Virtually Enhanced Fluid Laboratories for Teaching Meteorology

The “Weather in a Tank” project offers instructors a repertoire of rotating tank experiments and a curriculum in fluid dynamics to better assist students in learning how to move between phenomena in the real world and basic principles of rotating fluid dynamics that play a central role in determining the climate of the planet. Despite the increasing use of laboratory experiments in teaching meteorology, many teachers and students do not have access to suitable apparatuses and so cannot benefit from them. This article describes a “virtually enhanced” laboratory that could be very effective in getting across a flavor of the experiments and bring them to a wider audience. In the pedagogical spirit of Weather in a Tank, the focus is on how simple underlying principles, illustrated through laboratory experiments, shape the observed structure of the large-scale atmospheric circulation.National Science Foundation (U.S.) (Grant AGS-1338814

Observations, inferences, and mechanisms of the Atlantic Meridional Overturning Circulation: A review

This is a review about the Atlantic Meridional Overturning Circulation (AMOC), its mean structure, temporal variability, controlling mechanisms, and role in the coupled climate system. The AMOC plays a central role in climate through its heat and freshwater transports. Northward ocean heat transport achieved by the AMOC is responsible for the relative warmth of the Northern Hemisphere compared to the Southern Hemisphere and is thought to play a role in setting the mean position of the Intertropical Convergence Zone north of the equator. The AMOC is a key means by which heat anomalies are sequestered into the ocean's interior and thus modulates the trajectory of climate change. Fluctuations in the AMOC have been linked to low-frequency variability of Atlantic sea surface temperatures with a host of implications for climate variability over surrounding landmasses. On intra-annual timescales, variability in AMOC is large and primarily reflects the response to local wind forcing; meridional coherence of anomalies is limited to that of the wind field. On interannual to decadal timescales, AMOC changes are primarily geostrophic and related to buoyancy anomalies on the western boundary. A pacemaker region for decadal AMOC changes is located in a western “transition zone” along the boundary between the subtropical and subpolar gyres. Decadal AMOC anomalies are communicated meridionally from this region. AMOC observations, as well as the expanded ocean observational network provided by the Argo array and satellite altimetry, are inspiring efforts to develop decadal predictability systems using coupled atmosphere-ocean models initialized by ocean data.United States. National Oceanic and Atmospheric Administration (NA10OAR4310199)Unites States. National Oceanic and Atmospheric Administration (NA13OAR4310134)United States. National Oceanic and Atmospheric Administration (NA150AR4310100)United States. National Oceanic and Atmospheric Administration (NA09OAR4310058)United States. National Oceanic and Atmospheric Administration (NA14OAR4310160)National Science Foundation (U.S.) (1338427)United States. National Aeronautics and Space Administration (NNX14AM19G

REPRODUCTIVE CHARACTER DISPLACEMENT AND SPECIATION IN PERIODICAL CICADAS, WITH DESCRIPTION OF A NEW SPECIES, 13-YEAR MAGICICADA NEOTREDECIM

Acoustic mate-attracting signals of related sympatric, synchronic species are always distinguishable, but those of related allopatric species sometimes are not, thus suggesting that such signals may evolve to “reinforce” premating species isolation when similar species become sympatric. This hypothesis predicts divergences restricted to regions of sympatry in partially overlapping species, but such “reproductive character displacement” has rarely been confirmed. We report such a case in the acoustic signals of a previously unrecognized 13-year periodical cicada species, Magicicada neotredecim , described here as a new species (see Appendix). Where M. neotredecim overlaps M. tredecim in the central United States, the dominant male call pitch (frequency) of M. neotredecim increases from approximately 1.4 kHz to 1.7 kHz, whereas that of M. tredecim remains comparatively stable. The average preferences of female M. neotredecim for call pitch show a similar geographic pattern, changing with the call pitch of conspecific males. Magicicada neotredecim differs from 13-year M. tredecim in abdomen coloration, mitochondrial DNA, and call pitch, but is not consistently distinguishable from 17-year M. septendecim ; thus, like other Magicicada species, M. neotredecim appears most closely related to a geographically adjacent counterpart with the alternative life cycle. Speciation in Magicicada may be facilitated by life-cycle changes that create temporal isolation, and reinforcement could play a role by fostering divergence in premating signals prior to speciation. We present two theories of Magicicada speciation by life-cycle evolution: “nurse-brood facilitation” and “life-cycle canalization.”Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73691/1/j.0014-3820.2000.tb00564.x.pd

Gastrointestinal dysfunction in the critically ill: can we measure it?

Gastrointestinal dysfunction is an intuitively important, yet descriptively elusive component of the multiple organ dysfunction syndrome. Reintam and colleagues have attempted to quantify this dimension using a combination of intolerance of enteral feeding, and the development of intra-abdominal hypertension. While they show that both parameters are associated with an increased risk of death (and therefore that, in combination, the risk of death is even greater), they fall short in developing a novel descriptor of gastrointestinal dysfunction. Nonetheless, and even with its shortcomings, their effort is a welcome contribution to the surprisingly complex process of describing the morbidity of critical illness