Rate Of Surface Temperature Change Research Articles

Parameters That Influence Corrosion Detection in Reinforced Concrete Based on Eddy Current Thermography

This study introduces an eddy current thermography technique that can be used to detect and evaluate steel corrosion in a reinforced concrete structure. The rate of surface temperature changes in reinforced concrete is proposed as a means to characterize the degree of steel bar corrosion. The rate of surface temperature changes increased gradually with an increase in the corrosion degree. The influence of structural parameters on the rate of the temperature change was analyzed in detail. The results indicated that the rate of surface temperature change increased with a decrease in the concrete cover depth and with an increase in the humidity of the concrete, and this was affected by the diameter of the internal steel bar. Concrete cover was the most significant factor that affected the rate of the surface temperature change, except for the corrosion degree. The variations in the surface temperature of reinforced concrete can be explained using the law of electromagnetic induction and the electrochemical property change of corroded steel bar. This research provides a reliable basis for real‐world applications and is helpful to understand the application scope of eddy current thermography technology for the quantitative detection of steel corrosion.

A Call for New Approaches to Quantifying Biases in Observations of Sea Surface Temperature

Abstract Global surface temperature changes are a fundamental expression of climate change. Recent, much-debated variations in the observed rate of surface temperature change have highlighted the importance of uncertainty in adjustments applied to sea surface temperature (SST) measurements. These adjustments are applied to compensate for systematic biases and changes in observing protocol. Better quantification of the adjustments and their uncertainties would increase confidence in estimated surface temperature change and provide higher-quality gridded SST fields for use in many applications. Bias adjustments have been based on either physical models of the observing processes or the assumption of an unchanging relationship between SST and a reference dataset, such as night marine air temperature. These approaches produce similar estimates of SST bias on the largest space and time scales, but regional differences can exceed the estimated uncertainty. We describe challenges to improving our understanding of SST biases. Overcoming these will require clarification of past observational methods, improved modeling of biases associated with each observing method, and the development of statistical bias estimates that are less sensitive to the absence of metadata regarding the observing method. New approaches are required that embed bias models, specific to each type of observation, within a robust statistical framework. Mobile platforms and rapid changes in observation type require biases to be assessed for individual historic and present-day platforms (i.e., ships or buoys) or groups of platforms. Lack of observational metadata and high-quality observations for validation and bias model development are likely to remain major challenges.

Rates of temperature change of airless landscapes and implications for thermal stress weathering

Thermal stress weathering may play a role in the evolution of terrestrial‐planet landscapes, particularly those without atmospheres, by contributing to rock breakdown, regolith production, and crater degradation. Damage occurs in the form of microscopic cracks that result from a thermal cycle or thermal shock. Terrestrial studies typically evaluate the efficacy of this process by measuring the rate of surface temperature change (dT/dt), using a damage threshold of 2 K/min. While the extent of this damage is unknown, we investigate its relative efficacy by modeling rates of temperature change on various airless surfaces. The magnitude of dT/dt values is primarily controlled by sunrise/set durations on quickly rotating bodies, such as Vesta, and by distance to the sun on slowly rotating bodies, such as Mercury. The strongest temperature shocks are experienced by highly sloped east‐ or west‐facing surfaces. Hot thermal shocks (dT/dt > 0) tend to be stronger than cold shocks (dT/dt < 0), and on some bodies, daytime shadowing may produce higher dT/dt values than those caused by diurnal sunrise/set if the topography is optimally oriented. We find that high dT/dt values are not, however, always correlated with high temperature gradients within the rock. This adds to the ambiguity of the poorly understood damage threshold, warranting further research on the topic that goes beyond the simple 2 K/min criterion.

Arctic Surface, Cloud, and Radiation Properties Based on the AVHRR Polar Pathfinder Dataset. Part II: Recent Trends

Abstract Over the past 20 yr, some Arctic surface and cloud properties have changed significantly. Results of an analysis of satellite data show that the Arctic has warmed and become cloudier in spring and summer but has cooled and become less cloudy in winter. The annual rate of surface temperature change is 0.057°C for the Arctic region north of 60°N. The surface broadband albedo has decreased significantly in autumn, especially over the Arctic Ocean, indicating a later freeze-up and snowfall. The surface albedo has decreased at an annual rate of −0.15% (absolute). Cloud fraction has decreased at an annual rate of −0.6% (absolute) in winter and increased at annual rates of 0.32% and 0.16% in spring and summer, respectively. On an annual time scale, there is no trend in cloud fraction. During spring and summer, changes in sea ice albedo that result from surface warming tend to modulate the radiative effect of increasing cloud cover. On an annual time scale, the all-wave cloud forcing at the surface has decreased at an annual rate of –0.335 W m−2, indicating an increased cooling by clouds. There are large correlations between surface temperature anomalies and climate indices such as the Arctic Oscillation (AO) index for some areas, implying linkages between global climate change and Arctic climate change.

Lichen hotspots: raised rock temperatures beneath Verrucaria nigrescens on limestone

Field exposure trials and laboratory experiments are integrated to compare surface and internal temperature changes of limestone with an epilithic ( Verrucaria nigrescens) and endolithic ( Verrucaria baldensis) covering of lichens, and with no lichen cover (control). Blocks with covering of V. nigrescens experience both the highest surface and internal temperatures under a direct heating source during daytime and in laboratory experiments. Spectrophotometer data suggest that the black colour of the V. nigrescens thallus plays a significant role in determining the thermal response of the rock surface. When direct heating (by sun or lamp) is absent (at nighttime and for a diurnal cycle programmed in an environmental chamber), little differentiation occurs between surface and internal temperatures for all surface types compared. For all blocks exposed, maximum rates of daytime surface temperature change ranged from 1.47 to 3.04 °C min −1 and for two of the exposure periods, the highest rates of daytime surface temperature change were experienced by blocks with V. nigrescens cover. The blocks with V. nigrescens cover also experience the greatest thermal gradients in both field and laboratory experiments. The rates of surface temperature change and thermal gradients experienced beneath V. nigrescens in this study could be significant in increasing rock susceptibility to breakdown.

THERMAL RESPONSE CHARACTERISTICS OF STONE: IMPLICATIONS FOR WEATHERING OF SOILED SURFACES IN URBAN ENVIRONMENTS

Soiling of stone surfaces by particulate deposition increases absorption of radiant energy, raises surface/subsurface temperature gradients and accentuates rates of surface temperature change. Short-term fluctuation of raised surface temperatures, in response to variations in windspeed and cloud cover, may ultimately contribute to stone breakdown through ‘fatigue’ effects which reduce cohesive strength of intergranular bonds and initiate microfracture development. The effects of soiling are particularly marked for stone with low thermal conductivity and high albedo when clean. Albedo change has implications for the effectiveness of weathering processes and the durability of building stone by creating microenvironmental conditions which are more severe than those indicated by macroenvironmental regimes.

Daytime rock surface temperature variability and its implications for mechanical rock weathering: Tenerife, Canary Islands

Summary Summer and winter rock surface temperature measurements are presented from three sites along an altitudinal gradient. Significant between- and within-site variability is recognised related to insolation, cloud cover and air temperature differences, maritime influences and time of year. The variability argues against the use of a single rock temperature regime to characterise hot desertic environments in, for example, weathering simulation studies. Superimposed upon diurnal patterns of heating and cooling are numerous short- (3–15 minutes) and medium-term (1–2 hours) fluctuations related to wind-speed and cloud cover variations. Rates of surface temperature change are very high during these fluctuations(>3°C/minute) and it is proposed that they may enhance the operation of a number of mechanical rock weathering mechanisms.