bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assimilation of MLS ozone measurements in the global three‐dimensional chemistry transport model ROSE
Authors: Levelt P. F. , Khattatov B. V. , Gille J. C. , Brasseur G. P. , Tie X. X. , Waters J. W. 
Published: February 2004

A method for assimilating observations of ozone was implemented in the three‐dimensional global stratospheric chemistry transport model ROSE. The model contains an extensive photochemical scheme which includes heterogeneous chemistry and uses temperature and wind fields from the UKMO (United Kingdom Meteorological Office) stratospheric analysis.Ozone measurements obtained by the Microwave Limb Sounder (MLS) on board the Upper Atmosphere Research Satellite (UARS) were assimilated in the model using the sequential statistical interpolation approach. The analysis is performed using a time invariant background error covariance matrix that only includes horizontal covariances. Results from a sixty day simulation are presented and it is shown that assimilation of the MLS observations results in improved global three‐dimensional distributions of ozone as seen from comparisons with MLS data not assimilated in the model. For further validation, the stratospheric total ozone fields computed from the analysis are compared with the TOVS total ozone measurements and it is shown that they agree within the uncertainty of the data.
Upper plate contraction north of the migrating Mendocino triple junction, northern California: Implications for partitioning of strain
Authors: McCrory Patricia A. 
Published: February 2004

Geologic measurement of permanent contraction across the Cascadia subduction margin constrains one component of the tectonic deformation along the convergent plate boundary, the component critical for the seismic hazard assessment of crustal faults. A comprehensive survey of active faults in onshore subduction margin rocks at the southern end of the Cascadia subduction zone indicates that these thrust faults accommodate ∼10 mm/yr of convergence oriented 020°–045°. Seismotectonic models of subduction zones typically assign this upper plate strain to the estimate of aseismic slip on the megathrust. Geodetic models include this permanent crustal strain within estimates of elastic strain accumulation on the megathrust. Both types of models underestimate the seismic hazard associated with crustal faults. Subtracting the observed contraction from the plate convergence rate (40–50 mm/yr; directed 040°–055°) leaves 30–40 mm/yr of convergence to be partitioned between slip on the megathrust, contraction within the southern Juan de Fuca plate, and crustal contraction outside the subduction complex rocks. This simple estimate of slip partitioning neglects the discrepancy between the plate convergence and contraction directions in the vicinity of the Mendocino triple junction.The San Andreas and Cascadia limbs of the Mendocino triple junction are not collinear. The eastern edge of the broad San Andreas boundary is ∼85 km east of the Cascadia subduction boundary, and across this zone the Pacific plate converges directly with the North America plate. The skewed orientation of crustal structures just north of the leading edge of the Pacific plate suggests that they are deforming in a hybrid stress field resulting from both Juan de Fuca‐North America motion and Pacific‐North America motion. The composite convergence direction (50 mm/yr; directed 023°) is consistent with the compressive stress axis (020°) inferred from focal mechanisms of crustal earthquakes in the Humboldt region. Deformation in such a hybrid stress field implies that the crustal faults are being loaded from two major tectonic sources. The slip on crustal faults north of the Mendocino triple junction may consume 4–5 mm/yr of Pacific‐Humboldt convergence. The remaining 17–18 mm/yr of convergence may be consumed as distributed shortening expressed in the high rates of uplift in the Cape Mendocino region or as northward translation of the continental margin, north of the triple junction.
Overview of the meteorological conditions and atmospheric transport processes during INDOEX 1999
Authors: Verver G. H. L. , Sikka D. R. , Lobert J. M. , Stossmeister G. , Zachariasse M. 
Published: February 2004

We give an overview of the regional meteorological situation during the Indian Ocean Experiment INDOEX intensive field phase (IFP) in February and March 1999. The INDOEX domain, reaching from 30°N to 30°S and from 50°E to 100°E, was chosen because the low‐level outflow of pollution from India is carried by the northeasterly trades into the tropical convergence zone, where cloud processing modifies the properties of the aerosols. In contrast, there is also an inflow of pristine southern hemispheric air by the southeasterly trades into the convergence zone. However, during the 1999 IFP some deviations from the climatological mean were observed. In 1999 the Intertropical Convergence Zone (ITCZ) was broken into a northern convergence zone and a southern convergence zone. During February the northern zone was more active and the cross‐equatorial flow (N‐→S) was weak, both suggesting that less pollution was transported to the southern hemisphere. In February it was occasionally possible to sample a southern hemispheric air mass on the southern side of the INDOEX domain. During March 1999 the southern convergence zone became dominant and moved to a more southern position (near 5°–10°S).It is shown that four channels carry pollution into the INDOEX domain: (1) NE trades over the western Arabian Sea, (2) NW‐NE flow along the west coast of India, (3) NE trades over the west Bay of Bengal, and (4) NE flow from SE Asia. The strength of each channel is modulated by transients moving across Pakistan and northern India (western disturbances). The heating of the Indian subcontinent in March resulted in a eastern shift of the subtropical high from central India to the Bay of Bengal, which also affected channels 2, 3, and 4. Episodes of high and low carbon monoxide concentrations as measured in Kaashidhoo (Maldives) during the 1999 IFP can qualitatively be explained by the operationality of the flow channels, determined through trajectory analyses, in combination with the intensity of the northern convergence zone.
Ground‐based FTIR measurements of CLONO2 Vertical column amounts in the Arctic
Authors: Notholt J. , Clarmann T.V. , Adrian G. P. , Schrems O. 
Published: February 2004

During the EASOE campaign measurements have been performed in March at Ny‐Ålesund (79°N, 11°E) by high resolution FTIR spectroscopy to derive the vertical column amounts of ClONO2. For the first part of this period the polar vortex was found to be situated above Ny‐Ålesund.The measurements give ClONO2 zenith column amounts of about 3.9×1015 mol cm−2 outside the polar vortex, much higher than midlatitude values for an undisturbed atmosphere. Inside the vortex strong variabilities with burdens between 2.8 and 6.8×1015 mol cm−2 were observed. These high values might be explained by the reaction of ClO with NO2 and the relatively warm stratosphere ensuring that the ClONO2 so formed remains in the gas phase.
Groundbased measurements of stratospheric OClO, NO2, and O3 at Søndre Strømfjord in winter 1991/92
Authors: Perner D. , Roth A. , Klüpfel T. 
Published: February 2004

Experiment (EASOE) campaign Within the scope of the 1991/92 European Arctic Stratospheric Ozone stratospheric chlorine dioxide, OClO, nitrogen dioxide, NO2, bromine monoxide, BrO, and ozone, O3, were measured by groundbased UV‐VIS remote sensing in Søndre Strømfjord, Greenland (50.4°W, 67.0°N). The measurement period was from the middle of November 1991 until the end of January 1992. The anticipated correlation between potential vorticity and OClO appeared less pronounced in the beginning and its abundance was similar inside and outside of the polar vortex. During November 1991 stratospheric temperatures throughout the polar region were still above threshold for polar stratospheric cloud (PSC) formation. During January when NO2 column densities were at their lowest, OClO inside of the vortex appeared to be highly variable. Average vertical column densities reached about 1013 molec cm−2, less than found in previous years.The chemistry as well as the observations may have been disturbed by the aerosol cloud from Mt. Pinatubo eruption.
Collision of Schoemaker‐Levy 9 fragments A, E, H, L, Q1 with Jupiter: Mid‐infrared light curves
Authors: Lagage P. O. , Galdemard Ph. , Pantin E. , Jouan R. , Masse P. , Sauvage M. , Olofsson G. , Huldtgren M. , Nordh L. , Belmonte J. A. , Regulo C. , Espinosa J. M. Rodriguez , Vidal L. , Mosser B. , Ulla A. , Gautier D. 
Published: February 2004

Light curves of the 12 µm emission following the collision of Shoemaker‐Levy 9 fragments A, E, H, L, Q1 with Jupiter are presented. Impacts F, P2, Q2, T, U were monitored, but not detected. The observations were carried out with the Saclay CAMIRAS camera mounted on the 2.56 m Nordic Optical Telescope located at La Palma (Canary Island, Spain).Of particular interest is the light curve of the L impact (the brightest impact), where 3 different regions can be observed. A precursor flash (the debris cloud rising above the limb) is detected about 1 min 30 s after the detection from the Galileo spacecraft. Twelve minutes later, a huge infrared spot at a temperature of about 700 K appears at its peak intensity: 13 000 Jy. A new change of behaviour is observed 20 min after impact: a secondary bump appears, after which the flux decreases at a slower rate. Light curves of impacts Q1, H, E and A, up to more than one order of magnitude fainter than the L impact, are quite similar.Ballistic re‐entry of dust‐gas in the atmosphere must be considered in the interpretation of the IR spot.
Introduction to Special Section: Paleoseismology
Authors: Yeats Robert S. , Prentice Carol S. 
Published: February 2004

A proverb of Confucius states “Study the past if you would divine the future.” If we could learn about the past history of earthquakes on a specific fault, then we could serve society well by better forecasting the future earthquake behavior of that fault.For most of the world, the period of historical records is short: about 200 years in California and less than that in New Zealand, Oregon, and other parts of the world. And even where the historical record is thousands of years long, such as in north central China or the eastern Mediterranean region, it is commonly difficult to correlate a major historical earthquake with a specific active fault. Even if this correlation could be made without ambiguity, the recurrence intervals for many faults are longer than even a historical record of several thousand years. For these reasons, the history of large earthquakes on faults must, for the most part, be learned from the geological record.
Stimulating our piece of the universe: Active experiments in space
Authors: Raitt W. J. 
Published: February 2004

“Life science is the only space science discipline in which space experiments are performed.” This comment was made recently at a meeting of space scientists, striking those of us in physical science disciplines as somewhat bizarre. However, I realized on further reflection that in a sense the remark was largely correct except for one area of physical science space research known as active experiments in space.Since the beginning of the space age, physical science investigators have made measurements predominantly of the space environment using advanced experimental techniques. Space experiments in this discipline have been much rarer events. Specific experiments designed to study the response of the space environment to controlled disturbances are generally termed active space experiments. In recent years the distinction between making measurements of the space environment and performing controlled experiments in that environment has been emphasized in the space physics community by a distinction in funding considerations between “Space Physics” and “Physics in Space”, that is passive versus active experimentation. However, the distinction is not always clear since even passive experiments provide some disturbance to the space environment, and some experiments use active techniques with minimal disturbance to measure ambient properties of the local or remote space environment. In this report, my intention is to address primarily those experiments which set out to actively perturb the environment from space platforms and study the effects of that perturbation.
Seismology of the core
Authors: Tromp Jeroen 
Published: February 2004

The purpose of this report is to review seismological research related to the Earth's core published during the period 1991–1994. The review period 1987–1990 is covered in Masters [1991]. I have attempted to provide a complete overview of research conducted in the United States; research carried out in other parts of the world is only partially reviewed.This report is divided into two main sections concerned with the inner and outer core, respectively. The section on the inner core discusses exciting recent developments related to its apparent anisotropy, presents the latest views on its attenuation, and considers implications for its growth and composition. The discussion of the outer core focuses on its velocity profile and core oscillations.
Climate change: Does it matter?
Authors: Firor John 
Published: February 2004

Ever since Svante Arrhenius, early in this century, calculated how much our use of fossil fuel might raise the surface temperature of the earth, there have been speculations concerning the impact of this and other human‐induced climate changes on society (Arrhenius, 1908). The conversion of this speculation about impacts into well established estimates has been hampered by uncertainties concerning the rate at which the climate forcing activities are changing, uncertainties in our knowledge of the nature of the climate changes that will follow the changes in forcing, uncertainties in the reaction of important ecosystems to the changing climate, and the lack of any widely adopted and tested methodology for estimating societal impacts of a climate change. Despite these difficulties, a number of studies in the United States in the period 1991–1994 have considered the impact of a human‐induced climate change, and other studies have discussed the methodological issues inherent in such work.In this review, changes in all the systems mainly involving physical processes, e.g., atmosphere, ocean, ice caps, glaciers, and the hydrological cycle, will be regarded as part of the climate and not discussed here. The effect of changes in any of these physical systems on the biosphere, including humans and human societies, will be called impacts, and studies of these impacts will be at least sampled in this review. Changes in stratospheric ozone are sometimes considered to be climate changes, but this review will be restricted to the climate changes caused by increases in the concentrations of infrared‐trapping gases in the atmosphere.
When the sky fell on our heads: Identification and interpretation of impact products in the sedimentary record
Authors: Claeys Philippe 
Published: February 2004

Research on impact products, mechanisms and consequences has benefited greatly in the last ten years from the highly publicized Cretaceous‐Tertiary (KT) boundary debate. This debate has led to an increasing awareness among Earth scientists of the importance and potential effects of impact events in Earth history. With more and more researchers realizing the role played by impacts and becoming familiar with the characteristics of impact materials, it is likely that in the coming years, an increasing number of impact events will be identified, in agreement with the Earth cratering rate estimations (Grieve, 1984; Shoemaker et al., 1990).The increasing recognition of impact event is demonstrated by the discovery or identification in recent years of several impact craters, some of large diameter: Chicxulub, >180 km in Yucatan; Mjølnir, 40 km in the Barents Sea; Ames, 16 km in Oklahoma; Avak 12 km in Alaska; Pretoria Saltpan, 1.1 km and Kalkkop, 640 m both in South Africa. Sediments record impact events in the form of impact glass, shocked minerals, Ir anomalies, and perhaps also polymic‐chaotic breccias and/or tsunami deposits. Identification of impact products, particularly in ancient rocks, is hampered by poor preservation, diagenetic alteration, metamorphism, misinterpretation, or even lack of interest or awareness of their significance. Impact products represent very short term events, most likely geographically localized and stratigraphically concentrated over a thin interval of sediments and often diluted by normal background deposition. Finding these impact signatures requires very detailed petrographic and geochemical investigations with closely spaced sampling (a few cm). Such detail is not commonly used when studying ancient Mesozoic and Paleozoic sediments.
Atmospheric aerosol research in the U.S.: 1991–1994
Authors: Kreidenweis Sonia M. 
Published: February 2004

A common theme underlying many aspects of recent atmospheric aerosol research is the role of particulate matter in climate and climate change. Aerosols influence climate directly, by scattering and absorbing solar radiation, and indirectly via their role as cloud condensation nuclei (CCN), by modifying optical properties and lifetimes of clouds. The atmospheric cycles of two radiatively‐important species—sulfate and soot—have been significantly perturbed by anthropogenic activities, and thus it is expected that anthropogenic aerosols will have significant effects on global mean radiative forcing.There is general agreement that, despite uncertainty in estimates, the averaged global direct effects of aerosols are not negligible and are probably comparable in magnitude but opposite in sign to anthropogenic greenhouse gas forcing. However, all estimates are subject to significant uncertainty, in part because of gaps in understanding of critical factors and relationships. To minimize these uncertainties, a combination of activities must be undertaken (NRC (National Research Council) [1993] and Penner et al. [1993a]): long‐term observations at fixed sites, to establish background conditions and trends; short‐term intensive observations, surface‐based and airborne; laboratory analyses and process studies; model development; and satellite observations to connect local observations to global measurements. There is also a need for new techniques for automated and real‐time measurements of aerosol chemical and physical properties. Components of IGAC (International Global Atmospheric Chemistry Program) and its U.S. component, GTCP (Global Tropospheric Chemistry Program) are focused on obtaining the data needed for quantifying the effects of aerosols on climate (NRC (National Research Council) [1993]), and indeed much of the research reported here reflects this priority.
Preface
Authors: Pielke Roger A. 
Published: February 2004

This quadrennial report represents a departure from previous ones by incorporating inter‐and cross‐disciplinary articles in response to reader comments. Examples include volcanos and climates (the topic of a recent Chapman Conference); the atmospheric and hydrologic aspects of precipitation; air‐sea interaction; and surficial properties—a subject of interest to atmospheric scientists, hydrologists, planetologists, and solid earth scientists. These topics cut across two or more of the six major sections identified for the report; the major sections and their Editors are • Properties of the Solid Earth (covering volcanology, geochemistry, and petrology; geomagnetism and paleomagnetism), Ken Verosub; and • Dynamics of the Solid Earth and Other Planets (covering tectonophysics, seismology, and geodesy), Gerald Schubert; • Space Sciences (covering atmospheric studies of extraterrestrial bodies, space physics, and the Earths atmosphere from the mesosphere and above), George Siscoe. • Atmospheric Sciences(covering the Earth's atmosphere below the mesosphere), Steve Nelson; • Hydrology (including all aspects of surface and ground water), Rich Vogel; • Ocean Sciences (covering physical, chemical, and biological oceanography), Robert Weller;The authors for this volume were requested to structure their contributions into three basic segments: 1. undirected research (i.e., basic research); 2. directed research (i.e., applied research for specific applications ); and 3. development and implementation activities.
Fracture‐induced hydrothermal convection in the oceanic crust and the interpretation of heat‐flow data
Authors: Yang Jianwen , Edwards R. N. , Molson John W. , Sudicky E. A. 
Published: February 2004

Small‐scale seafloor heat‐flow variations with a characteristic wavelength of about 1200 m have been observed on a profile over a sediment‐sealed ridge flank. Two theories have been advanced to explain them‐low aspect ratio hydrothermal convection in a highly permeable basement layer 600 m thick or high aspect ratio convection in an anisotropic permeable layer 200 m thick, induced by 20 m topographic variations with a 1000 m half wavelength. Neither theory is totally satisfactory. The first requires a very thick highly permeable zone while the absence of any resolvable basement relief on a complementary seismic survey limits the credibility of the second.We hypothesize that sub‐critical hydrothermal convection in normal upper oceanic crust, driven by discrete fractures, can cause the observed heat flow anomalies. We test the hypothesis by using a finite‐element code to solve the coupled time‐dependent heat transport and fluid flow differential equations. Discrete fractures are incorporated explicitly. We show that the inclusion of fractures in layers 2A and 2B promotes convection. Fluid flow through fractures causes horizontal thermal gradients, and initiates and maintains sub‐critical convection within the upper basalts. The predicted heat flow variations are comparable with the observed data.