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This study documents the employment patterns and demographic characteristics of recent PhDs in earth and space science. It summarizes the latest annual survey of recent earth and space science PhDs conducted by the American Geological Institute, the American Geophysical Union, and the Statistical Research Center of the American Institute of Physics. This survey was completed by 223 new PhDs. Job market indicators for 2001 showed that the job market for recent PhDs in the geosciences is basically as strong as any in the previous 5 years. Starting salaries were up in every employment sector, and starting levels for postdoctoral appointments remained at the same level as 2000. Of the PhD class of 2001, 78% found work in the earth and space sciences, and 98% were employed in science or engineering. Time spent looking for initial employment remained low, and 10% of new PhDs over the past 6 years had been employed for at least 1 year by the time they received their doctorates. PhDs in the earth and space sciences remain, as a group, the oldest among all of natural sciences and engineering PhDs. This characteristic could be attributed to the delay between earning a bachelor's degree and beginning graduate school, rather than spending more time in school. (SLD)

This teacher package for grades 7-12 takes a broad approach in preparing students for earthquakes. "Hands-on/minds-on", inquiry-driven activities are balanced by library research and visits with disaster planning officials. Emphasis is placed on cooperative learning and the constructivist approach to teaching. Students not only study the causes of earthquakes but also study building construction and forces that damage buildings, then construct model buildings to test their knowledge. Students explore how their community prepares for emergencies and how it is empowered with tools to bring about change in community disaster preparedness. Some activities are interdisciplinary. Each unit section contains an overview of the contents and package layout. Each unit in turn has an introduction that gives specific information on the unit content. Lessons and activities include complete procedures, material lists, and master pages for the students. Unit 1 contains the introduction that serves as a foundation for the other units by pre-assessing student knowledge of earthquakes and hazards preparedness. Unit 2 covers causes of earthquakes, geologic time, and side effects of earthquakes. Unit 3 explores the science and history of seismology. Unit 4 covers building design and how earthquake forces act on various designs. Unit 5 focuses student attention on earthquake preparedness. Unit 6 offers a variety of summative and assessment activities. (PVD)

Sea turtles are an iconic group of marine megafauna that have been exposed to multiple anthropogenic threats across their different life stages, especially in the past decades. This has resulted in population declines, and consequently many sea turtle populations are now classified as threatened or endangered globally. Although some populations of sea turtles worldwide are showing early signs of recovery, many still face fundamental threats. This is problematic since sea turtles have important ecological roles. To encourage informed conservation planning and direct future research, we surveyed experts to identify the key contemporary threats (climate change, direct take, fisheries, pollution, disease, predation, and coastal and marine development) faced by sea turtles. Using the survey results and current literature, we also outline knowledge gaps in our understanding of the impact of these threats and how targeted future research, often involving emerging technologies, could close those gaps

To constrain the timing of the sediment cascade, the inherent stochastic nature of sediment and transport through landsliding requires an integrated approach accounting for different space scales and timescales. In this contribution, we examine the sediment production on hillslopes and evacuation to the river network of one landslide affecting a regional-scale river catchment located in the foothills of the Central Swiss Alps. We quantified sediment fluxes over annual, decadal, and millennial timescales using respectively unmanned aerial vehicle (UAV)–structure-from-motion (SfM) techniques, classic photogrammetry, and in situ produced cosmogenic radionuclides. At the decadal scale, sediment fluxes quantified for the period 1962–1998 are highly variable and are not directly linked to the intensity of sediment redistribution on the hillslope. At the millennial scale, landslide occurrence perturbs the regional positive linear relationship between sediment fluxes and downstream distance as the landslide-affected catchment is characterized by a decrease in sediment fluxes and a strong variability. Importantly, the average decadal sediment flux of the landslide-affected catchment is 2 orders of magnitude higher than millennial sediment fluxes computed over the same spatial extent. The discrepancy between decadal and millennial sediment fluxes, combined to the highly variable annual sediment evacuation from the hillslopes to the channel network suggest that phases of hillslope–channel geomorphic coupling are short and intermittent. During most of the time, the first-order catchments are transport-limited and sediment dynamics in the headwaters are uncoupled from the fluvial systems. In addition, our unique spatio-temporal database of sediment fluxes highlights the transient character of the intense geomorphic activity of the landslide-affected catchment in a regional context. Our data support the fact that episodic supply of sediment from landslides during intermittent pha

We define the new concept of an environmental neighborhood as the surrounding area influencing the environmental quality at a given point in a city, and we develop a method to measure its extent. Our novel approach illustrates that selecting this optimal neighborhood scale is critical for finding robust relations between environmental quality and urban attributes. Smaller footprints do not contain all the pertinent urban surface information, while larger footprints contain irrelevant, potentially misleading information. Both might result in erroneous conclusions. Using high spatial resolution datasets for air quality and urban parameters for New York City, we show that its environmental neighborhoods range in scale from 200 to 1000 m, and we identify the urban fabric and activity attributes that have the largest influence on its air quality. While the spatial extent of the environmental neighborhoods might change for different cities, the concept and methodology are generalizable and the data we use are becoming increasingly available for many cities around the world to replicate our analyses. The broader implications of our results are that spatial regression or machine learning models of air quality need to select the right environmental neighborhood scale to maximize model skill, and account for the full range of urban fabric and activity parameters. More importantly, our finding that the optimal footprints tend to be ~ 200 - 1000m in scale implies that, like social neighborhoods, environmental neighborhoods in cities are quite limited and areas with adverse air quality can be improved with localized intervention measures to reduce environmental and health disparities

Hydrological processes in plants are multi-scale, involving sub-cellular elements such as aquaporins as well as long distance transport in xylem tissues vulnerable to cavitation in diverse root and shoot architectures. Their integration in dynamic vegetation models faces a major challenge: the avoidance of over-complexification while retaining the essential features of hydrological phenomena across scales.

Geophysics is the application of physics, chemistry, and mathematics to the problems and processes of the earth, from its innermost core to its outermost environs in space. Fields within geophysics include the atmospheric sciences; geodesy; geomagnetism and paleomagnetism; hydrology; oceanography; planetology; seismology; solar-planetary relationships; tectonophysics; and volcanology, geochemistry, and petrology. This booklet, designed to serve as an introduction to geophysics for high school students, provides descriptions of each of the fields as well as brief comments on careers in geophysics. (JN)

This booklet was prepared by practicing oceanographers to help college students in their search for professional direction. The booklet: (1) points out some frontiers of current research; (2) describes five major subfields of oceanography (marine geology and geophysics, oceanographic engineering, physical oceanography, chemical oceanography, and biological oceanography); (3) outlines the necessary undergraduate preparation; (4) suggests how to approach graduate work; and (5) discusses career prospects. (JN)

Estimating actual evapotranspiration (ETa) spatial variability in orchards is key when trying to quantify water (and associated nutrients) leaching, both with the mass balance and inverse modeling methods. ETa measurements however generally occur at larger scales (e.g. Eddy-covariance method) or have a limited quantitative accuracy. In this study we propose to establish a statistical relation between field ETa and field averaged variables known to be closely related to it, such as stem water potential (WP), soil water storage (WS) and ETc. For that we use 4 years of soil and almond trees water status data to train artificial neural networks (ANNs) predicting field scale ETa and downscale the relation to the individual tree scale. ANNs composed of only two neurons in a hidden layer (11 2 parameters on total) proved to be the most accurate (overall RMSE = 0.0246 mm/h, R = 0.944), seemingly because adding more neurons generated overfitting of noise in the training dataset. According to the optimized weights in the best ANNs, the first hidden neuron could be considered in charge of relaying the ETc information while the other one would deal with the water stress response to stem WP, soil WS, and ETc. As individual trees had specific signatures for combinations of these variables, variability was generated in their ETa responses. The relative canopy cover was the main source of variability of ETa while stem WP was the most influent factor for the ETa / ETc ratio. Trees on drip-irrigated side of the orchard appeared to be less affected by low estimated soil WS in the root zone than on the fanjet micro-sprinklers side, possibly due to a combination of (i) more substantial root biomass increasing the plant hydraulic conductance, (ii) bias in the soil WS estimation due to soil moisture heterogeneity on the drip-side, and (iii) the access to deeper water resource. Tree scale ETa responses are in good agreement with soil-plant water relations reported in the literature, and we

Groundwater quality is specifically vulnerable in irrigated agricultural lands in California and many other(semi-)arid regions of the world. The routine application of nitrogen fertilizers with irrigation water in California is likely responsible for the high nitrate concentrations in groundwater, underlying much of its main agricultural areas. To optimize irrigation/fertigation practices, it is essential that irrigation and fertilizers are applied at the optimal concentration, place, and time to ensure maximum root uptake and minimize leaching losses to the groundwater. The applied irrigation water and dissolved fertilizer, as well as root growth and associated nitrate and water uptake, interact with soil properties and fertilizer source(s) in a complex manner that cannot easily be resolved. It is therefore that coupled experimental-modeling studies are required to allow for unraveling of the relevant complexities that result from typical field-wide spatial variations of soil texture and layering across farmer-managed fields. We present experimental approaches across a network of tree crop orchards in the San Joaquin Valley, that provide the necessary soil data of soil moisture, water potential and nitrate concentration to evaluate and optimize irrigation water management practices. Specifically, deep tensiometers were used to monitor in-situ continuous soil water potential gradients, for the purpose to compute leaching fluxes of water and nitrate at both the individual tree and field scale.

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We investigate the influence of the interior structure of the Galilean satellites on their rotation variations (or librations). Since the Galilean satellites are significantly aspherical due to rotation and static tides, Jupiter exerts a gravitational torque on them. In a circular orbit, the long axis of a satellite would always point towards Jupiter and the gravitational torque would be zero. However, the eccentric orbits of the Galilean satellites lead to misalignment of the long axis with the direction to Jupiter and result in non-zero gravitational torques that tend to modify the rotation of the satellites. Since the torque varies with the orbital phase, the main libration period is equal to the orbital period. In a first-order approximation, the libration amplitude is usually calculated by assuming that the satellite reacts rigidly to the gravitational torque. The corresponding amplitudes, expressed as a shift at the surface of the orientation of the long axis with respect to that for the mean rotation rate, decrease with increasing distance from Jupiter from a few hundred meters for Io to about ten meter for Callisto. Internal liquid layers, such as a subsurface ocean, can lead to differential rotation of the solid and liquid layers and to differences of the libration of surface with respect to that for a rigid libration. Here, we present a method to determine the influence of gravitational and pressure interactions between internal layers on the libration of the Galilean satellites. For Io, we show that the liquid core has only a small effect on the surface librations. For Europa, Ganymede and Callisto, the presence of a subsurface ocean can significantly increase the libration amplitude. We also study the effect of the possible existence of two liquid layers in Ganymede and Europa: a subsurface ocean and a liquid core. We quantify the sensitivity of the libration amplitude to the internal structure and assess expected improvements in the interior structure o

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The report "Comptes Rendus of the XXI General Assembly of the IUGG" contains the proceedings of the International Union of Geodesy and Geophysics (IUGG) General Assembly, the statutes and bylaws of the IUGG and each of its seven Associations, and a listing of the assembly registrants. "Geophysics and the Environment" was the theme for the XXI General Assembly of IUGG. Contributed papers covered all areas of geophysics. The officers of the Union, five Union lectures, and the resolutions adopted by the Union at the General Assembly are provided in their entirety. The administrative, scientific, and financial reports from the meeting are included. In addition, reports from the Union commissions, IUGG Liaison officers, and IUGG representatives on ICSU and other committees are enclosed for perusal. This report also provides an account of the Association Presidential addresses, the minutes from the Council meetings, the meeting program, and resolutions adopted at the XXI General Assembly by IUGG Associations.

The Tower Ocean Wave and Radar Dependence Experiment (TOWARD) is a coordinated effort, involving both field experimentation and theoretical investigations, to address the divergent hypotheses on the mechanisms involved in synthetic aperture radar (SAR) imaging of the ocean surface. In the formulation of the experiment it was recognized that three distinct disciplines were to be addressed: (1) hydrodynamics, (2) radar backscatter, and (3) SAR image processing. The field operations were executed in three 6-week segments during the period October 1984 to January 1986. The Naval Ocean Systems Center tower, located offshore of Mission Beach, San Diego, California, was used as the focal point for the field operations. The primary measurements included in situ capillary and short gravity waves, long surface and internal waves, ambient current and detailed meteorological measurements, stereophotography, tower-based multifrequency radars and an L band SAR deployed on board the NASA CV-990. The single most significant result is the determination that none of the available hypotheses on SAR imaging of long surface waves could be demonstrated to explain all the SAR observations obtained in TOWARD., Journal of Geophysical Research, v93, nC11, Nov 15, 1988, v95, nC9, Sep 15, 1990.