An Argo mixed layer climatology and database

Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 44 (2017): 5618–5626, doi:10.1002/2017GL073426.A global climatology and database of mixed layer properties are computed from nearly 1,250,000 Argo profiles. The climatology is calculated with both a hybrid algorithm for detecting the mixed layer depth (MLD) and a standard threshold method. The climatology provides accurate information about the depth, properties, extent, and seasonal patterns of global mixed layers. The individual profile results in the database can be used to construct time series of mixed layer properties in specific regions of interest. The climatology and database are available online at http://mixedlayer.ucsd.edu. The MLDs calculated by the hybrid algorithm are shallower and generally more accurate than those of the threshold method, particularly in regions of deep winter mixed layers; the new climatology differs the most from existing mixed layer climatologies in these regions. Examples are presented from the Labrador and Irminger Seas, the Southern Ocean, and the North Atlantic Ocean near the Gulf Stream. In these regions the threshold method tends to overestimate winter MLDs by approximately 10% compared to the algorithm.National Science Foundation (NSF) Grant Numbers: OCE-0327544, OCE-0960928, OCE-1459474; NOAA Grant Number: NA10OAR43101392017-12-1

Food Environment, Built Environment, and Women\u27s BMI: Evidence from Erie County, New York

The authors present the results of a neighborhood-scaled exploratory study that tests the association of the food environment and the built environment with women’s body mass index (BMI) in Erie County, New York. The proximity of women’s homes to a supermarket relative to a convenience store is associated with lower BMI. A diverse land use mix in a neighborhood is positively associated with women’s BMI, especially when restaurants dominate nonresidential land use. The article offers suggestions for how food environments may be improved using planning strategies

The global warming hiatus: Slowdown or redistribution?

Global mean surface temperatures (GMST) exhibited a smaller rate of warming during 1998-2013, compared to the warming in the latter half of the 20th Century. Although, not a "true" hiatus in the strict definition of the word, this has been termed the "global warming hiatus" by IPCC (2013). There have been other periods that have also been defined as the "hiatus" depending on the analysis. There are a number of uncertainties and knowledge gaps regarding the "hiatus." This report reviews these issues and also posits insights from a collective set of diverse information that helps us understand what we do and do not know. One salient insight is that the GMST phenomenon is a surface characteristic that does not represent a slowdown in warming of the climate system but rather is an energy redistribution within the oceans. Improved understanding of the ocean distribution and redistribution of heat will help better monitor Earth's energy budget and its consequences. A review of recent scientific publications on the "hiatus" shows the difficulty and complexities in pinpointing the oceanic sink of the "missing heat" from the atmosphere and the upper layer of the oceans, which defines the "hiatus." Advances in "hiatus" research and outlooks (recommendations) are given in this report

Fresh equatorial jets

A vertically sheared eastward jet in the Equatorial pacific in late 1991 and early 1992 carried relatively fresh water from the Western Pacific overriding the saltier surface layer of the central region. Salinity anomalies of about -1.0 psu were observed over a period of several months in a surface layer 50 m thick near the equator. Below this fresh layer there was a steep halocline having very little temperature stratification, so that the density changes were dominated by salinity. In December 1991, eastward surface velocities in the fresh jet at 170°W were 100 cm s-1 with a shear of about 40 cm s-1 in the top 100 m; the core of the jet was about 200 km in width, centered at 1.5°S. The jet decayed and vanished over the next few months, though the surface halocline remained. (D'après résumé d'auteur

Oceanic Boundary Currents

Measurements of oceanic boundary currents for integral quantities such as heat and freshwater transports are very important for studying their long-term impacts on the global climate. There are a variety of boundary currents, including surface, intermediate and deep boundary currents on both the western and eastern sides of ocean basins. The dynamics and physics of these boundary currents are different, as are the ways of monitoring them. Here, we choose to explore the strategies adopted for observing four representative boundary current systems which have been the subject of detailed studies in recent years: the Kuroshio; the East Australian Current; the Indonesian Throughflow; and the low-latitude boundary current System of the Atlantic. The transport of the Kuroshio south of Japan has been monitored using satellite altimeter data in conjunction with an empirical relation between the transport and sea surface height difference across the stream. Monitoring the transport of the East Australian Current has been achieved by repeated high-resolution expendable bathythermograph (XBT) and/or conductivity-temperature-depth profiler transects maintained at several locations, supplemented with satellite altimeter data. Repeated XBT transects have also been used to monitor transport of the Indonesian Throughflow, in association with current meter and other instrumental estimations of transport through a few major throughflow straits. Finally, the complicated flow field of the low-latitude boundary current system of the Atlantic has been revealed using neutrally buoyant floats, moored current meters and hydrographic observations. The survey will be continued using further advanced observation technologies

Spatial and Temporal Scales of Sverdrup Balance

Sverdrup balance underlies much of the theory of ocean circulation and provides a potential tool for describing the interior ocean transport from only the wind stress. Using both a model state estimate and an eddy-permitting coupled climate model, this study assesses to what extent and over what spatial and temporal scales Sverdrup balance describes the meridional transport. The authors find that Sverdrup balance holds to first order in the interior subtropical ocean when considered at spatial scales greater than approximately 5°. Outside the subtropics, in western boundary currents and at short spatial scales, significant departures occur due to failures in both the assumptions that there is a level of no motion at some depth and that the vorticity equation is linear. Despite the ocean transport adjustment occurring on time scales consistent with the basin-crossing times for Rossby waves, as predicted by theory, Sverdrup balance gives a useful measure of the subtropical circulation after only a few years. This is because the interannual transport variability is small compared to the mean transports. The vorticity input to the deep ocean by the interaction between deep currents and topography is found to be very large in both models. These deep transports, however, are separated from upper-layer transports that are in Sverdrup balance when considered over large scales