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1. The Evolution of the Hunga Hydration in a Moistening Stratosphere.

Author

Millán, L., Read, W. G., Santee, M. L., Lambert, A., Manney, G. L., Neu, J. L., Pitts, M. C., Werner, F., Livesey, N. J., and Schwartz, M. J.

Subjects
WATER vapor, ANTARCTIC ice, WATER masses, STRATOSPHERE, MICROWAVE measurements, POLAR vortex
Abstract

The 2022 Hunga eruption caused unprecedented stratospheric hydration. Aura Microwave Limb Sounder (MLS) measurements show that the stratospheric water vapor mass remains essentially unchanged as of early 2024 and that the Hunga hydration occurred atop a robust (possibly accelerating) moistening trend in the stratosphere. Enhanced by the excess Hunga water vapor, dehydration via polar stratospheric cloud sedimentation in the 2023 Antarctic vortex exceeded climatological values by ∼ ${\sim} $50%. Simple projections based on modeled exponential decay illustrate that the timing of the return to humidity levels that would have been expected absent the Hunga hydration depends on the ongoing stratospheric water vapor trend. With the Hunga hydration compounding an underlying moistening trend, the stratosphere could remain anomalously humid for an extended period. Plain Language Summary: The 2022 Hunga eruption injected an unprecedented amount of water vapor directly into the very dry stratosphere. This abrupt increase in water vapor from Hunga occurred at a time when the stratosphere was already gradually becoming moister. Using measurements from the Microwave Limb Sounder (MLS) on NASA's Aura satellite, we show that stratospheric water vapor remained elevated, essentially unchanged, from the time of the eruption until at least early 2024. MLS data further reveal that, in 2023, one of the main mechanisms for drying the stratosphere—permanent removal of water vapor by formation and settling of ice polar stratospheric cloud particles over Antarctica—was substantially more effective than usual, boosted by the excess water vapor from Hunga. Projections indicate that the return to moisture levels that would have been expected in the absence of the eruption depends on how humid the stratosphere continues to get. Considering the ongoing moistening trend and the water vapor injected by Hunga, the stratosphere could remain unusually humid for a considerable period. Key Points: The stratospheric water vapor mass has remained essentially unchanged since the Hunga hydration through at least early 2024Fueled by excess Hunga water vapor, 2023 Antarctic vortex polar stratospheric cloud dehydration exceeded the climatological mean by ∼50%Given its robust (and potentially accelerating) background moistening trend, the stratosphere could stay anomalously humid for years [ABSTRACT FROM AUTHOR]

Published
2024
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3. The Influence of Stratospheric Hydration From the Hunga Eruption on Chemical Processing in the 2023 Antarctic Vortex.

Author

Santee, M. L., Manney, G. L., Lambert, A., Millán, L. F., Livesey, N. J., Pitts, M. C., Froidevaux, L., Read, W. G., and Fuller, R. A.

Subjects
CHEMICAL processes, OZONE layer depletion, ICE clouds, WATER vapor, VOLCANIC eruptions, TRACE gases
Abstract

We use measurements of trace gases from the Microwave Limb Sounder and polar stratospheric clouds (PSCs) from the Cloud‐Aerosol Lidar with Orthogonal Polarization to investigate how the extraordinary stratospheric water vapor enhancement from the 2022 Hunga eruption affected polar processing during the 2023 Antarctic winter. Although the dynamical characteristics of the vortex itself were generally unexceptional, the excess moisture initially raised PSC formation threshold temperatures above typical values. Cold conditions, especially in early July, prompted ice PSC formation and unusually severe irreversible dehydration at higher levels (500–700 K), while atypical hydration occurred at lower levels (380–460 K). Heterogeneous chemical processing was more extensive, both vertically (up to 750–800 K) and temporally (earlier in the season), than in prior Antarctic winters. The resultant HCl depletion and ClO enhancement redefined their previously observed ranges at and above 600 K. Albeit unmatched in the satellite record, the early‐winter upper‐level chlorine activation was insufficient to induce substantial ozone loss. Chlorine activation, denitrification, and dehydration processes ran to completion by July/August, with trace gas evolution mostly following the climatological mean thereafter, but with chlorine deactivation starting slightly later than usual. While cumulative ozone losses at 410–550 K were relatively large, probably because of the delayed chlorine deactivation, they were not unprecedented. Thus, ozone depletion was unremarkable throughout the lower stratosphere. Although Hunga enhanced PSC formation and chemical processing in early winter, saturation of lower stratospheric denitrification, dehydration, and chlorine activation (as is typical in the Antarctic) prevented an exceptionally severe ozone hole in 2023. Plain Language Summary: The 2022 eruption of the Hunga volcano produced an increase in stratospheric water vapor unmatched in the satellite record. Excess moisture pervaded the Antarctic stratosphere at the beginning of the 2023 Southern Hemisphere winter. Cold moist conditions prompted formation of ice clouds in the Antarctic stratosphere at higher altitudes than usual. Falling ice particles caused unusually severe permanent removal of water vapor from these levels and deposited it at lower altitudes. Chemical processing on polar stratospheric cloud particles occurred both earlier in the season and over a broader vertical domain than typical, resulting in exceptional early‐winter upper‐level conversion of chlorine from nonreactive into ozone‐destroying forms. Chemical processing ran its course by midwinter (i.e., July/August), with trace gases, including ozone, mostly following average behavior thereafter. Deactivation (reconversion of chlorine into nonreactive forms) started slightly later than in most years. While cumulative seasonal ozone losses were relatively large at some levels, probably because of the delayed chlorine deactivation, they were not unprecedented. Thus, although Hunga accelerated and expanded the vertical extent of chemical processing in early winter, that chemical processing reached completion as usually happens in Antarctic midwinter, preventing an extraordinarily severe ozone hole in 2023. Key Points: Hydration from Hunga led to unusually early and vertically extensive polar stratospheric cloud activity in the 2023 Antarctic vortexAs a result, heterogeneous chlorine activation occurred weeks earlier and at higher altitudes and dehydration removed more H2O than typicalDespite exceptional early‐winter conditions, cumulative ozone losses were unremarkable because stratospheric chemical processing saturated [ABSTRACT FROM AUTHOR]

Published
2024
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5. Polar stratospheric clouds satellite observations, processes, and role in ozone depletion

Author

Tritscher, I., Pitts, M. C., Poole, L. R., Alexander, S. P., Cairo, F., Chipperfield, M. P., Grooß, J.‐U., Höpfner, M., Lambert, A., Luo, B. P., Molleker, S., Orr, A., Salawitch, R., Snels, M., Spang, R., Woiwode, W., Peter, T., Tritscher, I., Pitts, M. C., Poole, L. R., Alexander, S. P., Cairo, F., Chipperfield, M. P., Grooß, J.‐U., Höpfner, M., Lambert, A., Luo, B. P., Molleker, S., Orr, A., Salawitch, R., Snels, M., Spang, R., Woiwode, W., and Peter, T.

Abstract

Polar stratospheric clouds (PSCs) play important roles in stratospheric ozone depletion during winter and spring at high latitudes (e.g., the Antarctic ozone hole). PSC particles provide sites for heterogeneous reactions that convert stable chlorine reservoir species to radicals that destroy ozone catalytically. PSCs also prolong ozone depletion by delaying chlorine deactivation through the removal of gas‐phase HNO3 and H2O by sedimentation of large NAT (nitric acid trihydrate) and ice particles. Contemporary observations by the spaceborne instruments MIPAS (Michelson Interferometer for Passive Atmospheric Sounding), MLS (Microwave Limb Sounder), and CALIOP (Cloud‐Aerosol Lidar with Orthogonal Polarization) have provided an unprecedented polar vortex‐wide climatological view of PSC occurrence and composition in both hemispheres. These data have spurred advances in our understanding of PSC formation and related dynamical processes, especially the firm evidence of widespread heterogeneous nucleation of both NAT and ice PSC particles, perhaps on nuclei of meteoritic origin. Heterogeneous chlorine activation appears to be well understood. Reaction coefficients on/in liquid droplets have been measured accurately, and while uncertainties remain for reactions on solid NAT and ice particles, they are considered relatively unimportant since under most conditions chlorine activation occurs on/in liquid droplets. There have been notable advances in the ability of chemical transport and chemistry‐climate models to reproduce PSC temporal/spatial distributions and composition observed from space. Continued spaceborne PSC observations will facilitate further improvements in the representation of PSC processes in global models and enable more accurate projections of the evolution of polar ozone and the global ozone layer as climate changes.

Published
2021

6. Heterogeneous Formation of Polar Stratospheric Clouds- Part 1: Nucleation of Nitric Acid Trihydrate (NAT)

Author

Hoyle, C. R, Engel, I, Luo, B. P, Pitts, M. C, Poole, L. R, Grooss, J.-U, and Peter, T

Subjects
Meteorology And Climatology
Abstract

Satellite-based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT) in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid-December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along more than sixty thousand trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) observation points. Comparing the optical properties of the modelled NAT with these observations enabled a thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM). The parameterisation is based on active site theory, is simple to implement in models and provides substantial advantages over previous approaches which involved a constant rate of NAT nucleation in a given volume of air. It is shown that the new method is capable of reproducing observed polar stratospheric clouds (PSCs) very well, despite the varied conditions experienced by air parcels travelling along the different trajectories. In a companion paper, ZOMM is applied to a later period of the winter, when ice PSCs are also present, and it is shown that the observed PSCs are also represented extremely well under these conditions.

Published
2013
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8. Ozone Observations by the Gas and Aerosol Measurement Sensor during SOLVE II

Author

Pitts, M. C, Thomason, L. W, Zawodny, J. M, Wenny, B. N, Livingston, J. M, Russell, P. B, Yee, J.-H, Swartz, W. H, and Shetter, R. E

Subjects
Earth Resources And Remote Sensing
Abstract

The Gas and Aerosol Measurement Sensor (GAMS) was deployed aboard the NASA DC-8 aircraft during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II). GAMS acquired line-of-sight (LOS) direct solar irradiance spectra during the sunlit portions of ten science flights of the DC-8 between 12 January and 4 February 2003. Differential line-of-sight (DLOS) optical depth spectra are produced from the GAMS raw solar irradiance spectra. Then, DLOS ozone number densities are retrieved from the GAMS spectra using a multiple linear regression spectral fitting technique. Both the DLOS optical depth spectra and retrieved ozone data are compared with coincident measurements from two other solar instruments aboard the DC-8 platform to demonstrate the robustness and stability of the GAMS data. The GAMS ozone measurements are then utilized to evaluate the quality of the Wulf band ozone cross sections, a critical component of the SAGE III aerosol, water vapor, and temperature/pressure retrievals. Results suggest the ozone cross section compilation of Shettle and Anderson currently used operationally in SAGE III data processing may be in error by as much as 10-20% in theWulf bands, and their lack of reported temperature dependence is a significant deficiency. A second, more recent, cross section database compiled for the SCIAMACHY satellite mission appears to be of much better quality in the Wulf bands, but still may have errors as large as 5% near the Wulf band absorption peaks, which is slightly larger than their stated uncertainty. Additional laboratory measurements of the Wulf band cross sections should be pursued to further reduce their uncertainty and better quantify their temperature dependence.

Published
2006

9. Entry letter from a publisher 1969: Part 16

Author

Pitts, M. C.

Subjects
Booker Prize Papers, Administrative papers, 1969 prize papers
Abstract

Entry letters for the Booker Prize from publishers, Correspondence

Published
2018

10. State of the climate in 2016

Author

Aaron-Morrison, A. P., Ackerman, S. A., Adams, N. G., Adler, R. F., Albanil, A., Alfaro, E. J., Allan, R., Alves, L. M., Amador, J. A., Andreassen, L. M., Arendt, A., Arévalo, J., Arndt, D. S., Arzhanova, N. M., Aschan, M. M., Azorin-Molina, C., Banzon, V., Bardin, M. U., Barichivich, J., Baringer, M. O., Barreira, S., Baxter, S., Bazo, J., Becker, A., Bedka, K. M., Behrenfeld, M. J., Bell, G. D., Belmont, M., Benedetti, A., Bernhard, G., Berrisford, P., Berry, D. I., Bettolli, M. L., Bhatt, U. S., Bidegain, M., Bill, B. D., Billheimer, S., Bissolli, P., Blake, E. S., Blunden, J., Bosilovich, M. G., Boucher, O., Boudet, D., Box, J. E., Boyer, T., Braathen, G. O., Bromwich, D. H., Brown, R., Bulygina, O. N., Burgess, D., Calderón, B., Camargo, S. J., Campbell, J. D., Cappelen, J., Carrasco, G., Carter, B. R., Chambers, D. P., Chandler, E., Christiansen, H. H., Christy, J. R., Chung, D., Chung, E. S., Cinque, K., Clem, K. R., Coelho, C. A., Cogley, J. G., Coldewey-Egbers, M., Colwell, S., Cooper, O. R., Copland, L., Cosca, C. E., Cross, J. N., Crotwell, M. J., Crouch, J., Davis, S. M., Eyto, E., Jeu, R. A. M., Laat, J., Degasperi, C. L., Degenstein, D., Demircan, M., Derksen, C., Destin, D., Di Girolamo, L., Di Giuseppe, F., Diamond, H. J., Dlugokencky, E. J., Dohan, K., Dokulil, M. T., Dolgov, A. V., Dolman, A. J., Domingues, C. M., Donat, M. G., Dong, S., Dorigo, W. A., Dortch, Q., Doucette, G., Drozdov, D. S., Ducklow, H., Dunn, R. J. H., Durán-Quesada, A. M., Dutton, G. S., Ebrahim, A., Elkharrim, M., Elkins, J. W., Espinoza, J. C., Etienne-Leblanc, S., Evans, T. E., Famiglietti, J. S., Farrell, S., Fateh, S., Fausto, R. S., Fedaeff, N., Feely, R. A., Feng, Z., Fenimore, C., Fettweis, X., Fioletov, V. E., Flemming, J., Fogarty, C. T., Fogt, R. L., Folland, C., Fonseca, C., Fossheim, M., Foster, M. J., Fountain, A., Francis, S. D., Franz, B. A., Frey, R. A., Frith, S. M., Froidevaux, L., Ganter, C., Garzoli, S., Gerland, S., Gobron, N., Goldenberg, S. B., Gomez, R. S., Goni, G., Goto, A., Grooß, J. U., Gruber, A., Guard, C. C., Gugliemin, M., Gupta, S. K., Gutiérrez, J. M., Hagos, S., Hahn, S., Haimberger, L., Hakkarainen, J., Hall, B. D., Halpert, M. S., Hamlington, B. D., Hanna, E., Hansen, K., Hanssen-Bauer, I., Harris, I., Heidinger, A. K., Heikkilä, A., Heil, A., Heim, R. R., Hendricks, S., Hernández, M., Hidalgo, H. G., Hilburn, K., Ho, S. P. B., Holmes, R. M., Hu, Z. Z., Huang, B., Huelsing, H. K., Huffman, G. J., Hughes, C., Hurst, D. F., Ialongo, I., Ijampy, J. A., Ingvaldsen, R. B., Inness, A., Isaksen, K., Ishii, M., Jevrejeva, S., Jiménez, C., Jin, X., Johannesen, E., John, V., Johnsen, B., Johnson, B., Johnson, G. C., Jones, P. D., Joseph, A. C., Jumaux, G., Kabidi, K., Kaiser, J. W., Kato, S., Kazemi, A., Keller, L. M., Kendon, M., Kennedy, J., Kerr, K., Kholodov, A. L., Khoshkam, M., Killick, R., Kim, H., Kim, S. J., Kimberlain, T. B., Klotzbach, P. J., Knaff, J. A., Kobayashi, S., Kohler, J., Korhonen, J., Korshunova, N. N., Kovacs, K. M., Kramarova, N., Kratz, D. P., Kruger, A., Kruk, M. C., Kudela, R., Kumar, A., Lakatos, M., Lakkala, K., Lander, M. A., Landsea, C. W., Lankhorst, M., Lantz, K., Lazzara, M. A., Lemons, P., Leuliette, E., L’heureux, M., Lieser, J. L., Lin, I. I., Liu, H., Liu, Y., Locarnini, R., Loeb, N. G., Lo Monaco, C., Long, C. S., López Álvarez, L. A., Lorrey, A. M., Loyola, D., Lumpkin, R., Luo, J. J., Luojus, K., Lydersen, C., Lyman, J. M., Maberly, S. C., Maddux, B. C., Malheiros Ramos, A., Malkova, G. V., Manney, G., Marcellin, V., Marchenko, S. S., Marengo, J. A., Marra, J. J., Marszelewski, W., Martens, B., Martínez-Güingla, R., Massom, R. A., Mata, M. M., Mathis, J. T., May, L., Mayer, M., Mazloff, M., Mcbride, C., Mccabe, M. F., Mccarthy, M., Mcclelland, J. W., Mcgree, S., Mcvicar, T. R., Mears, C. A., Meier, W., Meinen, C. S., Mekonnen, A., Menéndez, M., Mengistu Tsidu, G., Menzel, W. P., Merchant, C. J., Meredith, M. P., Merrifield, M. A., Metzl, N., Minnis, P., Miralles, D. G., Mistelbauer, T., Mitchum, G. T., Monselesan, D., Monteiro, P., Montzka, S. A., Morice, C., Mote, T., Mudryk, L., Mühle, J., Mullan, A. B., Nash, E. R., Naveira-Garabato, A. C., Nerem, R. S., Newman, P. A., Nieto, J. J., Noetzli, J., O’neel, S., Osborn, T. J., Overland, J., Oyunjargal, L., Parinussa, R. M., Park, E. H., Parker, D., Parrington, M., Parsons, A. R., Pasch, R. J., Pascual-Ramírez, R., Paterson, A. M., Paulik, C., Pearce, P. R., Pelto, M. S., Peng, L., Perkins-Kirkpatrick, S. E., Perovich, D., Petropavlovskikh, I., Pezza, A. B., Phillips, D., Pinty, B., Pitts, M. C., Pons, M. R., Porter, A. O., Primicerio, R., Proshutinsky, A., Quegan, S., Quintana, J., Rahimzadeh, F., Rajeevan, M., Randriamarolaza, L., Razuvaev, V. N., Reagan, J., Reid, P., Reimer, C., Rémy, S., Renwick, J. A., Revadekar, J. V., Richter-Menge, J., Riffler, M., Rimmer, A., Rintoul, S., Robinson, D. A., Rodell, M., Rodríguez Solís, J. L., Romanovsky, V. E., Ronchail, J., Rosenlof, K. H., Roth, C., Rusak, J. A., Sabine, C. L., Sallée, J. B., Sánchez-Lugo, A., Santee, M. L., Sawaengphokhai, P., Sayouri, A., Scambos, T. A., Schemm, J., Schladow, S. G., Schmid, C., Schmid, M., Schmidtko, S., Schreck, C. J., Selkirk, H. B., Send, U., Sensoy, S., Setzer, A., Sharp, M., Shaw, A., Shi, L., Shiklomanov, A. I., Shiklomanov, N. I., Siegel, D. A., Signorini, S. R., Sima, F., Simmons, A. J., Smeets, C. J. P. P., Smith, S. L., Spence, J. M., Srivastava, A. K., Stackhouse, P. W., Stammerjohn, S., Steinbrecht, W., Stella, J. L., Stengel, M., Stennett-Brown, R., Stephenson, T. S., Strahan, S., Streletskiy, D. A., Sun-Mack, S., Swart, S., Sweet, W., Talley, L. D., Tamar, G., Tank, S. E., Taylor, M. A., Tedesco, M., Teubner, K., Thoman, R. L., Thompson, P., Thomson, L., Timmermans, M. L., Maxim Timofeyev, Tirnanes, J. A., Tobin, S., Trachte, K., Trainer, V. L., Tretiakov, M., Trewin, B. C., Trotman, A. R., Tschudi, M., As, D., Wal, R. S. W., A, R. J., Schalie, R., Schrier, G., Werf, G. R., Meerbeeck, C. J., Velicogna, I., Verburg, P., Vigneswaran, B., Vincent, L. A., Volkov, D., Vose, R. S., Wagner, W., Wåhlin, A., Wahr, J., Walsh, J., Wang, C., Wang, J., Wang, L., Wang, M., Wang, S. H., Wanninkhof, R., Watanabe, S., Weber, M., Weller, R. A., Weyhenmeyer, G. A., Whitewood, R., Wijffels, S. E., Wilber, A. C., Wild, J. D., Willett, K. M., Williams, M. J. M., Willie, S., Wolken, G., Wong, T., Wood, E. F., Woolway, R. I., Wouters, B., Xue, Y., Yamada, R., Yim, S. Y., Yin, X., Young, S. H., Yu, L., Zahid, H., Zambrano, E., Zhang, P., Zhao, G., Zhou, L., Ziemke, J. R., Love-Brotak, S. E., Gilbert, K., Maycock, T., Osborne, S., Sprain, M., Veasey, S. W., Ambrose, B. J., Griffin, J., Misch, D. J., Riddle, D. B., Young, T., Macias Fauria, M, Blunden, J, Arndt, D, Earth and Climate, Faculty of Earth and Life Sciences, Clinical Developmental Psychology, Climate Change and Landscape Dynamics, and Molecular Cell Physiology

Subjects
Meteor (satellite), Atmospheric Science, 010504 meteorology & atmospheric sciences, 0208 environmental biotechnology, 02 engineering and technology, 01 natural sciences, 020801 environmental engineering, Geography, 13. Climate action, Climatology, SDG 13 - Climate Action, SDG 14 - Life Below Water, 0105 earth and related environmental sciences
Abstract

In 2016, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-continued to increase and reach new record highs. The 3.5 +/- 0.1 ppm rise in global annual mean carbon dioxide from 2015 to 2016 was the largest annual increase observed in the 58-year measurement record. The annual global average carbon dioxide concentration at Earth's surface surpassed 400 ppm (402.9 +/- 0.1 ppm) for the first time in the modern atmospheric measurement record and in ice core records dating back as far as 800000 years. One of the strongest El Nino events since at least 1950 dissipated in spring, and a weak La Nina evolved later in the year. Owing at least in part to the combination of El Nino conditions early in the year and a long-term upward trend, Earth's surface observed record warmth for a third consecutive year, albeit by a much slimmer margin than by which that record was set in 2015. Above Earth's surface, the annual lower troposphere temperature was record high according to all datasets analyzed, while the lower stratospheric temperature was record low according to most of the in situ and satellite datasets. Several countries, including Mexico and India, reported record high annual temperatures while many others observed near-record highs. A week-long heat wave at the end of April over the northern and eastern Indian peninsula, with temperatures surpassing 44 degrees C, contributed to a water crisis for 330 million people and to 300 fatalities. In the Arctic the 2016 land surface temperature was 2.0 degrees C above the 1981-2010 average, breaking the previous record of 2007, 2011, and 2015 by 0.8 degrees C, representing a 3.5 degrees C increase since the record began in 1900. The increasing temperatures have led to decreasing Arctic sea ice extent and thickness. On 24 March, the sea ice extent at the end of the growth season saw its lowest maximum in the 37-year satellite record, tying with 2015 at 7.2% below the 1981-2010 average. The September 2016 Arctic sea ice minimum extent tied with 2007 for the second lowest value on record, 33% lower than the 1981-2010 average. Arctic sea ice cover remains relatively young and thin, making it vulnerable to continued extensive melt. The mass of the Greenland Ice Sheet, which has the capacity to contribute similar to 7 m to sea level rise, reached a record low value. The onset of its surface melt was the second earliest, after 2012, in the 37-year satellite record. Sea surface temperature was record high at the global scale, surpassing the previous record of 2015 by about 0.01 degrees C. The global sea surface temperature trend for the 21st century-to-date of +0.162 degrees C decade(-1) is much higher than the longer term 1950-2016 trend of +0.100 degrees C decade(-1). Global annual mean sea level also reached a new record high, marking the sixth consecutive year of increase. Global annual ocean heat content saw a slight drop compared to the record high in 2015. Alpine glacier retreat continued around the globe, and preliminary data indicate that 2016 is the 37th consecutive year of negative annual mass balance. Across the Northern Hemisphere, snow cover for each month from February to June was among its four least extensive in the 47-year satellite record. Continuing a pattern below the surface, record high temperatures at 20-m depth were measured at all permafrost observatories on the North Slope of Alaska and at the Canadian observatory on northernmost Ellesmere Island. In the Antarctic, record low monthly surface pressures were broken at many stations, with the southern annular mode setting record high index values in March and June. Monthly high surface pressure records for August and November were set at several stations. During this period, record low daily and monthly sea ice extents were observed, with the November mean sea ice extent more than 5 standard deviations below the 1981-2010 average. These record low sea ice values contrast sharply with the record high values observed during 2012-14. Over the region, springtime Antarctic stratospheric ozone depletion was less severe relative to the 1991-2006 average, but ozone levels were still low compared to pre-1990 levels. Closer to the equator, 93 named tropical storms were observed during 2016, above the 1981-2010 average of 82, but fewer than the 101 storms recorded in 2015. Three basins-the North Atlantic, and eastern and western North Pacific-experienced above-normal activity in 2016. The Australian basin recorded its least active season since the beginning of the satellite era in 1970. Overall, four tropical cyclones reached the Saffir-Simpson category 5 intensity level. The strong El Nino at the beginning of the year that transitioned to a weak La Nina contributed to enhanced precipitation variability around the world. Wet conditions were observed throughout the year across southern South America, causing repeated heavy flooding in Argentina, Paraguay, and Uruguay. Wetter-than-usual conditions were also observed for eastern Europe and central Asia, alleviating the drought conditions of 2014 and 2015 in southern Russia. In the United States, California had its first wetter-than-average year since 2012, after being plagued by drought for several years. Even so, the area covered by drought in 2016 at the global scale was among the largest in the post-1950 record. For each month, at least 12% of land surfaces experienced severe drought conditions or worse, the longest such stretch in the record. In northeastern Brazil, drought conditions were observed for the fifth consecutive year, making this the longest drought on record in the region. Dry conditions were also observed in western Bolivia and Peru; it was Bolivia's worst drought in the past 25 years. In May, with abnormally warm and dry conditions already prevailing over western Canada for about a year, the human-induced Fort McMurray wildfire burned nearly 590000 hectares and became the costliest disaster in Canadian history, with $3 billion (U.S. dollars) in insured losses.

Published
2017

11. The impact of the eruptions of Mount Pinatubo and Cerro Hudson on antarctic aerosol levels during the 1991 austral spring

Author

Pitts, M. C and Thomason, L. W

Subjects
Environment Pollution
Abstract

At the beginning of the 1991 Austral spring, volcanic aerosols from Mt. Pinatubo and Cerro Hudson were present in the polar stratosphere of the Southern Hemisphere. Satellite observations of aerosol extinction were used to identify and track the movement of these aerosols in the vicinity of the Antarctic vortex during August through November 1991. A layer of mature Mt. Pinatubo aerosols was identified near 21 km and a layer of fresh Cerro Hudson aerosols was identified near 12 km. This altitude separation of the Mt. Pinatubo and Cerro Hudson aerosols was observed throughout the period. Below 15 km, the polar stratosphere was subject to episodes of strong wave activity which transported the Cerro Hudson aerosols poleward and, after the middle of September, they became a persistent feature beneath the vortex. Above 15 km, signatures of Mt. Pinatubo aerosols were observed near the vortex boundary, but significant portions of the vortex interior remained free of any detectable intrusions of Mt. Pinatubo aerosols until the final warming in mid-November.

Published
1993

12. Background stratospheric aerosol and polar stratospheric cloud reference models

Author

Mccormick, M. P, Wang, P.-H, and Pitts, M. C

Subjects
Geophysics
Abstract

A global aerosol climatology is evolving from the NASA satellite experiments SAM II, SAGE I, and SAGE II. In addition, polar stratospheric cloud (PSC) data have been obtained from these experiments over the last decade. An undated reference model of the optical characteristics of the background aerosol is described and a new aerosol reference model derived from the latest available data is proposed. The aerosol models are referenced to the height above the tropopause. The impact of a number of volcanic eruptions is described. In addition, a model describing the seasonal, longitudinal, and interannual variations in PSCs is presented.

Published
1993
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13. Heterogeneous processes: Laboratory, field, and modeling studies

Author

Poole, Lamont R, Kurylo, Michael J, Jones, Rod L, Wahner, Andreas, Calvert, Jack G, Leu, M.-T, Fried, A, Molina, Mario J, Hampson, Robert F, and Pitts, M. C

Subjects
Environment Pollution
Abstract

The efficiencies of chemical families such as ClO(x) and NO(x) for altering the total abundance and distribution of stratospheric ozone are controlled by a partitioning between reactive (active) and nonreactive (reservoir) compounds within each family. Gas phase thermodynamics, photochemistry, and kinetics would dictate, for example, that only about 1 percent of the chlorine resident in the lower stratosphere would be in the form of active Cl or ClO, the remainder existing in the reservoir compounds HCl and ClONO2. The consistency of this picture was recently challenged by the recognition that important chemical transformations take place on polar regions: the Airborne Antarctic Ozone Experiment (AAOE) and the Airborne Arctic Stratospheric Expedition (AASA). Following the discovery of the Antarctic ozone hole, Solomon et al. suggested that the heterogeneous chemical reaction: ClONO2(g)+HCl(s) yields Cl2(g)+HNO3(s) could play a key role in converting chlorine from inactive forms into a species (Cl2) that would rapidly dissociate in sunlight to liberate atomic chlorine and initiate ozone depletion. The symbols (s) and (g) denote solid phase, or adsorbed onto a solid surface, and gas phase, respectively, and represent the approach by which such a reaction is modeled rather than the microscopic details of the reaction. The reaction was expected to be most important at altitudes where PSC's were most prevalent (10 to 25 km), thereby extending the altitude range over which chlorine compounds can efficiently destroy ozone from the 35 to 45 km region (where concentrations of active chlorine are usually highest) to lower altitudes where the ozone concentration is at its peak. This chapter will briefly review the current state of knowledge of heterogeneous processes in the stratosphere, emphasizing those results obtained since the World Meteorological Organization (WMO) conference. Sections are included on laboratory investigations of heterogeneous reactions, the characteristics and climatology of PSC's, stratospheric sulfate aerosols, and evidence of heterogeneous chemical processing.

Published
1991

14. SAGE II observations of polar stratospheric clouds near 50 deg N January 31 - February 2, 1989

Author

Pitts, M. C, Poole, L. R, and Mccormick, M. P

Subjects
Geophysics
Abstract

Polar stratospheric clouds (PSCs) form at very cold temperatures which typically occur only at high latitudes during local winter. However, meteorological circumstances in the Arctic during late January 1989 led to PSC formation unusually far to the south, at latitudes (near 50 deg N) being sampled during the period by the orbiting SAGE II instrument. These unusual PSC sightings and the evolution of meteorological conditions which produced the episode are described. Profiles of SAGE II extinction measurements at 0.525 and 1.02 microns show clear signatures of PSCs and indicate that the cloud particles were considerably larger than the background aerosol. It is most important to note that the clouds were sighted at a latitude where there was extensive sunlight, thus increasing the likelihood of ozone loss both locally and downstream due to enhancements in reactive chlorine expected from heterogeneous chemical processing within the PSCs.

Published
1990

15. SAM II aerosol measurements during the 1989 AASE

Author

Osborn, M. T, Pitts, M. C, Powell, K. A, and Mccormick, M. P

Subjects
Geophysics
Abstract

The Stratospheric Aerosol Measurement II (SAM II) satellite experiment measures 14 daily 1.0-micron aerosol extinction profiles in the high northern latitudes. These SAM II data were used to spot the locations of polar stratospheric clouds (PSCs) and provide an overview of the vertical structure of the upper tropospheric and stratospheric aerosols during the 1989 Airborne Arctic Stratospheric Expedition (AASE). Although SAM II measured a higher than average number of PSCs in January 1989 as compared to the previous 10 years, the number of PSCs sighted during the entire 1989 winter season is only slightly above average. Also discussed is the vertical gradient in aerosol extinction which occurs as the SAM II measurement locations cross the polar vortex.

Published
1990

16. Ozone reference models for the middle atmosphere

Author

Keating, G. M, Pitts, M. C, and Young, D. F

Subjects
Geophysics
Abstract

Data on monthly latitudinal variations in middle-atmosphere vertical ozone profiles are presented, based on extensive Nimbus-7, AE-2, and SME satellite measurements from the period 1978-1982. The coverage of the data sets, the characteristics of the sensors, and the analysis techniques applied are described, and the results are compiled in tables and graphs. These ozone data are intended to supplement the models of the 1986 COSPAR International Reference Atmosphere.

Published
1990
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17. Improved reference models for middle atmosphere ozone

Author

Keating, G. M, Pitts, M. C, and Chen, C

Subjects
Geophysics
Abstract

This paper describes the improvements introduced into the original version of ozone reference model of Keating and Young (1985, 1987) which is to be incorporated in the next COSPAR International Reference Atmosphere (CIRA). The ozone reference model will provide information on the global ozone distribution (including the ozone vertical structure as a function of month and latitude from 25 to 90 km) combining data from five recent satellite experiments: the Nimbus 7 LIMS, Nimbus 7 SBUV, AE-2 Stratospheric Aerosol Gas Experiment (SAGE), Solar Mesosphere Explorer (SME) UV Spectrometer, and SME 1.27 Micron Airglow. The improved version of the reference model uses reprocessed AE-2 SAGE data (sunset) and extends the use of SAGE data from 1981 to the 1981-1983 time period. Comparisons are presented between the results of this ozone model and various nonsatellite measurements at different levels in the middle atmosphere.

Published
1990
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18. Characterization of Polar Stratospheric Clouds with spaceborne lidar: CALIPSO and the 2006 Antarctic season

Author

Pitts, M. C., Larry Thomason, Poole, L. R., Winker, D. M., EGU, Publication, NASA Headquarters, and Science Systems and Applications, Inc. [Lanham] (SSAI)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:Chemistry, lcsh:QD1-999, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:Physics, lcsh:QC1-999
Abstract

The role of polar stratospheric clouds in polar ozone loss has been well documented. The CALIPSO satellite mission offers a new opportunity to characterize PSCs on spatial and temporal scales previously impossible. A PSC detection algorithm based on a single wavelength threshold approach has been developed for CALIPSO. The method appears to accurately detect PSCs of all opacities, including tenuous clouds, with a very low rate of false positives and few missed clouds. We applied the algorithm to CALIOP data acquired during the 2006 Antarctic winter season from 13 June through 31 October. The spatial and temporal distribution of CALIPSO PSC observations is illustrated with weekly maps of PSC occurrence. The evolution of the 2006 PSC season is depicted by time series of daily PSC frequency as a function of altitude. Comparisons with "virtual" solar occultation data indicate that CALIPSO provides a different view of the PSC season than attained with previous solar occultation satellites. Measurement-based time series of PSC areal coverage and vertically-integrated PSC volume are computed from the CALIOP data. The observed area covered with PSCs is significantly smaller than would be inferred from the commonly used temperature-based proxy TNAT but is similar in magnitude to that inferred from TSTS. The potential of CALIOP measurements for investigating PSC composition is illustrated using combinations of lidar backscatter and volume depolarization for two CALIPSO PSC scenes.

Published
2007

19. Sensitivity of polar stratospheric cloud formation to changes in water vapour and temperature

Author

Khosrawi, F., Urban, J., Lossow, S., Stiller, G., Weigel, K., Braesicke, P., Pitts, M. C., Rozanov, A., Burrows, J. P., and Murtagh, D.

Subjects
Earth sciences, ddc:550
Abstract

More than a decade ago it was suggested that a cooling of stratospheric temperatures by 1gK or an increase of 1gppmv of stratospheric water vapour could promote denitrification, the permanent removal of nitrogen species from the stratosphere by solid polar stratospheric cloud (PSC) particles. In fact, during the two Arctic winters 2009/10 and 2010/11 the strongest denitrification in the recent decade was observed. Sensitivity studies along air parcel trajectories are performed to test how a future stratospheric water vapour (H2O) increase of 1gppmv or a temperature decrease of 1gK would affect PSC formation. We perform our study based on measurements made during the Arctic winter 2010/11. Air parcel trajectories were calculated 6 days backward in time based on PSCs detected by CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder satellite observations). The sensitivity study was performed on single trajectories as well as on a trajectory ensemble. The sensitivity study shows a clear prolongation of the potential for PSC formation and PSC existence when the temperature in the stratosphere is decreased by 1gK and water vapour is increased by 1gppmv. Based on 15 years of satellite measurements (2000-2014) from UARS/HALOE, Envisat/MIPAS, Odin/SMR, Aura/MLS, Envisat/SCIAMACHY and SCISAT/ACE-FTS it is further investigated if there is a decrease in temperature and/or increase of water vapour (H2O) observed in the polar regions similar to that observed at midlatitudes and in the tropics. Performing linear regression analyses we derive from the Envisat/MIPAS (2002-2012) and Aura/MLS (2004-2014) observations predominantly positive changes in the potential temperature range 350 to 1000gK. The linear changes in water vapour derived from Envisat/MIPAS observations are largely insignificant, while those from Aura/MLS are mostly significant. For the temperature neither of the two instruments indicate any significant changes. Given the strong inter-annual variation observed in water vapour and particular temperature the severe denitrification observed in 2010/11 cannot be directly related to any changes in water vapour and temperature since the millennium. However, the observations indicate a clear correlation between cold winters and enhanced water vapour mixing ratios. This indicates a connection between dynamical and radiative processes that govern water vapour and temperature in the Arctic lower stratosphere. © Author(s) 2016.

Published
2015

20. Sensitivity of polar stratospheric cloud formation to changes in water vapour and temperature

Author

Khosrawi, Farahnaz, Urban, J., Lossow, S., Stiller, G., Weigel, K., Braesicke, P., Pitts, M. C., Rozanov, A., Burrows, J. P., Murtagh, D., Khosrawi, Farahnaz, Urban, J., Lossow, S., Stiller, G., Weigel, K., Braesicke, P., Pitts, M. C., Rozanov, A., Burrows, J. P., and Murtagh, D.

Abstract

More than a decade ago it was suggested that a cooling of stratospheric temperatures by 1 K or an increase of 1 ppmv of stratospheric water vapour could promote denitrification, the permanent removal of nitrogen species from the stratosphere by solid polar stratospheric cloud (PSC) particles. In fact, during the two Arctic winters 2009/10 and 2010/11 the strongest denitrification in the recent decade was observed. Sensitivity studies along air parcel trajectories are performed to test how a future stratospheric water vapour (H2O) increase of 1 ppmv or a temperature decrease of 1K would affect PSC formation. We perform our study based on measurements made during the Arctic winter 2010/11. Air parcel trajectories were calculated 6 days backward in time based on PSCs detected by CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder satellite observations). The sensitivity study was performed on single trajectories as well as on a trajectory ensemble. The sensitivity study shows a clear prolongation of the potential for PSC formation and PSC existence when the temperature in the stratosphere is decreased by 1K and water vapour is increased by 1 ppmv. Based on 15 years of satellite measurements (20002014) from UARS/HALOE, Envisat/MIPAS, Odin/SMR, Aura/MLS, Envisat/SCIAMACHY and SCISAT/ACE-FTS it is further investigated if there is a decrease in temperature and/or increase of water vapour (H2O) observed in the polar regions similar to that observed at midlatitudes and in the tropics. Performing linear regression analyses we derive from the Envisat/MIPAS (2002-2012) and Aura/MLS (2004-2014) observations predominantly positive changes in the potential temperature range 350 to 1000 K. The linear changes in water vapour derived from Envisat/MIPAS observations are largely insignificant, while those from Aura/MLS are mostly significant. For the temperature neither of the two instruments indicate any significant changes. Given the strong inter-annual variation observed in water v

Published
2016
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21. Multilevel cloud structures over Svalbard

Author

Dörnbrack, A., Gisinger, S., Pitts, M. C., Poole, L. R., Maturilli, Marion, Dörnbrack, A., Gisinger, S., Pitts, M. C., Poole, L. R., and Maturilli, Marion

Abstract

The presented picture of the month is a superposition of space-borne lidar observations and high-resolution temperature fields of the ECMWF integrated forecast system (IFS). It displays complex tropospheric and stratospheric clouds in the Arctic winter 2015/16. Near the end of December 2015, the unusual northeastward propagation of warm and humid subtropical air masses as far north as 80°N lifted the tropopause by more than 3 km in 24 h and cooled the stratosphere on a large scale. A widespread formation of thick cirrus clouds near the tropopause and of synoptic-scale polar stratospheric clouds (PSCs) occurred as the temperature dropped below the thresholds for the existence of cloud particles. Additionally, mountain waves were excited by the strong flow at the western edge of the ridge across Svalbard, leading to the formation of mesoscale ice PSCs. The most recent IFS cycle using a horizontal resolution of 8 km globally reproduces the large-scale and mesoscale flow features and leads to a remarkable agreement with the wave structure revealed by the space-borne observations.

Published
2016

22. Polar Stratospheric Cloud evolution and chlorine activation measured by CALIPSO and MLS, and modeled by ATLAS

Author

Nakajima, H., Wohltmann, Ingo, Wegner, T., Takeda, M., Pitts, M. C., Poole, L. R., Lehmann, Ralph, Santee, M. L., Rex, Markus, Nakajima, H., Wohltmann, Ingo, Wegner, T., Takeda, M., Pitts, M. C., Poole, L. R., Lehmann, Ralph, Santee, M. L., and Rex, Markus

Abstract

We examined observations of polar stratospheric clouds (PSCs) by CALIPSO and of HCl, ClO and HNO3 by MLS along air mass trajectories to investigate the dependence of the inferred PSC composition on the temperature history of the air parcels, and the dependence of the level of chlorine activation on PSC composition. Several case studies based on individual trajectories from the Arctic winter 2009/10 were conducted, with the trajectories chosen such that the first processing of the air mass by PSCs in this winter occurred on the trajectory. Transitions of PSC composition classes were observed to be highly dependent on the temperature history. In cases of a gradual temperature decrease, nitric acid trihydrate (NAT) and super-cooled ternary solution (STS) mixture clouds were observed. In cases of rapid temperature decrease, STS clouds were first observed, followed by NAT/STS mixture clouds. When temperatures dropped below the frost point, ice clouds formed, and then transformed into NAT/STS mixture clouds when temperature increased above the frost point. The threshold temperature for rapid chlorine activation on PSCs is approximately 4 K below the NAT existence temperature, TNAT. Furthermore, simulations of the ATLAS chemistry and transport box model along the trajectories were used to corroborate the measurements and show good agreement with the observations. Rapid chlorine activation was observed when an airmass encountered PSCs. The observed and modelled dependence of the rate of chlorine activation on the PSC composition class was small. Usually, chlorine activation was limited by the amount of available ClONO2. Where ClONO2 was not the limiting factor, a large dependence on temperature was evident.

Published
2016

25. Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions

Author

Hobe, M. Von, Bekki, S., Borrmann, S., Cairo, F., D'Amato, F., Di Donfrancesco, G., Dörnbrack, A., Ebersoldt, A., Ebert, M., Emde, C., Engel, I., Ern, M., Frey, W., Genco, S., Griessbach, S., Grooß, J.-U., Gulde, T., Günther, G., Hösen, E., Hoffmann, L., Homonnai, V., Hoyle, C. R., Isaksen, I. S. A., Jackson, D. R., Jánosi, I. M., Jones, R. L., Kandler, K., Kalicinsky, C., Keil, A., Khaykin, S. M., Khosrawi, F., Kivi, R., Kuttippurath, J., Laube, J. C., Lefèvre, F., Lehmann, R., Ludmann, S., Luo, B. P., Marchand, M., Meyer, J., Mitev, V., Molleker, S., Müller, R., Oelhaf, H., Olschewski, F., Orsolini, Y., Peter, T., Pfeilsticker, K., Piesch, C., Pitts, M. C., Poole, L. R., Pope, F. D., Ravegnani, F., Rex, M., Riese, M., Röckmann, T., Rognerud, B., Roiger, A., Rolf, C., Santee, M. L., Scheibe, M., Schiller, C., Schlager, H., Siciliani De Cumis, M., Sitnikov, N., Sovde, O. A., Spang, R., Spelten, N., Stordal, F., Sumi'ska-Ebersoldt, O., Ulanovski, A., Ungermann, J., Viciani, S., Volk, C. M., Vom Scheidt, M., Von Der Gathen, P., Walker, K., Wegner, T., Weigel, R., Weinbruch, S., Wetzel, G., Wienhold, F. G., Wohltmann, I., Woiwode, W., Young, I. A. K., Yushkov, V., Zobrist, B., and Stroh, F.

Subjects
Earth sciences, ddc:550
Published
2013

26. STATE OF THE CLIMATE IN 2011 Special Supplement to the Bulletin of the American Meteorological Society Vol. 93, No. 7, July 2012

Author

Arndt, D. S., Blunden, J., Willett, K. M., Dolman, A. J., Hall, B. D., Thorne, P. W., Gregg, M. C., Newlin, M. L., Xue, Y., Hu, Z., Kumar, A., Banzon, V., Smith, T. M., Rayner, N. A., Jeffries, M. O., Richter-Menge, J., Overland, J., Bhatt, U., Key, J., Liu, Y., Walsh, J., Wang, M., Fogt, R. L., Scambos, T. A., Wovrosh, A. J., Barreira, S., Sanchez-Lugo, A., Renwick, J. A., Thiaw, W. M., Weaver, S. J., Whitewood, R., Phillips, D., Achberger, C., Ackerman, S. A., Ahmed, F. H., Albanil-Encarnacion, A., Alfaro, E. J., Alves, L. M., Allan, R., Amador, J. A., Ambenje, P., Antoine, M. D., Antonov, J., Arevalo, J., Ashik, I., Atheru, Z., Baccini, A., Baez, J., Baringer, M. O., Barriopedro, D. E., Bates, J. J., Becker, A., Behrenfeld, M. J., Bell, G. D., Benedetti, A., Bernhard, G., Berrisford, P., Berry, D. I., Beszczynska-Moeller, A., Bhatt, U. S., Bidegain, M., Bieniek, P., Birkett, C., Bissolli, P., Blake, E. S., Boudet-Rouco, D., Box, J. E., Boyer, T., Braathen, G. O., Brackenridge, G. R., Brohan, P., Bromwich, D. H., Brown, L., Brown, R., Bruhwiler, L., Bulygina, O. N., Burrows, J., Calderon, B., Camargo, S. J., Cappellen, J., Carmack, E., Carrasco, G., Chambers, D. P., Christiansen, H. H., Christy, J., Chung, D., Ciais, P., Coehlo, C. A. S., Colwell, S., Comiso, J., Cretaux, J. F., Crouch, J., Cunningham, S. A., Jeu, R. A. M., Demircan, M., Derksen, C., Diamond, H. J., Dlugokencky, E. J., Dohan, K., Dorigo, W. A., Drozdov, D. S., Duguay, C., Dutton, E., Dutton, G. S., Elkins, J. W., Epstein, H. E., Famiglietti, J. S., Fanton D Andon, O. H., Feely, R. A., Fekete, B. M., Fenimore, C., Fernandez-Prieto, D., Fields, E., Fioletov, V., Folland, C., Foster, M. J., Frajka-Williams, E., Franz, B. A., Frey, K., Frith, S. H., Frolov, I., Frost, G. V., Ganter, C., Garzoli, S., Gitau, W., Gleason, K. L., Gobron, N., Goldenberg, S. B., Goni, G., Gonzalez-Garcia, I., Gonzalez-Rodriguez, N., Good, S. A., Goryl, P., Gottschalck, J., Gouveia, C. M., Griffiths, G. M., Grigoryan, V., Grooss, J. U., Guard, C., Guglielmin, M., Halpert, M. S., Heidinger, A. K., Heikkila, A., Heim, R. R., Hennon, P. A., Hidalgo, H. G., Hilburn, K., Ho, S. P., Hobbs, W. R., Holgate, S., Hook, S. J., Hovsepyan, A., Hu, Z. Z., Hugony, S., Hurst, D. F., Ingvaldsen, R., Itoh, M., Jaimes, E., Jeffries, M., Johns, W. E., Johnsen, B., Johnson, B., Johnson, G. C., Jones, L. T., Jumaux, G., Kabidi, K., Kaiser, J. W., Kang, K. K., Kanzow, T. O., Kao, H. Y., Keller, L. M., Kendon, M., Kennedy, J. J., Kervankiran, S., Khatiwala, S., Kholodov, A. L., Khoshkam, M., Kikuchi, T., Kimberlain, T. B., King, D., Knaff, J. A., Korshunova, N. N., Koskela, T., Kratz, D. P., Krishfield, R., Kruger, A., Kruk, M. C., Lagerloef, G., Lakkala, K., Lammers, R. B., Lander, M. A., Landsea, C. W., Lankhorst, M., Lapinel-Pedroso, B., Lazzara, M. A., Leduc, S., Lefale, P., Leon, G., Leon-Lee, A., Leuliette, E., Levitus, S., L Heureux, M., Lin, II, Liu, H. X., Liu, Y. J., Lobato-Sanchez, R., Locarnini, R., Loeb, N. G., Loeng, H., Long, C. S., Lorrey, A. M., Lumpkin, R., Myhre, C. L., Jing-Jia Luo, Lyman, J. M., Maccallum, S., Macdonald, A. M., Maddux, B. C., Manney, G., Marchenko, S. S., Marengo, J. A., Maritorena, S., Marotzke, J., Marra, J. J., Martinez-Sanchez, O., Maslanik, J., Massom, R. A., Mathis, J. T., Mcbride, C., Mcclain, C. R., Mcgrath, D., Mcgree, S., Mclaughlin, F., Mcvicar, T. R., Mears, C., Meier, W., Meinen, C. S., Menendez, M., Merchant, C., Merrifield, M. A., Miller, L., Mitchum, G. T., Montzka, S. A., Moore, S., Mora, N. P., Morcrette, J. J., Mote, T., Muhle, J., Mullan, A. B., Muller, R., Myhre, C., Nash, E. R., Nerem, R. S., Newman, P. A., Ngari, A., Nishino, S., Njau, L. N., Noetzli, J., Oberman, N. G., Obregon, A., Ogallo, L., Oludhe, C., Oyunjargal, L., Parinussa, R. M., Park, G. H., Parker, D. E., Pasch, R. J., Pascual-Ramirez, R., Pelto, M. S., Penalba, O., Perez-Suarez, R., Perovich, D., Pezza, A. B., Pickart, R., Pinty, B., Pinzon, J., Pitts, M. C., Pour, H. K., Prior, J., Privette, J. L., Proshutinsky, A., Quegan, S., Quintana, J., Rabe, B., Rahimzadeh, F., Rajeevan, M., Rayner, D., Raynolds, M. K., Razuvaev, V. N., Reagan, J., Reid, P., Revadekar, J., Rex, M., Rivera, I. L., Robinson, D. A., Rodell, M., Roderick, M. L., Romanovsky, V. E., Ronchail, J., Rosenlof, K. H., Rudels, B., Sabine, C. L., Santee, M. L., Sawaengphokhai, P., Sayouri, A., Schauer, U., Schemm, J., Schmid, C., Schreck, C., Semiletov, I., Send, U., Sensoy, S., Shakhova, N., Sharp, M., Shiklomanov, N. I., Shimada, K., Shin, J., Siegel, D. A., Simmons, A., Skansi, M., Sokolov, V., Spence, J., Srivastava, A. K., Stackhouse, P. W., Stammerjohn, S., Steele, M., Steffen, K., Steinbrecht, W., Stephenson, T., Stolarski, R. S., Sweet, W., Takahashi, T., Taylor, M. A., Tedesco, M., Thepaut, J. N., Thompson, P., Timmermans, M. L., Tobin, S., Toole, J., Trachte, K., Trewin, B. C., Trigo, R. M., Trotman, A., Tucker, C. J., Ulupinar, Y., Wal, R. S. W., Werf, G. R., Vautard, R., Votaw, G., Wagner, W. W., Wahr, J., Walker, D. A., Wang, C. Z., Wang, J. H., Wang, L., Wang, M. H., Wang, S. H., Wanninkhof, R., Weaver, S., Weber, M., Weingartner, T., Weller, R. A., Wentz, F., Wilber, A. C., Williams, W., Willis, J. K., Wilson, R. C., Wolken, G., Wong, T. M., Woodgate, R., Yamada, R., Yamamoto-Kawai, M., Yoder, J. A., Yu, L. S., Yueh, S., Zhang, L. Y., Zhang, P. Q., Zhao, L., Zhou, X. J., Zimmermann, S., Zubair, L., Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), National Oceanic and Atmospheric Administration (NOAA), Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Space Technology Center, European Centre for Medium-Range Weather Forecasts (ECMWF), Climate Research Division [Toronto], Environment and Climate Change Canada, Earth and Space Research Institute [Seattle] (ESR), Department of Hydrology and Geo-Environmental Sciences [Amsterdam], Vrije Universiteit Amsterdam [Amsterdam] (VU), Vienna University of Technology (TU Wien), Instituto Dom Luiz, Universidade de Lisboa = University of Lisbon (ULISBOA), NOAA Earth System Research Laboratory (ESRL), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado [Boulder]-National Oceanic and Atmospheric Administration (NOAA), Department of Earth System Science [Irvine] (ESS), University of California [Irvine] (UC Irvine), University of California (UC)-University of California (UC), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), University of California Center for Hydrologic Modeling [Irvine] (UCCHM), NOAA Pacific Marine Environmental Laboratory [Seattle] (PMEL), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - 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[Hampton] (SSAI), National Snow and Ice Data Center (NSIDC), Naval Postgraduate School (NPS), University of California [Berkeley] (UC Berkeley), Centre de physique moléculaire optique et hertzienne (CPMOH), Université Sciences et Technologies - Bordeaux 1 (UB)-Centre National de la Recherche Scientifique (CNRS), CYRIC, Tohoku University [Sendai], The University of Tennessee [Knoxville], Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC, The University Centre in Svalbard (UNIS), Institute of Arctic Alpine Research [University of Colorado Boulder] (INSTAAR), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Meteorologisches Observatorium Hohenpeißenberg (MOHp), Deutscher Wetterdienst [Offenbach] (DWD), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Universidade de Lisboa (ULISBOA), University of California [Irvine] (UCI), University of California-University of California, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Universitá degli Studi dell’Insubria, University of Costa Rica, Météo France [Sainte-Clotilde], Météo France, University of Oxford [Oxford], Scripps Institution of Oceanography (SIO), Huazhong Agricultural University, University of California, NMR and Molecular Imaging Laboratory [Mons], University of Mons [Belgium] (UMONS), Lausanne University Hospital [Switzerland], Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Diderot - Paris 7 (UPD7), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Berkeley University of California (UC BERKELEY), Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1, and Institute of Arctic and Alpine Research (INSTAAR)

Subjects
[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract

International audience; Large-scale climate patterns influenced temperature and weather patterns around the globe in 2011. In particular, a moderate-to-strong La Nina at the beginning of the year dissipated during boreal spring but reemerged during fall. The phenomenon contributed to historical droughts in East Africa, the southern United States, and northern Mexico, as well the wettest two-year period (2010-11) on record for Australia, particularly remarkable as this follows a decade-long dry period. Precipitation patterns in South America were also influenced by La Nina. Heavy rain in Rio de Janeiro in January triggered the country's worst floods and landslides in Brazil's history. The 2011 combined average temperature across global land and ocean surfaces was the coolest since 2008, but was also among the 15 warmest years on record and above the 1981-2010 average. The global sea surface temperature cooled by 0.1 degrees C from 2010 to 2011, associated with cooling influences of La Nina. Global integrals of upper ocean heat content for 2011 were higher than for all prior years, demonstrating the Earth's dominant role of the oceans in the Earth's energy budget. In the upper atmosphere, tropical stratospheric temperatures were anomalously warm, while polar temperatures were anomalously cold. This led to large springtime stratospheric ozone reductions in polar latitudes in both hemispheres. Ozone concentrations in the Arctic stratosphere during March were the lowest for that period since satellite records began in 1979. An extensive, deep, and persistent ozone hole over the Antarctic in September indicates that the recovery to pre-1980 conditions is proceeding very slowly. Atmospheric carbon dioxide concentrations increased by 2.10 ppm in 2011, and exceeded 390 ppm for the first time since instrumental records began. Other greenhouse gases also continued to rise in concentration and the combined effect now represents a 30% increase in radiative forcing over a 1990 baseline. Most ozone depleting substances continued to fall. The global net ocean carbon dioxide uptake for the 2010 transition period from El Nino to La Nina, the most recent period for which analyzed data are available, was estimated to be 1.30 Pg C yr(-1), almost 12% below the 29-year long-term average. Relative to the long-term trend, global sea level dropped noticeably in mid-2010 and reached a local minimum in 2011. The drop has been linked to the La Nina conditions that prevailed throughout much of 2010-11. Global sea level increased sharply during the second half of 2011. Global tropical cyclone activity during 2011 was well-below average, with a total of 74 storms compared with the 1981-2010 average of 89. Similar to 2010, the North Atlantic was the only basin that experienced above-normal activity. For the first year since the widespread introduction of the Dvorak intensity-estimation method in the 1980s, only three tropical cyclones reached Category 5 intensity level-all in the Northwest Pacific basin. The Arctic continued to warm at about twice the rate compared with lower latitudes. Below-normal summer snowfall, a decreasing trend in surface albedo, and above-average surface and upper air temperatures resulted in a continued pattern of extreme surface melting, and net snow and ice loss on the Greenland ice sheet. Warmer-than-normal temperatures over the Eurasian Arctic in spring resulted in a new record-low June snow cover extent and spring snow cover duration in this region. In the Canadian Arctic, the mass loss from glaciers and ice caps was the greatest since GRACE measurements began in 2002, continuing a negative trend that began in 1987. New record high temperatures occurred at 20 m below the land surface at all permafrost observatories on the North Slope of Alaska, where measurements began in the late 1970s. Arctic sea ice extent in September 2011 was the second-lowest on record, while the extent of old ice (four and five years) reached a new record minimum that was just 19% of normal. On the opposite pole, austral winter and spring temperatures were more than 3 degrees C above normal over much of the Antarctic continent. However, winter temperatures were below normal in the northern Antarctic Peninsula, which continued the downward trend there during the last 15 years. In summer, an all-time record high temperature of -12.3 degrees C was set at the South Pole station on 25 December, exceeding the previous record by more than a full degree. Antarctic sea ice extent anomalies increased steadily through much of the year, from briefly setting a record low in April, to well above average in December. The latter trend reflects the dispersive effects of low pressure on sea ice and the generally cool conditions around the Antarctic perimeter.

Published
2012

27. Ozone depletion at temperature warmer than TNAT in the Arctic

Author

Pommereau, Jean-Pierre, Goutail, Florence, Pazmino, Andrea, Lefèvre, Franck, Pitts, M. C., Cardon, Catherine, STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and NASA Langley Research Center [Hampton] (LaRC)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [PHYS.PHYS.PHYS-AO-PH] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]
Abstract

The unprecedented ozone destruction in the Arctic vortex in 2011 that extended until the end of March offers a unique opportunity for testing the relationship between temperature, responsible for heterogeneous chlorine activation on PSCs and aerosols and the amplitude of ozone loss. Indeed, as shown by the total ozone evolution in the vortex during that winter from the SAOZ network compared to passive ozone simulations from the REPROBUS CTM, most of the total 39% total ozone depletion occurred after mid-February at a rate of near 0.8% /day when relatively low temperatures were still present in the Arctic. The evolution of ozone depletion is shown to fully match that of the cumulative area of temperatures below the chlorine activation threshold weighted by vortex sunlight illumination, assuming, as shown by Drlda and Mueller (2010), that chlorine activation occurs at 195 K at the 475 K level. However, if instead, the total integrated backscatter for combined liquid aerosols/PSCs inside the vortex reported by CALIPSO or the cumulated PSC surface at 191 K aligned to STS threshold are used, PSCs are seen to disappear in early March, that is three weeks before the end of ozone depletion. The suggestion is thus that chlorine activation takes place at temperature significantly warmer than that of NAT or STS PSC formation, on binary aerosol, still present and accounted for in the integrated backscatter, but of smaller surface area. The same analyses applied to all past winters since 1994 confirms the ozone depletion at relatively warm temperature in the absence of PSC. The mechanism involved is explored by a variety of model simulations, including or not, liquid binary aerosols, NAT and STS.

Published
2011

36. CALIPSO observations of stratospheric aerosols: a preliminary assessment

Author

Larry Thomason, Pitts, M. C., Winker, D. M., EGU, Publication, and NASA Headquarters

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:Chemistry, lcsh:QD1-999, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:Physics, lcsh:QC1-999
Abstract

We have examined the 532-nm aerosol backscatter coefficient measurements by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) for their use in the observation of stratospheric aerosol. CALIPSO makes observations that span from 82° S to 82° N each day and, for each profile, backscatter coefficient values reported up to ~40 km. The possibility of using CALIPSO for stratospheric aerosol observations is demonstrated by the clear observation of the 20 May 2006 eruption of Montserrat in the earliest CALIPSO data in early June as well as by observations showing the 7 October 2006 eruption of Tavurvur (Rabaul). However, the very low aerosol loading within the stratosphere makes routine observations of the stratospheric aerosol far more difficult than relatively dense volcanic plumes. Nonetheless, we found that averaging a complete days worth of nighttime only data into 5-deg latitude by 1-km vertical bins reveals a stratospheric aerosol layer centered near an altitude of 20 km, the clean wintertime polar vortices, and a small maximum in the lower tropical stratosphere. However, the derived values are clearly too small and often negative in much of the stratosphere. The data can be significantly improved by increasing the measured backscatter (molecular and aerosol) by approximately 5% suggesting that the current method of calibrating to a pure molecular atmosphere at 30 km is most likely the source of the low values.

Published
2007

38. Nitric acid trihydrate nucleation and denitrification in the Arctic stratosphere

Author

Grooß, J.-U., primary, Engel, I., additional, Borrmann, S., additional, Frey, W., additional, Günther, G., additional, Hoyle, C. R., additional, Kivi, R., additional, Luo, B. P., additional, Molleker, S., additional, Peter, T., additional, Pitts, M. C., additional, Schlager, H., additional, Stiller, G., additional, Vömel, H., additional, Walker, K. A., additional, and Müller, R., additional

Published
2014
Full Text
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39. Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions (RECONCILE): activities and results

Author

von Hobe, M., Bekki, S., Borrmann, S., Cairo, F., D'Amato, F., Di Donfrancesco, G., Dörnbrack, A., Ebersoldt, A., Ebert, M., Emde, C., Engel, I., Ern, M., Frey, W., Genco, S., Griessbach, S., Grooß, J.-U., Gulde, T., Günther, G., Hösen, E., Hoffmann, L., Homonnai, V., Hoyle, C. R., Isaksen, I. S. A., Jackson, D. R., Jánosi, I. M., Jones, R.L., Kandler, K., Kalicinsky, C., Keil, A., Khaykin, S. M., Khosrawi, F., Kivi, R., Kuttippurath, J., Laube, J. C., Lefèvre, F., Lehmann, Ralph, Ludmann, S., Luo, B. P., Marchand, M., Meyer, J., Mitev, V., Molleker, S., Müller, R., Oelhaf, H., Olschewski, F., Orsolini, Y., Peter, T., Pfeilsticker, K., Piesch, C., Pitts, M. C., Poole, L. R., Pope, F. D., Ravegnani, F., Rex, Markus, Riese, M., Röckmann, T., Rognerud, B., Roiger, A., Rolf, C., Santee, M. L., Scheibe, M., Schiller, C., Schlager, H., Siciliani de Cumis, M., Sitnikov, N., Søvde, O. A., Spang, R., Spelten, N., Stordal, F., Suminska-Ebersoldt, O., Ulanovski, A., Ungermann, J., Viciani, S., Volk, C. M., vom Scheidt, M., von der Gathen, Peter, Walker, K., Wegner, T., Weigel, R., Weinbuch, S., Wetzel, G., Wienhold, F. G., Wohltmann, Ingo, Woiwode, W., Young, I. A. K., Yushkov, V., Zobrist, B., Stroh, F., von Hobe, M., Bekki, S., Borrmann, S., Cairo, F., D'Amato, F., Di Donfrancesco, G., Dörnbrack, A., Ebersoldt, A., Ebert, M., Emde, C., Engel, I., Ern, M., Frey, W., Genco, S., Griessbach, S., Grooß, J.-U., Gulde, T., Günther, G., Hösen, E., Hoffmann, L., Homonnai, V., Hoyle, C. R., Isaksen, I. S. A., Jackson, D. R., Jánosi, I. M., Jones, R.L., Kandler, K., Kalicinsky, C., Keil, A., Khaykin, S. M., Khosrawi, F., Kivi, R., Kuttippurath, J., Laube, J. C., Lefèvre, F., Lehmann, Ralph, Ludmann, S., Luo, B. P., Marchand, M., Meyer, J., Mitev, V., Molleker, S., Müller, R., Oelhaf, H., Olschewski, F., Orsolini, Y., Peter, T., Pfeilsticker, K., Piesch, C., Pitts, M. C., Poole, L. R., Pope, F. D., Ravegnani, F., Rex, Markus, Riese, M., Röckmann, T., Rognerud, B., Roiger, A., Rolf, C., Santee, M. L., Scheibe, M., Schiller, C., Schlager, H., Siciliani de Cumis, M., Sitnikov, N., Søvde, O. A., Spang, R., Spelten, N., Stordal, F., Suminska-Ebersoldt, O., Ulanovski, A., Ungermann, J., Viciani, S., Volk, C. M., vom Scheidt, M., von der Gathen, Peter, Walker, K., Wegner, T., Weigel, R., Weinbuch, S., Wetzel, G., Wienhold, F. G., Wohltmann, Ingo, Woiwode, W., Young, I. A. K., Yushkov, V., Zobrist, B., and Stroh, F.

Published
2013

40. Denitrification and polar stratospheric cloud formation during the Arctic winter 2009/2010

Author

Khosrawi, Farahnaz, Urban, J., Pitts, M. C., Voelger, P., Achtert, Peggy, Kaphlanov, M., Santee, M. L., Manney, G. L., Murtagh, D., Fricke, K. H., Khosrawi, Farahnaz, Urban, J., Pitts, M. C., Voelger, P., Achtert, Peggy, Kaphlanov, M., Santee, M. L., Manney, G. L., Murtagh, D., and Fricke, K. H.

Abstract

The sedimentation of HNO3 containing PolarStratospheric Cloud (PSC) particles leads to a permanent re-moval of HNO3 and thus to a denitrification of the strato-sphere, an effect which plays an important role in strato-spheric ozone depletion. The polar vortex in the Arctic win-ter 2009/2010 was very cold and stable between end of De-cember and end of January. Strong denitrification between 475 to 525 K was observed in the Arctic in mid of Januaryby the Odin Sub Millimetre Radiometer (Odin/SMR). Thiswas the strongest denitrification that had been observed inthe entire Odin/SMR measuring period (2001–2010). Lidarmeasurements of PSCs were performed in the area of Kiruna,Northern Sweden with the IRF (Institutet för Rymdfysik) li-odar and with the Esrange lidar in January 2010. The measurements show that PSCs were present over the area of Kirunaduring the entire period of observations. The formation ofPSCs during the Arctic winter 2009/2010 is investigated using a microphysical box model. Box model simulationsare performed along air parcel trajectories calculated sixdays backward according to the PSC measurements with the ground-based lidar in the Kiruna area. From the temperaturehistory of the backward trajectories and the box model simulations we find two PSC regions, one over Kiruna accordingto the measurements made in Kiruna and one north of Scandinavia which is much colder, reaching also temperatures below Tice. Using the box model trajectories together with the observations of Odin/SMR,Aura/MLS (Microwave Limb Sounder), CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations)and the ground-based lidar we investigate how and by whichtype of PSC particles the denitrification that was observedduring the Arctic winter 2009/2010 was caused. From ouranalysis we find that due to an unusually strong synopticcooling event in mid January, ice particle formation on NATmay be a possible formation mechanism during that particu-lar winter that may have cause, authorCount :10

Published
2011
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41. Arctic stratospheric dehydration – Part 1: Unprecedented observation of vertical redistribution of water

Author

Khaykin, S. M., primary, Engel, I., additional, Vömel, H., additional, Formanyuk, I. M., additional, Kivi, R., additional, Korshunov, L. I., additional, Krämer, M., additional, Lykov, A. D., additional, Meier, S., additional, Naebert, T., additional, Pitts, M. C., additional, Santee, M. L., additional, Spelten, N., additional, Wienhold, F. G., additional, Yushkov, V. A., additional, and Peter, T., additional

Published
2013
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45. Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions (RECONCILE): activities and results

Author

von Hobe, M., primary, Bekki, S., additional, Borrmann, S., additional, Cairo, F., additional, D'Amato, F., additional, Di Donfrancesco, G., additional, Dörnbrack, A., additional, Ebersoldt, A., additional, Ebert, M., additional, Emde, C., additional, Engel, I., additional, Ern, M., additional, Frey, W., additional, Genco, S., additional, Griessbach, S., additional, Grooß, J.-U., additional, Gulde, T., additional, Günther, G., additional, Hösen, E., additional, Hoffmann, L., additional, Homonnai, V., additional, Hoyle, C. R., additional, Isaksen, I. S. A., additional, Jackson, D. R., additional, Jánosi, I. M., additional, Jones, R. L., additional, Kandler, K., additional, Kalicinsky, C., additional, Keil, A., additional, Khaykin, S. M., additional, Khosrawi, F., additional, Kivi, R., additional, Kuttippurath, J., additional, Laube, J. C., additional, Lefèvre, F., additional, Lehmann, R., additional, Ludmann, S., additional, Luo, B. P., additional, Marchand, M., additional, Meyer, J., additional, Mitev, V., additional, Molleker, S., additional, Müller, R., additional, Oelhaf, H., additional, Olschewski, F., additional, Orsolini, Y., additional, Peter, T., additional, Pfeilsticker, K., additional, Piesch, C., additional, Pitts, M. C., additional, Poole, L. R., additional, Pope, F. D., additional, Ravegnani, F., additional, Rex, M., additional, Riese, M., additional, Röckmann, T., additional, Rognerud, B., additional, Roiger, A., additional, Rolf, C., additional, Santee, M. L., additional, Scheibe, M., additional, Schiller, C., additional, Schlager, H., additional, Siciliani de Cumis, M., additional, Sitnikov, N., additional, Søvde, O. A., additional, Spang, R., additional, Spelten, N., additional, Stordal, F., additional, Sumińska-Ebersoldt, O., additional, Ulanovski, A., additional, Ungermann, J., additional, Viciani, S., additional, Volk, C. M., additional, vom Scheidt, M., additional, von der Gathen, P., additional, Walker, K., additional, Wegner, T., additional, Weigel, R., additional, Weinbruch, S., additional, Wetzel, G., additional, Wienhold, F. G., additional, Wohltmann, I., additional, Woiwode, W., additional, Young, I. A. K., additional, Yushkov, V., additional, Zobrist, B., additional, and Stroh, F., additional

Published
2013
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46. NAT nucleation and denitrification in the Arctic stratosphere

Author

Grooß, J.-U., primary, Engel, I., additional, Borrmann, S., additional, Frey, W., additional, Günther, G., additional, Hoyle, C. R., additional, Kivi, R., additional, Luo, B. P., additional, Molleker, S., additional, Peter, T., additional, Pitts, M. C., additional, Schlager, H., additional, Stiller, G., additional, Vömel, H., additional, Walker, K. A., additional, and Müller, R., additional

Published
2013
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