Search

Microscale turbulence in the atmospheric boundary layer (ABL) is characterized by significant spatiotemporal variability. Consequently, a change in the turbulence forecasting paradigm needs to occur, moving beyond average turbulence estimates at mesoscale grid resolutions (several kilometers) to eddy‐resolving forecasts. To that end, the viability of dynamic downscaling to large‐eddy simulation scales is evaluated. We present for the first time, multiday dynamic downscaling from currently available numerical weather prediction forecasts to a high‐resolution grid spacing of 25 m. It is found that these eddy‐resolving forecasts can realistically reproduce turbulence levels and peak events in the bulk of the daytime ABL, adequately capturing turbulence variability at subminute intervals. Moreover, probability distributions of turbulence quantities are in very good agreement when compared to in situ sonic‐anemometer observations. These results demonstrate the feasibility of eddy‐resolving forecasts to derive accurate probabilistic estimates of turbulence in the ABL and provide a path toward real‐time large‐eddy simulation scale prediction. Forecasting of turbulence for near‐surface applications including wind energy and wind power production, atmospheric transport and dispersion, and wildland fire requires high‐fidelity spatiotemporal information. State‐of‐the‐art turbulence forecasting algorithms rely on numerical weather prediction models, which have spatial resolutions of several kilometers. These operational numerical weather prediction models are therefore not able to capture the relevant variability of turbulence in the atmospheric boundary layer. Herein, we demonstrate the feasibility of dynamic downscaling from operational weather forecasts to large‐eddy simulation scales (25 m), with which the most relevant turbulent structures are explicitly resolved. Comparison to sonic‐anemometer observations at the Boulder Atmospheric Observatory tower reveals that these eddy‐resolving forecasts can be used to derive accurate probabilistic predictions of turbulence in the atmospheric boundary layer and provides a path toward real‐time large‐eddy simulation scale prediction in the near future. Dynamic downscaling from operational weather forecasts to large‐eddy simulation is performedEddy‐resolving forecasts at  = 25 m realistically reproduce observed turbulence characteristics during daytime conditionsEddy‐resolving forecasts can be used to derive probabilistic estimates of turbulence in the atmospheric boundary layer

The one‐third power of the energy dissipation rate (EDR), a primary aviation turbulence metric, is calculated using high vertical‐resolution radiosonde data (HVRRD) and compared with flight‐EDR observed from commercial airlines. Comparisons are made along the main flight routes over the United States and at z= 20–45 kft for 6 years (2012–2017). The horizontal distributions of moderate‐or‐greater (MOG) ratio of HVRRD‐EDR show large values over the Rocky Mountains, consistent with those of flight‐EDR. Vertically, the MOG ratios of HVRRD‐EDR show local peaks at z= 20–23 kft and 41–44 kft, while those of flight‐EDR at z= 23–26 kft and 35–41 kft. Temporally, HVRRD‐EDR has maximum MOG values in JJA and minimum values in DJF at z= 20–30 kft, which is opposite to the flight‐EDR. At z= 30–40 kft, HVRRD‐EDR shows nearly no seasonal variation but flight‐EDR has large values in MAM and small values in JJA. At z= 40–45 kft, HVRRD‐EDR (flight‐EDR) shows large values in MAM and small values in SON (DJF). Discrepancies in spatiotemporal distributions between the two data sets likely stem from: (a) turbulence observed from the two data sets cannot be the same event, (b) the limitation of HVRRD‐EDR in capturing shear‐instability under statically stable condition (i.e., Kelvin‐Helmholtz instability) which probably accounts for most flight‐EDR events at upper levels, and (c) limitation in aircraft measurements response to fluctuations at smaller scales than the aircraft size. We calculated a primary aviation turbulence metric, eddy dissipation rate (EDR), using operational high‐resolution radiosonde data and compared it with flight‐EDR observed from commercial airlines. EDR is an index for representing the intensity of turbulence. Analyzing 6 years of data (2012–2017) over the United States, we find that the horizontal distributions of both EDRs from radiosonde data and flight data show large values over the Rocky Mountains. However, they show large differences in vertical and temporal distributions in terms of their peak location and timing. We attribute these discrepancies to three factors. First, turbulence observed from the two data sets cannot be the same event, because the radiosonde and aircraft cannot coincide at the same location and time. Second, the sources of turbulence derived from radiosonde and flight observation may be different: static‐instability and dynamic‐instability for radiosonde‐EDR and flight‐EDR, respectively. Third, aircraft have limitations detecting fluctuation at scales smaller than the aircraft size. Given the limited global data on atmospheric turbulence, EDR estimated from operational radiosonde data can be a valuable resource for research and development for the aviation industry and numerical weather forecasting models. Radiosonde‐derived turbulence is applied to aviation turbulence metricSpatiotemporal distributions of radiosonde‐ and flight‐turbulence are comparedCauses of discrepancies between radiosonde‐ and flight‐turbulence are discussed Radiosonde‐derived turbulence is applied to aviation turbulence metric Spatiotemporal distributions of radiosonde‐ and flight‐turbulence are compared Causes of discrepancies between radiosonde‐ and flight‐turbulence are discussed

Palliative and end-of-life patients in their homes are at risk of developing symptom crises requiring urgent care. The usual care for these patients involves transport to an Emergency Department (ED) despite the preference of most palliative patients to stay home. The objective of this initiative was to develop an innovative strategy to provide collaborative care in the home to alleviate symptoms and avoid transport. A partnership was created among Emergency Medical Services and Community Care staff, physicians, and leaders to enable patients to stay at home with existing resources during symptom crisis. As a result of the initiative, patients were able to stay at home more frequently. When patients required transport to the ED, it occurred after attempted symptom management in the home. A total of 110 calls were tracked in the first 18 months of the initiative. Of those, 61% ended with the patient staying home, in alignment with their preferred place of care at the end of life. A collaborative approach by care providers in the community enabled patients to stay home despite symptom crisis near the end of life.

On 2 November 2015, unrealistically large areas of light‐or‐stronger turbulence were predicted by the WRF‐RAP (Weather Research and Forecast Rapid Refresh)‐based operational turbulence forecast system over the western U.S. mountainous regions, which were not supported by available observations. These areas are reduced by applying additional terrain averaging, which damps out the unphysical components of small‐scale (~2Δx) energy aloft induced by unfiltered topography in the initialization of the WRF model. First, a control simulation with the same design of the WRF‐RAP model shows that the large‐scale atmospheric conditions are well simulated but predict strong turbulence over the western mountainous region. Four experiments with different levels of additional terrain smoothing are applied in the initialization of the model integrations, which significantly reduce spurious mountain‐wave‐like features, leading to better turbulence forecasts more consistent with the observed data. Large areas of forecasted stronger turbulence over the western U.S. mountainous regions are reduced by additional terrain averagingUnphysical energy spectra induced by unfiltered small‐scale (~2Δx) topography are damped out in the initialization of the modelReducing unphysical mountain‐wave‐like features significantly improves operational turbulence forecasts over the mountain region

Spatial and temporal distributions of Clear‐Air Turbulence (CAT) in the Northern Hemisphere were investigated using 41 years (1979–2019) of the European Centre for Medium‐range Weather Forecast Reanalysis version 5 (ERA5) data. We used two groups of CAT diagnostics to determine occurrence frequencies: (a) commonly used empirical turbulence indices (TI1, TI2, and TI3) and their components [vertical wind shear (VWS), deformation, ‐divergence, and divergence tendency], and (b) theoretical instability indicators [Richardson number (Ri), potential vorticity (PV), and Brunt‐Vӓisӓlӓ frequency]. The empirical indices showed high frequencies of moderate‐or‐greater (MOG)‐level CAT potential over the East Asian, Eastern Pacific, and Northwestern Atlantic regions in winter. Over East Asia, the entrance region of strong upper‐level jets showed the highest frequencies in TI1, TI2, and TI3 due mainly to strong VWS. The Eastern Pacific and Northwestern Atlantic areas near the exit region of jets had relatively high frequencies of these indices and also Ri. PV frequency was high on the southern side of jet primarily due to negative relative vorticity. Long‐term increasing trends of MOG‐level CAT potential also appeared in those three regions mainly due to warming in lower latitudes. The most significant increasing trend was found over East Asia, due to the strengthening of the East Asian jet and increased VWS due to the strong meridional temperature gradients in the mid‐troposphere induced by warming in the tropics and cooling in eastern Eurasia. These trends over East Asia, if continued, are expected to be of importance to efficient aviation operations across the northwestern Pacific Ocean. Strong bumpiness of cruising aircraft can lead to physical injuries for crews and passengers, which is mostly occurred due to atmospheric turbulence by enhanced wind shear near upper‐level jet stream. Spatial characteristics of turbulence and their long‐term trends at cruising altitude in Northern Hemisphere were examined using the up‐to‐date global reanalysis data. The result showed that East Asia, Eastern Pacific, and Northwestern Atlantic regions have a higher frequency of turbulence than other areas. In particular, East Asia was found to be the highest frequency and the largest increasing trend of strong turbulence, which is collocated with a heavy air‐traffic region between East Asia and North America across the North Pacific Ocean. This implies that the potential of encountering turbulence over East Asia could be increased further, if the jet stream will be strengthened continually due to climate change in this region. Spatial and temporal distributions of Clear‐Air Turbulence (CAT) indices for 41 years in the Northern Hemisphere are derived using the highest resolution of reanalysis dataThe CAT potentials are high in three regions: the East Asian, Eastern Pacific, and Northwestern Atlantic regions due to upper‐level jetsIncreasing trend of CAT potentials is the largest in East Asia due to warming in tropics and cooling over the Eurasian continent, which have a high impact on transpacific flights Spatial and temporal distributions of Clear‐Air Turbulence (CAT) indices for 41 years in the Northern Hemisphere are derived using the highest resolution of reanalysis data The CAT potentials are high in three regions: the East Asian, Eastern Pacific, and Northwestern Atlantic regions due to upper‐level jets Increasing trend of CAT potentials is the largest in East Asia due to warming in tropics and cooling over the Eurasian continent, which have a high impact on transpacific flights

It has been well documented that ischemic preconditioning limits ischemicreperfusion injury in cardiac muscle, but the ability of ischemic preconditioning to limit skeletal muscle injury is less clear. Previous reports have emphasized the beneficial effects of ischemic preconditioning on skeletal muscle structure and capillary perfusion but have not evaluated muscle function. We investigated the morphologic and functional consequences of ischemic preconditioning, followed by a 2hour period of tourniquet ischemia on muscles in the rat hindlimb. The 2hour ischemia was imposed without preconditioning, or was preceded by three brief 10 minutes on10 minutes off preischemic conditioning intervals. We compared muscle morphology, isometric contractile function, and muscle fatigue properties in predominantly fasttwitch, tibialis anterior muscles 3 n8 and 7 n8 days after ischemiareperfusion. Two hours of ischemia, followed by reperfusion, results in a 20 percent reduction of muscle mass p< 0.05 and a 33 percent reduction in tetanic tension p< 0.05 when compared with controls n8 at 3 days. The same protocol, when preceded by ischemic preconditioning, results in similar decreases in muscle mass and contractile function. Neuromuscular transmission was also impaired in both ischemic groups 7 days after ischemia. Nerveevoked maximum tetanic tension was 69 percent of the tension produced by direct muscle stimulation in the ischemia group and 65 percent of direct tension in the ischemic preconditioningischemia group. In summary, ischemic preconditioning, using the same protocol reported to be effective in limiting infarct size in porcine muscle, had no significant benefit in limiting injury or improving recovery in the ischemic rat tibialis anterior. The value of ischemic preconditioning in reducing imposed ischemicreperfusioninduced functional deficits in skeletal muscle remains to be demonstrated. Plast. Reconstr. Surg.100 1767, 1997.

Bloodless surgical procedures on the extremities are achieved by application of a pneumatic tourniquet. The ischemia produced has deleterious effects on nerve and muscle function. It has been suggested that temporary interruption of ischemia by a reperfusion interval can prevent muscle and nerve injury. We investigated the muscle and nerve response to 3 hours of tourniquet ischemia, with and without a reperfusion interval after the first 2 hours of application, in a rodent model. Morphometric, contractile, and histologic parameters were measured. Tourniquet ischemia, with and without a reperfusion interval, results in muscle injury and a transient depression of muscle function. Introduction of a reperfusion interval reduces the severity of injury and increases the early rate of recovery. However, the later stages of recovery appear to be unaffected by reperfusion.