Abstract. Possible mechanisms behind the longevity of intense Long IslandSound (LIS) water temperature events are examined using an event-basedapproach. By decomposing an LIS surface water temperature time series intonegative and positive events, it is revealed that the most intense LIS watertemperature event in the 1979–2013 period occurred around 2012, coincidingwith the 2012 ocean heat wave across the Mid-Atlantic Bight. The LIS eventsare related to a ridge–trough dipole pattern whose strength and evolution canbe determined using a dipole index. The dipole index was shown to be stronglycorrelated with LIS water temperature anomalies, explaining close to 64 %of cool-season LIS water temperature variability. Consistently, a majordipole pattern event coincided with the intense 2012 LIS warm event. Acomposite analysis revealed that long-lived intense LIS water temperatureevents are associated with tropical sea surface temperature (SST) patterns.The onset and mature phases of LIS cold events were shown to coincide withcentral Pacific El Niño events, whereas the termination of LIS coldevents was shown to possibly coincide with canonical El Niño events or ElNiño events that are a mixture of eastern and central Pacific El Niñoflavors. The mature phase of LIS warm events was shown to be associated withnegative SST anomalies across the central equatorial Pacific, though theresults were not found to be robust. The dipole pattern was also shown to berelated to tropical SST patterns, and fluctuations in central Pacific SSTanomalies were shown to evolve coherently with the dipole pattern and thestrongly related East Pacific–North Pacific pattern on decadal timescales.The results from this study have important implications for seasonal anddecadal prediction of the LIS thermal system.
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Probing dipole-dipole interaction at cold-atom density range using optical two-dimensional coherent spectroscopy
We experimentally demonstrate that the dipole-dipole interaction in a potassium vapor at cold atom density can be observed using optical 2D coherent spectroscopy. This paves the way to implement 2D spectroscopy in cold atoms.
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- Award ID(s):
- 1707364
- NSF-PAR ID:
- 10095204
- Date Published:
- Journal Name:
- Conference on Lasers and Electro-Optics, OSA Technical Digest (online) (Optical Society of America, 2018)
- Page Range / eLocation ID:
- JTh2A.41
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Dipolar interactions are ever‐present in supramolecular architectures, though their impact is typically revealed by making dipoles stronger. While it is also possible to assess the role of dipoles by altering their orientations by using synthetic design, doing so without altering the molecular shape is not straightforward. We have now done this by flipping one triazole unit in a rigid macrocycle, tricarb. The macrocycle is composed of three carbazoles (2 Debye) and three triazoles (5 Debye) defining an array of dipoles aligned radially but organized alternately in and out. These dipoles are believed to dictate edge‐to‐edge tiling and face‐to‐face stacking. We modified our synthesis to prepare isosteric macrocycles with the orientation of one triazole dipole rotated 40°. The new dipole orientation guides edge‐to‐edge contacts to reorder the stability of two surface‐bound 2D polymorphs. The impact on dipole‐enhanced π stacking, however, was unexpected. Our stacking model identified an unchanged set of short‐range (3.4 Å)
anti ‐parallel dipole contacts. Despite this situation, the reduction in self‐association was attributed to long‐range (~6.4 Å) dipolar repulsions between π‐stacked macrocycles. This work highlights our ability to control the build‐up and symmetry of macrocyclic skeletons by synthetic design, and the work needed to further our understanding of how dipoles control self‐assembly.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1364/CLEO_AT.2018.JTh2A.41
