The Roles of Climate Change and Climate Variability in the 2017 Atlantic Hurricane Season.

The 2017 Atlantic hurricane season was extremely active with six major hurricanes, the third most on record. The sea-surface temperatures (SSTs) over the eastern Main Development Region (EMDR), where many tropical cyclones (TCs) developed during active months of August/September, were ~0.96 °C above the 1901-2017 average (warmest on record): about ~0.42 °C from a long-term upward trend and the rest (~80%) attributed to the Atlantic Meridional Mode (AMM). The contribution to the SST from the North Atlantic Oscillation (NAO) over the EMDR was a weak warming, while that from El Niño-Southern Oscillation (ENSO) was negligible. Nevertheless, ENSO, the NAO, and the AMM all contributed to favorable wind shear conditions, while the AMM also produced enhanced atmospheric instability. Compared with the strong hurricane years of 2005/2010, the ocean heat content (OHC) during 2017 was larger across the tropics, with higher SST anomalies over the EMDR and Caribbean Sea. On the other hand, the dynamical/thermodynamical atmospheric conditions, while favorable for enhanced TC activity, were less prominent than in 2005/2010 across the tropics. The results suggest that unusually warm SST in the EMDR together with the long fetch of the resulting storms in the presence of record-breaking OHC may be key factors in driving the strong TC activity in 2017.

The impact of SST-forced and unforced teleconnections on 2015/16 El Niño winter precipitation over the western United States.

The factors impacting western U.S. winter precipitation during the 2015/16 El Niño are investigated using the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) data, and simulations with the Goddard Earth Observing System version 5 (GEOS-5) atmospheric general circulation model forced with specified sea surface temperatures (SSTs). Results reveal that the simulated response to the tropical Pacific SST associated with the 2015/16 El Niño was to produce wetter than normal conditions over much of the west coast including California - a result at odds with the negative precipitation anomalies observed over much of the Southwestern U.S. It is shown that two factors acted to partly counter the canonical ENSO response in that region. First, a potentially predictable but modest response to the unusually strong and persistent warm SST in the northeastern Pacific decreased precipitation in the Southwestern U.S. by increasing sea level pressure, driving anticyclonic circulation and atmospheric descent, and reducing moisture transport into that region. Second, large-scale unforced (by SST) components of atmospheric variability (consisting of the leading modes of unpredictable intra-ensemble variability) resembling the positive phase of the North Atlantic Oscillation and Arctic Oscillation are found to be an important contributor to the drying over the western U.S. While a statistical reconstruction of the precipitation from our simulations that account for internal atmospheric variability does much to close the gap between the ensemble mean and observed precipitation in the Southwestern U.S., some differences remain, indicating that model error is also playing a role.

The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2).

The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) is the latest atmospheric reanalysis of the modern satellite era produced by NASA's Global Modeling and Assimilation Office (GMAO). MERRA-2 assimilates observation types not available to its predecessor, MERRA, and includes updates to the Goddard Earth Observing System (GEOS) model and analysis scheme so as to provide a viable ongoing climate analysis beyond MERRA's terminus. While addressing known limitations of MERRA, MERRA-2 is also intended to be a development milestone for a future integrated Earth system analysis (IESA) currently under development at GMAO. This paper provides an overview of the MERRA-2 system and various performance metrics. Among the advances in MERRA-2 relevant to IESA are the assimilation of aerosol observations, several improvements to the representation of the stratosphere including ozone, and improved representations of cryospheric processes. Other improvements in the quality of MERRA-2 compared with MERRA include the reduction of some spurious trends and jumps related to changes in the observing system, and reduced biases and imbalances in aspects of the water cycle. Remaining deficiencies are also identified. Production of MERRA-2 began in June 2014 in four processing streams, and converged to a single near-real time stream in mid 2015. MERRA-2 products are accessible online through the NASA Goddard Earth Sciences Data Information Services Center (GES DISC).

Large-scale Controls on Atlantic Tropical Cyclone Activity on Seasonal Time Scales.

Interannual variations in seasonal tropical cyclone (TC) activity (e.g., genesis frequency and location, track pattern, and landfall) over the Atlantic are explored by employing observationally-constrained simulations with the NASA Goddard Earth Observing System version (GEOS-5) atmospheric general circulation model. The climate modes investigated are El Niño-Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), and the Atlantic Meridional Mode (AMM). The results show that the NAO and AMM can strongly modify and even oppose the well-known ENSO impacts, like in 2005, when a strong positive AMM (associated with warm SSTs and a negative SLP anomaly over the western tropical Atlantic), led to a very active TC season with enhanced TC genesis over the Caribbean Sea and a number of landfalls over North America, under a neutral ENSO condition. On the other end, the weak TC activity during 2013 (characterized by weak negative Niño index) appears caused by a NAO-induced positive SLP anomaly with enhanced vertical wind shear over the tropical North Atlantic. During 2010, the combined impact of the three modes produced positive SST anomalies across the entire low- latitudinal Atlantic and a weaker subtropical high, leading to more early recurvers and thus fewer landfalls despite enhanced TC genesis. The study provides evidence that TC number and track are very sensitive to the relative phases and intensities of these three modes, and not just to ENSO alone. Examination of seasonal predictability reveals that predictive skill of the three modes is limited over tropics to sub-tropics, with the AMM having the highest predictability over the North Atlantic, followed by ENSO and NAO.

High resolution energy analyzer for broad ion beam characterization.

Characterization of the ion energy distribution function (IEDF) of low energy high current density ion beams by conventional retarding field and deflection type energy analyzers is limited due to finite ion beam emittance and beam space charge spreading inside the analyzer. These deficiencies are, to a large extent, overcome with the recent development of the variable-focusing retarding field energy analyzer (RFEA), which has a cylindrical focusing electrode preceding the planar retarding grid. The principal concept of this analyzer is conversion of a divergent charged particle beam into a quasiparallel beam before analyzing it by the planar retarding field. This allows analysis of the beam particle total kinetic energy distribution with greatly improved energy resolution. Whereas this concept was first applied to analyze 5-10 keV pulsed electron beams, the present authors have adapted it to analyze the energy distribution of a low energy (

[Evaluation of CT guided cervical epidural injections in patients with mechanical cervicobrachial neuralgia]. / Evaluation des infiltrations épidurales cervicales sous contrôle tomodensitométrique dans le traitement des névralgies cervico-brachiales mécaniques.

PURPOSE: Prospective study evaluating the efficacy and tolerability of CT guided cervical epidural injections for mechanical cervicobrachial neuralgia. MATERIALS AND METHODS: Between July 2003 and August 2004, 34 patients (16 females, 18 males) with mean age of 44.5 years were enrolled. Enrollment criteria included mechanical cervicobrachial neuralgia of more than 1 month's duration, refractory to medical management, with good correlation between clinical and imaging findings. An evaluation using the Neck Pain Disability Score (NPDS) and associated Secondary criteria was performed by a single observer at day 0, day 30 and day 90. The injections were performed under CT guidance. RESULTS: The symptomatic efficacy of CT guided injections at 3 months was 45% using the NPDS, 47.1% using an analog pain scale, and 58.8% as graded by patients (effective/very effective). Tolerability was excellent (55.9%), moderate (41.2%) and poor (2.9%). CONCLUSION: CT guided cervical epidural injections appear effective and well-tolerated. A blinded randomized study could validate its value. However, a study comparing steroids and placebo raises ethical concerns.

On the cause of the 1930s Dust Bowl.

During the 1930s, the United States experienced one of the most devastating droughts of the past century. The drought affected almost two-thirds of the country and parts of Mexico and Canada and was infamous for the numerous dust storms that occurred in the southern Great Plains. In this study, we present model results that indicate that the drought was caused by anomalous tropical sea surface temperatures during that decade and that interactions between the atmosphere and the land surface increased its severity. We also contrast the 1930s drought with other North American droughts of the 20th century.

The influence of time of day on the foraging behavior of the honeybee, Apis mellifera.

The honeybee time sense, or Zeitgedächtnis, is highly adaptive, allowing bees to synchronize their foraging behavior with the peak time of daily floral nectar rhythms. Each foraging group within the honeybee colony shows a high degree of fidelity to one species of flower. Across the day, the temporal accuracy of foraging visits to experimental feeding times varies considerably, being nearly exact for morning-trained foraging groups but becoming less so for foraging groups trained later in the day. The evidence gained in this study suggests that the diel change in accuracy exhibited by foraging groups, which persists after the removal of many potential environmental time cues, is an endogenously driven behavior pattern. Furthermore, it appears that individual bees are continuously and accurately aware of the time of day, but are programmed to forage with greater anticipation to late-day food sources. Therefore, two separate processes contributing to the honeybee time sense are implicated. The first varies with time of day and determines the amount of anticipatory activity directed toward the food source. The second process is invariant across the day and is involved with the individual forager's continuous, accurate awareness of time.

Influence of vitamin D on bicarbonate reabsorption.

The effects of acute administration of 25 hydroxycholecalciferol on bicarbonate reabsorption was studied in dogs. 25 hydroxycholecalciferol infused into the renal artery at a dose of 0.2 microgram/kg/hour led to a small but significant bilateral increase in bicarbonate reabsorption in intact dogs. 25 hydroxycholecalciferol had no effect on bicarbonate reabsorption in thyroparathyroidectomized dogs. The phosphaturia of bicarbonate administration was not altered by 25 hydroxycholecalciferol administration.