scholarly journals Thermal impact of Heinrich stadials in cave temperature and speleothem oxygen isotope records

2020 ◽  
pp. 1-14
Author(s):  
David Domínguez-Villar ◽  
Kristina Krklec ◽  
José Antonio López-Sáez ◽  
Francisco J. Sierro
Keyword(s):  
Thermal Conduction ◽  
Temperature Anomaly ◽  
Thermal Anomaly ◽  
Thermal Impact ◽  
Conduction Model ◽  
Temperature Changes ◽  
One Dimensional ◽  
Average Temperature ◽  
The Tropics ◽  
Thermal Variability

Abstract During each Heinrich stadial (HS), temperatures in southern Europe typically dropped several degrees during several hundred to few thousand years. We have developed a one-dimensional thermal conduction model that transfers the typical surface temperature anomaly of a HS to a series of hypothetical underlying caves. The results show that with increasing depth, the thermal anomaly is attenuated, the lag time increases, and the signal structure experiences larger modifications. The model suggests that in most cases, it is not acceptable to assume a synchronous thermal variability and similar average temperature values between the surface atmosphere and the cave interior at millennial timescales. We also simulated the thermal impact of the modeled HS on speleothem δ18O records. The outputs of most model scenarios suggest that temperature changes associated with the HS produce δ18O anomalies capable of contributing significantly or even decisively to the speleothem isotope variability. Therefore, despite controls other than temperature often being considered more important when interpreting Pleistocene speleothem δ18O records in temperate climates, this research suggests that temperature is expected to be one of the major controls of δ18O values in most cave sites outside the tropics and should be included as a significant parameter affecting Pleistocene speleothem δ18O records.

scholarly journals Microwave Absorption in Layered Media: Application to Landmine Detection

2000 ◽  
Vol 53 (5) ◽  
pp. 723 ◽  
Author(s):  
J. A. Hermann
Keyword(s):  
Thermal Properties ◽  
Microwave Absorption ◽  
Time Evolution ◽  
Microwave Radiation ◽  
Thermal Energy ◽  
Thermal Conduction ◽  
Landmine Detection ◽  
Composite Media ◽  
Conduction Model ◽  
One Dimensional

The absorption of microwave radiation and subsequent thermal conduction by simple composite media, consisting of parallel layers with disparate thermal properties,is analysed.The solutions for a one-dimensional conduction model are used to investigate the time evolution and distribution of thermal energy within moisture-laden soils containing non-absorbing objects.The application of these results to the detection of landmines is discussed and evaluated.

Measurement of Heat Flux From Fires

Volume 4 ◽  
2004 ◽  
Author(s):  
Cecilia S. Lam ◽  
Alexander L. Brown ◽  
Elizabeth J. Weckman ◽  
Walter Gill
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Unit Area ◽  
Inverse Heat Conduction ◽  
Thermal Impact ◽  
Temperature Changes ◽  
One Dimensional ◽  
Conduction Heat Transfer ◽  
Flux Measurements

Heat flux is an important parameter for characterization of the thermal impact of a fire on its surroundings. However, heat flux cannot be measured directly because it represents the rate of heat transfer to a unit area of surface. Therefore, most heat flux measurements are based on the measurement of temperature changes at or near the surface of interest [1,2]. Some instruments, such as the Gardon gauge [3] and the thermopile [2], measure the temperature difference between a surface and a heat sink. In radiation-dominated environments, this difference in temperature is often assumed to be linearly related to the incident heat flux. Other sensors measure a surface and/or interior temperature and inverse heat conduction methods frequently must be employed to calculate the corresponding heat flux [1,4]. Typical assumptions include one-dimensional conduction heat transfer and negligible heat loss from the surface. The thermal properties of the gauge materials must be known and, since these properties are functions of temperature, the problem often becomes non-linear.

Conduction of Heat across Rectangular Cellular Enclosures

1981 ◽  
Vol 103 (3) ◽  
pp. 591-595 ◽  
Author(s):  
J. Eftekhar ◽  
G. Darkazalli ◽  
A. Haji-Sheikh
Keyword(s):  
Heat Flux ◽  
Analytical Model ◽  
Thermal Conduction ◽  
Three Dimensional ◽  
Closed Form Solution ◽  
Numerical Data ◽  
Form Solution ◽  
Geometrical Configuration ◽  
Conduction Model ◽  
One Dimensional

A simplified analytical model for the computation of thermal conduction across rectangular-celled enclosures based on the assumption of quasi-one-dimensional conduction in the cell partitions is presented. The rectangular enclosures may contain solid or liquid for which the conduction is two or three-dimensional depending on the geometrical configuration. Additional assumptions concerning radiation interchange between participating surfaces are necessary when the enclosure contains a stagnant gas. This analytical model leads to a closed form solution for temperature distribution in the partitions and the multidimensional conductive region. A parametric study of heat flux is presented. The numerical data define a range of parameters for which a one-dimensional conduction model is satisfactory.

scholarly journals Discontinuous Daily Temperatures in the WATCH Forcing Datasets

2015 ◽  
Vol 16 (1) ◽  
pp. 465-472 ◽  
Author(s):  
Henning W. Rust ◽  
Tim Kruschke ◽  
Andreas Dobler ◽  
Madlen Fischer ◽  
Uwe Ulbrich
Keyword(s):  
Land Surface ◽  
Water Cycle ◽  
Research Unit ◽  
Climatic Research Unit ◽  
Daily Maximum ◽  
Monthly Means ◽  
Tropical Africa ◽  
Average Temperature ◽  
Surface Models ◽  
The Tropics

Abstract The Water and Global Change (WATCH) forcing datasets have been created to support the use of hydrological and land surface models for the assessment of the water cycle within climate change studies. They are based on 40-yr ECMWF Re-Analysis (ERA-40) or ECMWF interim reanalysis (ERA-Interim) with temperatures (among other variables) adjusted such that their monthly means match the monthly temperature dataset from the Climatic Research Unit. To this end, daily minimum, maximum, and mean temperatures within one calendar month have been subjected to a correction involving monthly means of the respective month. As these corrections can be largely different for adjacent months, this procedure potentially leads to implausible differences in daily temperatures across the boundaries of calendar months. We analyze day-to-day temperature fluctuations within and across months and find that across-months differences are significantly larger, mostly in the tropics and frigid zones. Average across-months differences in daily mean temperature are typically between 10% and 40% larger than their corresponding within-months average temperature differences. However, regions with differences up to 200% can be found in tropical Africa. Particularly in regions where snowmelt is a relevant player for hydrology, a few degrees Celsius difference can be decisive for triggering this process. Daily maximum and minimum temperatures are affected in the same regions, but in a less severe way.

scholarly journals An application of pulsed infrared thermal imaging in the diagnosis of diabetic microangiopathy

2019 ◽  
Vol 23 (3 Part A) ◽  
pp. 1473-1478
Author(s):  
Yanying Yin ◽  
Chen Li ◽  
Ge Song
Keyword(s):  
Lower Extremity ◽  
Atherosclerotic Plaque ◽  
Thermal Imaging ◽  
Thermal Conduction ◽  
Clinical Symptoms ◽  
Diabetic Microangiopathy ◽  
Conduction Model ◽  
Infrared Thermal Imaging ◽  
Imaging Technology ◽  
Working Principle

Diabetic microangiopathy is an important cause of morbidity and mortality of diabetes foot ulcers. Its early detection is very important for early intervention avoiding severe clinical symptoms. In this article, theoretical study on a pulsed infrared thermal imaging technology detecting early diabetic microangiopathy in lower extremity was carried out. The working principle of pulsed infrared thermal imaging technology was described and the 3-D thermal conduction model for atherosclerotic plaque in microvessel of distal lower extremity using pulsed infrared thermal imaging technology was established and calculated. The effect of atherosclerotic plaque geometry size including length and thickness to the measurement parameter was studied, and the influence law has been got, which can provide a theoretical basis for the diagnosis of diabetic microangiopathy using pulsed infrared thermal imaging technology.

scholarly journals Cloud Changes in the Period of Global Warming: the Results of the International Satellite Project

2019 ◽  
pp. 3-13
Author(s):  
O. M. Pokrovsky
Keyword(s):  
Temperature Series ◽  
The Other ◽  
Coefficient Of Determination ◽  
Smoothing Algorithm ◽  
Temperature Changes ◽  
Lower Cloud ◽  
Statistical Time ◽  
The One ◽  
The Tropics ◽  
Climatic Series

The results of analysis of climatic series of global and regional cloudiness for 1983–2009. Data were obtained in the framework of the international satellite project ISCCP. The technology of statistical time series analysis including smoothing algorithm and wavelet analysis is described. Both methods are intended for the analysis of non-stationary series. The results of the analysis show that both global and regional cloudiness show a decrease of 2–6%. The greatest decrease is observed in the tropics and over the oceans. Over land, the decrease is minimal. The correlation coefficient between the global cloud series on the one hand and the global air and ocean surface temperature series on the other hand reaches values (–0.84) — (–0.86). The coefficient of determination that characterizes the accuracy of the regression for the prediction of global temperature changes based on data on changes in the lower cloud, in this case is 0.316.

scholarly journals Contactless Monitoring of Microcirculation Reaction on Local Temperature Changes

2019 ◽  
Vol 9 (22) ◽  
pp. 4947 ◽  
Author(s):  
Volynsky ◽  
Margaryants ◽  
Mamontov ◽  
Kamshilin
Keyword(s):  
Blood Flow ◽  
Skin Temperature ◽  
Polarized Light ◽  
Thermal Exposure ◽  
Thermal Impact ◽  
Vasomotor Response ◽  
Temperature Changes ◽  
Custom Made ◽  
Electrocardiogram Ecg ◽  
System Operating

Assessment of skin blood flow is an important clinical task which is required to study mechanisms of microcirculation regulation including thermoregulation. Contactless assessment of vasomotor reactivity in response to thermal exposure is currently not available. The aim of this study is to show the applicability of the imaging photoplethysmography (IPPG) method to measure quantitatively the vasomotor response to local thermal exposure. Seventeen healthy subjects aged 23 ± 7 years participated in the study. A warm transparent compress applied to subject’s forehead served as a thermal impact. A custom-made IPPG system operating at green polarized light was used to monitor the subject’s face continuously and simultaneously with skin temperature and electrocardiogram (ECG) recordings. We found that the thermal impact leads to an increase in the amplitude of blood pulsations (BPA) simultaneously with the skin temperature increase. However, a multiple increase in BPA remained after the compress was removed, whereas the skin temperature returned to the baseline. Moreover, the BPA increase and duration of the vasomotor response was associated with the degree of external heating. Therefore, the IPPG method allows us to quantify the parameters of capillary blood flow during local thermal exposure to the skin. This proposed technique of assessing the thermal reactivity of microcirculation can be applied for both clinical use and for biomedical research.

scholarly journals Holocene temperature variations inferred from Antarctic ice cores

1994 ◽  
Vol 20 ◽  
pp. 427-436 ◽  
Author(s):  
P. Ciais ◽  
J. Jouzel ◽  
J. R. Petit ◽  
V. Lipenkov ◽  
J. W. C. White
Keyword(s):  
Late Holocene ◽  
Ice Core ◽  
Ice Cores ◽  
Temperature Fluctuations ◽  
Base Line ◽  
Temperature Changes ◽  
Average Temperature ◽  
The Past ◽  
Reconstructed Temperature ◽  
Line Temperature

We have reconstructed temperature changes over the past 15 000 years from ice-core data in Antarctica. We used measurements of the D/H isotope ratio in ice as a proxy of temperature for central sites (Vostok, Dome C and Komsomolskaya; as well as coastal sites (D47, D15 and D10). First, we examined the dating of each core and built up a common temporal framework for the ensemble of the data. Secondly, we addressed the problem of inferring small-amplitude temperature fluctuations from the isotope data, in the light of noise-generating mechanisms involved in snow deposition. Temperature was reconstructed so as to minimize distortion created by the sampling of ice cores in the field. The seven ice cores studied yield an average temperature curve which can be put in perspective with nearby paleoclimatic records. The early Holocene experienced climates warmer than today by 1-2°C. The late Holocene period shows more discernible, shorter-duration, temperature fluctuations, superimposed on a fairly stable "base-line" temperature.

Assimilation of SSM/I and GOES Humidity Retrievals with a One-Dimensional Variational Analysis Scheme

1995 ◽  
Vol 34 (7) ◽  
pp. 1536-1550 ◽  
Author(s):  
Godelieve Deblonde ◽  
Louis Garand ◽  
Pierre Gauthier ◽  
Christopher Grassotti
Keyword(s):  
Variational Analysis ◽  
Lower Troposphere ◽  
Precipitable Water ◽  
Error Variance ◽  
Specific Humidity ◽  
One Dimensional ◽  
Brightness Temperatures ◽  
Analysis Technique ◽  
Analysis Scheme ◽  
The Tropics

Abstract Total precipitable water (TPW) retrieved from Special Sensor Microwave/lmager (SSM/I) brightness temperatures and specific humidity retrieved from Geostationary Operational Environmental Satellite (GOES) radiances are assimilated using a one-dimensional (ID) variational analysis technique. The study is divided into two parts. First, collocations with radiosondes are performed to arm the quality of the satellite water vapor retrievals. Collocations are also performed with 6-h forecast Acids. Second, SSM/I TPW and GOES specific humidity are assimilated using a ID variational analysis technique that minimizes the error variance of the analyzed field. A global collocation study over the oceans for SSM/I TPW retrievals and 6-h forecasts of TPW shows that the rmse (with respect to radiosondes) are, respectively, 4.7 and 5.0 kg m−2. A separate collocation study over both the oceans and land for GOES retrieved TPW and 6-h forecasts of TPW yields rmse of 4.6 and 4.4 kg m−2, respectively, in the midlatitudes and 6.8 and 5.9 kg m−2 in the Tropics. The reduction of the 6-h forecast rmse when assimilating SSM/I TPW is 1 kg m−2, which is a reduction of 20% in the rmse. When GOES retrievals of specific humidity are assimilated, the elective reduction is 0.6 kg m−2. It is shown that in the upper levels of the troposphere (above 600 mb), the error reduction of specific humidity is largely due to the GOES retrievals, whereas in the lower troposphere (850 and 700 mb), the reduction is mostly due to the SSM/I TPW. This emphasizes the complementarity of the information contained at different wavelengths and the advantage of using multisensor retrievals in data analysis.

Sign in / Sign up

Export Citation Format

Share Document