcia, Omaira, additional, Röhling, Amelie N., additional, Schneider, Matthias, additional, Blumenstock, Thomas, additional, Tully, Matt, additional, Paton‐Walsh, Clare, additional, Jones, Nicholas, additional, Querel, Richard, additional, Strahan, Susan, additional, Stauffer, Ryan M., additional, Thompson, Anne M., additional, Inness, Antje, additional, Engelen, Richard, additional, Chang, Kai‐Lan, additional, and Cooper, Owen R., additional

Published
2021
Full Text
View/download PDF

12. Did the COVID-19 Crisis Reduce Free Tropospheric Ozone across the Northern Hemisphere?

Author

Steinbrecht, Wolfgang, primary, Kubistin, Dagmar, additional, Plass-Dulmer, Christian, additional, Tarasick, David W., additional, Davies, Jonathan, additional, von der Gathen, Peter, additional, Deckelmann, Holger, additional, Jepsen, Nis, additional, Kivi, Rigel, additional, Lyall, Norrie, additional, Palm, Mathias, additional, Notholt, Justus, additional, Kois, Bogumil, additional, Oelsner, Peter, additional, Allaart, Marc, additional, Piters, Ankie, additional, Gill, Michael, additional, Van Malderen, Roeland, additional, Delcloo, Andy, additional, Sussmann, Ralf, additional, Servais, Christian, additional, Mahieu, Emmanuel, additional, Romanens, Gonzague, additional, Stübi, René, additional, Ancellet, Gerard, additional, Godin-Beekmann, Sophie, additional, Yamanouchi, Shoma, additional, Strong, Kimberly, additional, Johnson, Bryan J. J., additional, Cullis, Patrick, additional, Petropavlovskikh, Irina, additional, Hannigan, James W, additional, Hernandez, Jose-Luis, additional, Rodriguez, Ana Diaz, additional, Nakano, Tatsumi, additional, Leblanc, Thierry, additional, Chouza, Fernando, additional, Torres, Carlos, additional, García, Omaira, additional, Röhling, Amelie, additional, Schneider, Matthias, additional, Blumenstock, Thomas, additional, Tully, Matthew Brian, additional, Paton-Walsh, Clare, additional, Jones, Nicholas Brian, additional, Querel, Richard, additional, Strahan, Susan E, additional, Inness, Antje, additional, Engelen, Richard J., additional, Chang, Kai-Lan, additional, Cooper, Owen R. R., additional, Stauffer, Ryan Michael, additional, and Thompson, Anne M., additional

Published
2020
Full Text
View/download PDF

14. Use of automatic radiosonde launchers to measure temperature and humidity profiles from the GRUAN perspective

Author

Madonna, Fabio, primary, Kivi, Rigel, additional, Dupont, Jean-Charles, additional, Ingleby, Bruce, additional, Fujiwara, Masatomo, additional, Romanens, Gonzague, additional, Hernandez, Miguel, additional, Calbet, Xavier, additional, Rosoldi, Marco, additional, Giunta, Aldo, additional, Karppinen, Tomi, additional, Iwabuchi, Masami, additional, Hoshino, Shunsuke, additional, von Rohden, Christoph, additional, and Thorne, Peter William, additional

Published
2020
Full Text
View/download PDF

17. DVAS -Data Visualization and Analysis Software: processing and analysis of the radiosounding data for the next WMO Upper-Air Instruments Intercomparaison - UAII2021.

Author

Martucci, Giovanni, primary, Dirksen, Ruud, additional, Romanens, Gonzague, additional, Haefele, Alexander, additional, Vogt, Frédéric P.A., additional, Sommer, Michael, additional, Félix, Christian, additional, Lehmann, Volker, additional, Voemel, Holger, additional, Edwards, David, additional, Taylor, Stewart, additional, Gardiner, Tom, additional, Ansari, Mohd. Imran, additional, Mahmoud, Emad Eldin, additional, Oakley, Tim, additional, Ruedi, Isabelle, additional, Premec, Krunoslav, additional, Berger, Franz, additional, and Calpini, Bertrand, additional

Published
2020
Full Text
View/download PDF

18. Radiosondes Show That After Decades of Cooling, the Lower Stratosphere Is Now Warming

Author

Philipona, Rolf, Mears, Carl, Fujiwara, Masatomo, Jeannet, Pierre, Thorne, Peter, Bodeker, Greg, Haimberger, Leopold, Hervo, Maxime, Popp, Christoph, Romanens, Gonzague, Steinbrecht, Wolfgang, Stübi, Rene, Van Malderen, Roeland, Philipona, Rolf, Mears, Carl, Fujiwara, Masatomo, Jeannet, Pierre, Thorne, Peter, Bodeker, Greg, Haimberger, Leopold, Hervo, Maxime, Popp, Christoph, Romanens, Gonzague, Steinbrecht, Wolfgang, Stübi, Rene, and Van Malderen, Roeland

Abstract

Since the mid-twentieth century, radiosonde and satellite measurements show that the troposphere has warmed and the stratosphere has cooled. These changes are primarily due to increasing concentrations of well-mixed greenhouse gases and the depletion of stratospheric ozone. In response to continued greenhouse gas increases and stratospheric ozone depletion, climate models project continued tropospheric warming and stratospheric cooling over the coming decades. Global average satellite observations of lower stratospheric temperatures exhibit no significant trends since the turn of the century. In contrast, an analysis of vertically resolved radiosonde measurements from 60 stations shows an increase of lower stratospheric temperature since the turn of the century at altitudes between 15 and 30 km and over most continents. Trend estimates are somewhat sensitive to homogeneity assessment choices, but all investigated radiosonde data sets suggest a change from late twentieth century cooling to early 21st century warming in the lower stratosphere, which is consistent with a reversal from ozone depletion to recovery from the effects of ozone-depleting substances. In comparison, satellite observations at the radiosonde locations show only minor early 21st century warming, possibly due to the compensating effects of continued cooling above the radiosonde altitude range.

Published
2018

19. Radiosondes Show That After Decades of Cooling, the Lower Stratosphere Is Now Warming

Author

Philipona, R., Mears, Carl A., Fujiwara, Masatomo, Jeannet, Pierre, Thorne, Peter, Bodeker, Greg, Haimberger, L., Hervo, Maxime, Popp, Christoph, Romanens, Gonzague, Steinbrecht, Wolfgang, Stübi, Rene, Van Malderen, Roeland, Philipona, R., Mears, Carl A., Fujiwara, Masatomo, Jeannet, Pierre, Thorne, Peter, Bodeker, Greg, Haimberger, L., Hervo, Maxime, Popp, Christoph, Romanens, Gonzague, Steinbrecht, Wolfgang, Stübi, Rene, and Van Malderen, Roeland

Abstract

Since the mid-twentieth century, radiosonde and satellite measurements show that the troposphere has warmed and the stratosphere has cooled. These changes are primarily due to increasing concentrations of well-mixed greenhouse gases and the depletion of stratospheric ozone. In response to continued greenhouse gas increases and stratospheric ozone depletion, climate models project continued tropospheric warming and stratospheric cooling over the coming decades. Global average satellite observations of lower stratospheric temperatures exhibit no significant trends since the turn of the century. In contrast, an analysis of vertically resolved radiosonde measurements from 60 stations shows an increase of lower stratospheric temperature since the turn of the century at altitudes between 15 and 30 km and over most continents. Trend estimates are somewhat sensitive to homogeneity assessment choices, but all investigated radiosonde data sets suggest a change from late twentieth century cooling to early 21st century warming in the lower stratosphere, which is consistent with a reversal from ozone depletion to recovery from the effects of ozone-depleting substances. In comparison, satellite observations at the radiosonde locations show only minor early 21st century warming, possibly due to the compensating effects of continued cooling above the radiosonde altitude range.

Published
2018

20. Validation of temperature data from the RAman Lidar for Meteorological Observations (RALMO) at Payerne. An application to liquid cloud supersaturation.

Author

Martucci, Giovanni, Navas-Guzman, Francisco, Renaud, Ludovic, Romanens, Gonzague, Gamage, S. Mahagammulla, Hervo, Maxime, Jeannet, Pierre, and Haefele, Alexander

Subjects
METEOROLOGICAL observations, CLOUD computing, SUPERSATURATION, NUMERICAL weather forecasting, STRATUS clouds
Abstract

The RAman Lidar for Meteorological Observations (RALMO) is operated at the MeteoSwiss station of Payerne (Switzerland) and provides, amongst other products, continuous measurements of temperature since 2010. The temperature profiles are retrieved from the pure rotational Raman (PRR) signals detected around the 355-nm Cabannes line. The transmitter-receiver system of RALMO is described in detail and the reception and acquisition units of the PRR channels are thoroughly characterized. The FastCom P7888 card used to acquire the PRR signal, the calculation of the dead-time and the desaturation procedure are also presented. The temperature profiles retrieved from RALMO data during the period going from July 2017 to the end of December 2018 have been validated against two reference operational radiosounding systems (ORS) co-located with RALMO, i.e. the Meteolabor SRS-C50 and the Vaisala RS41. These radiosondes have also been used to perform seven calibrations during the validation period. The maximum bias (ΔTmax), mean bias (μ) and mean standard deviation (σ) of RALMO temperature Tral with respect to the reference ORS Tors are used to characterize the accuracy and precision of Tral in the troposphere. The ΔTmax, μ and σ of the daytime differences ΔT=Tral−Tors in the lower troposphere are 0.28 K, 0.02±0.1 K and 0.62±0.03 K, respectively. The nighttime differences suffer a mean bias of μ = 0.05±0.34 K, a mean standard deviation σ=0.66±0.06 , and a maximum bias ΔTmax=0.29 K over the whole troposphere. The small ΔTmax, μ and σ values obtained for both daytime and nighttime comparisons indicate the high stability of RALMO that has been calibrated only seven times over 18 months. The retrieval method can correct for the largest sources of correlated and uncorrelated errors, e.g. signal noise, dead-time of the acquisition system and solar background. Especially the solar radiation (scattered into the field of view from the Zenith angle Phi affects the quality of PRR signals and represents a source of systematic error for the retrieved temperature. An imperfect subtraction of the background from the daytime PRR profiles induces a bias of up to 2 K at all heights. An empirical correction f(Φ) ranging from 0.99 to 1, has therefore been applied to the mean background of the PRR signals to remove the bias. The correction function f(Φ) has been validated against the numerical weather prediction model COSMO suggesting that f(Φ) does not introduce any additional source of systematic or random error to Tral. A seasonality study has been performed to help understanding if the overall daytime and nighttime zero-bias hides seasonal non-zero biases that cancel out when combined in the full dataset. Finally, the validated RALMO temperature has been used in combination with the humidity profiles retrieved from RALMO to calculate the relative humidity and to perform a qualitative study of supersaturation occurring in liquid stratus clouds. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

21. Effects of the prewhitening method, the time granularity and the time segmentation on the Mann-Kendall trend detection and the associated Sen's slope.

Author

Coen, Martine Collaud, Andrews, Elisabeth, Bigi, Alesssandro, Romanens, Gonzague, Martucci, Giovanni, and Vuilleumier, Laurent

Subjects
TREND analysis, TIME series analysis, STATISTICAL significance, CONFIDENCE intervals, ABSORPTION coefficients, OPTICAL depth (Astrophysics)
Abstract

The most widely used non-parametric method for trend analysis is the Mann-Kendall test associated with the Sen's slope. The Mann-Kendall test requires serially uncorrelated time series, whereas most of the atmospheric processes exhibit positive autocorrelation. Several prewhitening methods have been designed to overcome the presence of lag-1 autocorrelation. These include a prewhitening, a detrending and/or a correction for the detrended slope and the original variance of the time series. The choice of which prewhitening method and temporal segmentation to apply has consequences for the statistical significance, the value of the slope and of the confidence limits. Here, the effects of various prewhitening methods are analyzed for seven time series comprising in-situ aerosol measurements (scattering coefficient, absorption coefficient, number concentration and aerosol optical depth), Raman Lidar water vapor mixing ratio and the tropopause and zero degree levels measured by radio-sounding. These time series are characterized by a broad variety of distributions, ranges and lag-1 autocorrelation values and vary in length between 10 and 60 years. A common way to work around the autocorrelation problem is to decrease it by averaging the data over longer time intervals than in the original time series. Thus, the second focus of this study is evaluation of the effect of time granularity on long-term trend analysis. Finally, a new algorithm involving three prewhitening methods is proposed in order to maximize the power of the test, to minimize the amount of erroneous detected trends in the absence of a real trend and to ensure the best slope estimate for the considered length of the time series. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

22. Validation of aerosol backscatter profiles from Raman lidar and ceilometer using balloon-borne measurements.

Author

Brunamonti, Simone, Martucci, Giovanni, Romanens, Gonzague, Poltera, Yann, Wienhold, Frank G., Haefele, Alexander, and Navas-Guzmán, Francisco

Abstract

Remote sensing measurements by light detection and ranging (lidar) instruments are fundamental for the monitoring of altitude-resolved aerosol optical properties. Here, we validate vertical profiles of aerosol backscatter coefficient (βaer) measured by two independent lidar systems using co-located balloon-borne measurements performed by Compact Optical Backscatter Aerosol Detector (COBALD) sondes. COBALD provides high-precision in-situ measurements of βaer at two wavelengths (455 and 940 nm). The two analyzed lidar systems are the research Raman Lidar for Meteorological Observations (RALMO) and the commercial CHM15K ceilometer (Lufft, Germany). We consider in total 17 RALMO and 31 CHM15K profiles, co-located with simultaneous COBALD soundings performed throughout the years 2014-2019 at the MeteoSwiss observatory of Payerne (Switzerland). The RALMO (355 nm) and CHM15K (1064 nm) measurements are converted to respectively 455 nm and 940 nm using the Angstrom exponent profiles retrieved from COBALD data. To account for the different receiver field of view (FOV) angles between the two lidars (0.01-0.02°) and COBALD (6°), we derive a custom-made correction using Mie-theory scattering simulations. Our analysis shows that both RALMO and CHM15K achieve a good agreement with COBALD measurements in the boundary layer and free troposphere, up to 6 km altitude, and including fine structures in the aerosol's vertical distribution. For altitudes below 2 km, the mean ± standard deviation difference in βaer is + 6 % ± 40 % (+ 0.005 ± 0.319 Mm-1 sr-1) for RALMO - COBALD at 455 nm, and + 13 % ± 51 % (+ 0.038 ± 0.207 Mm-1 sr-1) for CHM15K - COBALD at 940 nm. The large standard deviations can be at least partly attributed to atmospheric variability effects, associated with the balloon's horizontal drift with altitude (away from the lidar beam) and the different integration times of the two techniques. Combined with the high spatial and temporal variability of atmospheric aerosols, these effects often lead to a slight altitude displacement between aerosol backscatter features that are seen by both techniques. For altitudes between 2-6 km, the absolute standard deviations of both RALMO and CHM15K decrease (below 0.13 and 0.16 Mm-1sr-1, respectively), while their corresponding relative deviations increase (often exceeding 100 % COBALD of the signal). This is due to the low aerosol content (i.e. low absolute backscattered signal) in the free troposphere, and the vertically decreasing signal-to-noise ratio of the lidar measurements (especially CHM15K). Overall, we conclude that the βaer profiles measured by the RALMO and CHM15K lidar systems are in good agreement with in-situ measurements by COBALD sondes up to 6 km altitude. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

23. Radiosondes Show That After Decades of Cooling, the Lower Stratosphere Is Now Warming

Author

Philipona, Rolf, primary, Mears, Carl, additional, Fujiwara, Masatomo, additional, Jeannet, Pierre, additional, Thorne, Peter, additional, Bodeker, Greg, additional, Haimberger, Leopold, additional, Hervo, Maxime, additional, Popp, Christoph, additional, Romanens, Gonzague, additional, Steinbrecht, Wolfgang, additional, Stübi, Rene, additional, and Van Malderen, Roeland, additional

Published
2018
Full Text
View/download PDF

24. Controlled weather balloon ascents and descents for atmospheric research and climate monitoring

Author

Kräuchi, Andreas, Philipona, Rolf, Romanens, Gonzague, Hurst, Dale F., Hall, Emrys G., and Jordan, Allen F.

Abstract

In situ upper-air measurements are often made with instruments attached to weather balloons launched at the surface and lifted into the stratosphere. Present-day balloon-borne sensors allow near-continuous measurements from the Earth's surface to about 35km (3–5hPa), where the balloons burst and their instrument payloads descend with parachutes. It has been demonstrated that ascending weather balloons can perturb the air measured by very sensitive humidity and temperature sensors trailing behind them, particularly in the upper troposphere and lower stratosphere (UTLS). The use of controlled balloon descent for such measurements has therefore been investigated and is described here. We distinguish between the single balloon technique that uses a simple automatic valve system to release helium from the balloon at a preset ambient pressure, and the double balloon technique that uses a carrier balloon to lift the payload and a parachute balloon to control the descent of instruments after the carrier balloon is released at preset altitude. The automatic valve technique has been used for several decades for water vapor soundings with frost point hygrometers, whereas the double balloon technique has recently been re-established and deployed to measure radiation and temperature profiles through the atmosphere. Double balloon soundings also strongly reduce pendulum motion of the payload, stabilizing radiation instruments during ascent. We present the flight characteristics of these two ballooning techniques and compare the quality of temperature and humidity measurements made during ascent and descent., Atmospheric Measurement Techniques, 9 (3), ISSN:1867-1381, ISSN:1867-8548

Published
2016

25. How stratospheric are deep stratospheric intrusions? LUAMI 2008

Author

Trickl, Thomas, primary, Vogelmann, Hannes, additional, Fix, Andreas, additional, Schäfler, Andreas, additional, Wirth, Martin, additional, Calpini, Bertrand, additional, Levrat, Gilbert, additional, Romanens, Gonzague, additional, Apituley, Arnoud, additional, Wilson, Keith M., additional, Begbie, Robert, additional, Reichardt, Jens, additional, Vömel, Holger, additional, and Sprenger, Michael, additional

Published
2016
Full Text
View/download PDF

26. How stratospheric are deep stratospheric intrusions? − LUAMI 2008

Author

Trickl, Thomas, primary, Vogelmann, Hannes, additional, Fix, Andreas, additional, Schäfler, Andreas, additional, Wirth, Martin, additional, Calpini, Bertrand, additional, Levrat, Gilbert, additional, Romanens, Gonzague, additional, Apituley, Arnoud, additional, Wilson, Keith M., additional, Begbie, Robert, additional, Reichardt, Jens, additional, Vömel, Holger, additional, and Sprenger, Michael, additional

Published
2016
Full Text
View/download PDF

27. How stratospheric are deep stratospheric intrusions? − LUAMI 2008.

Author

Trickl, Thomas, Vogelmann, Hannes, Fix, Andreas, Schäfler, Andreas, Wirth, Martin, Calpini, Bertrand, Levrat, Gilbert, Romanens, Gonzague, Apituley, Arnoud, Wilson, Keith M., Begbie, Robert, Reichardt, Jens, Vömel, Holger, and Sprenger, Michael

Abstract

A large-scale comparison of water-vapour vertical-sounding instruments took place over Central Europe on 17 October 2008, during a rather homogeneous deep stratospheric intrusion event (LUAMI, Lindenberg Upper-Air Methods Intercomparison). The measurements were carried out at four observational sites, Payerne (Switzerland), Bilthoven (The Netherlands), Lindenberg (North-East Germany) and the Zugspitze mountain (Garmisch-Partenkichen, German Alps), and by an air-borne water-vapour lidar system creating a transect of humidity profiles between all four stations. A high data quality was verified that strongly underlines the scientific findings. The intrusion layer was very dry with minimum mixing ratios of 0 to 65 ppm on its lower west side, but did not drop below 120 ppm on the higher-lying east side (Lindenberg). The dryness hardens the findings of a preceding study ("Part 1") that, e.g., 73% of deep intrusions reaching the German Alps and travelling six days and less exhibit minimum mixing ratios of 50 ppm and less. These low values reflect values found in the lowermost stratosphere and indicate very slow mixing with tropospheric air during the downward transport to the lower troposphere. The peak ozone values were around 70 ppb, confirming the idea that intrusion layers depart from the lowermost edge of the stratosphere. The data suggest an increase of ozone from the lower to the higher edge of the intrusion layer. This behaviour is also confirmed by stratospheric aerosol caught in the layer. Both observations are in agreement with the idea that sections of the vertical distributions of these constituents in the the source region were transferred to Central Europe without major change. LAGRANTO trajectory calculations demonstrated a rather shallow outflow the stratosphere from just above the dynamical tropopause, for the first time confirming the conclusions in "Part 1" from the Zugspitze CO observations. The trajectories qualitatively explain the temporal evolution of the intrusion layers above the four stations participating in the campaign. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

29. COVID‐19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere

Author

Steinbrecht, Wolfgang, Kubistin, Dagmar, Plass‐Dülmer, Christian, Davies, Jonathan, Tarasick, David W., Gathen, Peter Von Der, Deckelmann, Holger, Jepsen, Nis, Kivi, Rigel, Lyall, Norrie, Palm, Matthias, Notholt, Justus, Kois, Bogumil, Oelsner, Peter, Allaart, Marc, Piters, Ankie, Gill, Michael, Van Malderen, Roeland, Delcloo, Andy W., Sussmann, Ralf, Mahieu, Emmanuel, Servais, Christian, Romanens, Gonzague, Stübi, Rene, Ancellet, Gerard, Godin‐Beekmann, Sophie, Yamanouchi, Shoma, Strong, Kimberly, Johnson, Bryan, Cullis, Patrick, Petropavlovskikh, Irina, Hannigan, James W., Hernandez, Jose‐Luis, Diaz Rodriguez, Ana, Nakano, Tatsumi, Chouza, Fernando, Leblanc, Thierry, Torres, Carlos, Garcia, Omaira, Röhling, Amelie N., Schneider, Matthias, Blumenstock, Thomas, Tully, Matt, Paton‐Walsh, Clare, Jones, Nicholas, Querel, Richard, Strahan, Susan, Stauffer, Ryan M., Thompson, Anne M., Inness, Antje, Engelen, Richard, Chang, Kai‐Lan, and Cooper, Owen R.

Subjects
13. Climate action
Abstract

Throughout spring and summer 2020, ozone stations in the northern extratropics recorded unusually low ozone in the free troposphere. From April to August, and from 1 to 8 kilometers altitude, ozone was on average 7% (≈4 nmol/mol) below the 2000–2020 climatological mean. Such low ozone, over several months, and at so many stations, has not been observed in any previous year since at least 2000. Atmospheric composition analyses from the Copernicus Atmosphere Monitoring Service and simulations from the NASA GMI model indicate that the large 2020 springtime ozone depletion in the Arctic stratosphere contributed less than one‐quarter of the observed tropospheric anomaly. The observed anomaly is consistent with recent chemistry‐climate model simulations, which assume emissions reductions similar to those caused by the COVID‐19 crisis. COVID‐19 related emissions reductions appear to be the major cause for the observed reduced free tropospheric ozone in 2020.

30. COVID‐19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere

Author

Steinbrecht, Wolfgang, Kubistin, Dagmar, Plass‐Dülmer, Christian, Davies, Jonathan, Tarasick, David W., Gathen, Peter Von Der, Deckelmann, Holger, Jepsen, Nis, Kivi, Rigel, Lyall, Norrie, Palm, Matthias, Notholt, Justus, Kois, Bogumil, Oelsner, Peter, Allaart, Marc, Piters, Ankie, Gill, Michael, Van Malderen, Roeland, Delcloo, Andy W., Sussmann, Ralf, Mahieu, Emmanuel, Servais, Christian, Romanens, Gonzague, Stübi, Rene, Ancellet, Gerard, Godin‐Beekmann, Sophie, Yamanouchi, Shoma, Strong, Kimberly, Johnson, Bryan, Cullis, Patrick, Petropavlovskikh, Irina, Hannigan, James W., Hernandez, Jose‐Luis, Diaz Rodriguez, Ana, Nakano, Tatsumi, Chouza, Fernando, Leblanc, Thierry, Torres, Carlos, Garcia, Omaira, Röhling, Amelie N., Schneider, Matthias, Blumenstock, Thomas, Tully, Matt, Paton‐Walsh, Clare, Jones, Nicholas, Querel, Richard, Strahan, Susan, Stauffer, Ryan M., Thompson, Anne M., Inness, Antje, Engelen, Richard, Chang, Kai‐Lan, and Cooper, Owen R.

Subjects
13. Climate action
Abstract

Throughout spring and summer 2020, ozone stations in the northern extratropics recorded unusually low ozone in the free troposphere. From April to August, and from 1 to 8 kilometers altitude, ozone was on average 7% (≈4 nmol/mol) below the 2000–2020 climatological mean. Such low ozone, over several months, and at so many stations, has not been observed in any previous year since at least 2000. Atmospheric composition analyses from the Copernicus Atmosphere Monitoring Service and simulations from the NASA GMI model indicate that the large 2020 springtime ozone depletion in the Arctic stratosphere contributed less than one‐quarter of the observed tropospheric anomaly. The observed anomaly is consistent with recent chemistry‐climate model simulations, which assume emissions reductions similar to those caused by the COVID‐19 crisis. COVID‐19 related emissions reductions appear to be the major cause for the observed reduced free tropospheric ozone in 2020., Plain Language Summary: Worldwide actions to contain the COVID‐19 virus have closed factories, grounded airplanes, and have generally reduced travel and transportation. Less fuel was burnt, and less exhaust was emitted into the atmosphere. Due to these measures, the concentration of nitrogen oxides and volatile organic compounds (VOCs) decreased in the atmosphere. These substances are important for photochemical production and destruction of ozone in the atmosphere. In clean or mildly polluted air, reducing nitrogen oxides and/or VOCs will reduce the photochemical production of ozone and result in less ozone. In heavily polluted air, in contrast, reducing nitrogen oxides can increase ozone concentrations, because less nitrogen oxide is available to destroy ozone. In this study, we use data from three types of ozone instruments, but mostly from ozonesondes on weather balloons. The sondes fly from the ground up to 30 kilometers altitude. In the first 8 km, we find significantly reduced ozone concentrations in the northern extratropics during spring and summer of 2020, less than in any other year since at least 2000. We suggest that reduced emissions due to the COVID‐19 crisis have lowered photochemical ozone production and have caused the observed ozone reductions in the troposphere., Key Points: 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, NASA | Earth Sciences Division (NASA Earth Science Division) http://dx.doi.org/10.13039/100014573, Gouvernement du Canada | Natural Sciences and Engineering Research Council of Canada (NSERC) http://dx.doi.org/10.13039/501100000038, Australian Research Council, Fonds De La Recherche Scientifique ‐ FNRS (FNRS) http://dx.doi.org/10.13039/501100002661, Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659, Bundesministerium für Wirtschaft und Energie (BMWi) http://dx.doi.org/10.13039/501100006360

32. COVID‐19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere

Author

Marc Allaart, Susan E. Strahan, Ryan M. Stauffer, Richard Querel, Anne M. Thompson, Nicholas B. Jones, Clare Paton-Walsh, Patrick Cullis, Tatsumi Nakano, Bryan J. Johnson, Gérard Ancellet, Thomas Blumenstock, Ankie Piters, Holger Deckelmann, Omaira García, Matthias Palm, Roeland Van Malderen, Kai-Lan Chang, Nis Jepsen, Antje Inness, M.B. Tully, Ralf Sussmann, Amelie N. Röhling, Gonzague Romanens, Dagmar Kubistin, Ana Diaz Rodriguez, Fernando Chouza, René Stübi, Owen R. Cooper, Emmanuel Mahieu, Kimberly Strong, Christian Plass-Dülmer, Jonathan Davies, Richard Engelen, Peter Oelsner, David W. Tarasick, Peter von der Gathen, Jose-Luis Hernandez, Michael Gill, Justus Notholt, Thierry Leblanc, Christian Servais, Irina Petropavlovskikh, Matthias Schneider, Norrie Lyall, Rigel Kivi, Carlos Torres, Shoma Yamanouchi, Sophie Godin-Beekmann, Bogumil Kois, James W. Hannigan, Wolfgang Steinbrecht, Andy Delcloo, Deutscher Wetterdienst [Offenbach] (DWD), Environment and Climate Change Canada, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Danish Meteorological Institute (DMI), Finnish Meteorological Institute (FMI), Met Office Lerwick, Universität Bremen, Institute of Meteorology and Water Management - National Research Institute (IMGW - PIB), Royal Netherlands Meteorological Institute (KNMI), Irish Meteorological Service (MET ÉIREANN), Institut Royal Météorologique de Belgique [Bruxelles] (IRM), Institut für Meteorologie und Klimaforschung - Atmosphärische Umweltforschung (IMK-IFU), Karlsruher Institut für Technologie (KIT), Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Federal Office of Meteorology and Climatology MeteoSwiss, TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), STRATO - LATMOS, University of Toronto, ESRL Global Monitoring Laboratory [Boulder] (GML), NOAA Earth System Research Laboratory (ESRL), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado [Boulder]-National Oceanic and Atmospheric Administration (NOAA), National Center for Atmospheric Research [Boulder] (NCAR), Agencia Estatal de Meteorología (AEMet), Meteorological Research Institute [Tsukuba] (MRI), Japan Meteorological Agency (JMA), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Institut für Meteorologie und Klimaforschung - Atmosphärische Spurengase und Fernerkundung (IMK-ASF), Australian Bureau of Meteorology [Melbourne] (BoM), Australian Government, University of Wollongong [Australia], National Institute of Water and Atmospheric Research [Lauder] (NIWA), GSFC Earth Sciences Division, NASA Goddard Space Flight Center (GSFC), Earth Science System Interdisciplinary Center [College Park] (ESSIC), College of Computer, Mathematical, and Natural Sciences [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System-University of Maryland [College Park], University of Maryland System-University of Maryland System, European Centre for Medium-Range Weather Forecasts (ECMWF), NOAA Chemical Sciences Laboratory (CSL), National Oceanic and Atmospheric Administration (NOAA), University of Wollongong, GFSC Earth Sciences Division, Kubistin, Dagmar, 1 Deutscher Wetterdienst Hohenpeißenberg Germany, Plass‐Dülmer, Christian, Davies, Jonathan, 2 Environment and Climate Change Canada Toronto ONT Canada, Tarasick, David W., Gathen, Peter von der, 3 Alfred Wegener Institut Helmholtz‐Zentrum für Polar‐ und Meeresforschung Potsdam Germany, Deckelmann, Holger, Jepsen, Nis, 4 Danish Meteorological Institute Copenhagen Denmark, Kivi, Rigel, 5 Finnish Meteorological Institute Sodankylä Finland, Lyall, Norrie, 6 British Meteorological Service Lerwick UK, Palm, Matthias, 7 University of Bremen Bremen Germany, Notholt, Justus, Kois, Bogumil, 8 Institute of Meteorology and Water Management Legionowo Poland, Oelsner, Peter, 9 Deutscher Wetterdienst Lindenberg Germany, Allaart, Marc, 10 Royal Netherlands Meteorological Institute DeBilt The Netherlands, Piters, Ankie, Gill, Michael, 11 Met Éireann (Irish Met. Service) Valentia Ireland, Van Malderen, Roeland, 12 Royal Meteorological Institute of Belgium Uccle Belgium, Delcloo, Andy W., Sussmann, Ralf, 13 Karlsruhe Institute of Technology IMK‐IFU Garmisch‐Partenkirchen Germany, Mahieu, Emmanuel, 14 Institute of Astrophysics and Geophysics University of Liège Liège Belgium, Servais, Christian, Romanens, Gonzague, 15 Federal Office of Meteorology and Climatology MeteoSwiss Payerne Switzerland, Stübi, Rene, Ancellet, Gerard, 16 LATMOS Sorbonne Université‐UVSQ‐CNRS/INSU Paris France, Godin‐Beekmann, Sophie, Yamanouchi, Shoma, 17 University of Toronto Toronto ONT Canada, Strong, Kimberly, Johnson, Bryan, 18 NOAA ESRL Global Monitoring Laboratory Boulder CO USA, Cullis, Patrick, Petropavlovskikh, Irina, Hannigan, James W., 20 National Center for Atmospheric Research Boulder CO USA, Hernandez, Jose‐Luis, 21 State Meteorological Agency (AEMET) Madrid Spain, Diaz Rodriguez, Ana, Nakano, Tatsumi, 22 Meteorological Research Institute Tsukuba Japan, Chouza, Fernando, 23 Jet Propulsion Laboratory California Institute of Technology Table Mountain Facility Wrightwood CA USA, Leblanc, Thierry, Torres, Carlos, 24 Izaña Atmospheric Research Center AEMET Tenerife Spain, Garcia, Omaira, Röhling, Amelie N., 25 Karlsruhe Institute of Technology IMK‐ASF Karlsruhe Germany, Schneider, Matthias, Blumenstock, Thomas, Tully, Matt, 26 Bureau of Meteorology Melbourne Australia, Paton‐Walsh, Clare, 27 Centre for Atmospheric Chemistry University of Wollongong Wollongong Australia, Jones, Nicholas, Querel, Richard, 28 National Institute of Water and Atmospheric Research Lauder New Zealand, Strahan, Susan, 29 NASA Goddard Space Flight Center Earth Sciences Division Greenbelt MD USA, Stauffer, Ryan M., Thompson, Anne M., Inness, Antje, 32 European Centre for Medium‐Range Weather Forecasts Reading UK, Engelen, Richard, Chang, Kai‐Lan, 19 Cooperative Institute for Research in Environmental Sciences (CIRES) University of Colorado Boulder CO USA, and Cooper, Owen R.

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Pollution: Urban, Regional and Global, Atmospheric Composition and Structure, Biogeosciences, 010502 geochemistry & geophysics, Atmospheric sciences, [SDV.MHEP.PSR]Life Sciences [q-bio]/Human health and pathology/Pulmonology and respiratory tract, 01 natural sciences, Biogeochemical Kinetics and Reaction Modeling, LIDAR, Troposphere, Oceanography: Biological and Chemical, chemistry.chemical_compound, [SDV.MHEP.MI]Life Sciences [q-bio]/Human health and pathology/Infectious diseases, Emission reductions, ddc:550, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, VERTICAL-DISTRIBUTION, Marine Pollution, RECORD, NOX, 551.51, Biogeochemistry, Ozone depletion, Oceanography: General, Pollution: Urban and Regional, Geophysics, Free troposphere, Emissions, Troposphere: Composition and Chemistry, The COVID‐19 pandemic: linking health, society and environment, Cryosphere, Biogeochemical Cycles, Processes, and Modeling, Ozone, Megacities and Urban Environment, URBAN, Atmosphere, Paleoceanography, Altitude, COVID‐19, Research Letter, Global Change, Tropospheric ozone, Stratosphere, Urban Systems, 0105 earth and related environmental sciences, Aerosols, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], emissions, Northern Hemisphere, COVID-19, PROFILES, Aerosols and Particles, TRENDS, Earth sciences, ozone, Physics and Astronomy, troposphere, chemistry, 13. Climate action, General Earth and Planetary Sciences, Environmental science, Natural Hazards
Abstract

Throughout spring and summer 2020, ozone stations in the northern extratropics recorded unusually low ozone in the free troposphere. From April to August, and from 1 to 8 kilometers altitude, ozone was on average 7% (≈4 nmol/mol) below the 2000–2020 climatological mean. Such low ozone, over several months, and at so many stations, has not been observed in any previous year since at least 2000. Atmospheric composition analyses from the Copernicus Atmosphere Monitoring Service and simulations from the NASA GMI model indicate that the large 2020 springtime ozone depletion in the Arctic stratosphere contributed less than one‐quarter of the observed tropospheric anomaly. The observed anomaly is consistent with recent chemistry‐climate model simulations, which assume emissions reductions similar to those caused by the COVID‐19 crisis. COVID‐19 related emissions reductions appear to be the major cause for the observed reduced free tropospheric ozone in 2020., Plain Language Summary: Worldwide actions to contain the COVID‐19 virus have closed factories, grounded airplanes, and have generally reduced travel and transportation. Less fuel was burnt, and less exhaust was emitted into the atmosphere. Due to these measures, the concentration of nitrogen oxides and volatile organic compounds (VOCs) decreased in the atmosphere. These substances are important for photochemical production and destruction of ozone in the atmosphere. In clean or mildly polluted air, reducing nitrogen oxides and/or VOCs will reduce the photochemical production of ozone and result in less ozone. In heavily polluted air, in contrast, reducing nitrogen oxides can increase ozone concentrations, because less nitrogen oxide is available to destroy ozone. In this study, we use data from three types of ozone instruments, but mostly from ozonesondes on weather balloons. The sondes fly from the ground up to 30 kilometers altitude. In the first 8 km, we find significantly reduced ozone concentrations in the northern extratropics during spring and summer of 2020, less than in any other year since at least 2000. We suggest that reduced emissions due to the COVID‐19 crisis have lowered photochemical ozone production and have caused the observed ozone reductions in the troposphere., Key Points: 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, NASA | Earth Sciences Division (NASA Earth Science Division) http://dx.doi.org/10.13039/100014573, Gouvernement du Canada | Natural Sciences and Engineering Research Council of Canada (NSERC) http://dx.doi.org/10.13039/501100000038, Australian Research Council, Fonds De La Recherche Scientifique ‐ FNRS (FNRS) http://dx.doi.org/10.13039/501100002661, Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659, Bundesministerium für Wirtschaft und Energie (BMWi) http://dx.doi.org/10.13039/501100006360

Published
2021
Full Text
View/download PDF

33. Controlled weather balloon ascents and descents for atmospheric research and climate monitoring.

Author

Kräuchi A, Philipona R, Romanens G, Hurst DF, Hall EG, and Jordan AF

Abstract

In situ upper-air measurements are often made with instruments attached to weather balloons launched at the surface and lifted into the stratosphere. Present-day balloon-borne sensors allow near-continuous measurements from the Earth's surface to about 35 km (3-5 hPa), where the balloons burst and their instrument payloads descend with parachutes. It has been demonstrated that ascending weather balloons can perturb the air measured by very sensitive humidity and temperature sensors trailing behind them, particularly in the upper troposphere and lower stratosphere (UTLS). The use of controlled balloon descent for such measurements has therefore been investigated and is described here. We distinguish between the single balloon technique that uses a simple automatic valve system to release helium from the balloon at a preset ambient pressure, and the double balloon technique that uses a carrier balloon to lift the payload and a parachute balloon to control the descent of instruments after the carrier balloon is released at preset altitude. The automatic valve technique has been used for several decades for water vapor soundings with frost point hygrometers, whereas the double balloon technique has recently been re-established and deployed to measure radiation and temperature profiles through the atmosphere. Double balloon soundings also strongly reduce pendulum motion of the payload, stabilizing radiation instruments during ascent. We present the flight characteristics of these two ballooning techniques and compare the quality of temperature and humidity measurements made during ascent and descent.

Published
2016
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results