Li
Qiang
Li
Qiang
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ArticleAcoustical measurement of nonlinear internal waves using the inverted echo sounder(American Meteorological Society, 2009-10) Li, Qiang ; Farmer, David M. ; Duda, Timothy F. ; Ramp, Steven R.The performance of pressure sensor–equipped inverted echo sounders for monitoring nonlinear internal waves is examined. The inverted echo sounder measures the round-trip acoustic travel time from the sea floor to the sea surface and thus acquires vertically integrated information on the thermal structure, from which the first baroclinic mode of thermocline motion may be inferred. This application of the technology differs from previous uses in that the wave period (30 min) is short, requiring a more rapid transmission rate and a different approach to the analysis. Sources of error affecting instrument performance include tidal effects, barotropic adjustment to internal waves, ambient acoustic noise, and sea surface roughness. The latter two effects are explored with a simulation that includes surface wave reconstruction, acoustic scattering based on the Kirchhoff approximation, wind-generated noise, sound propagation, and the instrument’s signal processing circuitry. Bias is introduced as a function of wind speed, but the simulation provides a basis for bias correction. The assumption that the waves do not significantly affect the mean stratification allows for a focus on the dynamic response. Model calculations are compared with observations in the South China Sea by using nearby temperature measurements to provide a test of instrument performance. After applying corrections for ambient noise and surface roughness effects, the inverted echo sounder exhibits an RMS variability of approximately 4 m in the estimated depth of the eigenfunction maximum in the wind speed range 0 ≤ U10 ≤ 10 m s−1. This uncertainty may be compared with isopycnal excursions for nonlinear internal waves of 100 m, showing that the observational approach is effective for measurements of nonlinear internal waves in this environment.
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ArticleEUREC4A(Copernicus Publications, 2021-08-25) Stevens, Bjorn ; Bony, Sandrine ; Farrell, David ; Ament, Felix ; Blyth, Alan ; Fairall, Christopher W. ; Karstensen, Johannes ; Quinn, Patricia K. ; Speich, Sabrina ; Acquistapace, Claudia ; Aemisegger, Franziska ; Albright, Anna Lea ; Bellenger, Hugo ; Bodenschatz, Eberhard ; Caesar, Kathy-Ann ; Chewitt-Lucas, Rebecca ; de Boer, Gijs ; Delanoë, Julien ; Denby, Leif ; Ewald, Florian ; Fildier, Benjamin ; Forde, Marvin ; George, Geet ; Gross, Silke ; Hagen, Martin ; Hausold, Andrea ; Heywood, Karen J. ; Hirsch, Lutz ; Jacob, Marek ; Jansen, Friedhelm ; Kinne, Stefan ; Klocke, Daniel ; Kölling, Tobias ; Konow, Heike ; Lothon, Marie ; Mohr, Wiebke ; Naumann, Ann Kristin ; Nuijens, Louise ; Olivier, Léa ; Pincus, Robert ; Pöhlker, Mira L. ; Reverdin, Gilles ; Roberts, Gregory ; Schnitt, Sabrina ; Schulz, Hauke ; Siebesma, Pier ; Stephan, Claudia Christine ; Sullivan, Peter P. ; Touzé-Peiffer, Ludovic ; Vial, Jessica ; Vogel, Raphaela ; Zuidema, Paquita ; Alexander, Nicola ; Alves, Lyndon ; Arixi, Sophian ; Asmath, Hamish ; Bagheri, Gholamhossein ; Baier, Katharina ; Bailey, Adriana ; Baranowski, Dariusz ; Baron, Alexandre ; Barrau, Sébastien ; Barrett, Paul A. ; Batier, Frédéric ; Behrendt, Andreas ; Bendinger, Arne ; Beucher, Florent ; Bigorre, Sebastien P. ; Blades, Edmund ; Blossey, Peter ; Bock, Olivier ; Böing, Steven ; Bosser, Pierre ; Bourras, Denis ; Bouruet-Aubertot, Pascale ; Bower, Keith ; Branellec, Pierre ; Branger, Hubert ; Brennek, Michal ; Brewer, Alan ; Brilouet, Pierre-Etienne ; Brügmann, Björn ; Buehler, Stefan A. ; Burke, Elmo ; Burton, Ralph ; Calmer, Radiance ; Canonici, Jean-Christophe ; Carton, Xavier ; Cato, Gregory, Jr. ; Charles, Jude Andre ; Chazette, Patrick ; Chen, Yanxu ; Chilinski, Michal T. ; Choularton, Thomas ; Chuang, Patrick ; Clarke, Shamal ; Coe, Hugh ; Cornet, Céline ; Coutris, Pierre ; Couvreux, Fleur ; Crewell, Susanne ; Cronin, Timothy W. ; Cui, Zhiqiang ; Cuypers, Yannis ; Daley, Alton ; Damerell, Gillian M. ; Dauhut, Thibaut ; Deneke, Hartwig ; Desbios, Jean-Philippe ; Dörner, Steffen ; Donner, Sebastian ; Douet, Vincent ; Drushka, Kyla ; Dütsch, Marina ; Ehrlich, André ; Emanuel, Kerry A. ; Emmanouilidis, Alexandros ; Etienne, Jean-Claude ; Etienne-Leblanc, Sheryl ; Faure, Ghislain ; Feingold, Graham ; Ferrero, Luca ; Fix, Andreas ; Flamant, Cyrille ; Flatau, Piotr Jacek ; Foltz, Gregory R. ; Forster, Linda ; Furtuna, Iulian ; Gadian, Alan ; Galewsky, Joseph ; Gallagher, Martin ; Gallimore, Peter ; Gaston, Cassandra J. ; Gentemann, Chelle L. ; Geyskens, Nicolas ; Giez, Andreas ; Gollop, John ; Gouirand, Isabelle ; Gourbeyre, Christophe ; de Graaf, Dörte ; de Graaf, Geiske E. ; Grosz, Robert ; Güttler, Johannes ; Gutleben, Manuel ; Hall, Kashawn ; Harris, George ; Helfer, Kevin C. ; Henze, Dean ; Herbert, Calvert ; Holanda, Bruna ; Ibanez-Landeta, Antonio ; Intrieri, Janet ; Iyer, Suneil ; Julien, Fabrice ; Kalesse, Heike ; Kazil, Jan ; Kellman, Alexander ; Kidane, Abiel T. ; Kirchner, Ulrike ; Klingebiel, Marcus ; Körner, Mareike ; Kremper, Leslie Ann ; Kretzschmar, Jan ; Krüger, Ovid O. ; Kumala, Wojciech ; Kurz, Armin ; L'Hégareta, Pierre ; Labaste, Matthieu ; Lachlan-Cope, Thomas ; Laing, Arlene ; Landschützer, Peter ; Lang, Theresa ; Lange, Diego ; Lange, Ingo ; Laplace, Clément ; Lavik, Gauke ; Laxenaire, Rémi ; Le Bihan, Caroline ; Leandro, Mason ; Lefevre, Nathalie ; Lena, Marius ; Lenschow, Donald ; Li, Qiang ; Lloyd, Gary ; Los, Sebastian ; Losi, Niccolò ; Lovell, Oscar ; Luneau, Christopher ; Makuch, Przemyslaw ; Malinowski, Szymon ; Manta, Gaston ; Marinou, Eleni ; Marsden, Nicholas ; Masson, Sebastien ; Maury, Nicolas ; Mayer, Bernhard ; Mayers-Als, Margarette ; Mazel, Christophe ; McGeary, Wayne ; McWilliams, James C. ; Mech, Mario ; Mehlmann, Melina ; Meroni, Agostino Niyonkuru ; Mieslinger, Theresa ; Minikin, Andreas ; Minnett, Peter J. ; Möller, Gregor ; Morfa Avalos, Yanmichel ; Muller, Caroline ; Musat, Ionela ; Napoli, Anna ; Neuberger, Almuth ; Noisel, Christophe ; Noone, David ; Nordsiek, Freja ; Nowak, Jakub L. ; Oswald, Lothar ; Parker, Douglas J. ; Peck, Carolyn ; Person, Renaud ; Philippi, Miriam ; Plueddemann, Albert J. ; Pöhlker, Christopher ; Pörtge, Veronika ; Pöschl, Ulrich ; Pologne, Lawrence ; Posyniak, Michał ; Prange, Marc ; Quinones Melendez, Estefania ; Radtke, Jule ; Ramage, Karim ; Reimann, Jens ; Renault, Lionel ; Reus, Klaus ; Reyes, Ashford ; Ribbe, Joachim ; Ringel, Maximilian ; Ritschel, Markus ; Rocha, Cesar B. ; Rochetin, Nicolas ; Röttenbacher, Johannes ; Rollo, Callum ; Royer, Haley M. ; Sadoulet, Pauline ; Saffin, Leo ; Sandiford, Sanola ; Sandu, Irina ; Schäfer, Michael ; Schemann, Vera ; Schirmacher, Imke ; Schlenczek, Oliver ; Schmidt, Jerome M. ; Schröder, Marcel ; Schwarzenboeck, Alfons ; Sealy, Andrea ; Senff, Christoph J. ; Serikov, Ilya ; Shohan, Samkeyat ; Siddle, Elizabeth ; Smirnov, Alexander ; Späth, Florian ; Spooner, Branden ; Stolla, M. Katharina ; Szkółka, Wojciech ; de Szoeke, Simon P. ; Tarot, Stéphane ; Tetoni, Eleni ; Thompson, Elizabeth ; Thomson, Jim ; Tomassini, Lorenzo ; Totems, Julien ; Ubele, Alma Anna ; Villiger, Leonie ; von Arx, Jan ; Wagner, Thomas ; Walther, Andi ; Webber, Ben ; Wendisch, Manfred ; Whitehall, Shanice ; Wiltshire, Anton ; Wing, Allison A. ; Wirth, Martin ; Wiskandt, Jonathan ; Wolf, Kevin ; Worbes, Ludwig ; Wright, Ethan ; Young, Shanea ; Zhang, Chidong ; Zhang, Dongxiao ; Ziemen, Florian ; Zinner, Tobias ; Zöger, MartinThe science guiding the EUREC4A campaign and its measurements is presented. EUREC4A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC4A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC4A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement.
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ArticleA seasonal circulation index for the ocean and its application to the South China Sea(Frontiers Media, 2023-06-01) Li, Qiang ; Huang, Rui Xin ; Xie, LinglingOcean circulation is crucial in redistributing mass and energy on Earth. However, it varies significantly on a seasonal time scale due to external forcing. To quantify the seasonality of ocean circulation, we propose a seasonal circulation index (SCI). This index is defined as the normalized maximum deviation from the velocity vector, whose magnitude is the largest in one period. We have substantiated the efficiency of this index using the monsoon wind in the South China Sea (SCS). By utilizing this index, we have obtained the 3D structure of the seasonality of ocean circulation in the SCS. The SCI and the seasonal circulation amplitude (SCA) exhibit large values over 0.9 and 0.8 m s-1 in the western boundary current. Alternating southwest-northeastward bands of SCI with high and low values are distributed from the north shelf to the south, especially in the eastern basin. Although SCA decreases significantly with depth, SCI exhibits values higher than 0.7 in both the middle and deep layers, indicating a noteworthy seasonality and middle-layer enhancement in the abyssal basin of the SCS.