Ground survey of active Central American volcanoes in November - December 1973

The author has identified the following significant results. Thermal anomalies at two volcanoes, Santiaguito and Izalco, have grown in size in the past six months, based on repeated ground survey. Thermal anomalies at Pacaya volcano have became less intense in the same period. Large (500 m diameter) thermal anomalies exist at 3 volcanoes presently, and smaller scale anomalies are found at nine other volcanoes

Thermal anomalies in membrane properties

Anomalities in water and aqueous systems, and temperature effects on membrane

Decadal Evolution of Ocean Thermal Anomalies in the North Atlantic: The Effects of Ekman, Overturning, and Horizontal Transport

Basin-scale thermal anomalies in the North Atlantic, extending to depths of 1–2 km, are more pronounced than the background warming over the last 60 years. A dynamical analysis based on reanalyses of historical data from 1965 to 2000 suggests that these thermal anomalies are formed by ocean heat convergences, augmented by the poorly known air–sea fluxes. The heat convergence is separated into contributions from the horizontal circulation and the meridional overturning circulation (MOC), the latter further separated into Ekman and MOC transport minus Ekman transport (MOC-Ekman) cells. The subtropical thermal anomalies are mainly controlled by wind-induced changes in the Ekman heat convergence, while the subpolar thermal anomalies are controlled by the MOC-Ekman heat convergence; the horizontal heat convergence is generally weaker, only becoming significant within the subpolar gyre. These thermal anomalies often have an opposing sign between the subtropical and subpolar gyres, associated with opposing changes in the meridional volume transport driving the Ekman and MOC-Ekman heat convergences. These changes in gyre-scale convergences in heat transport are probably induced by the winds, as they correlate with the zonal wind stress at gyre boundaries

Combination of Numerical Tools to Link Deep Temperatures, Geological Structures and Fluid Flow in Sedimentary Basins: Application to the Thermal Anomalies of the Provence Basin (South-East France)

International audienceIn the Provence basin, south-eastern France, more than 230 Bottom Hole Temperature (BHT) data have been compiled and corrected for transient disturbances to provide a thermal model of this Mesozoic to Cenozoic sedimentary basin. The thermal gradient of the area averages 29.9°C/km (32.5°C/km in all France), but some places show gradients reaching 36°C/km or 22°C/km. To characterize thermal anomalies, a three-dimensional model of the temperatures was built between the surface and 5km depth, allowing us to elaborate sets of thermal maps and cross-sections. The newly identified temperature anomalies may reach temperature difference up to 40°C at 3km depth through the basin. After attempting to find correlations between thermal anomalies and large scale features (Moho depths, sediment cover thickness), it appears that fluid circulation may better explain locations, amplitudes and wavelengths of thermal anomalies along faulted zones. In fact, spatial evolution of anomalous cold/warm zones follow directions of main faulted zones. In addition, it is shown that the account of a depth-dependent permeability allows the superimposition of positive and negative thermal anomalies. Away from permeable zones, thermal anomalies should be explained by conductive processes, among which heat refraction due to thermal conductivity contrasts may be significant. In particular, anisotropy of thermal conductivity of clayey formation is shown to enable the development of thermal anomalies similar to those observed between permeable zones. Evolution of fluid circulation in faulted zones (involving enhanced vertical heat transfer) combined with thick anisotropic sediments (involving enhanced horizontal heat transfer) may explain complex thermal patterns deduced from present-day temperature measurements

Volcanic activity and satellite-detected thermal anomalies at Central American volcanoes

The author has identified the following significant results. A large nuee ardente eruption occurred at Santiaguito volcano, within the test area on 16 September 1973. Through a system of local observers, the eruption has been described, reported to the international scientific community, extent of affected area mapped, and the new ash sampled. A more extensive report on this event will be prepared. The eruption is an excellent example of the kind of volcanic situation in which satellite thermal imagery might be useful. The Santiaguito dome is a complex mass with a whole series of historically active vents. It's location makes access difficult, yet its activity is of great concern to large agricultural populations who live downslope. Santiaguito has produced a number of large eruptions with little apparent warning. In the earlier ground survey large thermal anomalies were identified at Santiaguito. There is no way of knowing whether satellite monitoring could have detected changes in thermal anomaly patterns related to this recent event, but the position of thermal anomalies on Santiaguito and any changes in their character would be relevant information

An investigation of thermal anomalies in the Central American volcanic chain and evaluation of the utility of thermal anomaly monitoring in the prediction of volcanic eruptions

The author has identified the following significant results. Ground truth data collection proves that significant anomalies exist at 13 volcanoes within the test site of Central America. The dimensions and temperature contrast of these ten anomalies are large enough to be detected by the Skylab 192 instrument. The dimensions and intensity of thermal anomalies have changed at most of these volcanoes during the Skylab mission

Determination of anthropogenic changes on the urbanized territories using GIS technology

The research aim is to obtain a cartographic model of an urbanized territory by means of thermal survey in an infrared range. With this cartographic model, it will be then possible to reduce the zones in the urbanized territories differing in the level of superficial heat. Further, we will be able to reduce the proof thermal anomalies and thermal structures of the localities that are related to the natural and anthropogenic systems. On the examples of the cities of Ukraine – Energodar and Nikopol, we defined the sources of caloradiances from major industrial concerns as well as from thermal and nuclear power plants. For comparison, we built the model of thermal structure of the city of Tokai and the nuclear power plant with the same name Tokai (Japan). The sources of caloradiances can be, for example, pipes of thermal power stations, ponds-coolers, corps of steel-making production, and other similar objects. If the sizes of such source are known, then we are able to get the absolute values of temperatures

Volcanic Hot-Spot Detection Using SENTINEL-2: A Comparison with MODIS−MIROVA Thermal Data Series

In the satellite thermal remote sensing, the new generation of sensors with high-spatial resolution SWIR data open the door to an improved constraining of thermal phenomena related to volcanic processes, with strong implications for monitoring applications. In this paper, we describe a new hot-spot detection algorithm developed for SENTINEL-2/MSI data that combines spectral indices on the SWIR bands 8a-11-12 (with a 20-meter resolution) with a spatial and statistical analysis on clusters of alerted pixels. The algorithm is able to detect hot-spot-contaminated pixels (S2Pix) in a wide range of environments and for several types of volcanic activities, showing high accuracy performances of about 1% and 94% in averaged omission and commission rates, respectively, underlining a strong reliability on a global scale. The S2-derived thermal trends, retrieved at eight key-case volcanoes, are then compared with the Volcanic Radiative Power (VRP) derived from MODIS (Moderate Resolution Imaging Spectroradiometer) and processed by the MIROVA (Middle InfraRed Observation of Volcanic Activity) system during an almost four-year-long period, January 2016 to October 2019. The presented data indicate an overall excellent correlation between the two thermal signals, enhancing the higher sensitivity of SENTINEL-2 to detect subtle, low-temperature thermal signals. Moreover, for each case we explore the specific relationship between S2Pix and VRP showing how different volcanic processes (i.e., lava flows, domes, lakes and open-vent activity) produce a distinct pattern in terms of size and intensity of the thermal anomaly. These promising results indicate how the algorithm here presented could be applicable for volcanic monitoring purposes and integrated into operational systems. Moreover, the combination of high-resolution (S2/MSI) and moderate-resolution (MODIS) thermal timeseries constitutes a breakthrough for future multi-sensor hot-spot detection systems, with increased monitoring capabilities that are useful for communities which interact with active volcanoes

Thermal anomalies of the transmitter experiment package on the communications technology satellite

The causes of four temporary thermal-control-system malfunctions that gave rise to unexpected temperature excursions in the 12-gigahertz, 200-watt transmitter experiment package (TEP) on the Communications Technology Satellite were investigated. The TEP consists of a nominal 200-watt output stage tube (OST), a supporting power-processing system (PPS), and a variable-conductance heat-pipe system (VCHPS). The VCHPS, which uses three heat pipes to conduct heat from the body of the OST to a radiator fin, was designed to maintain the TEP at safe operating temperatures at all operating conditions. On four occasions during 1977, all near the spring and fall equinoxes, the OST body temperature and related temperatures displayed sudden, rapid, and unexpected rises above normal levels while the TEP was operating at essentially constant, normal conditions. The temperature excursions were terminated without TEP damage by reducing the radio frequency (RF) output power of the OST. Between the anomalies and since the fourth, the thermal control system has apparently functioned as designed. The results indicate the most probable cause of the temperature anomalies is depriming of the arteries in the variable-conductance heat pipes. A mode was identified in which the TEP, as presently configured, may operate with stable temperatures and with minimum change in performance level