An isopycnal model of the North Pacific is used to demonstrate that the seasonal cycle of heating and cooling and the resulting mixed layer depth entrainment and detrainment cycle play a role in the propagation of winddriven Rossby waves. The model is forced by realistic winds and seasonal heat flux to examine the interaction of nearly annual wind-driven Rossby waves with the seasonal mixed layer cycle. Comparison among four model runs, one adiabatic (without diapycnal mixing or explicit mixed layer dynamics), one diabatic (with diapycnal mixing and explicit mixed layer dynamics), one with the seasonal cycle of heating only, and one with only variable winds suggests that mixed layer entrainment changes the structure of the response substantially, particularly at midlatitudes. Specifically, the mixed layer seasonal cycle works against Ekman pumping in the forcing of first-mode Rossby waves between 178 and 288N. South of there the mixed layer seasonal cycle has little influence on the Rossby waves, while in the north, seasonal Rossby waves do not propagate. To examine the first baroclinic mode response in detail, a modal decomposition of the numerical model output is done. In addition, a comparison of the forcing by diapycnal pumping and Ekman pumping is done by a projection of Ekman pumping and diapycnal velocities on to the quasigeostrophic potential vorticity equation for each vertical mode. The first baroclinic mode’s forcing is split between Ekman pumping and diapycnal velocity at midlatitudes, providing an explanation for the changes in the response when a seasonal mixed layer response is included. This is confirmed by doing a comparison of the modal decomposition in the four runs described above, and by calculation of the first baroclinic mode Rossby wave response using the one-dimensional Rossby wave equation.
Of the seven galaxies in the central region of the Coma cluster which have shown supernova explosions, two belong to the rare class of 10 galaxies. This finding adds support to the contention of Oemler and Tinsley (1979) that 10 galaxies produce an unusually large number of Type I supernovae.
Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at Journal of Geophysical Research - Oceans. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing the latest version by default [v1]Multi-scale seasonal variability in Net Community Production and Chlorophyll in the Kuroshio ExtensionAuthorsSophieClaytoniDHilary IlanaPalevskyiDLuAnneThompsoniDPaul D.QuaySee all authors Sophie ClaytoniDCorresponding Author• Submitting AuthorOld Dominion UniversityiDhttps://orcid.org/0000-0001-7473-4873view email addressThe email was not providedcopy email addressHilary Ilana PalevskyiDBoston College, Department of Earth and Environmental SciencesiDhttps://orcid.org/0000-0002-0488-4531view email addressThe email was not providedcopy email addressLuAnne ThompsoniDUniversity of WashingtoniDhttps://orcid.org/0000-0001-8295-0533view email addressThe email was not providedcopy email addressPaul D. QuayUniversity of Washingtonview email addressThe email was not providedcopy email address
Abstract The reappearance of a northeast Pacific marine heatwave (MHW) sounded alarms in late summer 2019 for a warming event on par with the 2013–2016 MHW known as The Blob. Despite these two events having similar magnitudes in surface warming, differences in seasonality and salinity distinguish their evolutions. We compare and contrast the ocean's role in the evolution and persistence of the 2013–2016 and 2019–2020 MHWs using mapped temperature and salinity data from Argo floats. An unusual near‐surface freshwater anomaly in the Gulf of Alaska during 2019 increased the stability of the water column, preventing the MHW from penetrating deep as strongly as the 2013–2016 event. This freshwater anomaly likely contributed to the intensification of the MHW by increasing the near‐surface buoyancy. The gradual buildup of subsurface heat content throughout 2020 in the region suggests the potential for persistent ecological impacts.
Abstract This study explores the utility of the thin-plate spline (TPS) as a mapping procedure for oceanographic sections of bottle data in comparison with objective mapping (OM), sometimes referred to as objective interpolation. Standard OM techniques in oceanography require a priori assumptions about the structure of the errors associated with mapping when interpolating irregularly spaced data. Alternatively, the TPS can be used to approximate mapping errors by fitting a nonparametric model using multiple covariates with a less rigid, physically consistent, spatial correlation structure. The case is made that these errors reflect the sparsity of the data coverage and quantify mapping error better than the estimates using OM. It is demonstrated that the maps from the TPS recreate the essential large-scale features of chlorofluorocarbon- or freon-11 (CFC-11) concentrations and inferred “ages,” but smooth over smaller-scale features, such as eddies. The TPS can outperform OM when either the distance between the samples is larger than the correlation length scale or the signal-to-noise ratio is small. With more data, OM and TPS estimates yield increasingly similar results, but differ most markedly where there are extrema in the mapped fields, particularly at the domain boundaries. The TPS is recommended over OM when the spatial domain is sparsely sampled but the full range of covariates is known to be spanned by these samples.
The average seeing at the University of Hawaii 2.2 m telescope from 10 August 1985 to 9 January 1986 was 0.95 ± 0.02 arcsec full width at half-maximum at a wavelength of 0.70 pm. We believe that the dome makes substantial contributions to this average because the see-ing degrades with increasing temperature difference between a point near the primary mirror and the outside air. There is no significant dependence on wavelength (over the range 0.63-0.82 μm), wind direction, or time (over the interval covered to date). The data reported in this paper are the baseline against which we will assess the results of a long-term program of dome thermal balance improvements.
Data sets compiled for a review paper on Gender Equity in Oceanography, to appear in Annual Review of Marine Science, 2023. Includes: Annual Reviews of Marine Science invited author gender statistics; China and USA oceanography career progression gender statistics; Current employment fractions of 2010-2019 physical oceanography PhDs; Gordon Research Conference Oceanography gender statistics; JGR oceans author and reviewer gender statistics; Oceanography faculty gender statistics for China; Oceanography graduate degree gender statistics for China; Oceanography magazine author gender data.
Abstract Ocean heat transport (OHT) plays a key role in climate and its variability. Here, we identify modes of low-frequency North Atlantic OHT variability by applying a low-frequency component analysis (LFCA) to output from three global climate models. The first low-frequency component (LFC), computed using this method, is an index of OHT variability that maximizes the ratio of low-frequency variance (occurring at decadal and longer timescales) to total variance. Lead-lag regressions of atmospheric and ocean variables onto the LFC timeseries illuminate the dominant mechanisms controlling low-frequency OHT variability. Anomalous northwesterly winds from eastern North America over the North Atlantic act to increase upper ocean density in the Labrador Sea region, enhancing deep convection, which later increases OHT via changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC). The strengthened AMOC carries warm, salty water into the subpolar gyre, reducing deep convection and weakening AMOC and OHT. This mechanism, where changes in AMOC and OHT are driven primarily by changes in Labrador Sea deep convection, holds not only in models where the climatological (i.e., time-mean) deep convection is concentrated in the Labrador Sea, but also in models where the climatological deep convection is concentrated in the Greenland-Iceland-Norwegian (GIN) Seas or the Irminger and Iceland Basins. These results suggest that despite recent observational evidence suggesting that the Labrador Sea plays a minor role in driving the climatological AMOC, the Labrador Sea may still play an important role in driving low-frequency variability in AMOC and OHT.
