bluuebunny/crossref_metadata_2025 huggingface dataset:
Initial results from SKiYMET meteor radar at Thumba (8.5°N, 77°E): 1. Comparison of wind measurements with MF spaced antenna radar system
Authors: Kumar Karanam Kishore , Ramkumar Geetha , Shelbi S. T.
Published: December 2007

In the present communication, initial results from the allSKy interferometric METeor (SKiYMET) radar installed at Thumba (8.5°N, 77°E) are presented. The meteor radar system provides hourly zonal and meridional winds in the mesosphere lower thermosphere (MLT) region. The meteor radar measured zonal and meridional winds are compared with nearby MF radar at Tirunalveli (8.7°N, 77.8°E). The present study provided an opportunity to compare the winds measured by the two different techniques, namely, interferometry and spaced antenna drift methods. Simultaneous wind measurements for a total number of 273 days during September 2004 to May 2005 are compared. The comparison showed a very good agreement between these two techniques in the height region 82–90 km and poor agreement above this height region. In general, the zonal winds compare very well as compared to the meridional winds. The observed discrepancies in the wind comparison above 90 km are discussed in the light of existing limitations of both the radars. The detailed analysis revealed the consistency of the measured winds by both the techniques. However, the discrepancies are observed at higher altitudes and are attributed to the contamination of MF radar neutral wind measurements with Equatorial Electro Jet (EEJ) induced inospheric drifts rather than the limitations of the spaced antenna technique. The comparison of diurnal variation of zonal winds above 90 km measured by both the radars is in reasonably good agreement in the absence of EEJ (during local nighttime). It is also been noted that the difference in the zonal wind measurements by both the radars is directly related to the strength of EEJ, which is a noteworthy result from the present study.
Initial results from SKiYMET meteor radar at Thumba (8.5°N, 77°E): 2. Gravity wave observations in the MLT region
Authors: Kumar Karanam Kishore , Antonita T. Maria , Shelbi S. T.
Published: December 2007

In the present communication, allSKy interferometric METeor (SKiYMET) radar observations of gravity wave activity in the mesosphere lower thermosphere (MLT) region over Thumba (8.5°N, 77°E) are presented. The present meteor radar system provides hourly zonal and meridional winds in the MLT region, which can be readily used for studying the tides, planetary waves, gravity waves of periods 2–6 hours, and other long period oscillations in this region. However, these hourly winds are not sufficient for studying short period gravity waves having periods less than an hour, which demand high temporal resolution measurements. Even though the winds are estimated on an hourly basis, information such as zenith angle, azimuth angle, and radial velocity of each detected meteor are archived. Using these details of the meteor, an algorithm is developed to obtain the 15‐min temporal resolution wind data. The output of the algorithm is compared with hourly wind data, and it showed a good agreement during the high meteor shower periods. Most of the times high meteor counts are observed during late night and early morning hours (local) over this latitude. Continuous wind measurements during the high meteor shower periods are used for studying the gravity wave activity in the MLT region. As the wave activity is intermittent and nonstationary, wavelet analysis has been used for delineating the wave features. The results showed the upward propagating intermittent gravity waves with periods 1–2 and 4–5 hours. The new aspect of the present communication is the usage of meteor radar for gravity wave studies for the first time over this latitude and studying their seasonal variability.
Statistical modeling of storm level Kp occurrences: Solar cycle modulation
Authors: Love J. J. , Remick K. J. , Perkins D. M.
Published: December 2007

We consider the nonstationary, statistical modeling of the occurrence in time of large Kp geomagnetic storms over the course of multiple solar cycles. Previous work showed that wait times between storms can be represented by an exponential density function, consistent with the realization of a Poisson process. Here we also assume a Poisson process, but to account for solar cycle modulation of storm likelihood, we assume an occurrence rate given by a parametric constant plus a simple sinusoidal function of time. Parameter estimation is accomplished using maximum likelihood, yielding good fits to the Kp data. We find that the relative phase between storms and sunspots depends on storm size. We quantify previous observations that small storms tend to occur during the declining phase of the solar cycle, while large storms tend to occur very close to solar maximum. We predict average wait time between storms and the storm occurrence rate up through the year 2018.
Interactions between tectonics, erosion, and sedimentation during the recent evolution of the Alpine orogen: Analogue modeling insights
Authors: Bonnet Cécile , Malavieille Jacques , Mosar Jon
Published: December 2007

On the basis of a section across the northwestern Alpine wedge and foreland basin, analogue modeling is used to investigate the impact of surface processes on the orogenic evolution. The basis model takes into account both structural and lithological heritages of the wedge. During shortening, erosion and sedimentation are performed to maintain a critical wedge. Frontal accretion leads to the development of a foreland thrust belt; underplating leads to the formation of an antiformal nappe stack in the internal zones. Important volumes of analogue materials are eroded out of the geological record, which in the case of the Alps suggests that the original lengths and volumes may be underestimated. The foreland basin evolves differently depending on the amounts of erosion/sedimentation. Its evolution and internal structuring is governed by the wedge mechanics, thought to be the main controlling mechanism in the development of the Molasse basin in a feedback interaction with surface processes.
Thermochronologic evidence for the exhumational history of the Alpi Apuane metamorphic core complex, northern Apennines, Italy
Authors: Fellin Maria Giuditta , Reiners Peter W. , Brandon Mark T. , Wüthrich Eliane , Balestrieri Maria Laura , Molli Giancarlo
Published: December 2007

The Apennine Range is a young convergent orogen that formed over a retreating subduction zone. The Alpi Apuane massif in the northern Apennines exposes synorogenic metamorphic rocks, and provides information about exhumation processes associated with accretion and retreat. (U‐Th)/He and fission‐track ages on zircon and apatite are used to resolve exhumational histories for the Apuane metamorphic rocks and the structurally overlying, very low grade Macigno Formation. Stratigraphic, metamorphic, and thermochronologic data indicate that the Apuane rocks were structurally buried to 15–30 km and ∼400°C at about 20 Ma. Exhumation to 240°C and 9 km depth (below sea level) occurred at 10–13 Ma. By 5 Ma the Apuane rocks were exhumed to 70°C and ∼2 km. The Macigno and associated Tuscan nappe were also structurally buried and the Macigno reached its maximum depth of 7 km at ∼15 to 20 Ma. Stratigraphic evidence indicates that the Apennine wedge was submarine at this time. Thus we infer that initial exhumation of the Apuane was coeval with tectonic thickening higher in the wedge, as indicated by synchronous structural burial of the Tuscan nappe. From 6 to 4 Ma, thinning at shallow depth is indicated by continued differential exhumation between the Apuane and the Tuscan nappe at high rates. After 4 Ma, differential exhumation ceased and the Apuane and the Tuscan nappe were exhumed at similar rates (∼0.8 km/Ma), which we attribute to erosion of the Apennines, following their emergence above sea level.
A parameterization of flow separation over subaqueous dunes
Authors: Paarlberg Andries J. , Dohmen‐Janssen C. Marjolein , Hulscher Suzanne J. M. H. , Termes Paul
Published: December 2007

Flow separation plays a key role in the development of dunes, and modeling the complicated flow behavior inside the flow separation zone requires much computational effort. To make a first step toward modeling dune development at reasonable temporal and spatial scales, a parameterization of the shape of the flow separation zone over two‐dimensional dunes is proposed herein, in order to avoid modeling the complex flow inside the flow separation zone. Flow separation behind dunes, with an angle‐of‐repose slip face, is characterized by a large circulating leeside eddy, where a separation streamline forms the upper boundary of the recirculating eddy. Experimental data of turbulent flow over two‐dimensional subaqueous bed forms are used to parameterize this separation streamline. The bed forms have various heights and height to length ratios, and a wide range of flow conditions is analyzed. This paper shows that the shape of the flow separation zone can be approximated by a third‐order polynomial as a function of the distance away from the flow separation point. The coefficients of the polynomial can be estimated, independent of flow conditions, on the basis of bed form shape at the flow separation point and a constant angle of the separation streamline at the flow reattachment point.
Temperature retrieval from stratospheric O3 and NO3 GOMOS data
Authors: Marchand M. , Bekki S. , Lefèvre F. , Hauchecorne A.
Published: December 2007

The chemistry of some species is strongly dependent on temperature. The typical example is the nighttime NO3 chemistry. We use a simple steady state relationship for NO3 to derive temperature from measurements of O3 and NO3 by the satellite GOMOS (Global Ozone Monitoring by Occultation of Stars) instrument. GOMOS‐retrieved temperatures are validated against ECMWF (European Centre for Medium range Weather Forecast) temperatures. The temperature between 30 and 40 km can be retrieved with a bias of 3°K and a precision of about 3°K. The small bias can easily be removed by slightly adjusting the temperature‐dependency of the NO2 + O3 reaction in the steady state relationship. The results demonstrate that measurements of chemical species contain useful information on the temperature that can be extracted when the temperature‐dependent chemistry is known accurately. This temperature‐dependency of chemical systems could in the long term be exploited in weather data assimilation system.
Mantle flow and melting underneath oblique and ultraslow mid‐ocean ridges
Authors: Montési Laurent G. J. , Behn Mark D.
Published: December 2007

Mid‐ocean ridge morphology correlates strongly with spreading rate. As the spreading rate decreases, conductive cooling becomes more important in controlling ridge thermal structure and the axial lithosphere thickens. At ultraslow spreading rates, the ridge axis becomes sufficiently cold that peridotite blocks are emplaced directly at the seafloor and volcanism is limited to localized volcanic centers widely spaced along the ridge axis. Some slow‐spreading ridges adopt an ultraslow morphology when their axis is oblique to the spreading direction. We present an analytical solution for mantle flow beneath an oblique ridge and demonstrate that the thermal structure and crustal thickness are controlled by the effective spreading rate (product of the plate separation velocity and the cosine of obliquity). A global compilation of oblique ridges reveals that ultraslow morphology corresponds to effective half rates less than 6.5 mm/yr, resulting in lithosphere that is thicker than ∼30 km. We conclude that the transition from slow to ultraslow spreading is not related to a change of melt productivity but rather in the efficiency of vertical melt extraction.
Flow velocity and the hydrologic behavior of streams during baseflow
Authors: Wondzell Steven M. , Gooseff Michael N. , McGlynn Brian L.
Published: December 2007

Diel variations in stream discharge have long been recognized, but are relatively little studied. Here we demonstrate that these diel fluctuations can be used to investigate both streamflow generation and network routing. We treat evapo‐transpiration (ET) as a distributed impulse function in an advection model and analyze the effect of ET on diel fluctuations in discharge. We show that when flow velocity is high during high baseflow, discharge fluctuations tend to be in phase and constructive interference reinforces ET‐generated signals resulting in strong diel fluctuations measured at a gauging station at the mouth of the watershed. As flow velocity slows with baseflow recession, ET‐generated signals are increasingly out of phase so that fluctuations in discharge are masked by destructive interference. These results demonstrate that naturally produced fluctuations in discharge constitute discrete impulse functions that can be used to analyze eco‐hydrologic behavior of whole‐watersheds during baseflow periods.
Titan airglow spectra from Cassini Ultraviolet Imaging Spectrograph (UVIS): EUV analysis
Authors: Ajello Joseph M. , Stevens Michael H. , Stewart Ian , Larsen Kristopher , Esposito Larry , Colwell Josh , McClintock William , Holsclaw Greg , Gustin Jacques , Pryor Wayne
Published: December 2007

We present the first UV airglow observations of Titan's atmosphere by the Ultraviolet Imaging Spectrograph (UVIS) on Cassini. Using one spectral channel in the EUV from 561–1182 Å and one in the FUV from 1115–1913 Å, UVIS observed the disk on 13 December, 2004 at low solar activity. The EUV spectrum consists of three band systems of N2 (b 1∏u, b′ 1∑u+, c4′ 1∑u+ → X 1∑g+), while the FUV spectrum consists of one (a 1∏g → X 1∑g+). Both the EUV and FUV spectra contain many N I and N II multiplets that are produced primarily by photodissociative ionization. Spectral intensities of the N2 c4′ 1∑u+(v′ = 0) → X 1∑g+(v″ = 0–2) progression from 950–1010 Å are resolved for the first time. The UVIS observations reveal that the c4′ 1∑u+(0) → X 1∑g+ (0) vibrational band near 958 Å is weak and undetectable, and that N I multiplets near 953.2 and 964.5 Å are present instead. Magnetospheric particle excitation may be weak or sporadic, since the nightside EUV spectrum on this orbit shows no observable nitrogen emission features and only H Ly‐β.
Magnetic field gradients from the ST‐5 constellation: Improving magnetic and thermal models of the lithosphere
Authors: Purucker M. , Sabaka T. , Le G. , Slavin J. A. , Strangeway R. J. , Busby C.
Published: December 2007

We report the development of a new technique (magnetic gradiometry) for satellite‐based remote sensing of the lithosphere. The measurements reported here represent the first systematic measurements of lithospheric magnetic field gradients, and were collected from a spinning spacecraft. The three‐satellite ST‐5 mission collected vector magnetic field observations at 300–800+ km altitudes over mid and high‐northern latitudes in 2006. Away from the auroral oval, and over the continents, the gradients of the low altitude (<400 km) total anomaly field are dominated by lithospheric magnetic fields. Using a seismic starting model, and magnetic field observations from ST‐5 and other recent satellite missions, we demonstrate how these techniques can be used to improve our knowledge of the processes involved in the thickened crust of the Colorado Plateau and the Sierra Madre Occidental.
Relationship between temperature and precipitable water changes over tropical oceans
Authors: Mears Carl A. , Santer Benjamin D. , Wentz Frank J. , Taylor Karl E. , Wehner Michael F.
Published: December 2007

We use observations, climate models and reanalysis output to examine the relationship between changes in temperature and changes in precipitable water. In climate models these variables are highly correlated over the tropical oceans, with a similar scaling ratio for interannual and decadal time scales. This result is consistent with the most recently developed satellite datasets. In contrast, scaling rations based either on an earlier version of the satellite measurements or reanalysis show scaling ratios that are inconsistent with models, and are dependent on time scale. These results demonstrate that climate model output is useful for evaluating differences between divergent observational datasets.
Ultra‐relativistic acceleration of electrons in planetary magnetospheres
Authors: Summers Danny , Omura Yoshiharu
Published: December 2007

We present a new particle acceleration mechanism called ultra‐relativistic acceleration (URA). URA comprises electron energization due to a special form of nonlinear phase trapping by a coherent whistler‐mode wave for electrons with an initial Lorentz factor γ0 satisfying γ0 > ΩEQ/ω; ω is the wave frequency and ΩEQ is the electron cyclotron frequency at the equator of an assumed dipole magnetic field. Radiation belt electrons that encounter a combination of relativistic turning acceleration (RTA) followed by multiple URA interactions can undergo significant energy increase. Under ideal conditions, at Earth (L = 4) several‐hundred‐keV electrons can be energized to several MeV within a few seconds, while at Jupiter (L = 8), several‐hundred‐keV electrons can be energized by tens of MeV in a few tens of seconds. URA can play a prominent role in generating the several‐MeV electrons observed in Earth's outer zone and the tens‐of‐MeV electrons observed in Jupiter's magnetosphere. More generally, we expect URA to be an effective electron energization mechanism in cosmic plasma environments that contain a magnetic mirror geometry and electromagnetic whistler‐mode emissions.
Imaging thermal stratigraphy in freshwater lakes using georadar
Authors: Bradford John H. , Johnson Cody R. , Brosten Troy , McNamara James P. , Gooseff Michael N.
Published: December 2007

Thermal stratification exerts significant control over biogeochemical processing in freshwater lakes. Thus, the temporal and spatial distribution of the thermal structure is an important component in understanding lake ecosystems. We present the first reported observations of lake thermal stratification from surface based georadar measurements acquired over two small freshwater lakes. This method is very useful because it can provide rapid acquisition of 2D or 3D lotic stratification.
Seasonal and solar cycle variability in F‐region vertical plasma drifts over Ouagadougou
Authors: Oyekola O. S. , Ojo Akin , Akinrimisi J. , dePaula E. R.
Published: December 2007

F‐region vertical drifts were made using ionosonde for the Africa equatorial station Ouagadougou (12°N, 1.5°W; 5.9°N dip) from 3 a of data during January 1987 to December 1989 for solar cycle minimum, medium, and maximum conditions (F10.7 = 85, 141, and 214, respectively) under geomagnetic quiet‐time. The variations are found to be dominated by the characteristics morning peak and evening prereversal enhancement (PRE) velocities. Seasonal and solar cycle effects are prominent near the dusk sector with an increase of PRE from solar minimum to maximum. The average equinoctial evening prereversal enhancement increases by almost a factor of three from low to high flux. On the average, the values of daytime and nighttime ionosonde‐derived vertical drifts are smaller by about a factor of four than the magnitude often mentioned in publication for equatorial regions from other experimental techniques. In addition, the morning peak velocities maximize between about 0830–0930 LT with typical values of 12–18 m/s. In contrast, PRE have largest amplitude between about 1700–2200 LT with typical values of 5–10 m/s. The morning reversal times do not reveal any dependence on season and solar cycle; but the most probable time of occurrence is around 0530 LT. The evening reversal times are in excellent agreements for the three levels of solar activity periods apart from June solstice that exhibit considerable variations. The most likely time of occurrence is near 2000 LT. Of importance, the link between the onset / inhibition parameters of postsunset irregularities over Ouagadougou indicate anti‐correlations with solar variability.
Garnet yield strength at high pressures and implications for upper mantle and transition zone rheology
Authors: Kavner Abby
Published: December 2007

Garnet helps control the mechanical behavior of the Earth's crust, mantle, and transition zone. Here, measurements are presented suggesting that garnet, long considered to be a high‐viscosity phase, is actually weaker than the other dominant components in the transition zone. The mechanical behavior of garnet at high pressures was examined using radial diffraction techniques in the diamond anvil cell. The yield strength of grossular garnet was inferred from synchrotron X‐ray measurements of differential lattice strains. The differential stress was found to increase from 1.3 (±0.6) GPa at a hydrostatic pressure 5.8 (±1.1) GPa to 4.1 (±0.4) GPa at 15.7 (±1.0) GPa, where it was level to 19 GPa. The strength results are consistent with inferred strength values for majorite garnet from measurements in the diamond cell normal geometry, bolstering the idea that garnet‐structured materials may all have similar strengths. In this low‐temperature, high differential stress regime, garnet is shown to be significantly weaker than anhydrous ringwoodite and to have a strength similar to hydrous ringwoodite. This result suggests that the presence of water in the transition zone may not be required to explain a weak rheology, and therefore models of transition zone behavior built assuming that garnet is the high‐strength phase may need to be revised.
Applying a three‐dimensional velocity model, waveform cross correlation, and cluster analysis to locate southern California seismicity from 1981 to 2005
Authors: Lin Guoqing , Shearer Peter M. , Hauksson Egill
Published: December 2007

We compute high‐precision earthquake locations using southern California pick and waveform data from 1981 to 2005. Our latest results are significantly improved compared to our previous catalog by the following: (1) We locate events with respect to a new crustal P and S velocity model using three‐dimensional ray tracing, (2) we examine six more years of waveform data and compute cross‐correlation results for many more pairs than our last analysis, and (3) we compute locations within similar event clusters using a new method that applies a robust fitting method to obtain the best locations satisfying all the differential time constraints from the waveform cross correlation. These results build on the relocated catalogs of Hauksson and Shearer (2005) and Shearer et al. (2005) and provide additional insight regarding the fine‐scale fault structure in southern California and the relationship between the San Andreas Fault (SAF) and nearby seismicity. In particular, we present results for two regions in which the seismicity near the southern SAF seems to align on dipping faults.
Underthrusting‐accretion cycle: Work budget as revealed by the boundary element method
Authors: Del Castello Mario , Cooke Michele L.
Published: December 2007

Sandbox models of accretionary wedges have demonstrated that fault systems grow episodically via cycles of alternating wedge thickening, which is accommodated by slip along faults within the wedge (underthrusting), and wedge lengthening, which is accommodated by growth of new faults at the wedge toe (accretion). The transition between these two modes of deformation is controlled by the interplay of work against gravity, frictional heating, the work of deformation around faults, and the work of fault propagation and seismic/acoustic energy. Using numerical mechanical models based on the boundary element method, we have simulated the deformation observed in sandbox experiments, providing a mechanical analysis of the underthrusting/accretion transition. Our results show that the total work done by the contracting wedge increases during the underthrusting stage up to a critical value when the propagation of a new frontal thrust significantly reduces the work required for further deformation. The numerical models also predict the location of the maximum shear along the basal décollement during underthrusting as well as the energetically most viable position and vergence for the nucleation of a new thrust. These locations do not coincide, and the match of the energetically most favorable position with the experimental results suggests that the new thrust ramps develop first ahead and then link down and backward to the propagating basal décollement. The shear localization producing a new thrust ramp will occur where the energy spent by the deforming wedge is minimized due to an optimal combination of gravitational, frictional, internal, and propagation work terms.
Nonhydrostatic simulations of the regional circulation in the Monterey Bay area
Authors: Tseng Yu‐Heng , Breaker L. C.
Published: December 2007

The regional circulation in the vicinity of Monterey Bay is complex and highly variable. We use a one‐way coupled, nonhydrostatic version of the Dietrich Center for Air Sea Technology (DieCAST) ocean model to simulate the regional circulation. Seasonally varying local wind stress, topographic irregularities, coastal upwelling, and forcing from the open ocean are all important in this region. Satellite imagery often shows a cyclonic eddy inside the bay and an anticyclonic eddy outside the bay. The offshore anticyclonic eddy is also associated with a year‐round anticyclonic eddy over the Monterey Submarine Canyon (MSC). The offshore eddy is better organized during winter. It is found that the California Undercurrent (200–400 m) does not enter the bay itself but is diverted offshore past the entrance of the bay, presumably to reform farther north along the coast. The main branch flows northward contributing to the deep anticyclonic eddy located approximately 50 km offshore of Monterey Bay. The simulations show that vertical motion is greater during summer than winter, as expected. During spring upwelling, the deep waters often upwell along the walls of the canyon and then spread and mix with surrounding waters. The deep circulation enhances mixing significantly due to the topography. We further investigate the regional circulation by comparing it with the cases where the deep canyon was filled gradually. Vortex stretching over the canyon just beyond the entrance to Monterey Bay and along the adjacent continental slopes contributes to cyclonic circulation at deeper levels. Vertical sections of velocity along the axis of MSC indicate horizontal and vertical patterns of flow that are generally consistent with past observations on the circulation of Monterey Bay.
Global structure and long‐term variations of zonal mean temperature observed by TIMED/SABER
Authors: Xu Jiyao , Smith A. K. , Yuan W. , Liu H.‐L. , Wu Qian , Mlynczak M. G. , Russell J. M.
Published: December 2007

In this paper, we present a method of extracting zonal mean temperature and tides from TIMED/SABER satellite and discuss the features of the zonal mean temperature. The global temperature structure is presented, and the mean variations at each latitude and altitude are decomposed into semiannual (SAO), annual (AO), and quasi‐biennial (QBO) components. The SAO is strong in the tropical upper stratosphere, mesosphere, and lower thermosphere. The SAO phase (measured by the time of the maximum) is at the equinox at 85 km and at solstice at 75 km. The amplitude is large compared to the annual mean temperature structure, which leads to a mesospheric inversion layer (MIL) in the zonal mean temperature around the equator at equinox. The AO is most evident at middle latitudes and displays a clear hemispheric asymmetry at solstices. The QBO in temperature is strongest in the tropical lower stratosphere; its period there is 26.6 months. There are also weak QBO signals near the mesopause and throughout the middle atmosphere at midlatitudes. The analysis of longer‐term variations of the zonal mean temperature, probably affected by the solar cycle but also containing any other trends, indicates that in most regions, the zonal mean temperature decreases during the period of 5 years and is positively correlated with the solar radiation. These results use version 1.06 of the SABER temperature data, which have some known biases in the vicinity of the mesopause.
Solar occultation satellite data and derived meteorological products: Sampling issues and comparisons with Aura Microwave Limb Sounder
Authors: Manney Gloria L. , Daffer William H. , Zawodny Joseph M. , Bernath Peter F. , Hoppel Karl W. , Walker Kaley A. , Knosp Brian W. , Boone Chris , Remsberg Ellis E. , Santee Michelle L. , Harvey V. Lynn , Pawson Steven , Jackson David R. , Deaver Lance , McElroy C. Thomas , McLinden Chris A. , Drummond James R. , Pumphrey Hugh C. , Lambert Alyn , Schwartz Michael J. , Froidevaux Lucien , McLeod Sean , Takacs Lawrence L. , Suarez Max J. , Trepte Charles R. , Cuddy David C. , Livesey Nathaniel J. , Harwood Robert S. , Waters Joe W.
Published: December 2007

Derived Meteorological Products (DMPs, including potential temperature, potential vorticity (PV), equivalent latitude (EqL), horizontal winds and tropopause locations) from several meteorological analyses have been produced for the locations and times of measurements taken by several solar occultation instruments and the Aura Microwave Limb Sounder (MLS). MLS and solar occultation data are analyzed using DMPs to illustrate sampling issues that may affect interpretation and comparison of data sets with diverse sampling patterns and to provide guidance regarding the kinds of studies that benefit most from analyzing satellite data in relation to meteorological conditions using the DMPs. Using EqL or PV as a vortex‐centered coordinate does not alleviate all sampling problems, including those in studies using “vortex averages” of solar occultation data and in analyses of localized features (such as polar stratospheric clouds) and other fields that do not correlate well with PV. Using DMPs to view measurements with respect to their air mass characteristics is particularly valuable in studies of transport of long‐lived trace gases, polar processing in the winter lower stratosphere, and distributions and transport of O3 and other trace gases from the upper troposphere through the lower stratosphere. The comparisons shown here demonstrate good agreement between MLS and solar occultation data for O3, N2O, H2O, HNO3, and HCl; small biases are attributable to sampling effects or are consistent with detailed validation results presented elsewhere in this special section. The DMPs are valuable for many scientific studies and to facilitate validation of noncoincident measurements.
Role of moist energy advection in formulating anomalous Walker Circulation associated with El Niño
Authors: Ham Yoo‐Geun , Kug Jong‐Seong , Kang In‐Sik
Published: December 2007

The role of meridional moist energy advection in formulating anomalous Walker Circulation during El Niño events is investigated using observational data and linearized GCM. During the El Niño mature phase, the warm pool is extended to the central Pacific, so that the magnitudes of equatorial SST become uniform over the western‐central Pacific. In contrast to the uniform SST distribution over the western‐central Pacific, the maximum of equatorial convective activities are zonally displaced from the western to the central Pacific. That is in line with the fact that the strong anomalous descending motions are located over the western Pacific without local negative SST anomalies. It is demonstrated here that suppressed convection over the western Pacific is associated with cold‐dry moist energy advection due to low‐level equatorward winds. The meridional cold‐dry moist energy advection leads the vertical warm‐wet moist energy advection and adiabatic warming processes (descending motion) to balance the moist energy budget. It is shown that this meridional wind is a part of a cyclonic Rossby wave in response to the anomalous convection induced by El Niño SST. This mechanism, suggested here, is validated by using a linearized GCM. The model results show the downward branch of the anomalous Walker Circulation over the western Pacific is significantly reduced when the moist energy advection is not allowed.
Impact of data assimilation filtering methods on the mesosphere
Authors: Sankey David , Ren Shuzhan , Polavarapu Saroja , Rochon Yves J. , Nezlin Yulia , Beagley Stephen
Published: December 2007

Three‐dimensional data assimilation schemes typically produce analyses that are not in balance. This is evidenced by the generation of spurious high‐frequency waves during the first 2 d of forecasts which start from analyses. To remove these spurious waves, assimilation systems frequently filter analyses before using them in models. This work examines the behavior of various spurious wave filtering methods in the context of a model with a mesosphere. Since gravity waves comprise a significant portion of the mesospheric energy spectrum, it is necessary to retain naturally occurring high‐frequency waves while filtering spurious waves. The results show that filtering the full analysis state can remove many important high‐frequency oscillations from the mesosphere. On the other hand, filtering analysis increments preserves much more of the natural variability of the model. The incremental analysis updating scheme and the incremental digital filter, which are equivalent for linear models and identical coefficients, are shown to give very similar results in the context of a realistic nonlinear model. Results also show a nonlocal response to the insertion of analysis increments in the troposphere and stratosphere. The global mean temperature in the vicinity of the model lid and the diurnal tidal amplitudes are sensitive to the choice of filtering schemes because the filters reduce the amount of resolved waves available to propagate upward into mesosphere. This sensitivity of the mesosphere to the filtering of the lower atmosphere is exploited to choose an optimal filter for our system using measurements of the mesosphere.
Overview of the Atmospheric Brown Cloud East Asian Regional Experiment 2005 and a study of the aerosol direct radiative forcing in east Asia
Authors: Nakajima Teruyuki , Yoon Soon‐Chang , Ramanathan Veerabhadran , Shi Guang‐Yu , Takemura Toshihiko , Higurashi Akiko , Takamura Tamio , Aoki Kazuma , Sohn Byung‐Ju , Kim Sang‐Woo , Tsuruta Haruo , Sugimoto Nobuo , Shimizu Atsushi , Tanimoto Hiroshi , Sawa Yousuke , Lin Neng‐Huei , Lee Chung‐Te , Goto Daisuke , Schutgens Nick
Published: December 2007

This article introduces an international regional experiment, East Asian Regional Experiment 2005 (EAREX 2005), carried out in March–April 2005 in the east Asian region, as one of the first phase regional experiments under the UNEP Atmospheric Brown Cloud (ABC) project, and discusses some outstanding features of aerosol characteristics and its direct radiative forcing in the east Asian region, with some comparison with the results obtained in another ABC early phase regional experiment, ABC Maldives Monsoon Experiment (APMEX) conducted in the south Asian region. Time series of aerosol optical thickness (AOT), single scattering albedo (SSA), aerosol extinction cross section profile and CO concentration shows that air pollutants and mineral dust were transported every 5 to 7 days in the EAREX region to produce SSA values at wavelength of 700 nm from 0.86 to 0.96 and large clear‐sky shortwave forcing efficiency at 500 nm from 60 W m−2 to 90 W m−2, though there are some unexplained inconsistencies depending on the evaluation method. The simulated whole‐sky total forcing in the EAREX region is −1 to −2 W m−2 at TOA and −2 to −10 W m−2 at surface in March 2005 which is smaller in magnitude than in the APMEX region, mainly because of large cloud fraction in this region (0.70 at Gosan versus 0.51 at Hanimadhoo in the ISCCP total cloud fraction). We suggest there may be an underestimation of the forcing due to overestimation of the simulated cloudiness and aerosol scale height. On the other hand, the possible error in the simulated surface albedo may cause an overestimation of the magnitude of the forcing over the land area. We also propose simple formulae for shortwave radiative forcing to understand the role of aerosol parameters and surface condition to determine the aerosol forcing. Such simple formulae are useful to check the consistency among the observed quantities.
Physics of bodily tides in terrestrial planets and the appropriate scales of dynamical evolution
Authors: Efroimsky Michael , Lainey Valéry
Published: December 2007

Any model of tides is based on a specific hypothesis of how lagging depends on the tidal‐flexure frequency χ. For example, Gerstenkorn (1955), MacDonald (1964), and Kaula (1964) assumed constancy of the geometric lag angle δ, while Singer (1968) and Mignard (1979, 1980) asserted constancy of the time lag Δt. Thus each of these two models was based on a certain law of scaling of the geometric lag: the Gerstenkorn‐MacDonald‐Kaula theory implied that δ ∼ χ0, while the Singer‐Mignard theory postulated δ ∼ χ1. The actual dependence of the geometric lag on the frequency is more complicated and is determined by the rheology of the planet. Besides, each particular functional form of this dependence will unambiguously fix the appropriate form of the frequency dependence of the tidal quality factor, Q(χ). Since at present we know the shape of the function Q(χ), we can reverse our line of reasoning and single out the appropriate actual frequency dependence of the lag, δ(χ): as within the frequency range of our concern Q ∼ χα, α = 0.2–0.4, then δ ∼ χ−α. This dependence turns out to be different from those employed hitherto, and it entails considerable alterations in the timescales of the tide‐generated dynamical evolution. Phobos's fall on Mars is an example we consider.
Exhumation and uplift of the Shillong plateau and its influence on the eastern Himalayas: New constraints from apatite and zircon (U‐Th‐[Sm])/He and apatite fission track analyses
Authors: Biswas Subrata , Coutand Isabelle , Grujic Djordje , Hager Christian , Stöckli Daniel , Grasemann Bernhard
Published: December 2007

The Shillong plateau is the only raised topography in the foreland of the Himalayas. Located on the trajectory of the Indian Summer Monsoon (ISM), the plateau perturbs the regional distribution of precipitation. As such, the Shillong plateau‐eastern Himalaya‐ISM is a unique system to quantify the couplings between climate, tectonics, and erosion. A change in long‐term erosion rates along‐strike of the Bhutan Himalaya was recently attributed to a climatic modulation due to the uplift of the Shillong plateau. To test this interpretation, it is essential to constrain the timing and rate at which the plateau was uplifted and the amount of partitioning of the India‐Asia convergence into the plateau. We used apatite and zircon (U‐Th‐[Sm])/He and apatite fission track analyses to unravel the thermal histories of 13 basement samples collected along a N‐S transect across the central Shillong plateau. We find that (1) the exhumation of the plateau began at least 9–15 Ma ago, (2) its surface uplift was chronologically decoupled from its exhumation and started after ∼3–4 Ma at rates of 0.4–0.53 mm/a, (3) the long‐term horizontal shortening rate accommodated by the plateau is 0.65–2.3 mm/a, which represents only 10–15% of the India‐Asia convergence rate. The uplift of the Shillong plateau did not significantly modify the rock uplift rate in the Bhutan Himalaya, which is consistent with the hypothesis of climatic modulation of the Pliocene erosion, tectonic, and landscape evolution previously documented along this orogenic front.
Plate boundary forces are not enough: Second‐ and third‐order stress patterns highlighted in the World Stress Map database
Authors: Heidbach Oliver , Reinecker John , Tingay Mark , Müller Birgit , Sperner Blanka , Fuchs Karl , Wenzel Friedemann
Published: December 2007

The World Stress Map Project compiles a global database of contemporary tectonic stress information of the Earth's crust. Early releases of the World Stress Map Project demonstrated the existence of first‐order (plate‐scale) stress fields controlled by plate boundary forces and second‐order (regional) stress fields controlled by major intraplate stress sources such as mountain belts and zones of widespread glacial rebound. The 2005 release of the World Stress Map Project database provides, for some areas, high data density that enables us to investigate third‐order (local) stress field variations, and the forces controlling them such as active faults, local inclusions, detachment horizons, and density contrasts. These forces act as major controls on the stress field orientations when the magnitudes of the horizontal stresses are close to isotropic. We present and discuss examples for Venezuela, Australia, Romania, Brunei, western Europe, and southern Italy where a substantial increase of data records demonstrates some of the additional factors controlling regional and local stress patterns.
Testosterone protects rat hearts against ischaemic insults by enhancing the effects of α1‐adrenoceptor stimulation
Authors: Tsang S , Wu S , Liu J , Wong T M
Published: December 2007

Background and purpose:

Testosterone alleviates symptoms in patients with ischaemic heart disease. Androgen receptors are present in the heart, and testosterone upregulates gene expression of cardiac β1‐adrenoceptors. We hypothesize that testosterone may confer cardioprotection by interacting with adrenoceptors.

Experimental approach:

In isolated perfused hearts and ventricular myocytes from orchidectomized rats without or with testosterone (200 μg/100 g) replacement, we first determined the effect of ischaemia/reperfusion in the presence of noradrenaline (10−7 M). Then we determined the contribution of interactions between testosterone and α1‐ or β1‐adrenoceptors in cardiac injury/protection (infarct size, release of lactate dehydrogenase, viability of myocytes, recovery of contractile function and incidence of arrhythmias) upon ischaemia/reperfusion by pharmacological manipulation using selective adrenoceptor agonists (α1‐adrenoceptor agonist: phenylephrine 10−6 M; non‐selective β‐adrenoceptor agonist: isoprenaline 10−7 M) and antagonists (α1: prazosin or benoxathian 10−6 M; β1: CGP 20712A 5 × 10−7 M). We also determined the expression of α1and β1‐adrenoceptor in the hearts from rats with and without testosterone.

Key results:

Testosterone reduced injury induced by ischaemia/reperfusion and noradrenaline. This was achieved by enhancing the beneficial effect of α1‐adrenoceptor stimulation, which was greater than the deleterious effect of β1‐adrenoceptor stimulation (also enhanced by testosterone). The effects of testosterone were abolished or attenuated by blockade of androgen receptors. Testosterone also enhanced the expression of α1Aand β1‐adrenoceptor.

Conclusions and implications:

Testosterone conferred cardioprotection by upregulating the cardiac α1‐adrenoceptor and enhancing the effects of stimulation of this adrenoceptor. The effect of testosterone was at least partly mediated by androgen receptors.

British Journal of Pharmacology(2008)153, 693–709; doi:10.1038/sj.bjp.0707624; published online 24 December 2007
Experimental models, neurovascular mechanisms and translational issues in stroke research
Authors: Lo E H
Published: December 2007

Numerous failures in clinical stroke trials have led to some pessimism in the field. This short review examines the following questions: Can experimental models of stroke be validated? How can combination stroke therapies be productively pursued? Can we achieve neuroprotection without reperfusion? And finally, can we move from a pure neurobiology view of stroke towards a more integrative approach targeting all cell types within the entire neurovascular unit? Emerging data from both experimental models and clinical findings suggest that neurovascular mechanisms may provide new opportunities for treating stroke. Ultimately, both bench‐to‐bedside and bedside‐back‐to‐bench interactions may be required to overcome the translational hurdles for this challenging disease.

British Journal of Pharmacology (2008) 153, S396–S405; doi:10.1038/sj.bjp.0707626; published online 24 December 2007
Different mechanisms underlie the analgesic actions of paracetamol and dipyrone in a rat model of inflammatory pain
Authors: Rezende R M , França D S , Menezes G B , dos Reis W G P , Bakhle Y S , Francischi J N
Published: December 2007

Background and purpose:

The analgesics, paracetamol and dipyrone are weak inhibitors of the cyclooxygenase isoforms 1 or 2 (COX‐1, COX‐2) but more potent on COX‐3. Both are also weak anti‐inflammatory agents, relative to their analgesic and antipyretic activities. In a model of inflammatory pain mediated by prostaglandins, both compounds were analgesic. We have analysed this shared effect further in order to elucidate the underlying mechanisms.

Experimental approach:

Inflammation was induced in one hind paw of rats by intraplantar injection of 250 μg λ‐carrageenan (CG) and the contralateral paw injected with saline. Nociceptive thresholds to mechanical stimulation were measured immediately before and for 6 h after, injection of CG. The analgesics were s.c. or locally (intraplantar) injected either 30 min before or 2 h after CG. In some groups, naltrexone was injected (s.c. or intraplantar), 1 h before CG.

Key results:

Pretreatment with paracetamol or dipyrone (60–360 mg kg−1) reversed hyperalgesia induced by CG and increased nociceptive threshold in the inflamed paw above the basal level (hypoalgesia). Paracetamol, but not dipyrone, also raised nociceptive thresholds in the non‐inflamed paw. Subcutaneous, but not local, administration of naltrexone, a specific opioid antagonist, reversed the hypoalgesia induced by paracetamol, but similar naltrexone treatment had no effect on dipyrone‐induced analgesia.

Conclusions and implications:

Although both paracetamol and dipyrone are inhibitors of COX isoforms and thus of prostaglandin biosynthesis and were analgesic in our model, their analgesic actions were functionally and mechanistically different. Satisfactory mechanisms of action for these analgesics still remain to be established.

British Journal of Pharmacology(2008)153, 760–768; doi:10.1038/sj.bjp.0707630; published online 24 December 2007
A study of antagonist affinities for the human histamine H2receptor
Authors: Baker J G
Published: December 2007

Background and purpose:

Ligand affinity has been a fundamental concept in the field of pharmacology and has traditionally been considered to be constant for a given receptor–ligand interaction. Recent studies have demonstrated that this is not true for all three members of the Gs‐coupled β‐adrenoceptor family. This study evaluated antagonist affinity measurements at a different Gs‐coupled receptor, the histamine H2receptor, to determine whether antagonist affinity measurements made at a different family of GPCRs were constant.

Experimental approach:

CHO cells stably expressing the human histamine H2receptor and a CRE‐SPAP reporter were used and antagonist affinity was assessed in short‐term cAMP assays and longer term CRE gene transcription assays.

Key results:

Nine agonists and seven antagonists, of sufficient potency at the H2receptor to examine in detail, were identified. Measurements of antagonist affinity were the same regardless of the efficacy of the competing agonist, time of agonist incubation, cellular response measured or presence of a PDE inhibitor.

Conclusions and implications:

Antagonist affinity at the Gs‐coupled histamine H2receptor obeys the accepted dogma for antagonism at GPCRs. This study further confirms that something unusual is indeed happening with the β‐adrenoceptors and is not an artefact related to the transfected cell system used. As the human histamine H2receptor does not behave in a similar manner to any of the human β‐adrenoceptors, it is clear that information gathered from one GPCR cannot be simply extrapolated to predict the behaviour of another GPCR. Each GPCR therefore requires careful and detailed evaluation on its own.

British Journal of Pharmacology(2008)153, 1011–1021; doi:10.1038/sj.bjp.0707644; published online 24 December 2007