Genesis of Easterly Waves over the Tropical Eastern Pacific and the Intra-Americas Sea

2021 ◽  
Author(s):  
Victor M. Torres ◽  
Chris D. Thorncroft ◽  
Nicholas M. J. Hall
Keyword(s):  
West Africa ◽  
Propagation Speed ◽  
Finite Amplitude ◽  
Equation Model ◽  
Eastern Pacific ◽  
Tropical Eastern Pacific ◽  
Transient Heating ◽  
Easterly Waves ◽  
The Mean

AbstractThis paper explores a new mechanism for in situ genesis of Easterly Waves (EWs) over the tropical Eastern Pacific (EPAC). Using an idealized primitive equation model, it is shown that EWs can be triggered by finite-amplitude transient heating close to the mid-level jet at about 15°N over the EPAC and Intra Americas Seas region. The atmospheric response to heating initiates EWs downstream showing an EW structure within 4 days, with a wavelength and propagation speed of about 2000 km and 4.6 ms- 1, respectively; resembling EWs described in the literature. The most sensitive location for EW initiation from finite amplitude transient heating is located over the northern part of South America and extending to the EPAC. The closer the heating is to the jet, the bigger the response. A stratiform heating profile is the most efficient at triggering EPAC EWs. Comparisons of simulated EWs over the EPAC and West Africa reveal similar structures but with a shorter wavelength and much weaker amplitudes over the EPAC. EPAC EWs are dominated by horizontal tilts against the shear on the equatorial side of the jet consistent with barotropic growth with weaker low-level amplitudes compared to those seen over West Africa. These differences arise due to differences in the mean state EPAC having a shorter and weaker mid-level jet with less baroclinicity.

scholarly journals Three-Dimensional Structure and Dynamics of African Easterly Waves. Part I: Observations

2006 ◽  
Vol 63 (9) ◽  
pp. 2212-2230 ◽  
Author(s):  
George N. Kiladis ◽  
Chris D. Thorncroft ◽  
Nicholas M. J. Hall
Keyword(s):  
West Africa ◽  
Three Dimensional ◽  
Companion Paper ◽  
Radiosonde Data ◽  
Dimensional Structure ◽  
African Easterly Waves ◽  
Three Dimensional Structure ◽  
Easterly Waves ◽  
The Mean ◽  
The Waves

Abstract The mean structure of African easterly waves (AEWs) over West Africa and the adjacent Atlantic is isolated by projecting dynamical fields from reanalysis and radiosonde data onto space–time-filtered satellite-derived outgoing longwave radiation. These results are compared with previous studies and an idealized modeling study in a companion paper, which provides evidence that the waves bear a close structural resemblance to the fastest-growing linear normal mode of the summertime basic-state flow over Africa. There is a significant evolution in the three-dimensional structure of AEWs as they propagate along 10°N across West Africa. At this latitude, convection occurs in northerly flow to the east of the Greenwich meridian, then shifts into the wave trough, and finally into southerly flow as the waves propagate offshore into the Atlantic ITCZ. In contrast, to the north of the African easterly jet along 15°N convection remains in southerly flow throughout the waves’ trajectory. Along 10°N over West Africa, the location of convection is consistent with the adiabatic dynamical forcing implied by the advection of perturbation vorticity by the mean thermal wind in the zonal direction, as in the companion paper. Offshore, and along 15°N, the relationship between the convection and dynamics is more complex, and not as easily explained in terms of dynamical forcing alone.

Novel Formulation Development and Evaluation of Nanoparticles Based in Situ Gelling System for The Ophthalmic Delivery of Ciprofloxacin Hydrochloride

2015 ◽  
Vol 5 (4) ◽  
Author(s):  
Kranti Singh ◽  
Surajpal Verma ◽  
Shyam Prasad ◽  
Indu Bala
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Drug Loading ◽  
In Vitro Release ◽  
Formulation Development ◽  
Ciprofloxacin Hydrochloride ◽  
Potential Value ◽  
The Mean ◽  
In Situ Gelling

Ciprofloxacin hydrochloride loaded Eudragit RS100 nanoparticles were prepared by using w/o/w emulsification (multiple emulsification) solvent evaporation followed by drying of nanoparticles at 50°C. The nanoparticles were further incorporated into the pH-triggered in situ gel forming system which was prepared using Carbopol 940 in combination with HPMC as viscosifying agent. The developed nanoparticles was evaluated for particle size, zeta potential value and loading efficiency; nanoparticle incorporated in situ gelling system was evaluated for pH, clarity, gelling strength, rheological studies, in-vitro release studies and ex-vivo precorneal permeation studies. The nanopaticle showed the mean particle size varying between 263.5nm - 325.9 nm with the mean zeta potential value of -5.91 mV to -8.13 mV and drug loading capacity varied individually between 72.50% to 98.70% w/w. The formulation was clear with no suspended particles, showed good gelling properties. The gelling was quick and remained for longer time period. The developed formulation was therapeutically efficacious, stable and non-irritant. It provided the sustained release of drug over a period of 8-10 hours.

scholarly journals Investigation of dominant traveling 10-day wave components using long-term MERRA-2 database

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Chunming Huang ◽  
Wei Li ◽  
Shaodong Zhang ◽  
Gang Chen ◽  
Kaiming Huang ◽  
...  
Keyword(s):  
Flow Instability ◽  
Transmission Condition ◽  
Wave Number ◽  
Mean Flow ◽  
Excited Wave ◽  
Propagating Waves ◽  
Zonal Wave Number ◽  
The Mean

AbstractThe eastward- and westward-traveling 10-day waves with zonal wavenumbers up to 6 from surface to the middle mesosphere during the recent 12 years from 2007 to 2018 are deduced from MERRA-2 data. On the basis of climatology study, the westward-propagating wave with zonal wave number 1 (W1) and eastward-propagating waves with zonal wave numbers 1 (E1) and 2 (E2) are identified as the dominant traveling ones. They are all active at mid- and high-latitudes above the troposphere and display notable month-to-month variations. The W1 and E2 waves are strong in the NH from December to March and in the SH from June to October, respectively, while the E1 wave is active in the SH from August to October and also in the NH from December to February. Further case study on E1 and E2 waves shows that their latitude–altitude structures are dependent on the transmission condition of the background atmosphere. The presence of these two waves in the stratosphere and mesosphere might have originated from the downward-propagating wave excited in the mesosphere by the mean flow instability, the upward-propagating wave from the troposphere, and/or in situ excited wave in the stratosphere. The two eastward waves can exert strong zonal forcing on the mean flow in the stratosphere and mesosphere in specific periods. Compared with E2 wave, the dramatic forcing from the E1 waves is located in the poleward regions.

Study of transient heating using an in situ combustion system

2017 ◽  
Vol 114 ◽  
pp. 685-692
Author(s):  
Fabián E. Cano Ardila ◽  
Andrés A. Amell Arrieta
Keyword(s):  
Combustion System ◽  
Transient Heating ◽  
In Situ Combustion

Estimating Global Ocean Heat Content Changes in the Upper 1800 m since 1950 and the Influence of Climatology Choice*

2014 ◽  
Vol 27 (5) ◽  
pp. 1945-1957 ◽  
Author(s):  
John M. Lyman ◽  
Gregory C. Johnson
Keyword(s):  
Heat Content ◽  
Ocean Heat Content ◽  
Global Ocean ◽  
Ocean Temperature ◽  
Vertical Separation ◽  
Ocean Heat Uptake ◽  
Expendable Bathythermograph ◽  
Heat Uptake ◽  
The Mean

Abstract Ocean heat content anomalies are analyzed from 1950 to 2011 in five distinct depth layers (0–100, 100–300, 300–700, 700–900, and 900–1800 m). These layers correspond to historic increases in common maximum sampling depths of ocean temperature measurements with time, as different instruments—mechanical bathythermograph (MBT), shallow expendable bathythermograph (XBT), deep XBT, early sometimes shallower Argo profiling floats, and recent Argo floats capable of worldwide sampling to 2000 m—have come into widespread use. This vertical separation of maps allows computation of annual ocean heat content anomalies and their sampling uncertainties back to 1950 while taking account of in situ sampling advances and changing sampling patterns. The 0–100-m layer is measured over 50% of the globe annually starting in 1956, the 100–300-m layer starting in 1967, the 300–700-m layer starting in 1983, and the deepest two layers considered here starting in 2003 and 2004, during the implementation of Argo. Furthermore, global ocean heat uptake estimates since 1950 depend strongly on assumptions made concerning changes in undersampled or unsampled ocean regions. If unsampled areas are assumed to have zero anomalies and are included in the global integrals, the choice of climatological reference from which anomalies are estimated can strongly influence the global integral values and their trend: the sparser the sampling and the bigger the mean difference between climatological and actual values, the larger the influence.

Chemical characteristics and in situ ruminal parameters of barley for cattle: Comparison of the malting cultivar AC Metcalfe and five feed cultivars

2008 ◽  
Vol 88 (4) ◽  
pp. 711-719 ◽  
Author(s):  
Kenton J Hart ◽  
Brian G Rossnagel ◽  
Peiqiang Yu
Keyword(s):  
Nutritive Value ◽  
Degradation Kinetics ◽  
Starch Degradation ◽  
Barley Cultivars ◽  
Degradation Rates ◽  
Key Words Barley ◽  
In Situ Degradation ◽  
The Mean ◽  
Pass Through

The objective of this study was to compare the most widely grown barley cultivar in Canada, AC Metcalfe, a malting type barley, with five feed cultivars. Barley cultivars were grown at one location during 3 consecutive years and barley samples were milled to pass through a 1-mm screen and analysed to determine nutritive value. Additional samples were passed through a roller mill with a gap set at 1.12 mm and incubated ruminally for 0, 2, 4, 8, 12, 24, and 48 h in 3 dry Holstein cows fitted with rumen cannulae. The rate and extent of rumen digestion were estimated. AC Metcalfe had a higher (P < 0.001) concentration of NDF, and lower (P < 0.05) concentrations of non structural carbohydrates, starch, ADF, total digestible nutrients, and fermentable cell wall carbohydrates compared with the mean of the feed cultivars. The malting cultivar had a higher (P < 0.001) soluble DM fraction, lower (P < 0.05) CP and starch degradation rates, and a lower (P < 0.001) ruminally degradable starch concentration compared with the mean of the five feed cultivars. The results demonstrate that there are only small differences in terms of chemical composition and in situ degradation kinetics between the malting cultivar AC Metcalfe and the five feed cultivars of barley reported here. Key words: Barley, energy, protein, ruminants

Oxidation Behaviors of TiB2-TiCX and TiB2-TiCX/15SiC Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 179-183 ◽  
Author(s):  
De Gui Zhu ◽  
Hong Liang Sun ◽  
Yu Shu Wang ◽  
Liang Hui Wang
Keyword(s):  
Oxidation Resistance ◽  
Effective Temperature ◽  
Hot Isostatic Pressing ◽  
Ceramic Composites ◽  
Optical Micrograph ◽  
Different Temperatures ◽  
The Mean ◽  
Mean Time ◽  
Oxidation Behaviors

Fully dense samples of TiB2-TiCX and TiB2-TiCX/15SiC ceramic composites were fabricated by in-situ synthesis under hot isostatic pressing from TiH2, B4C and SiC powders. Their oxidized behaviors at different temperatures were tested. Optical micrograph studies and thermo-gravimetric analyses show that the highest effective temperature of oxidation resistance is 700°C for TiB2-TiCX, and 1100°C for TiB2-TiCX/15SiC. The weight gain of TiB2-TiCX/15SiC below 1100°C is quite low, and it rises up suddenly when the temperature reaches 1200°C. Thus, the highest effective temperature of oxidation resistance is 1100°C for TiB2-TiCX/15SiC. The oxidation dynamic curves of TiB2-TiCX/15SiC ceramics accord with the parabola’s law. The activation energy of TiB2-TiCx/15SiC (189.87kJ.mol-1) is higher than that of TiB2-TiCx (96.44kJ.mol-1). In the oxidation process of TiB2-TiCx/15SiC, TiB2 reacts with oxygen and generates TiO2 and B2O3 at first. A layer of whole homogeneous oxide film cannot be formed, in the mean time, the oxidation of TiC begins. When temperature goes up to 1000°C, TiC phase is totally oxidized. SiC is oxidized to SiO2 at about 900°C, Meanwhile, TiO2 forms denser film than B2O3, which grows and covers the surface of the material, and gives better property of oxidation resistance.

Relationship between the gas production profiles of mixtures of hay and maize and the patterns of rumen fermentation observed in sheep fed those mixtures

1998 ◽  
Vol 1998 ◽  
pp. 63-63
Author(s):  
C. Rymer ◽  
D.I. Givens
Keyword(s):  
Growth Rate ◽  
Feed Intake ◽  
Rumen Fermentation ◽  
Gas Production ◽  
Post Feeding ◽  
Molar Proportion ◽  
Rumen Ph ◽  
The Mean

The gas production (GP) technique has been developed to assess dynamics of ruminant digestion. Relationships have been observed between a feed's GP profile and in vivo parameters such as digestibility (Khazaal et al., 1993), feed intake and growth rate (Blümmel and Ørskov, 1993), and in situ degradability (Sileshi et al., 1997). However, there are few studies which relate GP data to the in vivo pattern of rumen fermentation (in terms of the rate of pH decline 2 h post-feeding and the mean rumen pH, concentration of total VFA and molar proportion of individual VFA). The object of this experiment was to determine whether such a relationship existed between a feed's GP profile and the pattern of rumen fermentation observed in animals fed that feed.

Sign in / Sign up

Export Citation Format

Share Document