bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of soil types and Meloidogyne hapla on the multi-purpose uses of arugula (Eruca sativa)
Authors: Melakeberhan Haddish , Kravchenko Alexandra , Dahl Jon , Warncke Darryl 
Published: January 2010

AbstractDeveloping multi-purpose alternatives to synthetic nematicides for managing the northern root-knot nematode, Meloidogyne hapla, a problem in a variety of temperate vegetable and nursery crop production soils, continues to be challenging. Arugula (Eruca sativa), a high-end green vegetable crop with biofumigant and cover crop attributes, is an effective trap crop (dead-end host) for populations of M. hapla in sandy loam soil. Exploiting arugula's multi-purpose attributes, however, depends on understanding its interaction with M. hapla under a range of conditions. The objectives of this study were to determine if soil types affect: i) the ability of M. hapla to infect arugula; and ii) if M. hapla infection has any effect on arugula's vegetative quality in the respective soils. When 2-week-old arugula cv. Roquette seedlings were inoculated with either 0 (control), 4000 or 8000 M. hapla eggs per 300 cm3 of either sandy, sandy loam or muck soil, and maintained for 23 and 24 days (28±2°C), more nematodes were recovered from sandy loam soil. However, the numbers of nematodes recovered between the inocula were similar in the three soil types and nematode infection had no effect on plant growth or nutritional quality. However, the growth and leaf nutritional quantity of arugula were significantly affected by soil type. The results support the hypothesis that M. hapla will infect arugula in different soil types without affecting its vegetative quantity and quality, providing the basis for testing arugula's trap, vegetable and, possibly, biofumigant attributes from one seeding in fields where M. hapla exists.
Oscheius carolinensis n. sp. (Nematoda: Rhabditidae), a potential entomopathogenic nematode from vermicompost
Authors: Torres-Barragan Andrea , Ye Weimin , Cardoza Yasmin 
Published: January 2010

AbstractOscheius carolinensis n. sp. (Rhabditidae) was recovered through the Galleria bait method from vermicompost produced in Raleigh, NC, USA. Morphological studies with light microscopy and scanning electron microscopy, as well as molecular analyses of the near-full-length small subunit rDNA gene (SSU), D2/D3 expansion segments of the large subunit rDNA gene (LSU) and internal transcribed spacer (ITS), revealed this as a new species, described herein as Oscheius carolinensis n. sp. The new species is characterised by a combination of characters including its unique DNA sequences, amphimictic reproduction, six separate lips with bristle-like sensilla, lateral field with four lines, leptoderan and open male bursa, arrangement of bursal papillae 1 + 1 + 1/3 + 3 + ph, evenly spaced first, second and third papillae, and separate spicules that are distally shaped like a crochet needle. Oscheius carolinensis n. sp. belongs to the Insectivorus-group and is closest to O. colombianus, O. chongmingensis n. comb., O. insectivorus and O. lucianii. A Bacillus-like bacterium appears to be associated with this nematode, based on our microscopic and SEM observations. Exposed Galleria larvae were killed within 5 days and numerous nematodes were recovered from the cadavers within 48 h. Preliminary tests revealed that this nematode is capable of infecting at least two other insect species (Pieris rapae and Tenebrio molitor) under laboratory conditions and therefore has potential as a biological control agent. The status of Heterorhabditidoides chongmingensis is discussed, the genus is proposed as a junior synonym of Oscheius, and O. chongmingensis n. comb. is proposed.
Climatology of Velocity and Temperature Turbulence Statistics Determined from Rawinsonde and ACARS/AMDAR Data
Authors: Frehlich Rod , Sharman Robert 
Published: January 2010

Abstract
The climatology of the spatial structure functions of velocity and temperature for various altitudes (pressure levels) and latitude bands is constructed from the global rawinsonde network and from Aircraft Communications, Addressing, and Reporting System/Aircraft Meteorological Data Relay (ACARS/AMDAR) data for the tropics and Northern Hemisphere. The ACARS/AMDAR data provide very dense coverage of winds and temperature over common commercial aircraft flight tracks and allow computation of structure functions to scales approaching 1 km, while the inclusion of rawinsonde data provides information on larger scales approaching 10 000 km. When taken together these data extend coverage of the spatial statistics of the atmosphere from previous studies to include larger geographic regions, lower altitudes, and a wider range of spatial scales. Simple empirical fits are used to approximate the structure function behavior as a function of altitude and latitude in the Northern Hemisphere. Results produced for spatial scales less than ∼2000 km are consistent with previous studies using other data sources. Estimates of the vertical and global horizontal structure of turbulence in terms of eddy dissipation rate ε and thermal structure constant CT2 are derived from the structure function levels at the smaller scales.
Climatological Conditions of Lake-Effect Precipitation Events Associated with the New York State Finger Lakes
Authors: Laird Neil , Sobash Ryan , Hodas Natasha 
Published: January 2010

Abstract
A climatological analysis was conducted of the environmental and atmospheric conditions that occurred during 125 identified lake-effect (LE) precipitation events in the New York State Finger Lakes region for the 11 winters (October–March) from 1995/96 through 2005/06. The results complement findings from an earlier study reporting on the frequency and temporal characteristics of Finger Lakes LE events that occurred as 1) isolated precipitation bands over and downwind of a lake (NYSFL events), 2) an enhancement of LE precipitation originating from Lake Ontario (LOenh events), 3) an LE precipitation band embedded within widespread synoptic precipitation (SYNOP events), or 4) a transition from one type to another. In comparison with SYNOP and LOenh events, NYSFL events developed with the 1) coldest temperatures, 2) largest lake–air temperature differences, 3) weakest wind speeds, 4) highest sea level pressure, and 5) lowest height of the stable-layer base. Several significant differences in conditions were found when only one or both of Cayuga and Seneca Lakes, the largest Finger Lakes, had LE precipitation as compared with when the smaller Finger Lakes also produced LE precipitation. In addition, transitional events containing an NYSFL time period occurred in association with significantly colder and drier air masses, larger lake–air temperature differences, and a less stable and shallower boundary layer in comparison with those associated with solitary NYSFL events.
Remote Sensing of Multilayer Cloud-Top Pressure Using Combined Measurements of MERIS and AATSR on board Envisat
Authors: Lindstrot Rasmus , Preusker Rene , Fischer Jürgen 
Published: January 2010

Abstract
A novel and unique algorithm for the retrieval of multilayer cloud-top pressure is presented, relying on synergetic observations of the Medium Resolution Imaging Spectrometer (MERIS) and Advanced Along Track Scanning Radiometer (AATSR) on board the Environmental Satellite (Envisat). The retrieval is based on the exploitation of the differing signals observed in the thermal infrared spectral region (AATSR) and the oxygen A band at 0.76 μm (MERIS). Past studies have shown that the cloud-top pressure retrieved from MERIS measurements is highly accurate in the case of low single-layered clouds. In contrast, in the presence of multilayered clouds like cirrus overlying water clouds, the derived cloud height is biased. In this framework, an optimal estimation algorithm for the correction of the measured O2 A transmission for the influence of the upper cloud layer was developed. The algorithm is best applicable in cases of optically thin cirrus (1 ≤ τ ≤ 5) above optically thick water clouds (τ &gt; 5), as found frequently in the vicinity of convective or frontal cloud systems. The split-window brightness temperature difference technique is used for the identification of suitable cases. The sensitivities of the AATSR and MERIS measurements to multilayered clouds are presented and discussed, revealing that in the case of dual-layered clouds, the AATSR-derived cloud height is close to the upper cloud layer, even if it is optically thin. In contrast, the cloud height retrieved from MERIS measurements represents the optical center of the cloud system, which is close to the lower layer in cases where the upper layer is optically thin. Two case studies of convective, multilayered cloud systems above the northern Atlantic Ocean are shown, demonstrating the plausibility of the approach. The presented work is relevant especially in view of the upcoming Global Monitoring for Environment and Security Sentinel-3 satellite to be launched in 2012 that will carry the respective MERIS and AATSR follow-up instruments Ocean and Land Colour Instrument (OLCI) and Sea and Land Surface Temperature Radiometer (SLSTR).
Validation of a Tropical Cyclone Steering Response Function with a Barotropic Adjoint Model
Authors: Hoover Brett T. , Morgan Michael C. 
Published: January 2010

Abstract
The steering of a tropical cyclone (TC) vortex is commonly understood as the advection of the TC vortex by an “environmental wind.” In past studies, the environmental steering wind vector has been defined by the horizontal and vertical averaging of the horizontal winds in a box centered on the TC. The components of this environmental steering have been proposed as response functions to derive adjoint-derived sensitivities of TC zonal and meridional steering. The appropriateness of these response functions in adjoint sensitivity studies of TC steering is tested using a two-dimensional barotropic model and its adjoint for a 24-h forecast. It is found that these response functions do not produce sensitivities to TC steering because perturbations to the model initial conditions that change the final-time location of the TC also change the response functions in ways that have nothing to do with the steering of the TC at model verification.
An alternate response function is proposed wherein the environmental steering vector is defined as the wind averaged over the response function box attributed to vorticity outside of that box. By redefining the response functions for the zonal and meridional steering as components of this environmental steering vector, the effect of small changes to the final-time location of the TC is removed, and the resultant sensitivity gradients can be shown to truly represent the sensitivity of TC steering to perturbations of the model forecast state.
A Direct Measure of Entrainment
Authors: Romps David M. 
Published: January 2010

Abstract
A method is introduced for directly measuring convective entrainment and detrainment in a cloud-resolving simulation. This technique is used to quantify the errors in the entrainment and detrainment estimates obtained using the standard bulk-plume method. The bulk-plume method diagnoses these rates from the convective flux of some conserved tracer, such as total water in nonprecipitating convection. By not accounting for the variability of this tracer in clouds and in the environment, it is argued that the bulk-plume equations systematically underestimate entrainment. Using tracers with different vertical profiles, it is also shown that the bulk-plume estimates are tracer dependent and, in some cases, unphysical. The new direct-measurement technique diagnoses entrainment and detrainment at the gridcell level without any recourse to conserved tracers. Using this method in large-eddy simulations of shallow and deep convection, it is found that the bulk-plume method underestimates entrainment by roughly a factor of 2. The directly measured entrainment rates are then compared to cloud height and cloud buoyancy. Contrary to existing theories, fractional entrainment is not found to scale like the inverse of height, the cloud buoyancy, or the gradient of cloud buoyancy. On the other hand, fractional detrainment is found to scale linearly with cloud buoyancy. Finally, direct measurement is used to diagnose the spatial distribution of entrainment and detrainment during the evolution of an individual deep cumulonimbus.
Intraseasonal Variability of the Saharan Heat Low and Its Link with Midlatitudes
Authors: Chauvin Fabrice , Roehrig Romain , Lafore Jean-Philippe 
Published: January 2010

Abstract
The Saharan heat low (SHL) is thought to be a key feature of the West African monsoon, and its variations during the summer season have not yet been systematically assessed. To characterize the intraseasonal variations of the SHL, real and complex empirical orthogonal function analyses were applied to the 850-hPa potential temperature field over northern Africa and the Mediterranean, using NCEP–Department of Energy (DOE) Atmospheric Model Intercomparison Project (AMIP-II) reanalysis results. A robust quasi-propagative mode was highlighted over North Africa and the Mediterranean. This mode consists of two phases. The west phase corresponds to a maximum temperature over the coast of Morocco–Mauritania, propagating southwestward, and a minimum between Libya and Sicily, propagating southeastward. The east phase corresponds to the opposite temperature structure, which propagates as in the west phase. A lag-composite analysis revealed that this SHL mode was preceded by large-scale, midlatitude, intraseasonal fluctuations of the atmosphere. The southward penetration of a Rossby wave disturbance over Europe and North Africa generates modulations of the three-dimensional atmospheric structure. The low-level ventilations and harmattan-like circulation are particularly impacted, as are the subtropical westerlies and the polar jets in the upper troposphere. The west phase is concomitant with an enhanced convective signal over the Darfur region, which propagates westward, as far as the middle of the Atlantic, at a speed similar to that of the well-known African easterly waves.
The SHL appears to be a bridge between the midlatitudes and the West African monsoon, which may offer promising sources of predictability over the Sahel on an intraseasonal time scale.
Impact of Changes in Climate and Halocarbons on Recent Lower Stratosphere Ozone and Temperature Trends
Authors: Lamarque Jean-François , Solomon Susan 
Published: January 2010

Abstract
The primary focus of this paper is the analysis of the roles of long-term increases in carbon dioxide (CO2) and sea surface temperatures (used as indicators of climate change) and man-made halocarbons (indicators of chemical ozone depletion linked to halogens) in explaining the observed trend of ozone in the tropical lower stratosphere and implications for related variables including temperature and tropopause height. Published estimates indicate a decrease of approximately 10% in observed ozone concentrations in this region between 1979 and 2005. Using a coupled chemistry–climate atmosphere model forced by observed sea surface temperatures and surface concentrations of long-lived greenhouse gases and halocarbons, the authors show that the simulations display substantial decreases in tropical ozone that compare well in both latitudinal and vertical structure with those observed. Based on sensitivity simulations, the analysis indicates that the decreases in the lower stratospheric (85–50 hPa) tropical ozone distribution are mostly associated with increases in CO2 and sea surface temperatures, in contrast to those at higher latitudes, which are largely driven by halocarbon increases. Factors influencing temperature trends and tropopause heights in this region are also probed. It is shown that the modeled temperature trends in the lower tropical stratosphere are also associated with increases in CO2 and sea surface temperatures. Following the analysis of lower stratospheric tropical temperature trends, the secondary focus of this paper is on related changes in tropopause height. Much of the simulated tropopause rise in the tropical zone as measured by tropopause height is found to be linked to increases in sea surface temperatures and CO2, while increases in halocarbons dominate the tropopause height changes in the subtropics near 30°; both drivers thus affect different regions of the simulated changes in the position of the tropopause. Finally, it is shown that halocarbon increases dominate the changes in the width of the region where modeled total ozone displays tropical character (as indicated by low values of the column abundance). Hence the findings suggest that climate changes and halocarbon changes make different contributions to different metrics used to characterize tropical change.
Mechanisms for the Onset of the African Humid Period and Sahara Greening 14.5–11 ka BP*
Authors: Timm Oliver , Köhler Peter , Timmermann Axel , Menviel Laurie 
Published: January 2010

Abstract
The mechanisms leading to the onset of the African Humid Period (AHP) 14 500–11 000 yr ago are elucidated using two different climate–vegetation models in a suite of transient glacial–interglacial simulations covering the last 21 000 yr. A series of sensitivity experiments investigated three key mechanisms (local summer insolation and ice sheet evolution, vegetation–albedo–precipitation feedback, and CO2 increase via radiative forcing and fertilization) that control the climate–vegetation history over North Africa during the last glacial termination. The simulations showed that neither orbital forcing nor the remote forcing from the retreating ice sheets alone was able to trigger the rapid formation of the AHP. Only both forcing factors together can effectively lead to the formation of the AHP. The vegetation–albedo–precipitation feedback enhances the intensity of the monsoon and further accelerates the onset of the AHP. The experiments indicate that orbital forcing and vegetation–albedo–precipitation feedback alone are insufficient to trigger the rapid onset of the AHP. The sensitivity experiments further show that the increasing radiative forcing from rising CO2 concentrations had no significant impact on the temporal evolution of the African monsoon during the last deglaciation. However, the fertilization effect of CO2 is important for the terrestrial carbon storage. The modeling results are discussed and compared with paleoproxy records of the African monsoon system. It is concluded that the model results presented here do not lend support to the notion that simple insolation thresholds govern the abrupt transitions of North African vegetation during the early to middle Holocene.
Buoyancy and Wind-Driven Convection at Mixed Layer Density Fronts
Authors: Taylor John R. , Ferrari Raffaele 
Published: January 2010

Abstract
In this study, the influence of a geostrophically balanced horizontal density gradient on turbulent convection in the ocean is examined using numerical simulations and a theoretical scaling analysis. Starting with uniform horizontal and vertical buoyancy gradients, convection is driven by imposing a heat loss or a destabilizing wind stress at the upper boundary, and a turbulent layer soon develops. For weak lateral fronts, turbulent convection results in a nearly homogeneous mixed layer (ML) whose depth grows in time. For strong fronts, a turbulent layer develops, but this layer is not an ML in the traditional sense because it is characterized by persistent horizontal and vertical gradients in density. The turbulent layer is, however, nearly homogeneous in potential vorticity (PV), with a value near zero. Using the PV budget, a scaling for the depth of the turbulent low PV layer and its time dependence is derived that compares well with numerical simulations. Two dynamical regimes are identified. In a convective layer near the surface, turbulence is generated by the buoyancy loss at the surface; below this layer, turbulence is generated by a symmetric instability of the lateral density gradient. This work extends classical scalings for the depth of turbulent boundary layers to account for the ubiquitous presence of lateral density gradients in the ocean. The new results indicate that a lateral density gradient, in addition to the surface forcing, can affect the stratification and the rate of growth of the surface boundary layer.
Oceanic Heat Content Variability in the Eastern Pacific Ocean for Hurricane Intensity Forecasting
Authors: Shay Lynn K. , Brewster Jodi K. 
Published: January 2010

Abstract
Recent evidence supports the premise that the subsurface ocean structure plays an important role in modulating air–sea fluxes during hurricane passage, which in turn, affects intensity change. Given the generally sparse in situ data, it has been difficult to provide region-to-basin-wide estimates of isotherm depths and upper-ocean heat content (OHC). In this broader context, satellite-derived sea surface height anomalies (SSHAs) from multiple platforms carrying radar altimeters are blended, objectively analyzed, and combined with a hurricane-season climatology to estimate isotherm depths and OHC within the context of a reduced gravity model at 0.25° spatial intervals in the eastern Pacific Ocean where tropical cyclone intensity change occurs.
Measurements from the Eastern Pacific Investigation of Climate in 2001, long-term tropical ocean atmosphere mooring network, and volunteer observing ship deploying expendable bathythermograph (XBT) profilers are used to carefully evaluate satellite-based measurements of upper-ocean variability. Regression statistics reveal small biases with slopes of 0.8–0.9 between the subsurface measurements compared with isotherm depths (20° and 26°C), and OHC fields derived from objectively analyzed SSHA field. Root-mean-square differences in OHC range between 10 and 15 kJ cm−2 or roughly 10%–15% of the mean signals. Similar values are found for isotherm depth differences between in situ and inferred satellite-derived values. Blended daily values are used in the Statistical Hurricane Intensity Prediction Scheme (SHIPS) forecasts as are OHC estimates for the Atlantic Ocean basin. An equivalent OHC variable is introduced that incorporates the strength of the thermocline at the base of the oceanic mixed layer using a climatological stratification parameter  /No, which seems better correlated to hurricane intensity change than just anomalies as observed in Hurricane Juliette in 2001.