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51. Dynamics of the equatorial mesosphere observed using the Jicamarca MST radar during June and August 1987

Author

Fritts, David C., Kao Tsu, Emperor of China, Hitchman, Matthew H., Coy, Lawrence, Kudeki, Erhan, and Woodman, Ronald F.

Subjects
Atmospheric research -- Observations, Mesosphere -- Research, Radar meteorology -- Research, Earth sciences, Science and technology
Abstract

The Jicamarca MST radar was used in two campaigns during June and August 1987 to measure wave influences, flow variability, and mean structure in the equatorial stratosphere and mesosphere. This paper presents observations of motions and momentum fluxes in the mesosphere during each campaign. A companion paper by Hitchman et al. addresses the mean structure and fluxes as well as comparisons with other datasets. Results presented here indicate that the equatorial mesosphere is dynamically very active, with considerable gravity-wave and tidal motions and persuasive evidence of inertial instability and wave-filtering processes. Vertical velocities at high frequencies are comparable to those observed at other locations. Hourly mean horizontal motions and momentum fluxes are likewise large and variable, exhibiting enormous vertical shears and strong modulation of the wave spectrum and momentum fluxes at higher frequencies. Daily mean profiles reveal persistent structures with vertical scales of approximately 6-10 km, vertical shears of the meridional velocity of approximately 0.03 s to the -1, and large mean momentum fluxes. Also discussed are the implications of these observations for wave forcing and instability in the equatorial middle atmosphere.

Published
1992

52. Mean winds and momentum fluxes over Jicamarca, Peru, during June and August 1987

Author

Hitchman, Matthew H., Bywaters, Kenneth W., Fritts, David C., Coy, Lawrence, Kudeki, Erhan, and Surucu, Fahri

Subjects
Atmospheric turbulence -- Analysis, Atmospheric research -- Observations, Atmospheric circulation -- Analysis, Dynamic meteorology -- Research, Earth sciences, Science and technology
Abstract

Data from the mesosphere-stratosphere-troposphere (MST) radar at Jicamarca, Peru, together with other available data, are used to diagnose the mean structure of winds and gravity-wave momentum fluxes from the surface to 90 km during two ten-day campaigns in June and August of 1987. In the stratosphere a layer of maximum eastward flow associated with the quasi-biennial oscillation (QBO) was seen to strengthen and descend rapidly from June to August, overlying persistent westward flow. A layer of enhanced signal return, suggestive of a turbulent layer, was observed just above the descending QBO eastward maximum. Notable zonal asymmetries were present during this transition and the local meridional circulation departed from zonal-mean QBO theory. A substantial northeastward momentum flux was found below 25 km, which may be related to topographic gravity waves excited by southeastward flow across the Andes. In the lower mesosphere a relatively weak 'second' mesopause semiannual oscillation is confirmed. Gravity-wave zonal and meridional momentum fluxes usually opposed the flow, yielding body forces of approximately 10-100 m s to the -1 day to the -1. In both the lower stratosphere and mesosphere, body forces were comparable in magnitude to inferred Coriolis torques.

Published
1992

53. State of the climate in 2017

Author

Abernethy, R., Ackerman, Steven A., Adler, R., Albanil Encarnación, Adelina, Aldeco, Laura S., Alfaro, Eric J., Aliaga-Nestares, Vannia, Allan, Richard P., Allan, Rob, Alves, Lincoln M., Amador, Jorge A., Anderson, John, Andreassen, L. M., Argüez, Anthony, Armitage, C., Arndt, Derek S., Avalos, Grinia, Azorin-Molina, César, Báez, Julián, Bardin, M. Yu, Barichivich, Jonathan, Baringer, Molly O., Barreira, Sandra, Baxter, Stephen, Beck, H. E., Becker, Andreas, Bedka, Kristopher M., Behe, Carolina, Bell, Gerald D., Bellouin, Nicolas, Belmont, M., Benedetti, Angela, Bernhard, G. H., Berrisford, Paul, Berry, David I., Bhatt, U. S., Bissolli, Peter, Bjerke, J., Blake, Eric S., Blenkinsop, Stephen, Blunden, Jessica, Bolmgren, K., Bosilovich, Michael G., Boucher, Olivier, Bouchon, Marilú, Box, J. E., Boyer, Tim, Braathen, Geir O., Bromwich, David H., Brown, R., Buehler, S., Bulygina, Olga N., Burgess, D., Calderón, Blanca, Camargo, Suzana J., Campbell, Ethan C., Campbell, Jayaka D., Cappelen, J., Carrea, Laura, Carter, Brendan R., Castro, Anabel, Chambers, Don P., Cheng, Lijing, Christiansen, Hanne H., Christy, John R., Chung, E. S., Clem, Kyle R., Coelho, Caio A.S., Coldewey-Egbers, Melanie, Colwell, Steve, Cooper, Owen R., Copland, L., Costanza, Carol, Covey, Curt, Coy, Lawrence, Cronin, T., Crouch, Jake, Cruzado, Luis, Daniel, Raychelle, Davis, Sean M., Davletshin, S. G., De Eyto, Elvira, De Jeu, Richard A.M., De La Cour, Jacqueline L., De Laat, Jos, De Gasperi, Curtis L., Degenstein, Doug, Deline, P., Demircan, Mesut, Derksen, C., Dewitte, Boris, Dhurmea, R., Di Girolamo, Larry, Diamond, Howard J., Dickerson, C., Dlugokencky, Ed J., Dohan, Kathleen, Dokulil, Martin T., Dolman, A. Johannes, Domingues, Catia M., Domingues, Ricardo, Donat, Markus G., Dong, Shenfu, Dorigo, Wouter A., Drozdov, D. S., Dunn, Robert J.H., Durre, Imke, Dutton, Geoff S., Eakin, C. Mark, El Kharrim, M., Elkins, James W., Epstein, H. E., Espinoza, Jhan C., Famiglietti, James S., Farmer, J., Farrell, S., Fauchald, P., Fausto, R. S., Feely, Richard A., Feng, Z., Fenimore, Chris, Fettweis, X., Fioletov, Vitali E., Flemming, Johannes, Fogt, Ryan L., Folland, Chris, Forbes, B. C., Foster, Michael J., Francis, S. D., Franz, Bryan A., Frey, Richard A., Frith, Stacey M., Froidevaux, Lucien, Ganter, Catherine, Geiger, Erick F., Gerland, S., Gilson, John, Gobron, Nadine, Goldenberg, Stanley B., Gomez, Andrea M., Goni, Gustavo, Grooß, Jens Uwe, Gruber, Alexander, Guard, Charles P., Gugliemin, Mario, Gupta, S. K., Gutiérrez, Dimitri, Haas, C., Hagos, S., Hahn, Sebastian, Haimberger, Leo, Hall, Brad D., Halpert, Michael S., Hamlington, Benjamin D., Hanna, E., Hansen, K., Hanssen-Bauer, L., Harris, Ian, Hartfield, Gail, Heidinger, Andrew K., Heim, Richard R., Helfrich, S., Hemming, D. L., Hendricks, S., Hernández, Rafael, Hernández, Sosa Marieta, Heron, Scott F., Heuzé, C., Hidalgo, Hugo G., Ho, Shu Peng, Hobbs, William R., Horstkotte, T., Huang, Boyin, Hubert, Daan, Hueuzé, Céline, Hurst, Dale F., Ialongo, Iolanda, Ibrahim, M. M., Ijampy, J. A., Inness, Antje, Isaac, Victor, Isaksen, K., Ishii, Masayoshi, Jacobs, Stephanie J., Jeffries, Martin O., Jevrejeva, Svetlana, Jiménez, C., Jin, Xiangze, John, Viju, Johns, William E., Johnsen, Bjørn, Johnson, Bryan, Johnson, Gregory C., Johnson, Kenneth S., Jones, Philip D., Jumaux, Guillaume, Kabidi, Khadija, Kaiser, J. W., Karaköylü, Erdem M., Kato, Seiji, Kazemi, A., Keller, Linda M., Kennedy, John, Kerr, Kenneth, Khan, M. S., Kholodov, A. L., Khoshkam, Mahbobeh, Killick, Rachel, Kim, Hyungjun, Kim, S. J., Klotzbach, Philip J., Knaff, John A., Kohler, J., Korhonen, Johanna, Korshunova, Natalia N., Kramarova, Natalya, Kratz, D. P., Kruger, Andries, Kruk, Michael C., Krumpen, T., Ladd, C., Lakatos, Mónika, Lakkala, Kaisa, Lander, Mark A., Landschützer, Peter, Landsea, Chris W., Lankhorst, Matthias, Lavado-Casimiro, Waldo, Lazzara, Matthew A., Lee, S. E., Lee, T. C., Leuliette, Eric, L'Heureux, Michelle, Li, Tim, Lieser, Jan L., Lin, I. I., Mears, Carl A., Liu, Gang, Li, Bailing, Liu, Hongxing, Locarnini, Ricardo, Loeb, Norman G., Long, Craig S., López, Luis A., Lorrey, Andrew M., Loyola, Diego, Lumpkin, Rick, Luo, Jing Jia, Luojus, K., Luthcke, S., Macias-Fauria, M., Malkova, G. V., Manney, Gloria L., Marcellin, Vernie, Marchenko, S. S., Marengo, José A., Marín, Dora, Marra, John J., Marszelewski, Wlodzimierz, Martens, B., Martin, A., Martínez, Alejandra G., Martínez-Güingla, Rodney, Martínez-Sánchez, Odalys, Marsh, Benjamin L., Lyman, John M., Massom, Robert A., May, Linda, Mayer, Michael, Mazloff, Matthew, McBride, Charlotte, McCabe, M. F., McCarthy, Mark, Meier, W., Meijers, Andrew J.S., Mekonnen, Ademe, Mengistu Tsidu, G., Menzel, W. Paul, Merchant, Christopher J., Meredith, Michael P., Merrifield, Mark A., Miller, Ben, Miralles, Diego G., Mitchum, Gary T., Mitro, Sukarni, Moat, Ben, Mochizuki, Y., Monselesan, Didier, Montzka, Stephen A., Mora, Natalie, Morice, Colin, Mosquera-Vásquez, Kobi, Mostafa, Awatif E., Mote, T., Mudryk, L., Mühle, Jens, Mullan, A. Brett, Müller, Rolf, Myneni, R., Nash, Eric R., Nerem, R. Steven, Newman, L., Newman, Paul A., Nielsen-Gammon, John W., Nieto, Juan José, Noetzli, Jeannette, Noll, Ben E., O'Neel, S., Osborn, Tim J., Osborne, Emily, Overland, J., Oyunjargal, Lamjav, Park, T., Pasch, Richard J., Pascual-Ramírez, Reynaldo, Pastor Saavedra, Maria Asuncion, Paterson, Andrew M., Paulik, Christoph, Pearce, Petra R., Peltier, Alexandre, Pelto, Mauri S., Peng, Liang, Perkins-Kirkpatrick, Sarah E., Perovich, Don, Petropavlovskikh, Irina, Pezza, Alexandre B., Phillips, C., Phillips, David, Phoenix, G., Pinty, Bernard, Pinzon, J., Po-Chedley, S., Polashenski, C., Purkey, Sarah G., Quispe, Nelson, Rajeevan, Madhavan, Rakotoarimalala, C., Rayner, Darren, Raynolds, M. K., Reagan, James, Reid, Phillip, Reimer, Christoph, Rémy, Samuel, Revadekar, Jayashree V., Richardson, A. D., Richter-Menge, Jacqueline, Ricker, R., Rimmer, Alon, Robinson, David A., Rodell, Matthew, Rodriguez Camino, Ernesto, Romanovsky, Vladimir E., Ronchail, Josyane, Rosenlof, Karen H., Rösner, Benjamin, Roth, Chris, Roth, David Mark, Rusak, James A., Rutishäuser, T., Sallée, Jean Bapiste, Sánchez-Lugo, Ahira, Santee, Michelle L., Sasgen, L., Sawaengphokhai, P., Sayad, T. A., Sayouri, Amal, Scambos, Ted A., Scanlon, T., Schenzinger, Verena, Schladow, S. Geoffrey, Schmid, Claudia, Schmid, Martin, Schreck, Carl J., Selkirk, H. B., Send, Uwe, Sensoy, Serhat, Sharp, M., Shi, Lei, Shiklomanov, Nikolai I., Shimaraeva, Svetlana V., Siegel, David A., Silow, Eugene, Sima, Fatou, Simmons, Adrian J., Skirving, William J., Smeed, David A., Smeets, C. J.P.P., Smith, Adam, Smith, Sharon L., Soden, B., Sofieva, Viktoria, Sparks, T. H., Spence, Jacqueline M., Spillane, Sandra, Srivastava, A. K., Stackhouse, Paul W., Stammerjohn, Sharon, Stanitski, Diane M., Steinbrecht, Wolfgang, Stella, José L., Stengel, M., Stephenson, Kimberly, Stephenson, Tannecia S., Strahan, Susan, Streletskiy, Dimitri A., Strong, Alan E., Sun-Mack, Sunny, Sutton, Adrienne J., Swart, Sebastiaan, Sweet, William, Takahashi, Kenneth S., Tamar, Gerard, Taylor, Michael A., Tedesco, M., Thackeray, S. J., Thoman, R. L., Thompson, Philip, Thomson, L., Thorsteinsson, T., Timbal, Bertrand, Timmermans, M. L., TImofeyev, Maxim A., Tirak, Kyle V., Tobin, Skie, Togawa, H., Tømmervik, H., Tourpali, Kleareti, Trachte, Katja, Trewin, Blair C., Triñanes, Joaquin A., Trotman, Adrian R., Tschudi, M., Tucker, C. J., Tye, Mari R., Van As, D., Van De Wal, R. S.W., Van Der Ronald, J. A., Van Der Schalie, Robin, Van Der Schrier, Gerard, Van Der Werf, Guido R., Van Meerbeeck, Cedric J., Velden, Christopher S., Velicogna, I., Verburg, Piet, Vickers, H., Vincent, Lucie A., Vömel, Holger, Vose, Russell S., Wagner, Wolfgang, Walker, D. A., Walsh, J., Wang, Bin, Wang, Junhong, Wang, Lei, Wang, M., Wang, Ray, Wang, Sheng Hung, Wanninkhof, Rik, Watanabe, Shohei, Weber, Mark, Webster, M., Weller, Robert A., Westberry, Toby K., Weyhenmeyer, Gesa A., Whitewood, Robert, Widlansky, Matthew J., Wiese, David N., Wijffels, Susan E., Wilber, Anne C., Wild, Jeanette D., Willett, Kate M., Willis, Josh K., Wolken, G., Wong, Takmeng, Wood, E. F., Wood, K., Woolway, R. Iestyn, Wouters, B., Xue, Yan, Yin, Xungang, Yoon, Huang, York, A., Yu, Lisan, Zambrano, Eduardo, Zhang, Huai Min, Zhang, Peiqun, Zhao, Guanguo, Zhao, Lin, Zhu, Zhiwei, Ziel, R., Ziemke, Jerry R., Ziese, Markus G., Griffin, Jessicca, Hammer, Gregory, Love-Brotak, S. Elizabeth, Misch, Deborah J., Riddle, Deborah B., Slagle, Mary, Sprain, Mara, Veasey, Sara W., McVicar, Tim R., Sub Dynamics Meteorology, Sub Soft Condensed Matter, LS Religiewetenschap, Sub Atmospheric physics and chemistry, Zonder bezoldiging NED, LS Taalverwerving, Leerstoel Tubergen, Afd Chemical Biology and Drug Discovery, Hafd Faculteitsbureau GW, Afd Pharmacology, Dep IRAS, Marine and Atmospheric Research, and OFR - Religious Studies

Subjects
Atmospheric Science
Abstract

In 2017, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-reached new record highs. The annual global average carbon dioxide concentration at Earth's surface for 2017 was 405.0 ± 0.1 ppm, 2.2 ppm greater than for 2016 and the highest in the modern atmospheric measurement record and in ice core records dating back as far as 800 000 years. The global growth rate of CO2 has nearly quadrupled since the early 1960s. With ENSO-neutral conditions present in the central and eastern equatorial Pacific Ocean during most of the year and weak La Niña conditions notable at the start and end, the global temperature across land and ocean surfaces ranked as the second or third highest, depending on the dataset, since records began in the mid-to-late 1800s. Notably, it was the warmest non-El Niño year in the instrumental record. Above Earth's surface, the annual lower tropospheric temperature was also either second or third highest according to all datasets analyzed. The lower stratospheric temperature was about 0.2°C higher than the record cold temperature of 2016 according to most of the in situ and satellite datasets. Several countries, including Argentina, Uruguay, Spain, and Bulgaria, reported record high annual temperatures. Mexico broke its annual record for the fourth consecutive year. On 27 January, the temperature reached 43.4°C at Puerto Madryn, Argentina-the highest temperature recorded so far south (43°S) anywhere in the world. On 28 May in Turbat, western Pakistan, the high of 53.5°C tied Pakistan's all-time highest temperature and became the world-record highest temperature for May. In the Arctic, the 2017 land surface temperature was 1.6°C above the 1981-2010 average, the second highest since the record began in 1900, behind only 2016. The five highest annual Arctic temperatures have all occurred since 2007. Exceptionally high temperatures were observed in the permafrost across the Arctic, with record values reported in much of Alaska and northwestern Canada. In August, high sea surface temperature (SST) records were broken for the Chukchi Sea, with some regions as warm as +11°C, or 3° to 4°C warmer than the longterm mean (1982-present). According to paleoclimate studies, today's abnormally warm Arctic air and SSTs have not been observed in the last 2000 years. The increasing temperatures have led to decreasing Arctic sea ice extent and thickness. On 7 March, sea ice extent at the end of the growth season saw its lowest maximum in the 37-year satellite record, covering 8% less area than the 1981-2010 average. The Arctic sea ice minimum on 13 September was the eighth lowest on record and covered 25% less area than the long-term mean. Preliminary data indicate that glaciers across the world lost mass for the 38th consecutive year on record; the declines are remarkably consistent from region to region. Cumulatively since 1980, this loss is equivalent to slicing 22 meters off the top of the average glacier. Antarctic sea ice extent remained below average for all of 2017, with record lows during the first four months. Over the continent, the austral summer seasonal melt extent and melt index were the second highest since 2005, mostly due to strong positive anomalies of air temperature over most of the West Antarctic coast. In contrast, the East Antarctic Plateau saw record low mean temperatures in March. The year was also distinguished by the second smallest Antarctic ozone hole observed since 1988. Across the global oceans, the overall long-term SST warming trend remained strong. Although SST cooled slightly from 2016 to 2017, the last three years produced the three highest annual values observed; these high anomalies have been associated with widespread coral bleaching. The most recent global coral bleaching lasted three full years, June 2014 to May 2017, and was the longest, most widespread, and almost certainly most destructive such event on record. Global integrals of 0-700-m and 0-2000-m ocean heat content reached record highs in 2017, and global mean sea level during the year became the highest annual average in the 25-year satellite altimetry record, rising to 77 mm above the 1993 average. In the tropics, 2017 saw 85 named tropical storms, slightly above the 1981-2010 average of 82. The North Atlantic basin was the only basin that featured an above-normal season, its seventh most active in the 164-year record. Three hurricanes in the basin were especially notable. Harvey produced record rainfall totals in areas of Texas and Louisiana, including a storm total of 1538.7 mm near Beaumont, Texas, which far exceeds the previous known U.S. tropical cyclone record of 1320.8 mm. Irma was the strongest tropical cyclone globally in 2017 and the strongest Atlantic hurricane outside of the Gulf of Mexico and Caribbean on record with maximum winds of 295 km h-1. Maria caused catastrophic destruction across the Caribbean Islands, including devastating wind damage and flooding across Puerto Rico. Elsewhere, the western North Pacific, South Indian, and Australian basins were all particularly quiet. Precipitation over global land areas in 2017 was clearly above the long-term average. Among noteworthy regional precipitation records in 2017, Russia reported its second wettest year on record (after 2013) and Norway experienced its sixth wettest year since records began in 1900. Across India, heavy rain and flood-related incidents during the monsoon season claimed around 800 lives. In August and September, above-normal precipitation triggered the most devastating floods in more than a decade in the Venezuelan states of Bolívar and Delta Amacuro. In Nigeria, heavy rain during August and September caused the Niger and Benue Rivers to overflow, bringing floods that displaced more than 100 000 people. Global fire activity was the lowest since at least 2003; however, high activity occurred in parts of North America, South America, and Europe, with an unusually long season in Spain and Portugal, which had their second and third driest years on record, respectively. Devastating fires impacted British Columbia, destroying 1.2 million hectares of timber, bush, and grassland, due in part to the region's driest summer on record. In the United States, an extreme western wildfire season burned over 4 million hectares; the total costs of $18 billion tripled the previous U.S. annual wildfire cost record set in 1991.

Published
2018

54. Choosing Meteorological Input for the Global Modeling Initiative Assessment of High Speed Aircraft

Author

Douglass, A. R, Prather, M. P, Hall, T. M, Strahan, S. E, Raesch, P. J, Sparling, L. C, Coy, Lawrence, and Rodriquez, J. M

Subjects
Meteorology And Climatology
Abstract

The Global Modeling Initiative (GMI) science team is developing a three dimensional chemistry and transport model (CTM) to be used in assessment of the atmospheric effects of aviation. Requirements are that this model be documented be validated against observations, use a realistic atmospheric circulation, and contain numerical transport and photochemical modules representing atmospheric processes. The model must also retain computational efficiency to be tractable to use for multiple scenarios and sensitivity studies. To meet these requirements, a facility model concept was developed in which the different components of the CTM are evaluated separately. The first use of the GMI model will be to evaluate the impact of the exhaust of supersonic aircraft on the stratosphere. The assessment calculations will depend strongly on the wind and temperature fields used by the CTM. Three meteorological data sets for the stratosphere are available to GMI: the National Center for Atmospheric Research Community Climate Model (CCM2), the Goddard Earth Observing System Data Assimilation System (GEOS DAS), and the Goddard Institute for Space Studies general circulation model (GISS). Objective criteria were established by the GMI team to identify the data set which provides the best representation of the stratosphere. Simulations of gases with simple chemical control were chosen to test various aspects of model transport. The three meteorological data sets were evaluated and graded based on their ability to simulate these aspects of stratospheric measurements. This paper describes the criteria used in grading the meteorological fields. The meteorological data set which has the highest score and therefore was selected for GMI is CCM2. This type of objective model evaluation establishes a physical basis for interpretation of differences between models and observations. Further, the method provides a quantitative basis for defining model errors, for discriminating between different models, and for ready re-evaluation of improved models. These in turn will lead to a higher level of confidence in assessment calculations.

Published
1999

61. Diagnosis of Middle-Atmosphere Climate Sensitivity by the Climate Feedback-Response Analysis Method.

Author

Zhu, Xun, Yee, Jeng-Hwa, Cai, Ming, Swartz, William H., Coy, Lawrence, Aquila, Valentina, Garcia, Rolando, and Talaat, Elsayed R

Subjects
CLIMATE research, ATMOSPHERIC research, CARBON dioxide, TEMPERATURE measurements, SOLAR cycle
Abstract

The authors present a new method to diagnose the middle-atmosphere climate sensitivity by extending the climate feedback-response analysis method (CFRAM) for the coupled atmosphere-surface system to the middle atmosphere. The middle-atmosphere CFRAM (MCFRAM) is built on the atmospheric energy equation per unit mass with radiative heating and cooling rates as its major thermal energy sources. MCFRAM preserves CFRAM's unique feature of additivity, such that partial temperature changes due to variations in external forcing and feedback processes can be added to give a total temperature change for direct comparison with the observed temperature change. In addition, MCFRAM establishes a physical relationship of radiative damping between the energy perturbations associated with various feedback processes and temperature perturbations associated with thermal responses. In this study, MCFRAM is applied to both observations and model output fields to diagnose the middle-atmosphere climate sensitivity. The authors found that the largest component of the middle-atmosphere temperature response to the 11-yr solar cycle (solar maximum vs solar minimum) is the partial temperature change due to the variation of the solar flux. Increasing CO2 cools the middle atmosphere, whereas the partial temperature change due to changes in O3 can be either positive or negative. The application of MCFRAM to model dynamical fields reconfirms the advantage of introducing the residual circulation to characterize middle-atmosphere dynamics in terms of the partial temperature changes. The radiatively driven globally averaged partial temperature change is approximately equal to the observed temperature change, ranging from −0.5 K near 25 km to −1.0 K near 70 km between solar maximum and solar minimum. [ABSTRACT FROM AUTHOR]

Published
2016
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63. Tidally induced variations of polar mesospheric cloud altitudes and ice water content using a data assimilation system

Author

Stevens, Michael H., primary, Siskind, David E., additional, Eckermann, Stephen D., additional, Coy, Lawrence, additional, McCormack, John P., additional, Englert, Christoph R., additional, Hoppel, Karl W., additional, Nielsen, Kim, additional, Kochenash, Andrew J., additional, Hervig, Mark E., additional, Randall, Cora E., additional, Lumpe, Jerry, additional, Bailey, Scott M., additional, Rapp, Markus, additional, and Hoffmann, Peter, additional

Published
2010
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64. Gravity wave structure between 60 and 90 km inferred from Space Shuttle reentry data

Author

Fritts, David C, Blanchard, Robert C, and Coy, Lawrence

Subjects
Geophysics
Abstract

Density fluctuations obtained along seven Space Shuttle reentry tracks are used to examine the horizontal structure and the vertical distribution of density variance in the mesosphere and lower thermosphere. The tracks lie primarily over open ocean at middle and low latitudes and represent the only measurements of horizontal atmospheric structure at these heights available to date. The density fluctuations are interpreted in terms of gravity-wave motions and reveal significant density (and velocity) variance at horizontal scales ranging from about 10 to 1000 km. Fluctuation amplitudes are used to infer corresponding velocity perturbations and characteristic vertical scales and frequencies of the wave spectrum. Results suggest that the mean velocity variance is smaller over the Pacific ocean than over major land masses, and that the variance increases with height in a manner consistent with that expected in the present of wave saturation processes.

Published
1989
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68. Singular vectors and their nonlinear evolution during the January 2009 stratospheric sudden warming.

Author

Coy, Lawrence and Reynolds, Carolyn A.

Subjects
*STRATOSPHERIC circulation, *GLOBAL warming research, *POLAR vortex, *ASTRONOMICAL perturbation, *STRATOSPHERE, *ARCTIC oscillation
Abstract

The evolution and structure of stratospheric singular vectors (SVs) during the major stratospheric sudden warming (SSW) of January 2009 are investigated. SV analyses, optimized for growth at stratospheric levels over 72 h, were examined for selected dates before and during the SSW. It was found that the initial and final SV fields have larger horizontal structures during the SSW event than before the SSW event. A high-altitude forecast model was initialized with perturbations taken from the initial time SV structures and integrated for 144 h to study growth and nonlinear changes in a highly disturbed polar vortex. When large-amplitude initial SV perturbations were forecast during the SSW, large changes occurred in the descent of the SSW event and poleward focusing of the Eliassen-Palm fluxes. Examination of the development of SV analysis suggests that stratospheric SV growth occurs through wave-action conservation as initial SV perturbations propagate into the polar vortex jet. [ABSTRACT FROM AUTHOR]

Published
2014
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79. Dynamics of the Disrupted 2015-16 Quasi-Biennial Oscillation.

Author

Coy L, Newman PA, Pawson S, and Lait LR

Abstract

A significant disruption of the Quasi-Biennial Oscillation (QBO) occurred during the Northern Hemisphere (NH) winter of 2015-16. Since the QBO is the major wind variability source in the tropical lower stratosphere and influences the rate of ascent of air entering the stratosphere, understanding the cause of this singular disruption may provide new insights into the variability and sensitivity of the global climate system. Here we examine this disruptive event using global reanalysis winds and temperatures from 1980-2016. Results reveal record maxima in tropical horizontal momentum fluxes and wave forcing of the tropical zonal mean zonal wind over the NH 2015-16 winter. The Rossby waves responsible for these record tropical values appear to originate in the NH and were focused strongly into the tropics at the 40 hPa level. Two additional NH winters, 1987-88 and 2010-11 were also found to have large, tropical lower stratosphere, momentum flux divergences; however, the QBO westerlies did not change to easterlies in those cases.

Published
2017
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