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Talley, LD.  1983.  Radiating Barotropic Instability. Journal of Physical Oceanography. 13:972-987.   10.1175/1520-0485(1983)013<0972:rbi>;2   AbstractWebsite

The linear stability of zonal, parallel shear flow on a beta-plane is discussed. While the localized shear region supports unstable waves, the far-field can support Rossby waves because of the ambient potential-vorticity gradient. An infinite zonal flow with a continuous cross-stream velocity gradient is approximated with segments of uniform flow, joined together by segments of uniform potential vorticity. This simplification allows an exact dispersion relation to be found. There are two classes of linearly unstable solutions. One type is trapped to the source of energy and has large growth rates. The second type is weaker instabilities which excite Rossby waves in the far-field: the influence of these weaker instabilities extends far beyond that of the most unstable waves.

Talley, LD.  1983.  Radiating Instabilities of Thin Baroclinic Jets. Journal of Physical Oceanography. 13:2161-2181.   10.1175/1520-0485(1983)013<2161:riotbj>;2   AbstractWebsite

The linear stability of thin, quasi-geostrophic, two-layer zonal jets on the β-plane is considered. The meridional structure of the jets is approximated in such a way as to allow an exact dispersion relation to be found. Necessary conditions for instability and energy integrals are extended to these piece-wise continuous profiles. The linearly unstable modes which arise can be related directly to instabilities arising from the vertical and horizontal shear. It is found empirically that the necessary conditions for instability are sufficient for the cases considered. Attention is focused on unstable modes that penetrate far into the locally stable ocean interior and which are found when conditions allow the jet instability phase speeds to overlap the far-field. free-wave phase speeds. These radiating instabilities exist in addition to more unstable waves which are trapped within a few deformation radii of the jet. The growth rates of the radiating instabilities depend strongly on the size of the overlap of instability and free-wave phase speeds. The extreme cases of this are westward jets which have vigorously growing, radiating instabilities and purely eastward jets which do not radiate at all. Radiating instabilities are divided into two types: a subset of the jets' main unstable waves near marginal stability and instabilities which appear to be destabilized free waves of the interior ocean. It is suggested that the fully developed field of instabilities of a zonal current consists of the most unstable, trapped waves directly in the current with a shift to less unstable, radiating waves some distance from the current. A brief comparison of the model results with observations south of the Gulf Stream is made.

Feely, RA, Talley LD, Johnson GC, Sabine CL, Wanninkhof R.  2005.  Repeat hydrography cruises reveal chemical changes in the North Atlantic. Eos, Transactions American Geophysical Union. 86:399,404-405. Abstract
Haentjens, N, Boss E, Talley LD.  2017.  Revisiting Ocean Color algorithms for chlorophyll a and particulate organic carbon in the Southern Ocean using biogeochemical floats. Journal of Geophysical Research-Oceans. 122:6583-6593.   10.1002/2017jc012844   AbstractWebsite

The Southern Ocean (SO) ecosystem plays a key role in the carbon cycle by sinking a major part (43%) of the ocean uptake of anthropogenic CO2, and being an important source of nutrients for primary producers. However, undersampling of SO biogeochemical properties limits our understanding of the mechanisms taking place in this remote area. The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project has been deploying a large number of autonomous biogeochemical floats to study the SO (as of December 2016, 74 floats out of 200 have been deployed). SOCCOM floats measurements can be used to extend remote sensing chlorophyll a (chl a) and particulate organic carbon (POC) products under clouds or during the polar night as well as adding the depth dimension to the satellite-based view of the SO. Chlorophyll a concentrations measured by a sensor embedded on the floats and POC concentrations derived from backscattering coefficients were calibrated with samples collected during the floats' deployment cruise. Float chl a and POC were compared with products derived from observations of MODIS and VIIRS sensors. We find the Ocean Color Index (OCI) global algorithm to agree well with the matchups (within 9%, on average, for the Visible Infrared Imaging Radiometer Suite (VIIRS) and 12%, on average, for the Moderate Resolution Imaging Spectroradiometer Aqua (MODIS)). SO-specific algorithms estimating chl a are offset by similar to 45% south of the Sea Ice Extent Front (similar to 60 degrees S). In addition, POC estimates based on floats agree well with NASA's POC algorithm.

Holte, JW, Talley LD, Chereskin TK, Sloyan BM.  2012.  The role of air-sea fluxes in Subantarctic Mode Water formation. Journal of Geophysical Research-Oceans. 117   10.1029/2011jc007798   AbstractWebsite

Two hydrographic surveys and a one-dimensional mixed layer model are used to assess the role of air-sea fluxes in forming deep Subantarctic Mode Water (SAMW) mixed layers in the southeast Pacific Ocean. Forty-two SAMW mixed layers deeper than 400 m were observed north of the Subantarctic Front during the 2005 winter cruise, with the deepest mixed layers reaching 550 m. The densest, coldest, and freshest mixed layers were found in the cruise's eastern sections near 77 degrees W. The deep. SAMW mixed layers were observed concurrently with surface ocean heat loss of approximately -200 W m(-2). The heat, momentum, and precipitation flux fields of five flux products are used to force a one-dimensional KPP mixed layer model initialized with profiles from the 2006 summer cruise. The simulated winter mixed layers generated by all of the forcing products resemble Argo observations of SAMW; this agreement also validates the flux products. Mixing driven by buoyancy loss and wind forcing is strong enough to deepen the SAMW layers. Wind-driven mixing is central to SAMW formation, as model runs forced with buoyancy forcing alone produce shallow mixed layers. Air-sea fluxes indirectly influence winter SAMW properties by controlling how deeply the profiles mix. The stratification and heat content of the initial profiles determine the properties of the SAMW and the likelihood of deep mixing. Summer profiles from just upstream of Drake Passage have less heat stored between 100 and 600 m than upstream profiles, and so, with sufficiently strong winter forcing, form a cold, dense variety of SAMW.

Talley, LD, Yun JY.  2001.  The role of cabbeling and double diffusion in setting the density of the North Pacific intermediate water salinity minimum. Journal of Physical Oceanography. 31:1538-1549.   10.1175/1520-0485(2001)031<1538:trocad>;2   AbstractWebsite

The top of the North Pacific Intermediate Water (NPIW) in the subtropical North Pacific is identified with the main salinity minimum in the density range sigma (theta) = 26.7-26.8. The most likely source of low salinity for the NPIW salinity minimum is the Oyashio winter mixed layer, of density sigma (theta) = 26.5- 26.65. The Oyashio waters mix with Kuroshio waters in the broad region known as the Mixed Water Region (MWR), between the separated Kuroshio and Oyashio Fronts just east of Japan. It is shown that cabbeling during mixing of the cold, fresh Oyashio winter mixed layer water with the warm, saline Kuroshio water increases the density of the mixture by up to sigma (theta) = 0.07 at densities around sigma (theta) = 26.6-26.65, regardless of the mixing mechanism. Thus cabbeling accounts for about half of the observed density difference between the Oyashio winter mixed layer water and the top of the NPIW. Double diffusion during mixing of the interleaving layers of Oyashio and Kuroshio waters in the MWR can also change the density of the mixing intrusions. Density ratios favorable to double diffusion are shown to be especially prominent in Oyashio intrusions into a Kuroshio warm core ring in the 1989 data examined here. The average potential temperature-salinity profile of the new subtropical NPIW just east of the MWR, with its nearly uniform salinity, suggests the dominance of salt fingering over diffusive layering. Using the observed salinity and density differences between Oyashio surface water and the NPIW salinity minimum, after subtracting the density difference ascribed to cabbeling, an effective flux ratio of about 0.8 is estimated for possible double diffusive processes in the MWR.