Study on the estimation of near-surface air temperature from MODIS data by statistical methods

Spatially distributed air temperature is desired for various scientific studies, including climatalogical, hydrological, agricultural, environmental and ecological studies. In this study, empirical models with regard to land cover and spatial scale were introduced and compared to estimate air temperature from satellite-derived land surface temperature and other environmental parameters. Aqua MODIS (Moderate Resolution Imaging Spectroradiometer) data and meteorological data obtained throughout 2005 in the Yangtze River Delta were adopted to develop statistical algorithms of air temperature. Four empirical regression models with different forms and different independent variables resulted in errors ranging from 2.20°C to 2.34°C. Considering the different relationships between air temperature and land surface temperature for different land types, these four models were evaluated and the most proper equation for each land-cover type was determined. The model containing these selected equations gave a slightly improved mean absolute error (MAE) of 2.18°C. Then the spatial scale effect of this empirical model was analysed with observed air temperature and spatially averaged land surface characteristics. The result shows that the estimation error of air temperature tends to be lower as spatial window size increases, suggesting that the model performances are improved by spatially averaging land surface characteristics. Comprehensively considering the accuracy and computational demand, 5 × 5 pixel size is the most favourable window size for estimating air temperature. The validation of the empirical model at 5 × 5 pixel size shows that it achieves an MAE of 1.98°C and an R ² of 0.9215. This satisfactory result indicates that this approach is proper for estimating air temperature, and spatial window size is an important factor that should be considered when calculating air temperature. It is expected that better accuracy will be achieved if the different weights of pixels at different distances can be set according to high-density micro-meteorological data.     

Remote sensing of temperature variations around major power plants as point sources of heat

Variations in land surface temperature (LST) around major point sources of heat were studied using the Tampa Bay region as a case study. LST in the Tampa Bay region, FL, USA, was retrieved from Landsat Thematic Mapper (TM) 6 and Enhanced Thematic Mapper Plus (ETM+) 6 high-gain thermal bands. The TM6 image data were obtained on 29 January (winter season) and 3 April 2007 (spring season). The ETM+6 data were obtained on 11 April 2007 (spring season). Spatial profiles of LST around four major fossil-fuelled power plants (FFPPs) were considered in this study. Temperatures were found to be highest at power plants and to decay to an average background temperature within 1.2–2.0 km from the FFPPs. The average background temperatures obtained in January and April were 17°C and 29°C, respectively. Results indicate that LST in close proximity to the FFPPs could be up to 10°C hotter than the surrounding areas. These findings suggest that FFPPs are significant heat sources and populations living within 1–2 km from an FFPP might be at significantly higher risk of heat-related illnesses and mortality.     

Effects of wearing aircrew protective clothing on physiological and cognitive responses under various ambient conditions

Heat stress can be a significant problem for pilots wearing protective clothing during flights, because they provide extra insulation which prevents evaporative heat loss. Heat stress can influence human cognitive activity, which might be critical in the flying situation, requiring efficient and error-free performance. This study investigated the effect of wearing protective clothing under various ambient conditions on physiological and cognitive performance. On several occasions, eight subjects were exposed for 3 h to three different environmental conditions; 0°C at 80% RH, 23°C at 63% RH and 40°C at 19% RH. The subjects were equipped with thermistors, dressed as they normally do for flights (including helmet, two layers of underwear and an uninsulated survival suit). During three separate exposures the subjects carried out two cognitive performance tests (Vigilance test and DG test). Performance was scored as correct, incorrect, missed reaction and reaction time. Skin temperature, deep body temperature, heart rate, oxygen consumption, temperature and humidity inside the clothing, sweat loss, subjective sensation of temperature and thermal comfort were measured. Rises in rectal temperature, skin temperature, heart rate and body water loss indicated a high level of heat stress in the 40°C ambient temperature condition in comparison with 0°C and 23°C. Performance of the DG test was unaffected by ambient temperature. However, the number of incorrect reactions in the Vigilance test was significantly higher at 40°C than at 23°C (p = 0.006) or 0°C (p = 0.03). The effect on Vigilance performance correlated with changes in deep-body temperature, and this is in accordance with earlier studies that have demonstrated that cognitive performance is virtually unaffected unless environmental conditions are sufficient to change deep body temperature.     

Landsat-TM data for estimating ground temperature and depth of subsurface coal fire in the Jharia coalfield,India

Coal fires are a ubiquitous problem in coal-mines, the world over. They burn our prime energy resource, lead to atmospheric pollution and render mining of coal hazardous. Processes leading to coal combustion and spread of subsurface fires are briefly examined in this paper and the role of remote sensing in surveillance of coal fires is presented.

The present study aims at developing a quick method for estimating the temperature of the ground surface directly above subsurface coal fires. Utility of TM6 and TM7-band data for temperature estimation is briefly reviewed. It is argued that temperature calculations of surface anomalies related to subsurface fires can only be done on the basis of 8–14 μm band data, due to the low temperatures involved.

In the Jharia coalfield, it is noted that subsurface fires in various coal-mines are associated with surface thermal anomalies, as has also been confirmed by ground checks. The pattern of TM6 data distribution and ground truth is used to isolate thermal anomalies, and the TM6 digital numbers are converted into kinetic temperature values. It is observed that for the Landsat-TM scene ( 28 November 1990) the kinetic temperatures range from 16·0°C to 31·6°C in the Jharia coalfield, with a threshold value of 25·6°C associated with the anomalies. Depth estimation of fire has been carried out using field structural geology data and pixel locations of thermal anomalies. It is inferred that the depth of subsurface coal fire ranges between 45–55 m, in most cases, which is in general agreement with the field data. Limitations of the method are indicated.     

Micro-environment changes inside impermeable protective clothing during a continuous work exposure

Protective clothing (PC) results in a micro-environment between itself and the body. Workers are then exposed to a heat stress greater than the ambient environment alone, which is a reflection of micro-environment, metabolic rate and time. Adjustments to the ambient environment to account for the micro-environment have been formulated as a means to predict heat strain for safety and productivity purposes. Measurement of the actual micro-environment was made for a mean of 63.1 - 7.9 min using a remote sensor at the shoulder, hip and thigh levels on 15 subjects during a continuous work protocol (300 kcal/h) in impermeable PC at an ambient temperature of 30.1°C wet bulb globe temperature (WBGT) (32°C dry, 29°C wet, 33°C globe). Micro-environment temperature increased over the duration of the work period. There was no statistically significant difference (p >0.05) between the measurements made at the three different body sites for temperature or humidity. The mean micro-environmental WBGT at the end of work was 34.6°C WBGT. Micro-environment WBGT increased rapidly in the first 20 min of work then slowed, rising only 0.5°C WBGT from 40 to 60 min. These results suggest that at this particular high ambient temperature (30.1°C WBGT) an adjustment factor of 5°C WBGT would give a more accurate indication of thermal stress for up to 1 h of continuous moderate work within PC. For shorter work durations, an even smaller adjustment would be appropriate.     

Thermal dimensional stability of glass substrates for poly‐Si TFT‐LCD application

Abstract— Thermal dimensional stability of Fusion‐drawn Corning Code 1737 glass was investigated at simulated thermal cycles for low‐temperature poly‐Si TFT fabrication. For low‐temperature poly‐Si TFT processes between 550 and 600°C, annealed Code 1737 is required to meet a typical thermal shrinkage requirement of less than 20 ppm. For super‐low‐temperature poly‐Si TFT processes between 400 and 450°C, Code 1737 meets the requirement in the unannealed state. Code 1737 glass having a high strain point of 666°C provides thermal capabilities as a substrate for low‐temperature poly‐Si TFT‐LCD applications.     

Too hot to carry on? Disinclination to persist at a task in a warm office environment

We investigated the effect of an elevated ambient temperature on performance in a persistence task. The task involved the coding of incorrect symbols and participants were free to decide how long to spend performing this task. Applying a between-subject design, we tested 125 students in an office-like environment in one of the three temperature conditions. The comfort condition (Predicted Mean Vote [PMV] = 0.01) featured an average air temperature of 24 °C. The elevated ambient temperature condition was 28 °C (PMV = 1.17). Condition three employed an airstream of approximately 0.8 m/s, intended to compensate for performance decrements at the elevated air temperature (28 °C, PMV = 0.13), according to Fanger’s thermal comfort equation. Participants in the warm condition were significantly less persistent compared with participants in the control and compensation conditions. As predicted by the thermal comfort equation, the airstream seemed to compensate for the higher temperature. Participants’ persistence in the compensation and comfort conditions did not differ.

Practitioner Summary: A laboratory experiment involving a simulated office environment and three ambient temperature conditions (24 °C, 28 °C and 28 °C plus airstream) showed that persistence at a task is significantly impaired at 28 °C. An airstream of 0.8 m/s at 28 °C compensated for the disinclination to persist with the task.     

The influence of heated or cooled seats on the acceptable ambient temperature range

In 11 climate chamber experiments at air temperatures ranging from 15 to 45°C, a total of 24 subjects, dressed in appropriate clothing for entering a vehicle at these temperatures, were each exposed to four different seat temperatures, ranging from cool to warm. In one simulated summer series, subjects were preconditioned to be too hot, while in other series they were preconditioned to be thermally neutral. They reported their thermal sensations, overall thermal acceptability and comfort on visual analogue scales at regular intervals. Instantaneous heat flow to the seat was measured continuously. At each ambient room temperature, the percentage dissatisfied was found to be a second-order polynomial function of local heat flow. Zero heat flow was preferred at an air temperature of 22°C and the heat flow that minimized the percentage dissatisfied was found to be a single linear function of air temperature in all conditions. The analysis indicates that providing optimal seat temperature would extend the conventional 80% acceptable range of air temperature for drivers and passengers in vehicle cabins by 9.3°C downwards and by 6.4°C upwards.     

Multitemporal analysis of land surface temperature using NOAA-AVHRR: preliminary relationships between climatic anomalies and forest fires

Advanced Very High Resolution Radiometer (AVHRR) National Oceanic and Atmospheric Administration (NOAA)-14 imagery was used to analyse changes in land surface temperature in an area of Central Mexico during the course of each dry season (November–April) for the period 1996–2000. Daily surface temperature was obtained by the split-window method and cloud-free monthly composites were subsequently built. This value was related to maximum air temperatures recorded at meteorological stations and to forest fires detected from night-time images. During 1996–1997 and 1997–1998 (El Niño) dry seasons, monthly surface temperature ranged from 35°C to 46°C and from 33°C to 51°C, respectively; during 1998–1999 (La Niña) and 1999–2000 it was lower, ranging from 28°C to 47°C, and from 28°C to 41°C, respectively. At the end of El Niño, land surface temperatures higher than 50°C were registered, and 730 forest fires were detected, suggesting that this temperature increment also contributed to the vulnerability of vegetation to fire. It is concluded that land surface temperature during the first four months of the dry season can be used as a variable for modelling the probability of forest fire occurrence, in combination with other environmental variables. Similarities between land surface temperature and maximum air temperature suggest the potential use of NOAA-AVHRR imagery for evaluating El Niño/La Niña effects on the continental surface.     

Comparison of thermal comfort performance of two different types of road vehicle climate control systems

The performance of climate control systems in vehicles becomes more and more important, especially against the background of the important relationship between compartment climate and driver mental condition and, thus, traffic safety. The performance of two different types of climate control systems, an un-air-conditioned heating/cooling device (VW) and an air-conditioning climate control unit (BMW), is compared using modern and practical evaluation techniques quantifying both the dynamic 3-D temperature distribution and the local air refreshment rate. Both systems suffer from considerable temperature gradients: temperature gradients in the U-AC (VW) car up to 8–9°C are encountered, while the AC (BMW) delivers clear improvement resulting in temperature gradients of 5–6°C. The experiments clearly demonstrate the effect of the presence of even a single passenger on the thermal regime, increasing the existing thermal discrepancies in the compartment with 15% independent of ventilation rate. Furthermore, in terms of air refreshment rates in the vehicle compartment, an air-conditioning unit halves the air refreshment time at all positions in the vehicle cabin, delivering a significant improvement in terms of human comfort. Similarly, extra air inlets in the back compartment of a car deliver progress in terms of cabin refreshment rate (93 s down to 50 s).     

Capability evaluation of 3–5 µm and 8–12.5 µm airborne thermal data for underground coal fire detection

Based on ground temperature measurement, thermal anomalies induced by underground coal fires were extracted from airborne night-time 8–12.5?µm, daytime 8–12.5?µm, and daytime 3–5?µm images by density slicing. The thermal anomalies extracted from these images had different sizes and were partially overlapped. Integration of the three processed images revealed detailed structures of the surface thermal anomalies. The temperature difference (ΔT) between a threshold temperature and the background temperature can be taken as a criterion for the evaluation of detection capabilities of different thermal data. The ΔTs for night-time, daytime 8–12.5?µm data and 3–5?µm data are 2.7, 4.4 and 7.1°C, respectively. The detection capabilities for sub-pixel sized coal fires from different thermal data were evaluated by assuming these fires cause the equivalent spectral radiance as a full pixel thermal anomaly does. The 3–5?µm data are more sensitive to sub-pixel-sized high-temperature (i.e. >165°C) thermal anomalies.     

A MEMS-based thermal infrared emitter for an integrated NDIR spectrometer

A novel micromachined thermal infrared emitter using a heavily boron doped silicon slab as radiating element is presented. The fabrication process has been designed to allow the integration of such infrared emitters with an array of thermopile infrared detectors, with the aim of achieving an integrated non-dispersive infrared microspectrometer. A first set of infrared emitters with a common size for the doped silicon radiating slab (1,100?×?300?×?8?μm³) has been successfully fabricated and characterized. The working temperature of the Joule-heated radiating slabs has been controlled by means of DC and pulsed electrical signals, achieving temperatures well beyond 700°C. The thermal time constant measured in pulsed operation, around 50?ms, is adequate to enable the direct electrical modulation of the emitted radiation up to a frequency of 5?Hz while maintaining the full modulation depth. The temperature distribution in the radiating elements has been analyzed using two different thermal imaging methods.     

Behavioural,physiological and psychological responses of passengers to the thermal environment of boarding a flight in winter

In practice, passengers actively respond to the thermal environment when they board an aircraft in winter, which is not considered in the current standards. In this study, the behavioural, physiological and psychological responses to the thermal environment were examined at 22 °C (with 68 subjects), 20 °C and 26 °C (with 32 subjects). The results showed that the three air temperature levels had significant effect on nozzle usage and clothing adjustment behaviours, surface skin temperature, and thermal sensation vote (TSV). The walking/waiting states prior to boarding the aircraft cabin had a significant effect on the proportion of jacket removal, TSV and thermal comfort vote. After 10 min in the aircraft cabin, the subjects maintained their comfort in a wider range of the thermal environment when the behavioural adjustments existed compared to when they did not. Thus, a suggestion was made for behavioural adjustments to be provided in aircraft cabins.

Practitioner Summary: Experimental investigation of human responses was conducted in an aircraft cabin. Analysis showed that the subjects maintained their comfort in a wider range of the thermal environment when the behavioural adjustments existed compared to when they did not. Thus, a suggestion was made for behavioural adjustments to be provided in aircraft cabins.     

Effects of heated seat and foot heater on thermal comfort and heater energy consumption in vehicle

Subjective experiments involving 12 different conditions were conducted to investigate the effects of heated seats and foot heaters in vehicles on thermal sensation and thermal comfort. The experimental conditions involved various combinations of the operative temperature in the test room (10 or 20°C), a heated seat (on/off) and a foot heater (room operative temperature +10 or +20°C). The heated seat and foot heater improved the occupant's thermal sensation and comfort in cool environments. The room operative temperature at which the occupants felt a ‘neutral’ overall thermal sensation was decreased by about 3°C by using the heated seat or foot heater and by about 6°C when both devices were used. Moreover, the effects of these devices on vehicle heater energy consumption were investigated using simulations. As a result, it was revealed that heated seats and foot heaters can reduce the total heater energy consumption of vehicles.

Statement of Relevance: Subjective experiments were conducted to investigate the effects of heated seats and foot heaters in vehicles on thermal comfort. The heated seat and foot heater improved the occupant's thermal sensation and comfort in cool environments. These devices can reduce the total heater energy consumption in vehicles.     

Comfort design and optimization of direct expansion multi-connected radiant air conditioning based on 3D flow field simulation

The air conditioning method based on radiation heat exchange has the characteristics of small vertical temperature gradient, high thermal comfort and energy saving, and has become a hot spot of attention. The Fluent numerical simulation, the experiment in this paper studies the direct expansion multi-line radiant air conditioner under the artificially simulated climate environment in winter heating, summer cooling and dehumidification. The temperature difference of the radiation + fresh air mode at the same time indoors under heating conditions is less than 2.5 °C, and the time to reach the indoor set temperature of 24 °C is about 2–3 h. Under cooling conditions, the temperature difference of the radiation + fresh air mode at the same time in the room is about 0.5–2 °C, and the time to reach the indoor set temperature of 26 °C is about 1–3 h. In the fresh air mode, the indoor temperature difference and response time at the same time are slightly larger than the radiation + fresh air mode. The freezing and dehumidification effect of fresh air is obvious, the moisture content of dehumidifying fresh air is between 6.3 and 10.5 g/kg, and the dehumidification efficiency can reach 50%. Under the same artificial simulated climate environment, the consumption of the three modes is not much different. When the outdoor temperature in heating conditions is higher than 9 °C, the fresh air mode can get better, and the radiation + fresh air mode can achieve better comfort when running indoors under various conditions.     

Automatic method for detection of characteristic areas in thermal face images

The use of thermal images of a selected area of the head in screening systems, which perform fast and accurate analysis of the temperature distribution of individual areas, requires the use of profiled image analysis methods. There exist methods for automated face analysis which are used at airports or train stations and are designed to detect people with fever. However, they do not enable automatic separation of specific areas of the face. This paper presents an algorithm for image analysis which enables localization of characteristic areas of the face in thermograms. The algorithm is resistant to subjects’ variability and also to changes in the position and orientation of the head. In addition, an attempt was made to eliminate the impact of background and interference caused by hair and hairline. The algorithm automatically adjusts its operation parameters to suit the prevailing room conditions. Compared to previous studies (Marzec et al., J Med Inform Tech 16:151–159, 2010), the set of thermal images was expanded by 34 images. As a result, the research material was a total of 125 patients’ thermograms performed in the Department of Pediatrics and Child and Adolescent Neurology in Katowice, Poland. The images were taken interchangeably with several thermal cameras: AGEMA 590 PAL (sensitivity of 0.1 °C), ThermaCam S65 (sensitivity of 0.08 °C), A310 (sensitivity of 0.05 °C), T335 (sensitivity of 0.05 °C) with a 320?×?240 pixel optical resolution of detectors, maintaining the principles related to taking thermal images for medical thermography. In comparison to (Marzec et al., J Med Inform Tech 16:151–159, 2010), the approach presented there has been extended and modified. Based on the comparison with other methods presented in the literature, it was demonstrated that this method is more complex as it enables to determine the approximate areas of selected parts of the face including anthropometry. As a result of this comparison, better results were obtained in terms of localization accuracy of the center of the eye sockets and nostrils, giving an accuracy of 87 % for the eyes and 93 % for the nostrils.     

Radar and infrared remote sensing of geothermal features at Pilgrim Springs,Alaska

Radar and thermal data collected by a high-altitude aircraft were used to study thermal anomalies and structural elements of the Pilgrim Springs, Alaska area. The radar data included like- and cross-polarized imagery acquired from perpendicular flight paths. The like-polarized imagery was most effective in delineating significant linears. A large number of linears were detected from the imagery. Many of these linears represent fractures and/or faults (lineaments); some of which may possibly provide conduits for the emergence of hot water at the springs. The lineaments have a wide range in orientation, but significant concentrations are parallel to the trends of the Kigluaik and Kuzitrin faults. Radiometer data and imagery from a thermal scanner were used to study radiant surface temperatures which ranged from 3°–17°C. Thermal anomalies associated with geothermal heat sources were detected on the evening imagery, utilizing density-slicing techniques. A radiant temperature difference of 2°C between surface features was required, before a recognizable signature could be detected. Areas of hot ground were detected in site-specific study, but gentle lateral gradients were not.     

Assessment of thermal expansion coefficient for pure metals

In this paper, thermal expansion coefficients of 42 pure metallic elements were evaluated on the basis of empirical and theoretical methods and the adjusted Debye–Grüneisen model. In Debye–Grüneisen model, Debye temperature was regarded as an undetermined constant. Parameters in the model were determined via the nonlinear least square fit method through MATLAB program. Besides, for pure metallic elements with phase transition, segment fitting can be realized and the computational results fit experimental data well; meanwhile, reliable forecast for high-temperature or low-temperature thermal expansion can be provided, and a set of average Debye temperatures based on thermal expansion coefficients have been obtained.     

Microwave brightness temperature as an indicator of near-surface air temperature over snow in Canadian northern regions

During the past 50 years, winter temperatures have risen more rapidly than in summer in northern high latitudes. However, there are relatively few meteorological stations in these areas, and a better characterization of this trend is needed. This article investigates whether satellite microwave brightness temperature can be used as an indicator of near-surface air temperature over snow. The Helsinki University of Technology (HUT) snow emission model is used to generate a dry snow emissivity relationship between 19 and 37 GHz under the assumption that the air–snow interface temperatures and air temperatures (T_air ) are similar. This relationship allows the development of a near-surface air temperature retrieval model. A second empirical linear correction is also applied to reduce the residual observed bias. The comparison between retrieved near-surface air temperature and in situ air temperature for the Canadian northern regions shows a significant correlation (R ² of 0.76) but with a root mean square error (RMSE) of 4.94°C. Results also show that the satellite-derived temperatures can be compared to the thermal infrared skin temperature (RMSE of 5.9°C). The proposed approach gives better results than the direct correlation between brightness temperature (T _b) and in situ air temperature (RMSE reduced by 50%).     

A novel hermetic‐sealing material for FEDs

Abstract— An hermetic‐sealing material for FEDs composed of thermosetting polyimide and glass fiber, has been developed. The main backbone and end‐capping material of polyimide were investigated to satisfy both high Tg and high flowability. A thermosetting function, 4‐phenylethynylphthalic anhydride (PEPA), was used as the end‐capping material. The fracture of a rigid and softening structure was optimized in the main polymer structure. The obtained polyimide demonstrated both a high Tg (265°C) and low viscosity (98 Pa‐sec at a sealing temperature of 350°C). In order to improve the gas permeability and the mechanical and thermal characteristics of the sealing material, a mixture of various types of ceramic fillers and polyimide has been investigated, and glass fiber was adopted. When 30 wt.% of glass fiber was combined when the developed polyimide, the Ar permeability and coefficient of thermal expansion of the sealing material decreased to below one‐half of the base polyimide. This material enables us to seal at a temperature of about 350°C in nitrogen atmosphere and shows superior performance suitable for glass‐to‐glass sealing.