Miracle-dz/UniFAR-FTUs huggingface dataset:
Observations of ozone and related species in the northeast Pacific during the PHOBEA campaigns: 2. Airborne observations

During late March and April of 1999 the University of Wyoming's King Air research aircraft measured atmospheric concentrations of NO, O3, peroxyacetyl nitrate (PAN), CO, CH4, VOCs, aerosols, and J(NO2) off the west coast of the United States. During 14 flights, measurements were made between 39°–48°N latitude, 125°–129°W longitude, and at altitudes from 0–8 km. These flights were part of the Photochemical Ozone Budget of the Eastern North Pacific Atmosphere (PHOBEA) experiment, which included both ground-based and airborne measurements. Flights were scheduled when meteorological conditions minimized the impact of local pollution sources. The resulting measurements were segregated by air mass source region as indicated by back isentropic trajectory analysis. The chemical composition of marine air masses whose 5-day back isentropic trajectories originated north of 40°N latitude or west of 180°W longitude (WNW) differed significantly from marine air masses whose 5-day back isentropic trajectories originated south of 40°N latitude and east of 180°W longitude (SW). Trajectory and chemical analyses indicated that the majority of all encountered air masses, both WNW and SW, likely originated from the north-western Pacific and have characteristics of emissions from the East Asian continental region. However, air masses with WNW back trajectories contained higher mixing ratios of NO, NOx, O3, PAN, CO, CH4, various VOC pollution tracers, and aerosol number concentration, compared to those air masses with SW back trajectories. Calculations of air mass age using two separate methods, photochemical and back trajectory, are consistent with transport from the northwestern Pacific in 8–10 days for air masses with WNW back trajectories and 16–20 days for air masses with SW back trajectories. Correlations, trajectory analysis, and comparisons with measurements made in the northwestern Pacific during NASA's Pacific Exploritory Mission-West Phase B (PEM-West B) experiment in 1994 are used to investigate the data. These analyses provide evidence that anthropogenically influenced air masses from the northwestern Pacific affect the overall chemical composition of the northeastern Pacific troposphere.
Models of ocean ridge lithospheric deformation: Dependence on crustal thickness, spreading rate, and segmentation

We use three-dimensional (3-D) temperature and rheology models to investigate the effects of crustal thickness and ridge segmentation on mid-ocean ridge lithospheric structure. We find that crustal thickness variations associated with focused magma accretion at a slow spreading ridge segment can cause significant along-axis gradients in crustal temperature and a “pita-pocket”-shaped weak zone in the lower crust that decouples brittle upper crust from upper mantle. In contrast, fast spreading ridge segments with little crustal thickness variation are found to be uniformly weak along axis. The overthickened crust produced by ridge-hotspot interaction alters the heat balance between magma emplacement and hydrothermal cooling, creating an extremely weak lithosphere in a steady state model. We apply a simple two-dimensional (2-D) cyclic faulting model to across-axis sections of temperature and rheological structure. Slow spreading segments are predicted to have relatively large along axis variations in fault height and spacing. In contrast, fast spreading and hotspot-affected segments are predicted to have much smaller variations in faulting styles, except in the immediate vicinity of a major transform fault. The presence or lack of a steady state axial rift valley is also predicted to depend on crustal thickness, spreading rate, and the ability of rift-bounding normal faults to propagate along axis. For fast spreading and hotspot-affected segments, the sizes of axial rift valleys are predicted to be small and may not be distinguishable from those of neovolcanic or magma-chamber-supported isostatic features. This is in contrast to most slow spreading segments, where axial rift valleys are predicted to be a dominant morphological feature. For a slow spreading segment of great length, however, the axial rift valley size is predicted to diminish toward the segment center because large faults formed at segment distal ends cannot propagate through a large decoupling zone created by locally thickened crust at the segment center.
Absence of HIV-1 superinfection 1 year after infection between 1985 and 1997 coincides with a reduction in sexual risk behavior in the seroincident Amsterdam cohort of homosexual men.

BACKGROUND Incidence rates of human immunodeficiency virus type 1 (HIV-1) superinfection differ among cohorts and, as yet, only 2 cohorts of homosexual men have been screened. Here, we investigated the incidence of HIV-1 superinfection during the first year after infection among homosexual participants in the Amsterdam Cohort Studies on HIV infection and AIDS who seroconverted between 1985 and 1997. METHODS We analyzed env C2-C4 diversity in the serum of therapy-naive participants, using a heteroduplex mobility assay; heteroduplexes were considered to be indicators of potential dual infections, in which case env C2-C4 polymerase chain reaction (PCR) products were cloned and sequenced. Sequences were subjected to phylogenetic analysis. Data on the sexual behavior of participants were collected from 1 year before seroconversion until the end of the investigated period. RESULTS For 89 seroconverters with a detectable viral load (>1000 copies/mL), env PCR products were generated from serum samples obtained at seroconversion and 1 year later. Heteroduplexes were observed in 68 of the 89 patients; among these 68 patients, a median of 9 molecular clones per time point was sequenced. Phylogenetic analysis did not reveal evidence for superinfection; 1 patient was HIV-1 coinfected. Shortly after diagnosis of HIV infection, the number of sex partners decreased, the frequency of anal intercourse declined, and condom use increased. CONCLUSIONS The incidence of HIV-1 superinfection soon after seroconversion in this cohort is low. Risk reduction shortly after HIV-1 diagnosis early during the HIV-1 epidemic in the Netherlands may have contributed to the absence of HIV-1 superinfection observed in this study.
Solute transport through large uniform and layered soil columns

Solute transport experiments are often conducted with homogeneous soils, whereas transport in real situations takes place in heterogeneous soils. An experiment was conducted to compare unsaturated solute transport through uniform and layered soils. Pulse inputs of tritiated water, bromide and chloride were applied under steady flow conditions to the tops of two large (0.95 m diameter by 6 m deep) soil columns. One column was uniformly filled with loamy fine sand and the other filled with alternating 20-cm-thick layers of loamy fine sand and silty clay loam. Soil solution samples were collected during the experiment with suction candles installed at various depths in the columns. Solute transport parameters were estimated by fitting the convection-dispersion equation to the observed breakthrough curves for each solute at various depths in each column. The match between the resulting calibrated curves and the experiment was better for the layered soil column than for the uniform soil column. The results displayed no clear relationship between the dispersion coefficients and depth for any of the tracers for either column. However, dispersivities were greater in the uniform column (3.5 cm) than in the layered column (1.2 cm), while retardation factors for bromide and chloride were similar (0.8 and 0.83, respectively, for the uniform and layered columns). A retardation factor less than one is attributed to anion exclusion. There was evidence of preferential flow in the uniform soil column. The peak concentrations at 5 m depth were greater than those observed at 4 m. Such behavior is inconsistent with one-dimensional flow. Similar results were observed in an experiment performed 3.5 years earlier using the same soil column and approximately the same flow rates, but using a different tracer and associated chemical analysis, different soil saturation prior to the execution of the experiment, and different experimental personnel. This supports the thesis that the anomalous behavior is due to some form of preferential flow rather than due to experimental error.
Hydrologic problems concerning the runoff in headwater regions

In this paper are discussed some of the concepts of watershed hydrology as related to surface, subsurface, and ground-water runoff. Data from Swiss and other watershed studies illustrate that true ground-water discharge may form the major part of flood flows, with minor or no contributions by surface runoff. Results of experiments with sand troughs to determine the effect of aquifer length are used to explain apparent anomalies in the comparison of the two Emmental watersheds. It is postulated that the length of the aquifer is a factor controlling ground-water storage and sensitivity of stream flow to rainfall. In the sand troughs and the Swiss watersheds the same volume of ground-water storage did not always produce the same runoff rate. The explanation is that outflow is controlled by the rate of filling. Short rains of high intensity, even without any surface runoff, will produce crests more pointed than those of rains of longer duration and lower intensity.
Northern Hemisphere Climatology and Trends of Statistical Moments Documented from GHCN-Daily Surface Air Temperature Station Data from 1950 to 2010

AbstractThe first four statistical moments and their trends are calculated for the average daily surface air temperature (SAT) from 1950 to 2010 using the Global Historical Climatology Network–Daily station data for each season relative to the 1961–90 climatology over the Northern Hemisphere. Temporal variation of daily SAT probability distributions are represented as generalized linear regression coefficients on the mean, standard deviation, skewness, and kurtosis calculated for each 10-yr moving time window from 1950–59 to 2001–10. The climatology and trends of these statistical moments suggest that daily SAT probability distributions are non-Gaussian and are changing in time. The climatology of the first four statistical moments has distinct spatial patterns with large coherent structure for mean and standard deviation and relatively smaller and more regionalized patterns for skewness and kurtosis. The linear temporal trends from 1950 to 2010 of the first four moments also have coherent spatial pattern.
Contribution to the atmospheric mineral aerosol load from land surface modification

An estimation of the contribution of mineral dust from disturbed soils (i.e., soils affected by human activity and/or climate variability) to the total atmospheric mineral aerosol load is presented. A three-dimensional atmospheric dust transport model was used to simulate the distribution of dust optical thickness in response to individual dust sources, which include natural soils known to have been affected by the Saharan/Sahelian boundary shift, cultivation, deforestation, and wind erosion. The distributions extracted from advanced very high resolution radiometer (AVHRR) optical thickness retrievals were used to constrain likely source combinations. The results indicate that observed features like the seasonal shift of maximum optical thickness caused by Saharan dust over the Atlantic ocean are best reproduced if disturbed sources contribute 30–50% of the total atmospheric dust loading.
Bubble transport in rip currents

A number of remote and in situ acoustical sensors were mounted in the surf zone off Scripps Pier, La Jolla, California, during March 1997 and used to characterize rip currents and their ability to transport bubbles offshore from the surf zone. The bubble size distributions and air fractions at the injection point were measured using an acoustical resonator and a conductivity sensor right in the surf zone. The offshore moving bubble plume was tracked with a multibeam 100 kHz Doppler sidescan sonar, giving the spatial extent and offshore variability in the rip events as well as information about the surface wave field. Furthermore, three acoustical resonators were mounted at 2.5 m depth 55–60 m farther offshore to probe the bubble field 300–400 s after injection. These results are interpreted using models that include bubble buoyancy and dissolution, rip current advection, and the turbulent boundary layer, which is represented by the Christoffersen and Jonsson [1985] formulation.
Can climate warming induce glacier advance in Taylor Valley, Antarctica?

Abstract Changes in the extent of the polar alpine glaciers within Taylor Valley, Antarctica, are important for understanding past climates and past changes in ice-dammed lakes. Comparison of ground-based photographs, taken over a 20 year period, shows glacier advances of 2-100 m. Over the past ~103 years the climate has warmed. We hypothesize that an increase in average air temperature alone can explain the observed glacier advance through ice softening. We test this hypothesis by using a flowband model that includes a temperature-dependent softness term. Results show that, for a 2˚C warming, a small glacier (50 km2) advances ~25m and the ablation zone thins, consistent with observations. A doubling of snow accumulation would also explain the glacial advance, but predicts ablation-zone thickening, rather than thinning as observed. Problems encountered in modeling glacier flow lead to two intriguing but unresolved issues. First, the current form of the shape factor, which distributes the stress in simple flow models, may need to be revised for polar glaciers. Second, the measured mass-balance gradient in Taylor Valley may be anomalously low, compared to past times, and a larger gradient is required to develop the glacier profiles observed today.
Highlight area inpainting guided by illumination model

In this paper, we proposed a two-step algorithm based on the combination of the exemplar-based algorithm and the illumination model to deal with specular images, especially those contain saturated pixels in the highlight areas. First the proposed modified exemplar-based algorithm is employed to process the unsaturated specular pixels under the supervision of illumination model. Then we inpaint the rest regions in which the pixels are saturated with original exemplar-based algorithm to obtain the final result. Experimental results demonstrate that the proposed algorithm performs better on the images with saturated pixels in the highlight areas compared with classical highlight removal and image inpainting algorithms.
Codes Identifying Sets of Vertices in Random Networks ∗

In this paper we deal with codes identifying sets of vertices in random networks; that is, (1,≤ l)-identifying codes. These codes enable us to detect sets of faulty processors in a multiprocessor system, assuming that the maximum number of faulty processors is bounded by a fixed constant l. The (1,≤ 1)-identifying codes are of special interest. For random graphs we use the model G(n, p), in which each one of the `
Modulation of Caribbean Precipitation by the Madden–Julian Oscillation

Abstract Based on 12 years of daily satellite precipitation data and reanalysis winds, intraseasonal (30–90 days) variability in Caribbean precipitation is linked to phases of the Madden–Julian oscillation (MJO). Intraseasonal variability is largest during September–November (SON), but some modulation of precipitation by the MJO appears throughout all seasons. Precipitation anomalies up to 50% above (below) the annual mean are observed in phases 1 and 2 (5 and 6) of the MJO. The changes in Caribbean precipitation associated with the MJO are shown to be related to changes in the low-level (925 hPa) winds. When precipitation anomalies are above (below) average in phases 1 and 2 (5 and 6), wind anomalies act to decrease (increase) the strength of the prevailing easterly trade winds. The changes in the low-level winds are most apparent in the region of the Caribbean low-level jet (CLLJ), and divergence anomalies associated with the entrance and exit regions of the CLLJ precede the precipitation anomalies. The.
Changes in the Spread of the Variability of the Seasonal Mean Atmospheric States Associated with ENSO

Abstract For a fixed sea surface temperature (SST) forcing, the variability of the observed seasonal mean atmospheric states in the extratropical latitudes can be characterized in terms of probability distribution functions (PDFs). Predictability of the seasonal mean anomalies related to interannual variations in the SSTs, therefore, entails understanding the influence of SST forcing on various moments of the probability distribution that characterize the variability of the seasonal means. Such an understanding for changes in the first moment of the PDF for the seasonal means with SSTs is well documented. In this paper the analysis is extended to include also the impact of SST forcing on the second moment of the PDFs. The analysis is primarily based on ensemble atmospheric general circulation model (AGCM) simulations forced with observed SSTs for the period 1950–94. To establish the robustness of the results and to ensure that they are not unduly affected by biases in a particular AGCM, the analysis is ba.
Southern Exposure: New Paleoclimate Insights From Southern Ocean and Antarctic Margin Sediments

Much of what is known about the evolution of Antarctica's cryosphere in the geologic past is derived from ice-distal deep-sea sedimentary records. Recent advances in drilling technology and climate proxy methods have made it possible to retrieve and interpret high-quality ice-proximal sedimentary sequences from Antarctica's margins and the Southern Ocean. These records contain a wealth of information about the individual histories of the East and West Antarctic Ice Sheets and associated temperature change in the circum-Antarctic seas. Emerging studies of Antarctic drill cores provide evidence of dynamic climate variability on both short and long timescales over the past 20 million years. This geologic information is critical for testing and improving computer model simulations used to predict future environmental change in the polar regions. Identifying the mechanistic links between past Antarctic ice-volume fluctuations and oceanographic change is necessary for understanding Earth's long-term climate evolution. While recent successes highlight the value of ice-proximal records, additional scientific drilling and climate proxy development are required to improve current knowledge of Antarctica's complex paleoenvironmental history.
Impact of Climate Change on Agricultural Production and Sustainability in Nigeria

Two major issues that have recently dominated international development debates are climate change on the one hand and the survival of agricultural production systems on the other hand. This study therefore attempts to provide sufficient empirical evidence-base for invigorated debate on the development of the agricultural sector in Nigeria in the context of climate change. The data analysis follows two approaches: when climate change is captured in the model and when it is not. After extensive and rigorous analysis of data, results reveal that if climate change is isolated from the model, irrigation, fertilizer, arable land and agricultural labour significantly correlate with crop production both on the aggregate and on individual samples; agricultural labour is a significant factor influencing livestock production; while agricultural machinery and population density significantly determine forestry output. After accounting for climate change, analysis indicates that crop and livestock sub-sectors are impacted by rainfall alone, while both rainfall and temperature impact on fishery. Conversely, forestry is not significantly affected by climate change. Findings equally reveal that the impact of other agricultural inputs is significantly reduced by climate change, indicating that beside the direct negative impact of climate change on agriculture, it can also have an indirect negative effect by reducing the impact of other agricultural production inputs. Further breakdown of the crop sub-sector shows that only the rainfall component of climate change will impact on cassava alone. The impact of climate change on yam, rice, sorghum, millet and maize is found to be insignificant. Also, irrigation, fertilizer, arable land and agricultural labour are found to be
Modeling Discharge Rates Using a Coupled Modeled Approach for the Merced River in Yosemite National Park

This study describes the application of the NASA version of the Carnegie‐Ames‐Stanford Approach (CASA) ecosystem model coupled with a surface hydrologic routing scheme previously called the Hydrological Routing Algorithm (HYDRA) to model monthly discharge rates from 2000 to 2007 on the Merced River drainage in Yosemite National Park, California. To assess CASA‐HYDRA's capability to estimate actual water flows in extreme precipitation years, the focus of this study is the 2007 water year, which was very dry, and the 2005 water year, which was a moderately wet year in the historical record. Prior to comparisons to gauge records, CASA‐HYDRA snowmelt algorithms were modified with equations from the U.S. Department of Agriculture Snowmelt‐Runoff Model (SRM), which has been designed to predict daily streamflow in mountain basins where snowmelt is a major runoff factor. Results show that model predictions closely matched monthly flow rates at the Pohono Bridge gauge station (USGS#11266500), with R2 = 0.67 and Nash‐Sutcliffe (E) = 0.65. By subdividing the upper Merced River basin into subbasins with high spatial resolution in the gridded modeling approach, we were able to determine which biophysical characteristics in the Sierra differed to the largest degree in extreme low‐flow and high‐flow years. Average elevation and snowpack accumulation were found to be the most important explanatory variables to understand subbasin contributions to monthly discharge rates.
The generalized inverse of a nonlinear quasigeostrophic ocean circulation model

Abstract The generalized inverse is constructed for a nonlinear, single-layer quasigeostrophic model, together with initial conditions and a finite number of interior data. With the exception of doubly Periodic boundary condition all constraints are weak. The inverse minimizes a penalty functional that is quadratic in the errors in prior estimates of the model forcing, the initial conditions, and the measurements. The quadratic form consists of the inverses of the prior error covariances. The nonlinear Euler-Lagrange equations are solved iteratively. Each iterate is a linear Euler-Lagrange problem, which in turn is solved in terms of a prior streamfunction estimate, plus a finite-linear combination of representers (one for each linear measurement functional). The sequence of inverse streamfunction estimates is bounded and so has at least one limit Point. The sequence of representer matrices is uniformly positive definite and so the limiting inverse is a minimum, rather than simply an extremum of the penal.
Aquifers as archives of paleoclimate

The isotopic and elemental compositions of groundwater are influenced by climatic conditions at the time of recharge and are therefore indicators of climate change. The potential of aquifers as archives of paleoclimate was discussed at a 3-day conference held at Lamont-Doherty Geological Observatory, Palisades, N.Y. , from May 18 to 20. About forty scientists from nine countries attended the meeting, which was sponsored by the Northeast Regional Center of the National Institute for Global Environmental Change (NIGEC) and the National Science Foundation. Fifteen invited papers were presented, which formed the background of extensive discussions on applying isotopic methods to deriving information on climate change during the last 30,000 years from the groundwater archive.