Observed Temperature Profiles Research Articles

Estimation of Hydraulic Conductivity in an Alluvial System Using Temperatures

Well water temperatures are often collected simultaneously with water levels; however, temperature data are generally considered only as a water quality parameter and are not utilized as an environmental tracer. In this paper, water levels and seasonal temperatures are used to estimate hydraulic conductivities in a stream-aquifer system. To demonstrate this method, temperatures and water levels are analyzed from six observation wells along an example study site, the Russian River in Sonoma County, California. The range in seasonal ground water temperatures in these wells varied from <0.2 degrees C in two wells to approximately 8 degrees C in the other four wells from June to October 2000. The temperature probes in the six wells are located at depths between 3.5 and 7.1 m relative to the river channel. Hydraulic conductivities are estimated by matching simulated ground water temperatures to the observed ground water temperatures. An anisotropy of 5 (horizontal to vertical hydraulic conductivity) generally gives the best fit to the observed temperatures. Estimated conductivities vary over an order of magnitude in the six locations analyzed. In some locations, a change in the observed temperature profile occurred during the study, most likely due to deposition of fine-grained sediment and organic matter plugging the streambed. A reasonable fit to this change in the temperature profile is obtained by decreasing the hydraulic conductivity in the simulations. This study demonstrates that seasonal ground water temperatures monitored in observation wells provide an effective means of estimating hydraulic conductivities in alluvial aquifers.

森林上から林内にかけての顕熱輸送メカニズム

The atmosphere-forest heat exchange mechanism was investigated based on the measurement applying eddy correlation method at 3 heights above and 2 heights inside the canopy of a coniferous forest. Counter gradient or zero gradient sensible heat transport was observed inside the canopy. Cospectral analysis indicates that this counter gradient flux is caused by the high frequency eddies, suggesting that the penetrating cold temperature gusts are contributing to this phenomena. Large eddies are contributing to the co-gradient flux even in the canopy. A 2nd order turbulence closure model for a horizontally homogeneous field was applied to compare with the observation. For the wind from the valley, the observed temperature profiles and sensible heat flux agreed with the computation. However, for the wind from the ridge, the observed temperature field suggested the occurrence of drainage flows which are not expressed by the computation.

Assimilating 20 years of Atlantic XBT data into HYCOM: a first look

Expendable bathythermographic (XBT) data for the years 1972–1991 have been assimilated into a Hybrid Coordinate Ocean Model (HYCOM) for the Atlantic Ocean. Climatological salinity profiles were combined with the observed temperature profiles to estimate companion potential-density profiles, which are used to determine the observation-based local structure of the model’s hybrid layers. The model’s density, temperature, and layer-interface-depth fields were corrected monthly via optimal interpolation. Preliminary results presented here show that the data have a major impact on the simulation, correcting model biases, and that the corrections persist between monthly assimilations.

Influence of interannual rainfall anomalies on sea level variations in the tropical Indian Ocean

A halo‐thermal, reduced‐gravity model with four active layers is used to investigate how interannual rainfall anomalies affect sea surface height (SSH) variability in the Indian Ocean. The model is forced by monthly varying winds observed over the period 1980–2000 in two experiments that differ by their rainfall forcing, Run FSU and Run Arkin, forced by climatological and interannually varying rainfall, respectively. Compared to the large impact of wind on SSH (about 30 cm), the impact of rain is much smaller. Its maximum (found in the southeastern Indian Ocean during the rainfall deficits of 1994 and 1997) is only 2 cm. Because rainfall significantly affects model salinity and temperature, the deficits make the layers of Run Arkin colder and saltier than in Run FSU, causing a −5 cm change in sea level. Baroclinic adjustments also occur such that the top (bottom) two layers are thicker (thinner), increasing sea level by 3 cm and hence significantly reducing the SSH change due to steric effects alone. SSH variability in either Run Arkin or Run FSU compares very well with TOPEX data. Although the impact of rainfall on SSH is negligible, salinity variations significantly affect dynamic‐height calculations of SSH. In the model, the neglect of salinity variations leads to an error of 5 to 10 cm along the eastern boundary, in the Bay of Bengal, and in the interior ocean south of 8°S. This error is validated by the difference between TOPEX data and SSH derived from observed temperature profiles.

A simple model for explosive combustion of premixed natural gas with air in a bubbling fluidized bed of inert sand

The combustion of premixed natural gas and air has been studied in a bubbling fluidized bed of inert particles. The temperature of the solids was carefully monitored, using 8 thermocouples, immersed in the bed at different heights. The observed temperature profiles were used to find the height above the distributor at which most of the combustion occurred and on this basis a clear distinction could be made between combustion above the bed and inside the bed. The region where most of the heat of combustion is evolved depends on the average bed temperature. If this temperature is low, the gases burn above the bed or just under its upper surface, but at higher temperatures the process is located close to the distributor. Rapid fluctuations in the measured temperature and pressure indicate that the process inside the bed is not a steady one. The model developed here assumes that combustion takes place inside bubbles of premixed gases, as they move through the bed. A detailed chemical kinetic model was used to calculate the induction period for ignition. The model can predict the height above the distributor at which bubbles should ignite and explode. Comparison of the experimental results with the modeling calculations indicates that the course taken by the process depends on temperature. At the lowest temperatures, the gases burn above the bed. In the high temperature range, where the bubbles ignite is determined by the induction period. At intermediate temperatures the location of the reaction is determined by the depth of the bed and bubble size, with ignition spreading from above the bed to bubbles, which are about to leave, but are still in the bed. That bubbles explode at different heights up the bed is reflected in the acoustic signals registered above and below the bed. The associated changes in the composition of the flue gases are also very characteristic.

Thermographic Detection of Fatigue Damage of Reactor Pressure Vessel (RPV) Steels

An IR (IR) thermography technique, as a nondestructive evaluation technique, was applied to investigate the fatigue damage of reactor pressure vessel (RPV) steels during 20 Hz and 1000 Hz fatigue testing. Five stages of temperature profile were observed: an initial increase of the average specimen temperature, a region of temperature decrease, an equilibrium (steady-state) temperature region, an abrupt increase of the temperature, and a drop of temperature following specimen failure. The relationship between the temperature, stress-strain state, and fatigue behavior is discussed. Both thermodynamic and heat-transfer theories are applied to model the observed temperature variation during fatigue. The stress-strain state of the material has been back-calculated from the observed temperature profiles. The predicted and measured temperature evolutions and mechanical behavior during fatigue were found to be in good agreement. Thermography appears to provide a useful method of investigating the stress-strain behavior during fatigue.

Temperature-Profile Methods for Estimating Percolation Rates in Arid Environments

Percolation rates are estimated using vertical temperature profiles from sequentially deeper vadose environments, progressing from sediments beneath stream channels, to expansive basin-fill materials, and finally to deep fractured bedrock underlying mountainous terrain. Beneath stream channels, vertical temperature profiles vary over time in response to downward heat transport, which is generally controlled by conductive heat transport during dry periods, or by advective transport during channel infiltration. During periods of stream-channel infiltration, two relatively simple approaches are possible: a heat-pulse technique, or a heat and liquid-water transport simulation code. Focused percolation rates beneath stream channels are examined for perennial, seasonal, and ephemeral channels in central New Mexico, with estimated percolation rates ranging from 100 to 2100 mm d−1. Deep within basin-fill and underlying mountainous terrain, vertical temperature gradients are dominated by the local geothermal gradient, which creates a profile with decreasing temperatures toward the surface. If simplifying assumptions are employed regarding stratigraphy and vapor fluxes, an analytical solution to the heat transport problem can be used to generate temperature profiles at specified percolation rates for comparison to the observed geothermal gradient. Comparisons to an observed temperature profile in the basin-fill sediments beneath Frenchman Flat, Nevada, yielded water fluxes near zero, with absolute values <10 mm yr−1. For the deep vadose environment beneath Yucca Mountain, Nevada, the complexities of stratigraphy and vapor movement are incorporated into a more elaborate heat and water transport model to compare simulated and observed temperature profiles for a pair of deep boreholes. Best matches resulted in a percolation rate near zero for one borehole and 11 mm yr−1 for the second borehole.

Temperature‐Profile Methods for Estimating Percolation Rates in Arid Environments

Percolation rates are estimated using vertical temperature profiles from sequentially deeper vadose environments, progressing from sediments beneath stream channels, to expansive basin‐fill materials, and finally to deep fractured bedrock underlying mountainous terrain. Beneath stream channels, vertical temperature profiles vary over time in response to downward heat transport, which is generally controlled by conductive heat transport during dry periods, or by advective transport during channel infiltration. During periods of stream‐channel infiltration, two relatively simple approaches are possible: a heat‐pulse technique, or a heat and liquid‐water transport simulation code. Focused percolation rates beneath stream channels are examined for perennial, seasonal, and ephemeral channels in central New Mexico, with estimated percolation rates ranging from 100 to 2100 mm d−1. Deep within basin‐fill and underlying mountainous terrain, vertical temperature gradients are dominated by the local geothermal gradient, which creates a profile with decreasing temperatures toward the surface. If simplifying assumptions are employed regarding stratigraphy and vapor fluxes, an analytical solution to the heat transport problem can be used to generate temperature profiles at specified percolation rates for comparison to the observed geothermal gradient. Comparisons to an observed temperature profile in the basin‐fill sediments beneath Frenchman Flat, Nevada, yielded water fluxes near zero, with absolute values &lt;10 mm yr−1. For the deep vadose environment beneath Yucca Mountain, Nevada, the complexities of stratigraphy and vapor movement are incorporated into a more elaborate heat and water transport model to compare simulated and observed temperature profiles for a pair of deep boreholes. Best matches resulted in a percolation rate near zero for one borehole and 11 mm yr−1 for the second borehole.

Temperature-Profile Methods for Estimating Percolation Rates in Arid Environments

Percolation rates are estimated using vertical temperature profiles from sequentially deeper vadose environments, progressing from sediments beneath stream channels, to expansive basin-fill materials, and finally to deep fractured bedrock underlying mountainous terrain. Beneath stream channels, vertical temperature profiles vary over time in response to downward heat transport, which is generally controlled by conductive heat transport during dry periods, or by advective transport during channel infiltration. During periods of stream-channel infiltration, two relatively simple approaches are possible: a heat-pulse technique, or a heat and liquid-water transport simulation code. Focused percolation rates beneath stream channels are examined for perennial, seasonal, and ephemeral channels in central New Mexico, with estimated percolation rates ranging from 100 to 2100 mm d−1. Deep within basin-fill and underlying mountainous terrain, vertical temperature gradients are dominated by the local geothermal gradient, which creates a profile with decreasing temperatures toward the surface. If simplifying assumptions are employed regarding stratigraphy and vapor fluxes, an analytical solution to the heat transport problem can be used to generate temperature profiles at specified percolation rates for comparison to the observed geothermal gradient. Comparisons to an observed temperature profile in the basin-fill sediments beneath Frenchman Flat, Nevada, yielded water fluxes near zero, with absolute values <10 mm yr−1. For the deep vadose environment beneath Yucca Mountain, Nevada, the complexities of stratigraphy and vapor movement are incorporated into a more elaborate heat and water transport model to compare simulated and observed temperature profiles for a pair of deep boreholes. Best matches resulted in a percolation rate near zero for one borehole and 11 mm yr−1 for the second borehole.

Titan's atmospheric engine: an overview

Heating occurs in Titan's stratosphere from the absorption of incident solar radiation by methane and aerosols. About 10% of the incident sunlight reaches Titan's surface and causes heating there. Thermal radiation redistributes heat within the atmosphere and cools to space. The resulting vertical temperature profile is stable against convection and a state of radiative equilibrium is established. Equating theoretical and observed temperature profiles enables an empirical determination of the vertical distribution of thermal opacity. A uniformly mixed aerosol is responsible for most of the opacity in the stratosphere, whereas collision-induced absorption of gases is the main contributor in the troposphere. Occasional clouds are observed in the troposphere in spite of the large degrees of methane supersaturation found there. Photochemistry converts CH 4 and N 2 into more complex hydrocarbons and nitriles in the stratosphere and above. Thin ice clouds of trace organics are formed in the winter and early spring polar regions of the lower stratosphere. Precipitating ice particles serve as condensation sites for supersaturated methane vapor in the troposphere below, resulting in lowered methane degrees of supersaturation in the polar regions. Latitudinal variations of stratospheric temperature are seasonal, and lag instantaneous response to solar irradiation by about one season for two reasons: (1) an actual instantaneous thermal response to a latitudinal distribution of absorbing gases, themselves out of phase with the sun by about one season, and (2) a sluggish dynamical response of the stratosphere to the latitudinal transport of angular momentum, induced by radiative heating and cooling. Mean vertical abundances of stratospheric organics and aerosols are determined primarily by atmospheric chemistry and condensation, whereas latitudinal distributions are more influenced by meridional circulations. In addition to preferential scavenging by precipitating ice particles from above, the polar depletion of supersaturated methane results from periodic scavenging by short-lived tropospheric clouds, coupled with the steady poleward march of the continuously drying atmosphere due to meridional transport.

A theoretical model analysis of the sudden narrow temperature-layer formation observed in the ALOHA-93 Campaign

The behavior of temperature and wind profiles observed on 21 October 1993 in the ALOHA-93 Campaign is theoretically and numerically analyzed. A sudden temperature rise took place in a very narrow vertical region (3–4 km) at about 87 km. Simultaneously observed radar wind profiles and mesospheric airglow wave structures that show a horizontal phase speed of 35 m/s and a period of about half an hour strongly suggest that a critical level may occur in the proximity of that altitude and that the energy dissipation due to the interaction of the gravity wave with the critical level causes the temperature rise. The numerical model used is a solution to the gravity wave – mean-flow interaction in the critical layer, including a simple cooling mechanism and a wave-energy dissipation simulated by the "optical model" technique. The solutions for the temperature variations so obtained show good agreement with the observed temperature profiles at different times, providing a quantitative explanation for the temperature inversion layer as a phenomenon of gravity wave – critical layer interaction. PACS Nos.: 91.10V, 94.10D

The mass profile of A1413 observed with $\vec {XMM}$–$\vec {Newton}$: Implications for the M–T relation

We present an XMM-Newton observation of A1413, a hot (kT= 6:5 keV) galaxy cluster at z= 0:143. We construct gas and temperature profiles over the radial range up to1700 kpc. This radius corresponds to a density contrast 500 with respect to the critical density at the redshift of the cluster, or equivalently0:7r200. The gas distribution is well described by a model in the outer regions, but is more concentrated in the inner250 kpc. We introduce a new parameterisation for the inner regions, which allows a steeper gas density distribution. The radial temperature profile does not exhibit a sharp drop, but rather declines gradually towards the outer regions, by20% between 0:1r200 and 0:5r200. The projected temperature profile is well described by a polytropic model with= 1:07 0:01. We find that neither projection nor PSF eects change substantially the form of the temperature profile. Assuming hydrostatic equilibrium and spherical symmetry, we use the observed temperature profile and the new parametric form for the gas density profile to produce the total mass distribution of the cluster. The mass profile is remarkably well fitted with the Moore et al. (1999) parameterisation, implying a very centrally peaked matter dis- tribution. The concentration parameter is in the range expected from numerical simulations. There are several indications that beyond a density contrast 600, the gas may no longer be in hydrostatic equilibrium. There is an oset with respect to adia- batic numerical simulations in the virialised part of the cluster, in the sense that the predicted mass for the cluster temperature is40% too high. The gas distribution is peaked in the centre primarily as a result of the cusp in the dark matter profile. The X-ray gas to total mass ratio rises with increasing radius to fgas 0:2. These data strongly support the validity of the current approach for the modeling of the dark matter collapse, but confirm that understanding the gas specific physics is essential.

Temperature Profiles of Nearby Clusters of Galaxies

We report results from the analysis of 21 nearby galaxy clusters, 11 with cooling flow (CF) and 10 without cooling flow, observed with BeppoSAX. The temperature profiles of both CF and non-CF systems are characterized by an isothermal core extending out to ~0.2r180; beyond this radius both CF and non-CF cluster profiles rapidly decline. Our results differ from those derived by other authors, who found either continuously declining profiles or substantially flat profiles. Neither the CF nor the non-CF profiles can be modeled by a polytropic temperature profile, the reason being that the radius at which the profiles break is much larger than the core radius characterizing the gas density profiles. For r > 0.2r180, where the gas can be treated as a polytrope, the polytropic indexes derived for CF and non-CF systems are respectively 1.20 ± 0.06 and 1.46 ± 0.06. The former index is closer to the isothermal value, 1, and the latter to the adiabatic value, . Published hydrodynamic simulations do not reproduce the peculiar shape of the observed temperature profile, probably suggesting that a fundamental ingredient is missing.

The influence of thermal stratification on the hydraulic behavior of waste stabilization ponds

Thermal stratification, which is characterized by a high vertical thermal gradient, is usually observed in deep lakes. However, although waste stabilization ponds have small depths, their high turbidity provides favorable conditions for the occurrence of this phenomenon, mainly during summer. During that time of the year, the layers nearest to the surface concentrate a larger amount of thermal energy compared to the deeper layers, which results in a temperature difference between the surface and the bottom of the pond. As a consequence a density profile appears, with the less dense layers located at the surface of the pond and the densest ones close to the bottom. This stratification in the water column induces alterations in the flow pattern and a decrease of the useful volume of the pond. This paper presents a mathematical model developed to forecast the conditions of thermal stratification in waste stabilization ponds and the volume actually used for wastewater treatment. With these values it is possible to correct the average residence time of the liquid in the pond. The theoretical results were compared with experimental observations, and maximum differences of 15% between the calculated and observed temperature profiles were found.

Salinity Adjustments in the Presence of Temperature Data Assimilation

Abstract This paper is an evaluation of the role of salinity in the framework of temperature data assimilation in a global ocean model that is used to initialize seasonal climate forecasts. It is shown that the univariate assimilation of temperature profiles, without attempting to correct salinity, can induce first-order errors in the subsurface temperature and salinity fields. A recently developed scheme by A. Troccoli and K. Haines is used to improve the salinity field. In this scheme, salinity increments are derived from the observed temperature, by using the model temperature and salinity profiles, assuming that the temperature–salinity relationship in the model profiles is preserved. In addition, the temperature and salinity fields are matched below the observed temperature profile by vertically displacing the original model profiles. Two data assimilation experiments were performed for the 6-yr period 1993–98. These show that the salinity scheme is effective at maintaining the haline and thermal str...

Thermal Resistance of Crystal Interface: Molecular Dynamics Simulation.

Non-equilibrium molecular dynamics computer simulation was carried out to investigate a thermal resistance phenomenon at interfaces of Lennard-Jones particle crystals. Inside an FCC crystal, one-dimensional steady thermal energy flow was realized using a pair of temperature-controlled heat-baths. Four types of sharp and flat interfaces between the following crystals were investigated : (i) crystals with different particle masses, (ii) crystals with different interaction parameters, (iii) crystals with various surface interaction parameters, and (iv) crystals with different size parameters. Except for the case (iv), observed temperature profiles have a discontinuity at the interface, from which the temperature gap Tgap is evaluated. Due to the temperature discontinuity, the thermal energy flux is smaller than that through a single crystal without an interface. The observed reduction of the energy flux is larger than that predicted with a simple acoustic model. Interfaces with finite width, or composistion gradient, were also examined.

The X-ray virial relations for relaxed lensing clusters observed withChandra

We examine the relations linking mass, X-ray temperature and bolometric luminosity for a sample of luminous, relatively relaxed clusters of galaxies observed with the Chandra Observatory, for which independent confirmation of the mass results is available from gravitational lensing studies. Within radii corresponding to a fixed overdensity Δ = 2500 with respect to the critical density at the redshifts of the clusters, the observed temperature profiles, scaled in units of T2500 and r2500, exhibit an approximately universal form which rises within r ∼ 0.3r2500 and then remains approximately constant out to r2500. We obtain best-fitting slopes for the mass–temperature and temperature–luminosity relations consistent with the predictions from simple scaling arguments i.e. and , respectively. We confirm the presence of a systematic offset of ∼40 per cent between the normalizations of the observed and predicted mass–temperature relations for both SCDM and ΛCDM cosmologies.

Energy partition between solar wind protons and pickup ions in the distant heliosphere: A three‐fluid approach

The solar wind in the outer heliosphere is fundamentally different from that in the inner heliosphere, with the influence from the local interstellar medium becoming significant. Observational evidence of pickup ions has accumulated as Voyager 2 continues its journey to the interstellar medium. Specifically, the nonadiabatic solar wind proton temperature profile, the slowdown of the solar wind, and an increased pressure associated with pickup ions are the manifestations of pickup ions in the outer heliosphere. In order to understand the solar wind in the outer heliosphere, we extend the three‐fluid model first proposed by Isenberg [1986] to include the energy sharing between the solar wind protons and pickup ions. For simplicity, we introduce a parameter, the energy partition ratio ε, to represent the division of the total energy provided by the pickup process between the solar wind protons and pickup ions. We find that only a small percentage of this total thermal energy is needed to heat the solar wind proton to produce the observed temperature profile. As expected, the higher the interstellar neutral hydrogen density, the smaller the percentage. The energy partition ratio has little effect on the slowdown of the solar wind and the pickup ion density distribution in the outer heliosphere, which is primarily controlled by the interstellar neutral hydrogen density. As far as the slowdown is concerned, a neutral hydrogen density of nH∞ = 0.08 cm−3 at the termination shock gives the best match to the observations [Wang et al., 2000]. In this case, the pickup ion density at 40 AU is also of the order of that estimated by Burlaga et al. [1996], and the energy partition ratio ε = 0.05 gives the best fit to the observed proton temperature profile.

Initialization of Seasonal Forecasts Assimilating Sea Level and Temperature Observations

Abstract In this paper, the combined assimilation of satellite observed sea level anomalies and in situ temperature data into a global ocean model, which is used to initialize a coupled ocean–atmosphere forecast system, is described. The altimeter data are first used to create synthetic temperature observations, which are then combined with the directly observed temperature profiles in an optimum interpolation scheme. In addition to temperature, salinity is corrected based on a preservation of the model's local temperature–salinity relationship. Coupled forecasts with a lead time of up to 6 months are initialized from the ocean analyses and the impact of the data assimilation on both the ocean analysis and the coupled forecasts is investigated. It is shown that forecasts of sea surface temperature anomalies in the Nino-3 area can be improved by initializing the coupled forecast model with the ocean analysis in which temperature and altimeter data are assimilated in combination. The results further imply t...

Carbon Monoxide Production and Excitation in Comet C/1995 O1 (Hale-Bopp): Isolation of Native and Distributed CO Sources

The release of carbon monoxide from Comet C/1995 O1 Hale-Bopp was studied between June 1996 and September 1997 using high resolution infrared spectroscopy near 4.7 μm. The excitation of CO molecules in the coma was assessed through measurement of the rotational temperature on several dates at an angular resolution of ∼1 arcsecond. An increase in T rot with distance from the nucleus was revealed, most likely because of photolytic heating by fast H-atoms. Observed temperature profiles varied from date to date, but overall the degree of heating was most pronounced near perihelion. The similar rotational temperatures observed for CO and HCN may indicate control of rotational populations by collisions with electrons. The spatial distribution of CO molecules in the coma revealed two distinct sources for CO, one being CO ice native to the nucleus, and another being CO released from a progenitor distributed in the coma. Only the native source was seen when the comet was beyond 2 AU from the Sun. Based on pre- and post-perihelion observations on five dates with heliocentric distance R h between 4.10 and 2.02 AU, a heliocentric dependence Q CO,native=(1.06±0.44)×10 30 R h −1.76±0.26 molecules s −1 was obtained. Within R h∼1.5 AU, however, both native and distributed sources were consistently present on all dates of observation. The total CO produced was the sum of the two sources and, based on seven dates, obeyed Q CO,total=(2.07±0.20)×10 30 R h −1.66±0.22 molecules s −1. This heliocentric dependence was consistent with that found for water (Q H 2O αR h −1.88±0.18 between 0.93 and 1.49 AU) and for mm-sized dust (R h −1.7±0.2 between 0.9 and 2.5 AU). Our derived total mixing ratio for CO was Q CO,total/Q H 2O =0.241±0.009, with native and distributed sources each contributing an abundance of approximately 12 percent that of water. This was the case even after correcting measured CO and H 2O column densities, and hence production rates, for opacity in the solar pump. The distributed source exhibited behavior consistent with thermal destruction of a precursor material. The observed variations in its production rate and spatial distribution along the slit suggested contributions from both a diffuse source in the coma and possibly from one or more jets enriched in CO or CO-containing material, such as CHON grains.