ALBERT

Description: The cascade from tides to turbulence has been hypothesized to serve as a major energy pathway for ocean mixing. We investigated this cascade along the Hawaiian Ridge using observations and numerical models. A divergence of internal tidal energy flux observed at the ridge agrees with the predictions of internal tide models. Large internal tidal waves with peak-to-peak amplitudes of up to 300 meters occur on the ridge. Internal-wave energy is enhanced, and turbulent dissipation in the region near the ridge is 10 times larger than open-ocean values. Given these major elements in the tides-to-turbulence cascade, an energy budget approaches closure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rudnick, Daniel L -- Boyd, Timothy J -- Brainard, Russell E -- Carter, Glenn S -- Egbert, Gary D -- Gregg, Michael C -- Holloway, Peter E -- Klymak, Jody M -- Kunze, Eric -- Lee, Craig M -- Levine, Murray D -- Luther, Douglas S -- Martin, Joseph P -- Merrifield, Mark A -- Moum, James N -- Nash, Jonathan D -- Pinkel, Robert -- Rainville, Luc -- Sanford, Thomas B -- New York, N.Y. -- Science. 2003 Jul 18;301(5631):355-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Scripps Institution of Oceanography, La Jolla, CA 92093-0213, USA. drudnick@ucsd.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12869758" target="_blank"〉PubMed〈/a〉

Description: Establishment of the temperature-salinity relationship in the ocean has concerned oceanographers for decades because of its importance for understanding ocean circulation. High-resolution measurements in the ocean mixed layer are used to show that temperature and salinity gradients on horizontal scales of 20 meters to 10 kilometers tend to compensate in their effect on density. These observations support the notion of a horizontal mixing in the mixed layer that depends on density gradient.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rudnick -- Ferrari -- New York, N.Y. -- Science. 1999 Jan 22;283(5401):526-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Scripps Institution of Oceanography, La Jolla, CA 92093-0230, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9915697" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Alford, Matthew H -- Peacock, Thomas -- MacKinnon, Jennifer A -- Nash, Jonathan D -- Buijsman, Maarten C -- Centurioni, Luca R -- Chao, Shenn-Yu -- Chang, Ming-Huei -- Farmer, David M -- Fringer, Oliver B -- Fu, Ke-Hsien -- Gallacher, Patrick C -- Graber, Hans C -- Helfrich, Karl R -- Jachec, Steven M -- Jackson, Christopher R -- Klymak, Jody M -- Ko, Dong S -- Jan, Sen -- Johnston, T M Shaun -- Legg, Sonya -- Lee, I-Huan -- Lien, Ren-Chieh -- Mercier, Matthieu J -- Moum, James N -- Musgrave, Ruth -- Park, Jae-Hun -- Pickering, Andrew I -- Pinkel, Robert -- Rainville, Luc -- Ramp, Steven R -- Rudnick, Daniel L -- Sarkar, Sutanu -- Scotti, Alberto -- Simmons, Harper L -- St Laurent, Louis C -- Venayagamoorthy, Subhas K -- Wang, Yu-Huai -- Wang, Joe -- Yang, Yiing J -- Paluszkiewicz, Theresa -- Tang, Tswen-Yung David -- England -- Nature. 2015 Dec 3;528(7580):152. doi: 10.1038/nature16157. Epub 2015 Nov 18.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26580017" target="_blank"〉PubMed〈/a〉

Description: Internal gravity waves, the subsurface analogue of the familiar surface gravity waves that break on beaches, are ubiquitous in the ocean. Because of their strong vertical and horizontal currents, and the turbulent mixing caused by their breaking, they affect a panoply of ocean processes, such as the supply of nutrients for photosynthesis, sediment and pollutant transport and acoustic transmission; they also pose hazards for man-made structures in the ocean. Generated primarily by the wind and the tides, internal waves can travel thousands of kilometres from their sources before breaking, making it challenging to observe them and to include them in numerical climate models, which are sensitive to their effects. For over a decade, studies have targeted the South China Sea, where the oceans' most powerful known internal waves are generated in the Luzon Strait and steepen dramatically as they propagate west. Confusion has persisted regarding their mechanism of generation, variability and energy budget, however, owing to the lack of in situ data from the Luzon Strait, where extreme flow conditions make measurements difficult. Here we use new observations and numerical models to (1) show that the waves begin as sinusoidal disturbances rather than arising from sharp hydraulic phenomena, (2) reveal the existence of 〉200-metre-high breaking internal waves in the region of generation that give rise to turbulence levels 〉10,000 times that in the open ocean, (3) determine that the Kuroshio western boundary current noticeably refracts the internal wave field emanating from the Luzon Strait, and (4) demonstrate a factor-of-two agreement between modelled and observed energy fluxes, which allows us to produce an observationally supported energy budget of the region. Together, these findings give a cradle-to-grave picture of internal waves on a basin scale, which will support further improvements of their representation in numerical climate predictions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Alford, Matthew H -- Peacock, Thomas -- MacKinnon, Jennifer A -- Nash, Jonathan D -- Buijsman, Maarten C -- Centuroni, Luca R -- Chao, Shenn-Yu -- Chang, Ming-Huei -- Farmer, David M -- Fringer, Oliver B -- Fu, Ke-Hsien -- Gallacher, Patrick C -- Graber, Hans C -- Helfrich, Karl R -- Jachec, Steven M -- Jackson, Christopher R -- Klymak, Jody M -- Ko, Dong S -- Jan, Sen -- Johnston, T M Shaun -- Legg, Sonya -- Lee, I-Huan -- Lien, Ren-Chieh -- Mercier, Matthieu J -- Moum, James N -- Musgrave, Ruth -- Park, Jae-Hun -- Pickering, Andrew I -- Pinkel, Robert -- Rainville, Luc -- Ramp, Steven R -- Rudnick, Daniel L -- Sarkar, Sutanu -- Scotti, Alberto -- Simmons, Harper L -- St Laurent, Louis C -- Venayagamoorthy, Subhas K -- Wang, Yu-Huai -- Wang, Joe -- Yang, Yiing J -- Paluszkiewicz, Theresa -- Tang, Tswen-Yung David -- England -- Nature. 2015 May 7;521(7550):65-9. doi: 10.1038/nature14399.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92037, USA [2] University of Washington, Seattle, Washington 98105, USA. ; Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, USA. ; Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92037, USA. ; Oregon State University, Corvallis, Oregon 97370, USA. ; University of Southern Mississippi, Stennis Space Center, Mississippi 39529, USA. ; University of Maryland, Cambridge, Maryland 21613, USA. ; Institute of Oceanography, National Taiwan University, Taipei 10617, Taiwan. ; University of Rhode Island, Rhode Island 02882, USA. ; Stanford University, Stanford, California 94305, USA. ; National Sun-Yat Sen University, Kaohsiung 80424, Taiwan. ; Naval Research Laboratories (NRL), Stennis Space Center, Mississippi 39529, USA. ; University of Miami, Miami, Florida 33149, USA. ; Woods Hole Oceanographic Institution, Falmouth, Massachusetts 02543, USA. ; Florida Institute of Technology, Melbourne, Florida 32901, USA. ; Global Ocean Associates, Alexandria, Virginia 22310, USA. ; University of Victoria, Victoria, British Columbia V8W 3P6, Canada. ; Princeton University, New Jersey 08542, USA. ; University of Washington, Seattle, Washington 98105, USA. ; Institut de Mecanique des Fluides de Toulouse, Toulouse 31400, France. ; Korea Institute of Ocean Science and Technology, Ansan 426-744, South Korea. ; 1] University of Washington, Seattle, Washington 98105, USA [2] Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, USA. ; Soliton Ocean Services, Carmel, California 93924, USA. ; University of California San Diego, La Jolla, California 92037, USA. ; University of North Carolina, Chapel Hill, North Carolina 25599, USA. ; University of Alaska at Fairbanks, Fairbanks, Alaska 99775, USA. ; Colorado State University, Fort Collins, Colorado 80523, USA. ; Office of Naval Research, Arlington, Virginia, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25951285" target="_blank"〉PubMed〈/a〉

Description: Brine rejection that accompanies ice formation in coastal polynyas is responsible for ventilating several globally important water masses in the Arctic and Antarctic. However, most previous studies of this process have been indirect, based on heat budget analyses or on warm-season water column inventories. Here, we present direct measurements of brine rejection and formation of North Pacific Intermediate Water in the Okhotsk Sea from moored winter observations. A steady, nearly linear salinity increase unambiguously caused by local ice formation was observed for more than a month.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shcherbina, Andrey Y -- Talley, Lynne D -- Rudnick, Daniel L -- New York, N.Y. -- Science. 2003 Dec 12;302(5652):1952-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Scripps Institution of Oceanography, University of California, San Diego, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14671300" target="_blank"〉PubMed〈/a〉

Description: A 6-year, 2009-2014 simulation using a 2-km horizontal resolution ocean circulation model of the Northeast Pacific coast is analyzed with focus on seasonal and interannual variability in along-slope subsurface oceanic properties. Specifically, the fields are sampled on the isopycnal surface σ = 26.5 kg m −3 that is found between depths of 150 and 300 m below the ocean surface over the continental slope. The fields analyzed include the depth z 26.5 , temperature T 26.5 , along-slope currents ν 26.5 and the average potential vorticity PV between σ = 26.5 and 26.25 kg m −3 . Each field is averaged in the cross-shore direction over the continental slope and presented as a function of the alongshore coordinate and time. The seasonal cycle in z 26.5 shows a coherent upwelling-downwelling pattern from Mexico to Canada propagating to the north with a speed of 0.5 m s −1 . The anomalously deep (−20 m) z 26.5 displacement in spring-summer 2014 is forced by the southern boundary condition at 24°N as a manifestation of an emerging strong El Niño. The seasonal cycle in T 26.5 is most pronounced between 36-53°N indicating that subarctic waters are replaced by warmer Californian waters in summer with the speed close 0.15 m s −1 , which is consistent with earlier estimates of the undercurrent speed and also present ν 26.5 analyses. The seasonal patterns and anomalies in z 26.5 and T 26.5 find confirmation in available long-term glider and ship-borne observations. The PV seasonality over the slope is qualitatively different to the south and north of the southern edge of Heceta Bank (43.9°N).

Description: To observe the across-ridge structure of internal tides, density and velocity were measured using SeaSoar and a Doppler sonar over the upper 400–600 m of the ocean extending 152 km on each side of the Hawaiian Ridge at Kauai Channel. Eighteen sections were completed in about 18 days with sampling intentionally detuned from the lunar semidiurnal (M2) tide so that averaging over all sections was equivalent to phase averaging the M2 tide. Velocity and displacement variance and several covariances involving velocity and displacement showed one M2 internal wave beam on each side of the ridge and reflection of the beams off of the surface. Theoretical ray slopes aligned with the observed beams and originated from the sides of the ridge. Energy flux was in agreement with internal wave generation at the ridge. Inferred turbulent dissipation was elevated relative to open ocean values near tidal beams. Energy flux was larger than total dissipation almost everywhere across the ridge. Internal wave energy flux and dissipation at Kauai Channel were 1.5–2.5 times greater than at the average location along the Hawaiian Ridge. The upper 400–600 m was about 1/3 to 1/2 as energetic as the full-depth ocean. Tidal beams interact with each other over the entire length of the beams causing gradients along beams in almost all covariances, momentum flux divergences, and mean flows. At Kauai Channel, momentum flux divergences corresponded to mean flows of 1–4 cm s−1.