Eric S Posmentier

• Ph.D. Columbia University
• Professor at Dartmouth College

Hydrogen (δD) and oxygen (δ¹⁸O) isotopic ratios are strongly correlated in precipitation over time and space, defining the meteoric water line, and the slope of this δD‐δ¹⁸O relationship reflects covariations of deuterium excess (d‐excess) with δD or δ¹⁸O. This δD‐δ¹⁸O line provides a tool for inferring hydrologic processes from the evaporation sou...

The meteoric water line, defined by the correlation of hydrogen (δD) and oxygen (δ¹⁸O) values, is one of the earliest described characteristics of precipitation isotopic variations. However, spatial and temporal variations in the slope of this line are less studied. The slope of the δD-δ¹⁸O relationship is coupled with how d-excess covaries with δD...

We develop a one-dimensional (1-D) steady-state isotope marine boundary layer (MBL) model that includes meteorologically important features missing in models of the Craig and Gordon type, namely height-dependent diffusion and mixing, lifting to deliver air to the free troposphere, and convergence of subsiding air. Kinetic isotopic fractionation res...

We have constructed a new isotope marine boundary layer (IMBL) model to calculate the isotopic composition of vapor in the marine boundary layer as well as that of vapor lifted to the free atmosphere. The model divides the MBL into three layers, each with its own transport characteristics. (1) the model solving for both isotopologue concentrations...

The hydrogen and oxygen isotopic composition of ice cores from Summit, Greenland, has provided invaluable information about variations in past climate. However, interpretations of these isotopic data have been made despite a paucity of direct isotopic studies of Summit precipitation. We provide insight to such interpretations by examining the annua...

We develop a one-dimensional (1D) steady state isotope marine boundary layer (MBL) model that includes meteorologically important features missing in Craig and Gordon type models, namely height-dependent diffusion/mixing, lifting to deliver air to the free troposphere, and convergence of subsiding air. Kinetic isotopic fractionation results from th...

Because water isotope ratios respond to phase changes during evaporation (E) and precipitation (P), they are candidate fingerprints of changing atmospheric hydrology. Moreover, through preservation in ice cores and other paleoproxies, they provide important insight into the past. Still, there is disagreement over what specific attributes of hydrocl...

Lake water hydrogen (δD) and oxygen (δ18O) isotopic ratios have been widely used to study the hydrologic cycle. In a given region, δD and δ18O values from multiple lakes are often correlated and define a local evaporation line (LEL). The slope of and extension of each lake along this line contain information of many variables with entangled effects...

Lagrangian air parcel tracking is a powerful tool for estimating vapor source locations, particularly for isotope hydrology applications. Identified vapor source regions may be sensitive to the distribution of altitudes at which back trajectories are initiated. Ideally, those initial altitudes should reflect the altitudes where precipitation forms....

In this study, precipitation isotopic variations at Barrow, AK, USA, are linked to conditions at the moisture source region, along the transport path, and at the precipitation site. Seventy precipitation events between January 2009 and March 2013 were analyzed for δ2H and deuterium excess. For each precipitation event, vapor source regions were ide...

Interpretation of variability in precipitation stable isotopic ratios often relies exclusively on empirical relationships to meteorological variables (e.g., temperature) at the precipitation site. Because of the difficulty of unambiguously determining the vapor source region(s), relatively fewer studies consider evaporation and transport conditions...

Significance There has been a growing consensus that a decrease in sea ice would cause an increase in Arctic precipitation because of the potential for increased local evaporation. We quantify the effect of sea ice on the percentage of moisture sourced from the Arctic, using measurements of the isotopic composition of precipitation at six sites acr...

We observed, for the first time, the vertical as well as horizontal components of vapor and isotopic gradients as relatively dry and isotopically depleted air advected over the surfaces of several lakes up to a 5 km fetch under winds of 1–5 m/s in Kangerlussuaq, Greenland. We modeled the vapor and isotopic distribution in air above the lake using a...

We present a study of the dynamics of small-scale (~100 km) atmospheric circulation in West Greenland which are dominated by interactions of marine and continental air masses. Water vapor concentration and isotopic ratios measured continuously over a 25 day period in Kangerlussuaq, Greenland were used to monitor the convergence of easterly katabati...

Interactions among Arctic sea ice, evaporation, terrestrial snowfall, and sea level have long been understood as a linchpin of Pleistocene ice age dynamics, but how does this feedback cycle influence decadal scale climate dynamics? The paucity of reliable Arctic hydrologic data has made it difficult to answer this question directly. However, new is...

For the last 50 years the Department of Earth Sciences at Dartmouth College has offered a term-long, undergraduate field program, informally called "the Stretch". A student typically enrolls during fall quarter of his or her junior year soon after choosing a major or minor. The program thus provides valuable field context for courses that a student...

Glacial lakes are an important component of the Arctic landscape. These lakes affect the local water cycles, ecosystem functioning, and, if reaching a substantial surface area, the surface albedo and energy balance. Understanding the current water balance of lakes is thus important for predicting the response of the Arctic to future climate change....

Atmospheric vapor isotope ratios (H218O/H216O and HD16O/H216O) were observed at high frequency for two years in Hanover, NH. Isotopic data were obtained every 100 seconds using a Los Gatos Research ringdown vapor analyzer, and concurrent meteorological data were obtained every 10 min using a collocated Davis Vantage PRO2 weather station. It was det...

Variation of stable isotopes in precipitation has been used to understand the earth's climate for many decades. Typically, these measurements are made on monthly or even annual accumulations of precipitation. Large intrastorm variation in isotopic ratio was observed during the very early days of isotopic research (Epstein, 1954), and the focus of a...

Isotopic variations of snowmelt provide important information for understanding snowmelt processes and the timing and contribution of snowmelt to catchments in spring. We report a new model for simulating the isotopic evolution of snowmelt. The model includes a hydraulic exchange between mobile and immobile water, and an isotopic exchange between l...

Summary Co-phase is a statistic designed for the detection and parameter estimation of signals by detector arrays. Ionospheric motions detected by an array of four phase-path sounders following a large earthquake are found by the co-phase technique to have a phase velocity equal to that of seismic Rayleigh waves of the same period, and to arrive fr...

Understanding an isotopic evolution of a snowpack is important for both climate and hydrological studies, because the snowmelt is a significant component of groundwater and surface runoff in temperate areas. In this work, we studied oxygen and hydrogen isotopic evolution from new snow to snow profile and to meltwater through two winter seasons (199...

The most widely cited climate feedback in the Arctic region is ice cover. Warming climate reduces the sea ice extent, which causes a lower surface albedo, resulting in more absorbed insolation and further warming - a positive feedback. Conversely, warming is also likely to result in increased Arctic evaporation and precipitation, leading to increas...

High-resolution water vapor isotopic measurements have recently been made possible using laser-based technologies, which open up new opportunities for studying atmospheric processes and atmosphere-land interactions. In this work, continuous high-resolution (90 second interval) oxygen (delta18Ov) and hydrogen (deltaDv) isotopic ratios in near-surfac...

We use data from Global Network of Isotopes in Precipitation (GNIP) database to explore how the atmosphere's meridional circulation cells control the latitudinal and seasonal distribution of δ18O and d-excess in precipitation. We demonstrate that the atmospheric general circulation (AGC) cells determine variations of zonally averaged isotopic compo...

The isotopic exchange rate between liquid water and ice is crucial in determining the isotopic evolution of a snowpack and its melt. The rate constant for oxygen isotopic exchange has been reported by Taylor et al. [Taylor, S., Feng, X., Renshaw, C.E., Kirchner, J.W., 2002a. Isotopic evolution of snowmelt-2. Verification and parameterization of a o...

We studied the influence of acid pretreatment on the effective distinction between elemental carbon (EC) and organic carbon (OC), and between char-EC and soot-EC. Though widely employed in the pretreatment of soils and sediments for EC quantification, the use of HCl, HF, and HNO(3) could decrease soot thermal stability as acid remains, leading to a...

Information can be inferred on the timing and amplitude of solar total irradiance changes over 1880- 1993 by simulating the global terrestrial surface temperature changes produced by these irradiance changes and comparing them with observed temperatures. The profiles of solar irradiance variations used in the climate simulations are adopted from se...

One of the oldest theories of ice ages posits the crucial role of sea ice in controlling the precipitation necessary to support the growth of continental ice sheets. This mechanism would also affect albedo, thus providing a negative feedback to global climate change. However, data has been lacking to estimate the magnitude of these effects. Our ana...

Understanding of isotopic variations in leaf water is important for reconstruction of paleoclimate and assessment of global biochemical processes. We report here a study of isotopic distributions within a single needle of two pine species, Pinus resinosa Ait and Pinus strobes L., with the objective of understanding how isotopic compositions of leaf...

We studied between-age oxygen and hydrogen isotopic variations of two pine species, red pine (Pinus resinosa Ait) and white pine (Pinus strobus L.), with particular attention paid to variations associated with needle maturity. The 2D model by Shu et al. (this volume) was applied to simulate oxygen isotopic ratios of the pine needles; calculated res...

Sixty five urban road dust samples were collected from different land use areas of ∼240 km2 in Xi’an, China. The concentrations of Ag, As, Cr, Cu, Hg, Pb, Sb and Zn were determined to investigate potentially harmful element (PHE) contamination, distribution and possible sources. In addition, the concentrations in different size fractions were measu...

We report a study of solute transport in snow, using artificial rain-on-snow experiments with conservative anions (F−, Br−, and SO42−). The tracers were mixed into tap water and sprayed onto the snow surface from two water supply tanks. The water flux out of the base of the snowpack was recorded, and discharge samples were collected and analyzed fo...

The boundary layer (BL) model for oxygen or hydrogen isotopic composition of leaf water has been widely used in the past four decades, and has been incorporated into models that require information about leaf water isotopic variations. However, since its introduction, model predictions of the bulk leaf water have often exceeded observed isotopic en...

A complete record derived from the core from the Daihai Lake in a remote area provides new insights into the changing atmospheric heavy metal deposition associated with historical industrial activities, the Asian monsoon, long-range transport, and the chemical composition of matter derived from weathering of catchment. The fluctuation of lithogenic...

INTRODUCTION Climate change is often manifested by changes in atmospheric circulation patterns and the global hydrologic cycle. Several general circulation model simulations have suggested that during the Last Glacial Maximum (LGM), the circumpolar vortex intensifi ed and enlarged, a glacial anti-cyclone developed over the Laurentide Ice Sheet, and...

MASCOTTE (Carvalho and Jones (2001), a simple, fully automated, and efficient method to determine the structural properties and evolution (tracking) of MCS cloud shields, has been described. This method is based on the maximum spatial correlation tracking technique for monitoring the evolution of MCS's using satellite images. MASCOTTE provides as M...

Though there are many studies of heavy metal contaminations of urban dusts in developed countries, little attention has been paid to this kind of study in developing countries, including China. Therefore, a series of investigations were performed to provide heavy metal signatures of urban dusts and to evaluate potential sources in Xi'an, Shaanxi Pr...

Major element and Sr concentrations and 87Sr/86Sr ratios were measured in groundwater, rainwater and stream samples collected in2004 from Luquillo Experimental Forest (LEF), Puerto Rico. The groundwater was obtained from wells augured across a ~20 m wide floodplain, which lies between a tributary of Rio Iacos and upslope forest (McDowell et al., Bi...

The hydrogen and oxygen isotopic ratios of meteoric water, as preserved in geologic materials, are widely used to reconstruct past climatic conditions. Correlation between temperature and isotopic composition of precipitation for temperate regions has been well documented, and modern day correlations are used in interpreting paleo-isotopic records,...

Northwest Alaska has two primary storm tracks: one coming from the South, bringing the Pacific air mass, and the other from the North bringing the Arctic air mass to the area. In general, the precipitation is cleaner in the southern source than the northern one because the latter involves the Arctic air mass contaminated by industrial pollutants fr...

It has been demonstrated that the oxygen and hydrogen isotopic compositions of tree rings contain information about the isotopic composition of the source water and the relative air humidity during photosynthesis. More recently, Shu et al. showed that the slope of the δD vs. δ18O plot contains information about covariation between isotopic composit...

Climate change often occurs through changes in seasonal influences, but paleoclimate records rarely have intra‐annual resolution. The precipitation δ ¹⁸ O, either directly measured or indirectly inferred from other datable materials, is one of the most widely used proxies for paleoclimate studies. It is important, therefore, that we understand the...

Climate change often occurs through changes in seasonal influences, but paleoclimate records rarely have intra-annual resolution. The precipitation δ18O, either directly measured or indirectly inferred from other datable materials, is one of the most widely used proxies for paleoclimate studies. It is important, therefore, that we understand the se...

Climate change often occurs through changes in seasonal influences, but paleoclimate records rarely have intra-annual resolution. The precipitation delta 18O, either directly measured or indirectly inferred from other datable materials, is one of the most widely used proxies for paleoclimate studies. It is important, therefore, that we understand t...

A likelihood of disastrous global environmental consequences has been surmised as a result of projected increases in anthropogenic greenhouse gas emissions. These estimates are based on computer climate modeling, a branch of science still in its infancy despite recent, substantial strides in knowledge. Because the expected anthropogenic climate for...

A likelihood of disastrous global environmental consequences has been surmised as a result of projected increases in anthropogenic greenhouse gas emissions. These estimates are based on computer climate modeling, a branch of science still in its infancy despite recent substantial strides in knowledge. Because the expected anthropogenic climate forc...

We compare the equilibrium climate responses of a quasi-dynamical energy balance model to radiative forcing by equivalent changes in CO2, solar total irradiance (Stot) and solar UV (SUV). The response is largest in the SUV case, in which the imposed UV radiative forcing is preferentially absorbed in the layer above 250 mb, in contrast to the weak r...

The temperature anomaly of the terrestrial lower troposphere, inferred from the Microwave Sounding Unit (MSU) radiometers, is found to be inversely correlated with the area of the Sun covered by coronal holes. The correlation between the monthly time series of global tropospheric temperature anomaly and total coronal hole area from January 1979 to...

There is considerable evidence in support of Milankovic's theory that variations in high-latitude summer insolation caused by Earth orbital variations are the cause of the Pleistocene ice cycles. The enigmatic discrepancy between the spectra of Milankovic forcing and of Pleistocene climate variations is believed to be resolved by the slow, nonlinea...

A model of double diffusively driven interleaving layers across a thermohaline, barotropic front is developed. The mechanism of the interleaving was proposed by Stern (1967) for small perturbations of continuous, large scale T-S gradients in the saltfingering regime by double diffusive interleaving. The model shows that this mechanism is also effec...

Numerical experiments with a nonlinear "toy' climate model demonstrate that very small changes in the values of climate feedback parameters, with no changes in the model's equilibrium climate state, can cause the model to switch among several modes of behaviour - periodic at intrinsic or forcing frequencies, periodic at a subharmonic of the forcing...

Merchant ship observations appear to indicate an increase in the strength of the surface winds in the tropical Pacific and elsewhere in recent decades. Here, trends in tropical Pacific sea surface temperature and sea level, which has repeatedly been shown to be closely related to the winds, are investigated. The results suggest that sea levels sinc...

It is hypothesized that double diffusive interleaving can act to enhance the temperature, salinity and buoyancy signatures of some mesoscale structures. The hypothesis is founded on theoretical results showing that the fluxes produced by double diffusive interleaving can have counter-gradient components, and on the observations that isolated mesosc...

A one-dimensional, two-layer, bulk-mixing model, driven by the climatic inputs of heat, fresh water, and wind, simulates the predominant evolving thermohaline characteristics of the shelf and slope waters in the Middle Atlantic Bight. The inclusion of sea surface temperature-dependent heating and implicit ``lateral fluxes'' has proven important to...

Data were examined to determine the structure of this intrusion (April 1-7, 1982) and to investigate its effects on water masses in the outer shelf region. A frontal eddy, made up of a warm filament separated from the main current by a region of cooler water, propagated southeastward at 30 cm/s, intruding onto the shelf near 26 deg N between April...

The growth rate of double-diffusive interleaving has been evaluated using Stern's (1967) model, which assumes vertical T/S gradients in the salt-fingering domain and compensating horizontal T/S gradients. The interleaving may take place along planes tilted with respect to the horizontal. For a given vertical scale, various cross-gradient and along-...

The shelf break frontal shape and the T-S relationships in the frontal vicinity have been observed to undergo a transition in the spring. It is shown that this transition should result from two simple assumptions: (1) during the early spring, the offshore density gradient becomes reversed in a layer of intermediate depth; and (2) the front is gravi...

In the present paper, a simple numerical model is used to study the warming of the mixed layer during the early summer. It is shown that the springtime temperature increase in the layer below the mixed layer (for example, in the cold pool on a continental shelf) has a maximum value which occurs for a limiting value of the surface heat flux. This is...

A conversion factor (T value) is presented to clarify the relationship between inaccuracy defined on the basis of settling velocity and inaccuracy defined on the basis of phi sizes in settling tubes. -Authors

The coefficient of longitudinal diffusion for salt has been calculated from the distribution of salinity observed in the Hudson Estuary at nine different times during 1974. The salinity distribution appears to be quasi steady-state, and the diffusion coefficient is spatially constant between the Upper Bay and Verplanck. The diffusion coefficient va...

diagram of CTD hydrographic stations near the shelf break in the New York Bight. These features occur within the shelf break frontal zone, which is associated with active interleaving between warm salty slope water and cooler fresher shelf water. Double-diffusive mixing is proposed as the mechanism responsible for the observed T-S correlations.

The nonlinear differential equation for the vertical diffusion of salt (or heat) has initially unstable solutions under conditions of high gravitational stability. These solutions stabilize as they approach alternating layers of high and low salinity gradient. A numerically computed example of this phenomenon resembles salinity finestructure observ...

During the next two decades, increasing numbers of spacecraft will be launched for the study of Earth processes. There will probably be an accelerated growth in the amount of data processed onboard and returned from spacecraft sensors. Data will become more sophisticated, because sensor technology will improve. The result of these developments is p...

Much of the responsibility for natural resource management, particularly for coastal zone management, lies with local, state, and regional agencies in the United States. Remote sensing data have the potential of making a major contribution to these management efforts. However, few of these agencies have the technical manpower and facilities necessa...

The individual background papers written by the members of the Working Group on Ocean Applications (WGOA) deal with the state-of-the-art of selected aspects of oceanic remote sensing and information systems, and of operational applications of these systems. Based on these papers, it is possible to determine a set of objectives which deserve high pr...

Vertical salinity profiles in the Hudson Estuary are extremely variable, and often contain finestructure similar to that in oceanic stratification. This finestructure may be caused by the stability-dependent vertical diffusion of salt. The interpretation of T-S diagrams indicates that, to a first order, temperature and salinity are controlled by co...

The 1- to 16-Hz infrasound detected by a four-element array of microphones was recorded for 75 s six times daily from April through June 1971. The spectra of these records are diurnally variable but stationary on a shorter time scale. The spectral slopes are inconsistent with theoretical spectral slopes of turbulent pressure fluctuations and of sou...

The five major program areas supported by this contract are reviewed. References to published papers and papers in various stages of preparation are given. Sample charts of E, P and E-P and the harmonic analysis of the E-P fields for the Equatorial Atlantic are given and ways to study variation in sub-surface salinity are described. The ways data f...

1‐ through 16‐Hz infrasound detected by a four‐element array of microphones was recorded six times daily from April through June 1971. Four records were selected as representative of extremely low‐amplitude conditions. Four other records were chosen as representative of highly coherent, strong‐amplitude records. These latter four records all exhibi...

Summary Infrasound with frequencies of 1–16 Hz, detected by an array of four thermistor flow-meter microphones in Sterling Forest, New York, was observed to have a continuous background with peak energy distributed near 16 Hz in frequency, with amplitudes of about 1 dyn cm-2, and arriving from the south-west and south-east at slightly above the spe...

An ad hoc statistic, Cophase, is introduced for use in processing data from an array of detectors sensing both a propagating signal and uncorrelated noise. Cophase is basically the normalized sum over all detector pairs and over all frequencies of the cosines of the differences between phase differences from Fourier analysis and phase differences f...

Climate change often manifests itself through changes in seasonal weather patterns and dynamics, but paleoclimate records rarely have intra-annual resolution. The precipitation delta 18O, either directly measured or indirectly inferred from other datable materials, is one of the most widely used proxies for paleoclimate studies. It is important, th...

Quantization in the phase plane orbits of a toy climate model suggests the possibility of explaining electron behaviour without appealing to the uncertainty principle. It is shown that a semi-classical model based on classical physics and one additional postulate predicts chaotic behaviour in the problem of an electron in a dissipative square well...

Thesis, Columbia University. Bibliography: leaves 49-51.

Recent studies are reported which have contributed to the knowledge of atmospheric structure and have established the practicality of infrasonic techniques for probing the atmosphere to heights of 120 km or more. Observations of a few types of infrasound are reviewed, and the theories used to account for the infrasound propagation and the deduced a...

Two distinct groups of infrasonic waves from Saturn V, 1967, were recorded at Palisades, New York, 1485 kilometers from the launch site. The first group, of 10-minute duration, began about 70 minutes after launch time; the second, having more than twice the amplitude and a duration of 9 minutes, commenced 81 minutes after launch time. From informat...

summaryA theory analogous to the Longuet-Higgins theory on the generation of microseisms explains the generation of microbaroms by standing water waves associated with marine storms. The spectral characteristics and the amplitude order-of-magnitude of microbaroms that are predicted by this theory agree well with observations. The theory is based on...

Nearly sinusoidal microoscillations of air pressure of the order of 1 to 10 microbars (dynes/cm²), which have been recorded on a Lamont tripartite array of line microphones, have been identified as infrasonic waves arising from an intense atmospheric low pressure system off Newfoundland. Although the nearly sinusoidal pressure variations show good...

An important class of infrasonicwaves in the atmosphere and seismic waves in the earth's crust are generated by ocean waves in marine storms. The determination of wave vectors from such large sources by detector arrays is limited by the systematic errors introduced by the large sources, as well as by the resolving power and ambiguities associa...

Micropressure fluctuations occurring at the same time as the arrival of seismic waves were recorded at many localities following the Alaskan earthquake of March 27, 1964. It is shown that at Palisades, New York, Berkeley, California, and Honolulu, Hawaii, the pressure waves were produced by vertical ground motion associated with local Rayleigh wave...