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Understanding the impacts of high‐resolution ocean model provides valuable insights for future research. However, the outcomes of sea surface state changes in both the tropics and mid‐latitudes remain unclear, and initialized seasonal forecasts have not been studied extensively. This study investigates the impact of ocean model resolution with the first long‐term hindcast experiment of an eddy‐resolving (0.1°) ocean model used for global seasonal forecasting. We show that using the high‐resolution ocean model significantly changes boreal winter jet streams in the atmosphere, based on the comparison of 30‐year hindcasts with ocean resolutions ranging from 1° to 0.1° for the Japan Meteorological Agency/Meteorological Research Institute Coupled Prediction System version 3. In boreal winters, the cold sea surface bias in the equatorial Pacific is significantly reduced, leading to an equatorward shift in the intertropical convergence zone (ITCZ) and enhanced convective activity in the western equatorial Pacific. The subtropical jet shifts equatorward due to the ITCZ shift and the weakening of equatorward propagation of mid‐latitude atmospheric eddies. The enhanced convective activity in the tropics has a remote influence in the mid‐latitudes, significantly reducing the upward eddy propagation of zonal wavenumber 1. Sea surface warm‐up in the mid‐latitudes partially cancels the reduction impact by enhancing the zonal wavenumber 2. Overall, the polar night jet accelerates due to the reduced supply of eddy forcing. Atmospheric and oceanic eddies play an important role in shaping the climate. In numerical climate simulations, the Earth is divided into a grid of discrete boxes, and the exchange of energy and mass between the boxes is computed step‐by‐step. Coarse grids are often used to reduce the computational cost, but recent studies have suggested that resolving fine ocean phenomena can make a significant difference. In this study, numerical seasonal forecasting experiments with ocean resolutions of 100 km, 25 km, and 10 km are compared to investigate the high‐resolution effects on the atmospheric flow for boreal winter. This is the first 30‐year‐long, retrospective seasonal forecast experiment for the past winters using a global eddy‐resolving (10 km) ocean model. The high‐resolution ocean model greatly warms the surface seawater in the tropical Pacific and in the mid‐latitude oceans. These changes in the sea surface influence atmospheric convection and eddies, with far‐reaching effects on distant regions and altitudes. Such effects on the westerly jet streams, which flow several kilometers to tens of kilometers above the sea surface, are observed in the southward shift of the subtropical jet and the strengthening of the polar night jet. Altering the ocean model resolution from 1° to 0.1° in a seasonal forecast model shifts and enhances the subtropical and polar night jetsAtmospheric responses to both tropical and mid‐latitude oceans are observedWave‐mean flow diagnostics indicates that the jet stream responses are more strongly influenced by the tropics Altering the ocean model resolution from 1° to 0.1° in a seasonal forecast model shifts and enhances the subtropical and polar night jets Atmospheric responses to both tropical and mid‐latitude oceans are observed Wave‐mean flow diagnostics indicates that the jet stream responses are more strongly influenced by the tropics

Objective: To evaluate the load dependence of effective regurgitant orifice area (ROA) in an animal model of chronic aortic regurgitation. Methods: Eight sheep were studied 10-20 weeks after the surgical [...]

The coastal ocean contributes to regulating atmospheric greenhouse gas concentrations by taking up carbon dioxide (CO2) and releasing nitrous oxide (N2O) and methane (CH4). In this second phase of the Regional Carbon Cycle Assessment and Processes (RECCAP2), we quantify global coastal ocean fluxes of CO2, N2O and CH4using an ensemble of global gap‐filled observation‐based products and ocean biogeochemical models. The global coastal ocean is a net sink of CO2in both observational products and models, but the magnitude of the median net global coastal uptake is ∼60% larger in models (−0.72 vs. −0.44 PgC year−1, 1998–2018, coastal ocean extending to 300 km offshore or 1,000 m isobath with area of 77 million km2). We attribute most of this model‐product difference to the seasonality in sea surface CO2partial pressure at mid‐ and high‐latitudes, where models simulate stronger winter CO2uptake. The coastal ocean CO2sink has increased in the past decades but the available time‐resolving observation‐based products and models show large discrepancies in the magnitude of this increase. The global coastal ocean is a major source of N2O (+0.70 PgCO2‐e year−1in observational product and +0.54 PgCO2‐e year−1in model median) and CH4(+0.21 PgCO2‐e year−1in observational product), which offsets a substantial proportion of the coastal CO2uptake in the net radiative balance (30%–60% in CO2‐equivalents), highlighting the importance of considering the three greenhouse gases when examining the influence of the coastal ocean on climate. The coastal ocean regulates greenhouse gases. It acts as a sink of carbon dioxide (CO2) but also releases nitrous oxide (N2O) and methane (CH4) into the atmosphere. This synthesis contributes to the second phase of the Regional Carbon Cycle Assessment and Processes (RECCAP2) and provides a comprehensive view of the coastal air‐sea fluxes of these three greenhouse gases at the global scale. We use a multi‐faceted approach combining gap‐filled observation‐based products and ocean biogeochemical models. We show that the global coastal ocean is a net sink of CO2in both observational products and models, but the coastal uptake of CO2is ∼60% larger in models than in observation‐based products due to model‐product differences in seasonality. The coastal CO2sink is strengthening but the magnitude of this strengthening is poorly constrained. We also find that the coastal emissions of N2O and CH4counteract a substantial part of the effect of coastal CO2uptake in the atmospheric radiative balance (by 30%–60% in CO2‐equivalents), highlighting the need to consider these three gases together to understand the influence of the coastal ocean on climate. We synthesize air‐sea fluxes of CO2, nitrous oxide and methane in the global coastal ocean using observation‐based products and ocean modelsThe coastal ocean CO2sink is 60% larger in ocean models than in observation‐based products due to systematic differences in seasonalityCoastal nitrous oxide and methane emissions offset 30%–60% of the CO2coastal uptake in the net radiative balance We synthesize air‐sea fluxes of CO2, nitrous oxide and methane in the global coastal ocean using observation‐based products and ocean models The coastal ocean CO2sink is 60% larger in ocean models than in observation‐based products due to systematic differences in seasonality Coastal nitrous oxide and methane emissions offset 30%–60% of the CO2coastal uptake in the net radiative balance

Using an eddy‐resolving ocean general circulation model, we examine the cold‐core rings pinched off from the Kuroshio Extension (KE), focusing on their tracer transport. The origin of the tracers in the rings and how they are trapped are directly investigated by releasing two passive tracers, corresponding to the KE water and the water in the Mixed‐Water Region (MWR) to the north of the KE. The cold‐core rings carry the tracer in the MWR wrapped by the KE water from the surface to the bottom at the pinch‐off. In and above the upper thermocline ( σθ< 26.4), these tracers are trapped in the ring and move along the ring until the rings rejoin the Kuroshio. Even in the lower thermocline ( σθ∼ 26.4–27.2), a substantial part of the tracers moves along the ring, while gradual leakage occurs. Vorticity balance in the rings is consistent with the passive tracer experiment, indicating that water in the upper thermocline moves along the rings, while the synchronous movement in and below the lower thermocline is severely contaminated by baroclinic Rossby waves. These direct estimations are compared with the indirect diagnoses using PV, the ratio of drift velocity of ring to its tangential velocity (nonlinear parameter), and the largest closed contour of stream function in the comoving frame of the ring. These indirect diagnoses are consistent with the direct estimation in the upper thermocline, but are not good indicators below the lower thermocline. The cause of their insufficient performance is discussed. Study of cold‐core rings from the Kuroshio Extension in an eddy‐resolving OGCMTracer transport is directly examined using passive tracers.Comparison to indirect methods is also discussed.

Background: Left ventricular aneurysm (LVA) may affect diastolic intraventricular blood flow. Color M-mode (CMM) Doppler flow propagation patterns are abnormal in the presence of apical aneurysms. The aim of this study was to validate the accuracy of CMM echocardiography for assessing the existence and size of LVA and to determine the intraventricular pressure gradient in LVA. Methods: CMM of the transmitral inflow in early diastole was obtained from the apical 4-chamber view in 19 sheep. The presence of the break point where the velocity decreased abruptly in the mitral inflow (point D) was determined and the distance between the apex and point D was measured. The intraventricular pressure difference between the base and the apex was measured by a catheter while it was calculated using CMM with the Euler equation. Results: The presence of the break point D showed 84% sensitivity and 100% specificity for determining the existence of an LVA. Distance between the apex and point D correlated well with scar size. Catheter- and CMM-derived intraventricular pressure difference correlated and agreed well (y = 1.0 x -0.2, r = 0.94). Conclusions: The point of abrupt decrease in propagation velocity of the CMM recording indicated the presence and size of LVA. Intraventricular pressure gradients were determined noninvasively by CMM echocardiography with reasonable accuracy.

Real-time 3-dimensional echocardiography (RT3DE), 2-dimensional echocardiography (2DE), and M-mode echocardiography were performed in 28 sheep with cardiac pathologies and 27 patients with heart disease to demonstrate the superiority of RT3DE over M-mode and 2DE for the determination of left ventricular mass. Postmortem examination and magnetic resonance imaging were used as a reference standard for the animal and clinical studies, respectively. In the animal study, the highest concordance correlation (0.92) was obtained between the actual weight of left ventricular mass and that estimated by RT3DE (0.69 for 2DE and 0.77 for M-mode, P < .001). In the clinical study, RT3DE also provided the best concordance correlation with left ventricular mass determined by magnetic resonance imaging (0.91 for RT3DE, 0.83 for 2DE, and 0.38 for M-mode; P < .0001).

Left atrial (LA) systolic and diastolic function were analyzed in an animal model of acute left ventricular ischemia with LA ischemia by proximal left circumflex coronary artery occlusion or without LA ischemia by midleft anterior descending coronary artery occlusion (7 sheep in each group). LA pressures and LA volumes were simultaneously recorded using a catheter and real-time 3-dimensional echocardiography, respectively. LA stroke volume represented 63% of left ventricular stroke volume during left anterior descending coronary artery occlusion, but only 32% during left circumflex coronary artery occlusion. This animal study with 3-dimensional echocardiographic determination of absolute LA volumes demonstrated dramatic depression of LA function during proximal left circumflex coronary artery occlusion as compared with left anterior descending coronary artery occlusion.

We developed an automated mitral annular tracking method based on a digital processing of high frame rate cineloop images of 2-dimensional echocardiography. In this study, its feasibility and accuracy was validated in 11 healthy volunteers and 16 patients with left ventricular (LV) dysfunction. The mitral annular excursion measured by automated mitral annular tracking agreed well with that measured by 3-dimensional echocardiography and correlated with LV ejection fraction. The longitudinal mitral annular excursion was reduced whereas the radial one was preserved for patients with LV dysfunction compared with control subjects. The novel automated mitral annular tracking method is clinically feasible and has potential capability to quantify the comprehensive mitral annular motion for evaluating LV function in a clinical setting.

A new method has been developed for measuring the volume flow rate of blood flowing through large vessels or outflow tracts of the heart. In this article we describe the principle of a method that can reduce the dependence of the Doppler angle of flow measurement by setting the sample points along a line to which every ultrasound beam is perpendicular. To evaluate the accuracy of this method, flow phantom experiments were made for both steady and pulsatile flows. The volume flow rate measured by this method agrees well with that observed by an ultrasound flowmeter (r=0.99) when the vessel diameter is large (25 mm). However, this method overestimates by 40% when the vessel diameter is small (8 mm). To make this method applicable to small vessels, an improvement in the lateral resolution of Doppler measurement is necessary. It has been concluded that this method can be used to measure the cardiac output or volume flow rates in large vessels.

Background: Quantifying regurgitant volumes is important for treatment of patients with valvular aortic regurgitation. Simple, reliable methods to quantify aortic regurgitation have been sought both in the catheterization laboratory and the echocardiography laboratory. Objectives: The aim of our study was to investigate the applicability of a new automated cardiac flow measurement method with color Doppler velocity data for quantifying retrograde flow volumes of aortic regurgitation in an ascending aorta model. Methods and Results: A 2-chamber pulsatile flow system with a modeled ascending aorta and a regurgitant aortic valve orifice was developed. The model could generate ''aortic regurgitation-like'' waveforms through the use of an electrically controlled valve. The regurgitant flows through the orifice (8.5 to 28.1 mL/beat) were measured by an ultrasound flowmeter; they were also calculated in the ascending aorta 1.0 cm above the orifice by the automated cardiac flow measurement method, which integrated spatially distributed digital flow velocity data through ''diastole.'' Calculated regurgitant volumes measured with the low color Doppler filter (5.4 cm/s) agreed well with those measured with the flowmeter (r = .99, P < .001, mean difference = 2.2 +/- 3.7 mL). However, the regurgitant volume was underestimated when 2 higher filter settings were used (9.6 and 10.9 cm/s). Although there was no significant difference in mean volume, higher frame rate (19 frames/s) provided more reproducible results with smaller standard deviation as compared with lower frame rate (7 frames/s). Conclusions: This new automated cardiac flow measurement method appears to be promising for semiautomatic quantification of aortic regurgitant volume. Appropriate choice of filter setting and high frame rate assists reliable data acquisition. (J Am Soc Echocardiogr 1998;11:874-81.)