bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Midsummer Dry Spell’s Impact on Vegetation in Jamaica
Authors: Allen Theodore L. , Curtis Scott , Gamble Douglas W. 
Published: March 2010

Abstract
The annual rainfall pattern of the intra-Americas sea reveals a bimodal feature with a minimum during the midsummer known as the midsummer dry spell (MSD). A first attempt is made to examine the impact of the MSD on vegetation through a normalized difference vegetation index (NDVI) analysis in Jamaica. Tropical Rainfall Measuring Mission rainfall estimates and NDVI derived from the Terra Moderate Resolution Imaging Spectroradiometer highlight a consistent MSD feature in both rainfall and vegetative vigor. Spatial variation of this MSD NDVI response is evident throughout Jamaica, with the strongest relationship between the rainfall reduction and NDVI decline throughout the southern portions of Jamaica including the area of major domestic food production. In all years except 2005 there is a notable reduction from early-summer NDVI to midsummer NDVI in this agricultural region. However, the lagged vegetative response undergoes clear interannual variation and is affected by other forcings besides rainfall, such as brush fires and extreme wind.
Dissipative Energization of Baroclinic Waves by Surface Ekman Pumping
Authors: Lee Sukyoung 
Published: March 2010

Abstract
A two-layer quasigeostrophic model is used to study the effect of lower boundary Ekman pumping on the energetics of baroclinic waves. Although the direct impact of the Ekman pumping is to damp the total eddy energy, either the eddy available potential energy (EAPE) or the eddy kinetic energy (EKE), individually, can grow because of the Ekman pumping. Growth of EAPE is favored if the phase difference between the upper and lower wave fields is less than a quarter wavelength, and EKE is favored if the phase difference is greater than a quarter wavelength. A numerical model calculation shows that the EAPE growth occurs directly through the Ekman pumping and that the increased EAPE can in turn lead to further growth by strengthening the baroclinic energy conversion from zonal available potential energy to the EAPE. Through this indirect effect, the Ekman pumping can increase the net production of total eddy energy.
The Impact of ENSO on Wave Breaking and Southern Annular Mode Events
Authors: Gong Tingting , Feldstein Steven B. , Luo Dehai 
Published: March 2010

Abstract
This study examines the relationship between intraseasonal southern annular mode (SAM) events and the El Niño–Southern Oscillation (ENSO) using daily 40-yr ECMWF Re-Analysis (ERA-40) data. The data coverage spans the years 1979–2002, for the austral spring and summer seasons. The focus of this study is on the question of why positive SAM events dominate during La Niña and negative SAM events during El Niño. A composite analysis is performed on the zonal-mean zonal wind, Eliassen–Palm fluxes, and two diagnostic variables: the meridional potential vorticity gradient, a zonal-mean quantity that is used to estimate the likelihood of wave breaking, and the wave breaking index (WBI), which is used to evaluate the strength of the wave breaking. The results of this investigation suggest that the background zonal-mean flow associated with La Niña (El Niño) is preconditioned for strong (weak) anticyclonic wave breaking on the equatorward side of the eddy-driven jet, the type of wave breaking that is found to drive positive (negative) SAM events. A probability density function analysis of the WBI, for both La Niña and El Niño, indicates that strong anticyclonic wave breaking takes place much more frequently during La Niña and weak anticyclonic wave breaking during El Niño. It is suggested that these wave breaking characteristics, and their dependency on the background flow, can explain the strong preference for SAM events of one phase during ENSO. The analysis also shows that austral spring SAM events that coincide with ENSO are preceded by strong stratospheric SAM anomalies and then are followed by a prolonged period of wave breaking that lasts for approximately 30 days. These findings suggest that the ENSO background flow also plays a role in the excitation of stratospheric SAM anomalies and that the presence of these stratospheric SAM anomalies in turn excites and then maintains the tropospheric SAM anomalies via a positive eddy feedback.
On the Phase Relations between the Western North Pacific, Indian, and Australian Monsoons*
Authors: Gu Dejun , Li Tim , Ji Zhongping , Zheng Bin 
Published: March 2010

Abstract
The phase relationships of the western North Pacific (WNP) summer monsoon (WNPM) with the Australian monsoon (AM) and Indian monsoon (IM) are investigated using observational rainfall, SST, and NCEP reanalysis data for the period of 1979–2005. It is found that a strong WNPM often follows a strong AM but leads a weak AM, and a significant simultaneous negative correlation appears between WNPM and IM. The in-phase relationship from AM to the succeeding WNPM occurs often during the El Niño decaying phase when the warm eastern Pacific SST anomaly (SSTA) weakens AM through anomalous Walker circulation and the persistence of an anomalous WNP anticyclone from the boreal winter to summer leads to a weak WNPM. The out-of-phase relation from WNPM to the succeeding AM occurs either during the El Niño early onset year when the warm SSTA in June–August (JJA) is strong enough to force a low-level cyclonic flow anomaly in WNP and in December–February (DJF) the same warm SSTA forces a weak AM, or during the El Niño decaying phase when the persistence of the WNP anomalous anticyclone causes a weak WNPM and the transition of a warm to a cold episode causes a strong AM in DJF. The simultaneous negative correlation between WNPM and IM often appears either during the El Niño early onset years when the warm eastern Pacific SSTA induces the cyclonic wind shear that strengthens WNPM but suppresses convection over India, or during the El Niño decaying summer when a weak WNPM results from the persistence of the local anomalous anticyclone and a strong IM results from the El Niño-to-La Niña transition or a basin-wide Indian Ocean warming.
The Role of Mesoscale Eddies in the Rectification of the Southern Ocean Response to Climate Change
Authors: Farneti Riccardo , Delworth Thomas L. , Rosati Anthony J. , Griffies Stephen M. , Zeng Fanrong 
Published: March 2010

Abstract
Simulations from a fine-resolution global coupled model, the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.4 (CM2.4), are presented, and the results are compared with a coarse version of the same coupled model, CM2.1, under idealized climate change scenarios. A particular focus is given to the dynamical response of the Southern Ocean and the role played by the eddies—parameterized or permitted—in setting the residual circulation and meridional density structure. Compared to the case in which eddies are parameterized and consistent with recent observational and idealized modeling studies, the eddy-permitting integrations of CM2.4 show that eddy activity is greatly energized with increasing mechanical and buoyancy forcings, buffering the ocean to atmospheric changes, and the magnitude of the residual oceanic circulation response is thus greatly reduced. Although compensation is far from being perfect, changes in poleward eddy fluxes partially compensate for the enhanced equatorward Ekman transport, leading to weak modifications in local isopycnal slopes, transport by the Antarctic Circumpolar Current, and overturning circulation. Since the presence of active ocean eddy dynamics buffers the oceanic response to atmospheric changes, the associated atmospheric response to those reduced ocean changes is also weakened. Further, it is hypothesized that present numerical approaches for the parameterization of eddy-induced transports could be too restrictive and prevent coarse-resolution models from faithfully representing the eddy response to variability and change in the forcing fields.
What Sets the Strength of the Middepth Stratification and Overturning Circulation in Eddying Ocean Models?
Authors: Wolfe Christopher L. , Cessi Paola 
Published: March 2010

Abstract
The processes maintaining stratification in the oceanic middepth (between approximately 1000 and 3000 m) are explored using an eddy-resolving general circulation model composed of a two-hemisphere, semienclosed basin with a zonal reentrant channel in the southernmost eighth of the domain. The middepth region lies below the wind-driven main thermocline but above the diffusively driven abyssal ocean. Here, it is argued that middepth stratification is determined primarily in the model’s Antarctic Circumpolar Current. Competition between mean and eddy overturning in the channel leads to steeper isotherms and thus deeper stratification throughout the basin than would exist without the channel. Isotherms that outcrop only in the channel are nearly horizontal in the semienclosed portion of the domain, whereas isotherms that also outcrop in the Northern Hemisphere deviate from horizontal and are accompanied by geostrophically balanced meridional transport. A northern source of deep water (water with temperatures in the range of those in the channel) leads to the formation of a thick middepth thermostad. Changes in wind forcing over the channel influence the stratification throughout the domain. Since the middepth stratification is controlled by adiabatic dynamics in the channel, it becomes independent of the interior diffusivity κ as κ → 0. The meridional overturning circulation (MOC), as diagnosed by the mean meridional volume transport, also shows a tendency to become independent of κ as κ → 0, whereas the MOC diagnosed by water mass transport shows a continuing dependence on κ as κ → 0. A nonlocal scaling for MOC is developed that relates the strength of the northern MOC to the depth of isotherms in the southern channel. The results of this paper compare favorably to observations of large-scale neutral density in the World Ocean.
A Study of the NOAA Near-Nadir AMSU-A Brightness Temperatures over Antarctica
Authors: Mo Tsan 
Published: March 2010

Abstract
Daily mean brightness temperatures over Antarctica derived from measurements by three Advanced Microwave Sounding Unit-A (AMSU-A) radiometers on board NOAA-18, NOAA-19, and MetOp-A satellites are studied. To demonstrate the characteristics of the data over this test site, time series of daily averages of the brightness temperatures are constructed. These time series provide a useful pattern of annual variation of the AMSU-A measurements for intercalibration of microwave radiometers on board multiple satellites. To investigate the diurnal effect on the measurements, the time series of daily averaged brightness temperatures are constructed separately for the ascending and descending passes. Results show that there are little diurnal differences in measurements during the Antarctic winter months from each satellite. Therefore these measurements provide a practical approach to obtain relative channel biases of intersatellite data. The monthly averages of the measurements over July 2009 are employed to obtain the relative channel biases because it is the coldest month in Antarctica. The resultant channel biases for the three satellites are within the range of ±0.1 K for channels 1–5 and ±0.3 K for channels 6–15. This is strong evidence that Antarctica is a potentially good test site for intercalibration of microwave radiometers on board multiple satellites. The small relative biases at channels 1–5 indicate that Antarctica is a very stable test site that is particularly useful for intercalibration of measurements from the window channels. The establishment of a natural test site for calibration references is important for calibration and validation of spaceborne microwave instruments.
Some Characteristics of Time Interpolation Errors for Fluid Flows
Authors: Hoffman Ross N. , Leidner S. Mark 
Published: March 2010

Abstract
The size of errors due to linear time interpolation varies parabolically with a maximum at the center of the interpolation interval in most of the cases examined here. These cases include simple situations that are analyzed analytically and mesoscale model simulations of the ocean surface wind that are analyzed empirically.
The Role of Trade Wind Surges in Tropical Cyclone Formations in the Western North Pacific
Authors: Chang Lung-Yao , Cheung Kevin K. W. , Lee Cheng-Shang 
Published: March 2010

Abstract
A total of 40 out of 531 tropical cyclones that formed in the western North Pacific during 1986–2005 have accompanied trade wind surges located 5°–15° latitude to the north of the pretropical cyclone disturbance centers. Composite and empirical orthogonal function analyses indicate that the trade wind surges are related to a midlatitude eastward-moving high pressure system often found during the East Asian winter monsoon. Therefore, these trade wind surge tropical cyclones tend to occur in late season (with one-third of them in December), and at lower latitudes (7° latitude lower than the climatological average formation position).
The evolution of mesoscale features during formation of trade wind surge tropical cyclones is examined. Various satellite datasets show similar mesoscale patterns during their formations. A few convective lines form by convergence between the trade wind surges and the strengthening cyclonic circulation associated with incipient vortex within the 24 h before formation. Some mesoscale convective systems are embedded in the convective line with lifetimes of about 5 h, and these are illustrated through case studies. Formations usually occur when the trade winds start to decrease in magnitude and a short period after the major episodes of convection in the convective lines and mesoscale convective systems. The relationships between the temporal variability of synoptic-scale trade wind surges, the mesoscale features, and associated tropical cyclone formations are discussed.
Numerical Simulations of Radiative Cooling beneath the Anvils of Supercell Thunderstorms
Authors: Frame Jeffrey , Markowski Paul 
Published: March 2010

Abstract
Numerical simulations of supercell thunderstorms that include parameterized radiative transfer and surface fluxes are performed using the Advanced Regional Prediction System (ARPS) to investigate the effects of anvil shadows on the near-storm environment. If the simulated storm is nearly stationary, the maximum low-level air temperature deficits within the shadows are about 2 K, which is roughly half the cooling found in some previous observations. It is shown that the extinction of downwelling shortwave radiation by the anvil cloud creates a differential in the flux of downwelling shortwave radiation between the sun and the shade that is at least an order of magnitude greater than the differential of any other term in either the surface radiation or the surface energy budgets. The loss of strong solar heating of the model surface within the shaded regions leads to a reduction of surface temperatures and stabilization of the model surface layer beneath the anvil. The reduction in vertical mixing results in a shallow, strongly vertically sheared layer near the surface and calmer near-surface winds, which are limited to regions in the anvil shadow. This difference in radiative heating is shown not to affect the vertical thermodynamic or wind profiles above the near-surface layer (approximately the lowest 500 m). It is also found that these results are highly sensitive to the magnitude of the near-surface winds. If the initial hodograph is shifted such that the simulated storm acquires a substantial eastward propagation speed, the temperature deficit within the shadow is greatly diminished. This is due to both a weaker surface sensible heat flux and less time during which surface cooling and boundary layer stabilization can occur beneath the anvil.
Predecessor Rain Events ahead of Tropical Cyclones
Authors: Galarneau Thomas J. , Bosart Lance F. , Schumacher Russ S. 
Published: March 2010

Abstract
Twenty-eight predecessor rain events (PREs) that occurred over the United States east of the Rockies during 1995–2008 are examined from a synoptic climatology and case study perspective. PREs are coherent mesoscale regions of heavy rainfall, with rainfall rates ≥100 mm (24 h)−1, that can occur approximately 1000 km poleward of recurving tropical cyclones (TCs). PREs occur most commonly in August and September, and approximately 36 h prior to the arrival of the main rain shield associated with the TC. A distinguishing feature of PREs is that they are sustained by deep tropical moisture that is transported poleward directly from the TC. PREs are high-impact weather events that can often result in significant inland flooding, either from the PRE itself or from the subsequent arrival of the main rain shield associated with the TC that falls onto soils already saturated by the PRE.
The composite analysis shows that on the synoptic-scale, PREs form in the equatorward jet-entrance region of a 200-hPa jet on the western flank of a 925-hPa equivalent potential temperature ridge located east of a 700-hPa trough. On the mesoscale, PREs occur in conjunction with low-level frontogenetical forcing along a baroclinic zone where heavy rainfall is focused. A case study analysis was conducted of a PRE ahead of TC Erin (2007) that produced record-breaking rainfall (&gt;250 mm) from southern Minnesota to Lake Michigan. This analysis highlighted the importance of frontogenetical forcing along a low-level baroclinic zone in the presence of deep tropical moisture from TC Erin in producing a long-lived, quasi-stationary mesoscale convective system.
Biomechanical Evaluation of Shear Force Vectors Leading to Injury of the Biceps Reflection Pulley
Authors: Braun Sepp , Millett Peter J. , Yongpravat Charlie , Pault Joseph D. , Anstett Tyler , Torry Michael R. , Giphart J. Erik 
Published: March 2010

Background The clinical importance of the biceps reflection pulley (BRP), which stabilizes the long head of the biceps tendon (LHB) as it exits the joint, has been shown. However, there is controversy on the pathomechanism of injury to the BRP. The angular orientation of the LHB relative to its origin and distal course changes with joint positions and may place the BRP at risk for injury. Purpose To measure the course of the LHB in common arm positions and to determine the shear and normal (stabilizing) force vectors as well as the excursion of the LHB. Study Design Descriptive laboratory study. Methods The LHBs of 8 fresh-frozen cadaveric shoulders were marked with arthroscopically injected microbeads and mounted in a custom-built shoulder rig. Data for neutral arm position, forward flexion, and abduction were collected in internal, neutral, and external rotation using biplane fluoroscopy. Bone and LHB position were reconstructed in 3 dimensions. Results The shear component of the resulting vector was significantly higher during internal (28.4% ± 18.1%) compared with external rotation (18.9% ± 9.7%; P = .0157) and was highest in neutral arm position with internal rotation (39.2% ± 12.7%) and forward flexion with neutral rotation (36.2% ± 10.7%). The normal force vector, stabilizing the LHB, was significantly higher in abduction (55.2% ± 9.6%) compared with forward flexion (39.1% ± 12.4%; P < .0001) and neutral positions (39.1% ± 11.4%; P < .0001). The LHB excursion was significantly lower for neutral arm positions (0.7 ± 6.0 mm) compared with forward flexion (12.6 ± 8.3 mm; P < .0001) and abduction (12.0 ± 6.5 mm; P < .0001). Conclusion Increased shear load at forward flexion with internal or neutral arm rotation and internal rotation at neutral arm position may cause injury to the BRP. Additionally, a sawing mechanism caused by the 12-mm linear excursion combined with a load of the LHB through the BRP during elevation may also lead to lesions. Clinical Relevance Knowledge of the pathomechanisms of BRP injury may help in developing specific treatment and rehabilitation strategies as well as tests for physical examination.
A Comparison of 11 O'clock versus Oblique Femoral Tunnels in the Anterior Cruciate Ligament—Reconstructed Knee
Authors: Markolf Keith L. , Jackson Steven R. , McAllister David R. 
Published: March 2010

Background Traditionally, a standard femoral tunnel for a single-bundle anterior cruciate ligament (ACL) reconstruction is positioned 6 to 7 mm anterior to the posterior wall at an 11 o'clock orientation in the femoral notch (right knee). However, some surgeons have advocated placing the femoral tunnel at a more oblique orientation at or near the femoral footprint of the ACL's posterolateral bundle (at approximately 9:30 to 10 o'clock in the notch) to provide the graft with a better mechanical advantage for controlling tibial rotation and eliminating the pivot shift. Hypothesis Moving the femoral tunnel from the standard location to an oblique position in the femoral notch will significantly reduce the magnitude of a simulated pivot shift. Study Design Controlled laboratory study. Methods Internal-external tibial rotation and anteroposterior (AP) displacement of the lateral tibial plateau were measured in 17 fresh-frozen cadaveric knees during a simulated pivot-shift event with a single-bundle ACL reconstruction placed in standard and oblique femoral tunnels. Baseline kinematic measurements were taken with the graft tensioned to restore intact AP knee laxity at 30° of flexion. The measurements were repeated as graft tension was decreased to produce approximately 2-mm incremental increases in laxity (up to +10 mm). Correlations between lateral tibial plateau displacement and tibial rotation during the pivot shift were determined for both tunnels. Results There were no significant differences in tibial rotations or tibial plateau displacements during the pivot shift between standard and oblique femoral tunnels when the graft was tensioned to restore intact knee laxity. The relationship between pivot-shift magnitude and AP laxity was highly linear for each knee specimen over the range of laxities tested; the mean slopes for anteromedial (AM) and posterolateral (PL) tunnels were not significantly different. There were near perfect linear correlations (mean r2 > .98) between lateral plateau displacement and tibial rotation for both femoral tunnel positions; the slope of the regression line was not significantly different between tunnels. Conclusion Moving the femoral tunnel from the standard location to a more oblique position in the notch did not significantly alter pivot-shift kinematics. Lateral plateau displacement was strongly correlated with tibial rotation, and either can be used to quantify the pivot shift. Clinical Relevance The rationale for placing the femoral tunnel at an oblique position in the notch to reduce the pivot shift is questioned.