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1. Long Island Sound temperature variability and its associations with the ridge–trough dipole and tropical modes of sea surface temperature variability

   https://doi.org/10.5194/os-15-161-2019  

   Schulte, Justin A. ; Lee, Sukyoung ( January 2019 , Ocean Science)

   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.more »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.« less
2. FDTD Simulations Of The Impedance Of A Dipole Antenna in A Plasma

   https://doi.org/10.1109/APUSNCURSINRSM.2019.8888864  

   Spencer, E. ; Latif, S. ( July 2019 , 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting)

   The impedance of a dipole antenna in the earth’s ionospheric plasma is dependent on the ambient plasma properties such as electron density and electron neutral collision frequency. Depending on the length of the dipole, it is possible to not only measure the plasma properties, but in addition, receive plasma waves that are found propagating in the ionosphere. Here we report on some FDTD simulations of a dipole antenna in a cold plasma, and present some approximate expressions that can be used to analyze this behavior. When the dipole antenna resonant wavelength /4 and associated frequency is far from the uppermore »hybrid, cyclotron and plasma frequencies of the local plasma, the expressions work fairly well. However, when the length of the antenna is such that it’s resonant wavelength coincides or is close to the plasma resonances, the expressions fail, and a full-wave FDTD simulation has to be performed to extract meaningful plasma data.« less
3. Diverse impacts of Indian Ocean Dipole on El Niño-Southern Oscillation

   https://doi.org/10.1175/JCLI-D-21-0085.1  

   Zhang, Lei ; Han, Weiqing ; Meehl, Gerald A. ; Hu, Aixue ; Rosenbloom, Nan ; Shinoda, Toshiaki ; McPhaden, Michael J. ( September 2021 , Journal of Climate)

   Abstract Understanding the impact of the Indian Ocean Dipole (IOD) on El Niño-Southern Oscillation (ENSO) is important for climate prediction. By analyzing observational data and performing Indian and Pacific Ocean pacemaker experiments using a state-of-the-art climate model, we find that a positive IOD (pIOD) can favor both cold and warm sea surface temperature anomalies (SSTA) in the tropical Pacific, in contrast to the previously identified pIOD-El Niño connection. The diverse impacts of the pIOD on ENSO are related to SSTA in the Seychelles-Chagos thermocline ridge (SCTR; 60°E-85°E and 7°S-15°S) as part of the warm pole of the pIOD. Specifically, amore »pIOD with SCTR warming can cause warm SSTA in the southeast Indian Ocean, which induces La Niña-like conditions in the tropical Pacific through interbasin interaction processes associated with a recently identified climate phenomenon dubbed the “Warm Pool Dipole”. This study identifies a new pIOD-ENSO relationship and examines the associated mechanisms.« less
4. Observation of the dipole- and quadrupole-bound anions of 1,4-dicyanocyclohexane

   https://doi.org/10.1039/c9cp04010b  

   Liu, Gaoxiang ; Ciborowski, Sandra M. ; Pitts, Cody Ross ; Graham, Jacob D. ; Buytendyk, Allyson M. ; Lectka, Thomas ; Bowen, Kit H. ( August 2019 , Physical Chemistry Chemical Physics)

   Quadrupole-bound anions are negative ions in which their excess electrons are loosely bound by long-range electron-quadrupole attractions. Experimental evidence for quadrupole-bound anions has been scarce; until now, only trans -succinonitrile had been experimentally confirmed to form a quadrupole-bound anion. In this study, we present experimental evidence for a new quadrupole-bound anion. Our combined Rydberg electron transfer/anion photoelectron spectroscopy study demonstrates that the ee conformer of 1,4-dicyanocyclohexane (DCCH) supports a quadrupole-bound anion state, and that the cis -DCCH conformer forms a dipole-bound anion state. The electron binding energies of the quadrupole- and dipole-bound anions are measured as 18 and 115 meV,more »respectively, both of which are in excellent agreement with theoretical calculations by Sommerfeld.« less
5. Improved Predictability of the Indian Ocean Dipole Using a Stochastic Dynamical Model Compared to the North American Multimodel Ensemble Forecast

   https://doi.org/10.1175/WAF-D-19-0184.1  

   Zhao, Sen ; Stuecker, Malte F. ; Jin, Fei-Fei ; Feng, Juan ; Ren, Hong-Li ; Zhang, Wenjun ; Li, Jianping ( April 2020 , Weather and Forecasting)

   Abstract This study assesses the predictive skill of eight North American Multimodel Ensemble (NMME) models in predicting the Indian Ocean dipole (IOD). We find that the forecasted ensemble-mean IOD–El Niño–Southern Oscillation (ENSO) relationship deteriorates away from the observed relationship with increasing lead time, which might be one reason that limits the IOD predictive skill in coupled models. We are able to improve the IOD predictive skill using a recently developed stochastic dynamical model (SDM) forced by forecasted ENSO conditions. The results are consistent with the previous result that operational IOD predictability beyond persistence at lead times beyond one season ismore »mostly controlled by ENSO predictability and the signal-to-noise ratio of the Indo-Pacific climate system. The multimodel ensemble (MME) investigated here is found to be of superior skill compared to each individual model at most lead times. Importantly, the skill of the SDM IOD predictions forced with forecasted ENSO conditions were either similar or better than those of the MME IOD forecasts. Moreover, the SDM forced with observed ENSO conditions exhibits significantly higher IOD prediction skill than the MME at longer lead times, suggesting the large potential skill increase that could be achieved by improving operational ENSO forecasts. We find that both cold and warm biases of the predicted Niño-3.4 index may cause false alarms of negative and positive IOD events, respectively, in NMME models. Many false alarms for IOD forecasts at lead times longer than one season in the original forecasts disappear or are significantly reduced in the SDM forced by forecasted ENSO conditions.« less