bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Leading Intraseasonal Variability Mode of Wintertime Surface Air Temperature over the North American Sector
Authors: Guan Weina , Jiang Xianan , Ren Xuejuan , Chen Gang , Lin Pu , Lin Hai 
Published: August 2020

AbstractIn this study, detailed characteristics of the leading intraseasonal variability mode of boreal winter surface air temperature (SAT) over the North American (NA) sector are investigated. This intraseasonal SAT mode, characterized by two anomalous centers with an opposite sign—one over central NA and another over east Siberia (ES)/Alaska—bears a great resemblance to the “warm Arctic–cold continent” pattern of the interannual SAT variability over NA. This intraseasonal SAT mode and associated circulation exert a pronounced influence on regional weather extremes, including precipitation over the northwest coast of NA, sea ice concentration over the Chukchi and Bering Seas, and extreme warm and cold events over the NA continent and Arctic region. Surface warming and cooling signals of the intraseasonal SAT mode are connected to temperature anomalies in a deep-tropospheric layer up to 300 hPa with a decreasing amplitude with altitude. Particularly, a coupling between the troposphere and stratosphere is found during evolution of the intraseasonal SAT variability, although whether the stratospheric processes are essential in sustaining the leading intraseasonal SAT mode is difficult to determine based on observations alone. Two origins of wave sources are identified in contributing to vertically propagating planetary waves near Alaska: one over ES/Alaska associated with local intraseasonal variability and another from the subtropical North Pacific via Rossby wave trains induced by tropical convective activity over the western Pacific, possibly associated with the Madden–Julian oscillation.
The Contribution of Boreal Spring South Pacific Atmospheric Variability to El Niño Occurrence
Authors: Min Qingye , Zhang Renhe 
Published: August 2020

AbstractDespite the fact that great efforts have been made to improve the prediction of El Niño events, it remains challenging because of limited understanding of El Niño and its precursors. This research focuses on the influence of South Pacific atmospheric variability on the development of the sea surface temperature anomaly (SSTA) in the tropical Pacific. It is found that as early as in the boreal spring of El Niño years, the sea level pressure anomaly (SLPA) shows a configuration characterized by two significant negative anomaly centers in the north and a positive anomaly center in the south between the subtropics and high latitudes in South Pacific. Such an anomalous SLPA pattern becomes stronger in the following late boreal spring and summer associated with the strengthening of westerly anomalies in the tropical Pacific, weakening the southeasterly trade winds and promoting the warming of tropical eastern Pacific, which is conducive to the development of El Niño events. It is demonstrated that the SLPA pattern in boreal spring revealed in this study is closely associated with boreal summer South Pacific Oscillation (SPO) and South Pacific meridional mode (SPMM). As a precursor in boreal spring, the prediction skill of the South Pacific SLPA in boreal spring for the SSTA in the eastern equatorial Pacific is better than that of the SPMM. This study is helpful to deepen our understanding of the contribution of South Pacific extratropical atmospheric variability to El Niño occurrence.
Differences in Western North Pacific Tropical Cyclone Activity among Three El Niño Phases
Authors: Song Jinjie , Klotzbach Philip J. , Duan Yihong 
Published: August 2020

AbstractThe impacts of El Niño on tropical cyclone (TC) activity over the western North Pacific (WNP) are examined through investigation of three types of tropical Pacific warming episodes according to where the maximum sea surface temperature (SST) anomalies occur in the equatorial Pacific: the eastern Pacific El Niño (EPE), the central Pacific El Niño (CPE), and the mixed El Niño (ME). More TCs form over the eastern part of the WNP in all three El Niño types, whereas the frequency of TCs over the western part of the WNP increases as the peak SST anomalies migrate from east to west. Although TCs more frequently recurve at higher latitudes during EPE and CPE, the most frequent region for recurving is much closer to the East Asian continent in CPE years than in EPE years. In contrast, more TCs track westward and threaten the Philippines in ME years. The increased TC genesis over the western part of the WNP can be explained by enhanced low-level relative vorticity, reduced vertical wind shear, and increased maximum potential intensity during CPE and increased midlevel moisture during EPE and ME. This increase is further related to updraft anomalies near the date line driven by an anomalous Walker circulation and an anomalous low-level cyclonic circulation over the WNP. The TC track differences among the different El Niño types are linked to the east–west shift of the western Pacific subtropical high, possibly caused by an anomalous Hadley circulation from 120° to 130°E that is strongly coupled with the anomalous Walker circulation.
Decline in Temperature Variability on Svalbard
Authors: Hølleland Sondre , Karlsen Hans Arnfinn 
Published: August 2020

AbstractThe variability in the temperature on Svalbard, Norway, has been decreasing over the last four decades. This may be due to the reduction in sea ice, transitioning the regional climate to a more stable, coastal one. We quantify this transition in terms of decreasing volatility in a daily average temperature time series at Svalbard Airport from 1976 to 2019. We use two different approaches: a nonstochastic model and a time-dependent generalized autoregressive conditional heteroskedasticity (GARCH) model. These parametric approaches include a time-dependent trend, where the slope depends on the day of the year. For Svalbard, the slope has a minimum in late August and the steepest slope during winter is estimated to be −0.1°C2 yr−1. The nonstochastic model, for which the conditional and unconditional variances are the same, only depends on the marginal distribution and is perhaps the easiest to interpret. The GARCH model extends the nonstochastic model by including short-range temporal dependence in the volatility and is thus more locally adapted. Volatility modeling is important for a complete statistical description of the temperature dynamics on Svalbard as an Arctic representative. In combination with increasing temperatures, the volatility reduction makes the extremely cold days during winter occur less frequently. Although we focus exclusively on the Svalbard Airport series, the models should be suitable for other temperature or climatic time series.
Tracing North Atlantic Oscillation Forecast Errors to Stratospheric Origins
Authors: Kolstad Erik W. , Wulff C. Ole , Domeisen Daniela I. V. , Woollings Tim 
Published: August 2020

AbstractThe North Atlantic Oscillation (NAO) is the main driver of weather variability in parts of Eurasia, Greenland, North America, and North Africa on a range of time scales. Successful extended-range NAO predictions would equate to improved predictions of precipitation and temperature in these regions. It has become clear that the NAO is influenced by the stratosphere, but because this downward coupling is not fully reproduced by all forecast models the potential for improved NAO forecasts has not been fully realized. Here, an analysis of 21 winters of subseasonal forecast data from the European Centre for Medium-Range Weather Forecasts monthly forecasting system is presented. By dividing the forecasts into clusters according to their errors in North Atlantic Ocean sea level pressure 15–30 days into the forecasts, we identify relationships between these errors and the state of the stratospheric polar vortex when the forecasts were initialized. A key finding is that the model overestimates the persistence of both the negative NAO response following a weak polar vortex and the positive NAO response following a strong polar vortex. A case in point is the sudden stratospheric warming in early 2019, which was followed by five consecutive weeks of an overestimation of the negative NAO regime. A consequence on the ground was temperature predictions for northern Europe that were too cold. Another important finding is that the model appears to misrepresent the gradual downward impact of stratospheric vortex anomalies. This result suggests that an improved representation and prediction of stratosphere–troposphere coupling in models might yield substantial benefits for extended-range weather forecasting in the Northern Hemisphere midlatitudes.
Precipitation Downscaling with Gibbs Sampling: An Improved Method for Producing Realistic, Weather-Dependent, and Anisotropic Fields
Authors: Bellier Joseph , Scheuerer Michael , Hamill Thomas M. 
Published: August 2020

AbstractDownscaling precipitation fields is a necessary step in a number of applications, especially in hydrological modeling where the meteorological forcings are frequently available at too coarse resolution. In this article, we review the Gibbs sampling disaggregation model (GSDM), a stochastic downscaling technique originally proposed by Gagnon et al. The method is capable of introducing realistic, weather-dependent, and possibly anisotropic fine-scale details, while preserving the mean rain rate over the coarse-scale pixels. The main developments compared to the former version are (i) an adapted Gibbs sampling algorithm that enforces the downscaled fields to have a similar texture to that of the analysis fields, (ii) an extensive test of various meteorological predictors for controlling specific aspects of the texture such as the anisotropy and the spatial variability, and (iii) a review of the regression equations used in the model for defining the conditional distributions. A perfect-model experiment is conducted over a domain in the southeastern United States. The metrics used for verification are based on the concept of gridded, stratified variogram, which is introduced as an effective way of reproducing the abilities of human eyes for detecting differences in the field texture. Results indicate that the best overall performances are obtained with the most sophisticated, predictor-based GSDM variant. The 600-hPa wind is found to be the best year-round predictor for controlling the anisotropy. For the spatial variability, kinematic predictors such as wind shear are found to be best during the convective periods, while instability indices are more informative elsewhere.
An Anisotropic Subgrid-Scale Parameterization for Large-Eddy Simulations of Stratified Turbulence
Authors: Khani Sina , Waite Michael L. 
Published: August 2020

AbstractSubgrid-scale (SGS) parameterizations in atmosphere and ocean models are often defined independently in the horizontal and vertical directions because the grid spacing is not the same in these directions (anisotropic grids). In this paper, we introduce a new anisotropic SGS model in large-eddy simulations (LES) of stratified turbulence based on horizontal filtering of the equations of motion. Unlike the common horizontal SGS parameterizations in atmosphere and ocean models, the vertical derivatives of the horizontal SGS fluxes are included in our anisotropic SGS scheme, and therefore the horizontal and vertical SGS dissipation mechanisms are not disconnected in the newly developed model. Our model is tested with two vertical grid spacings and various horizontal resolutions, where the horizontal grid spacing is comparatively larger than that in the vertical. Our anisotropic LES model can successfully reproduce the results of direct numerical simulations, while the computational cost is significantly reduced in the LES. We suggest the new anisotropic SGS model as an alternative to current SGS parameterizations in atmosphere and ocean models, in which the schemes for horizontal and vertical scales are often decoupled. The new SGS scheme may improve the dissipative performance of atmosphere and ocean models without adding any backscatter or other energizing terms at small horizontal scales.
On the Consequences of PBL Scheme Diffusion on UTLS Wave and Turbulence Representation in High-Resolution NWP Models
Authors: Muñoz-Esparza Domingo , Sharman Robert D. , Trier Stanley B. 
Published: August 2020

AbstractMesoscale numerical weather prediction (NWP) models are routinely exercised at kilometer-scale horizontal grid spacings (Δx). Such fine grids will usually allow at least partial resolution of small-scale gravity waves and turbulence in the upper troposphere and lower stratosphere (UTLS). However, planetary boundary layer (PBL) parameterization schemes used with these NWP model simulations typically apply explicit subgrid-scale vertical diffusion throughout the entire vertical extent of the domain, an effect that cannot be ignored. By way of an example case of observed widespread turbulence over the U.S. Great Plains, we demonstrate that the PBL scheme’s mixing in NWP model simulations of Δx = 1 km can have significant effects on the onset and characteristics of the modeled UTLS gravity waves. Qualitatively, PBL scheme diffusion is found to affect not only background conditions responsible for UTLS wave activity, but also to control the local vertical mixing that triggers or hinders the onset and propagation of these waves. Comparisons are made to a reference large-eddy simulation with Δx = 250 m to statistically quantify these effects. A significant and systematic overestimation of resolved vertical velocities, wave-scale fluxes, and kinetic energy is uncovered in the 1-km simulations, both in clear-air and in-cloud conditions. These findings are especially relevant for upper-level gravity wave and turbulence simulations using high-resolution kilometer-scale NWP models.
The Strong, Dry Winds of Central and Northern California: Climatology and Synoptic Evolution
Authors: McClung Brandon , Mass Clifford F. 
Published: August 2020

AbstractStrong, dry downslope winds over Northern and central California have played a critical role in regional wildfires. These events, sometimes called Diablo or North winds, are more frequent over the Bay Area and nearby coastal terrain than along the western slopes of the Sierra Nevada, where the highest frequency occurs over the midslopes of the barrier. For the Bay Area, there is a frequency minimum during midsummer, a maximum in October, and a declining trend from November to June. The Sierra Nevada locations have their minimum frequency from February to August, and a maximum from October to January. There is little trend in event frequency during the past two decades over either region. For the Bay Area sites, there is a maximum frequency during the early morning hours and a large decline midday, while the Sierra Nevada locations have a maximum frequency approximately three hours earlier. Before the onset of these downslope wind events, there is substantial amplification of upper-level ridging over the eastern Pacific, with sea level pressure increasing first over the Pacific Northwest and then over the Intermountain West. The coincident development of a coastal sea level pressure trough leads to a large pressure gradient over the Sierra Nevada and Northern California. Diablo–North wind events are associated with below-normal temperatures east of the Sierra Nevada, with rapid warming of the air as it subsides into coastal California. The large horizontal variability in the frequency and magnitude of these events suggests the importance of exposure, elevation, and mountain-wave-related downslope acceleration.
Evaluating Benefits of Two-Way Ocean–Atmosphere Coupling for Global NWP Forecasts
Authors: Vellinga Michael , Copsey Dan , Graham Tim , Milton Sean , Johns Tim 
Published: August 2020

AbstractWe evaluate the impact of adding two-way coupling between atmosphere and ocean to the Met Office deterministic global forecast model. As part of preoperational testing of this coupled NWP configuration we have three years of daily forecasts, run in parallel to the uncoupled operational forecasts. Skill in the middle and upper troposphere out to T + 168 h is generally increased compared to the uncoupled model. Improvements are strongest in the tropics and largely neutral in midlatitudes. We attribute the additional skill in the atmosphere to the ability of the coupled model to predict sea surface temperature (SST) variability in the (sub)tropics with greater skill than persisted SSTs as used in uncoupled forecasts. In the midlatitude, ocean skill for SST is currently marginally worse than persistence, possibly explaining why there is no additional skill for the atmosphere in midlatitudes. Sea ice is predicted more skillfully than persistence out to day 7 but the impact of this on skill in the atmosphere is difficult to verify. Two-way air–sea coupling benefits tropical cyclone forecasts by reducing median track and central pressure errors by around 5%, predominantly from T + 90 to T + 132 h. Benefits from coupling are largest for large cyclones, and for smaller storms coupling can be detrimental. In this study skill in forecasts of the Madden–Julian oscillation does not change with two-way air–sea coupling out to T + 168 h.
Implications for Telemedicine for Surgery Patients After COVID-19: Survey of Patient and Provider Experiences
Authors: Zhu Clara , Williamson John , Lin Andrew , Bush Kathryn , Hakim Abraham , Upadhyaya Kirtan , Hunter Krystal , Sensenig Richard , Spitz Francis , Atabek Umur , Hong Young Ki 
Published: August 2020

Introduction The coronavirus disease 2019 (COVID-19) pandemic has expanded the utilization of telemedicine in clinical practice to minimize potential risks to both patients and providers. We aim to describe the perception of telemedicine by both surgical patients and providers to understand the preferences for future incorporation in future surgical practice. Methods An anonymous survey was administered to providers that transitioned clinic visits to telemedicine encounters since the start of the COVID-19 pandemic. In the second part of the study, patients who underwent video telemedicine appointments answered survey questions via telephone. Results Twenty-six out of 36 (72.7%) providers responded. Over 75% reported that they could effectively communicate with patients over telemedicine. Six (23.1%) reported that they could adequately assess surgical sites. Of 361 patients, 187 consented to the study (consent rate 51.8%). Among patients, the most common result to choose a telemedicine appointment was to avoid the risk of COVID-19 transmission (84, 44.9%), though the minority reported that they would choose telemedicine after the pandemic (64, 34.2%). Those patients who would choose an in-person visit were more likely to have a higher Charlson Comorbidity Score, body mass index, and use friends or family for transportation. In open-ended feedback, patients suggested that telemedicine would be better suited for long-term follow-up rather than the immediate postoperative setting. Conclusions Patients and providers reported a high degree of satisfaction using telemedicine during the COVID-19 pandemic but noted concern with limited physical examinations. Telemedicine may be suited for preoperative evaluation and medium-term and long-term postoperative follow-up for surgical patients.
Experience of Administering Life Grid in the Qualitative Interviews with Adolescent Children of Parents with Mental Illness
Authors: Ballal Divya , Janardhana N , Chandra Prabha 
Published: August 2020

Background: Methodological literature on qualitative research with children and young people suggests that traditional data collection methods can be strengthened through the use of creative and task-based methods. This article discusses the experience of using one such task-based method called the life grid, to explore the experiences of adolescent children who have a parent with psychotic illness, in the Indian context. Methods: The life grid was adapted for the present study and used with 24 adolescents aged 15–19 years. Feedback about their experience was collected on a five-point rating scale and via open-ended questions. The researchers’ observations and reflections were noted down as field notes. Results: A majority of the adolescents (83%) reported liking the activity. They appreciated the opportunity to use the life grid to generate a holistic perspective of their lives. Difficulties in recalling negative past events and language barriers were some of the challenges in the activity. Conclusions: The life grid appears to be an appropriate and useful tool for qualitative research with adolescents in India. This article contributes to ongoing discussions over culturally relevant methodologies and issues among child researchers in India.
Ultrasound evaluation of postsurgical shoulder after rotator cuff repair: comparison of clinical results
Authors: Kim Haejung , Park Hee Jin , Lee So Yeon , Kim Ji Na , Moon Juhee , Kim Mi Sung , Kim Eugene 
Published: August 2020

Background The relationship between the imaging parameters on postoperative ultrasound (US) other than repaired tendon integrity with clinical outcome such as postoperative residual pain has not been well defined. Purpose To investigate whether the repaired tendon thickness and subdeltoid fluid collection after rotator cuff repair are correlated with early postoperative clinical outcome. Material and Methods This retrospective study included 54 patients who underwent repair of the arthroscopic rotator cuff either by suture-bridge or single-row technique and postoperative US. We assessed the relationship between the sonographic parameters, including repaired supraspinatus tendon thickness and subdeltoid fluid collection, with the clinical outcome represented by the Korean Shoulder Scoring system (KSS) score using correlation coefficients (R). Also, the subgroup analysis was done to assess the differences by surgical technique and patients’ age. Results There was a significant inverse relationship between the amount of subdeltoid fluid collection and degree of self-assessed pain improvement of the patients ( P < 0.05), although every KSS category showed statistically insignificant tendency of inverse relationship with the fluid thickness. However, there was no statistically significant relationship between the thickness of repaired supraspinatus tendon and KSS scores. In patients aged >60 years, a statistically significant inverse relationship between thickness of subdeltoid fluid collection and difference value of the KSS scores in category of function was observed with both interpreters ( P = 0.015 and P = 0.04, respectively). Conclusion Subdeltoid fluid collection measured on US after repair of the arthroscopic rotator cuff in the early postoperative period has significant association with the patients’ subjective clinical outcome.