![]() ![]() air temperature, humidity and solar radiation, and make assumptions about radiation-related parameters, such as surface emissivity, albedo and transmittance, which are set to default values and treated as constant (Kántor and Unger 2011). Models currently used are based on standard meteorological measurements, i.e. For long-term studies without direct measurements of radiation fluxes, the MRT can be derived using a theoretical method, i.e. In most cases, however, measurements are not available and/or not provided with continuity. The experimental method consists in measuring the MRT on field using instruments, such as pyranometers and globe thermometers, that can sample different radiation components in a three-dimensional environment. ![]() ![]() 2013).ĭifferent methods exist to estimate the MRT in outdoor settings (Thorsson et al. Thermal stress indices that require MRT as input parameter are, for instance, the wet-bulb globe temperature (WBGT), the physiological equivalent temperature (PET) and the universal thermal climate index (UTCI) (Budd 2008 Höppe 1999 Błażejczyk et al. multi-variate parameters describing the overall heat load experienced by the human body when attempting to maintain a thermal equilibrium with the surroundings. In biometeorology, the MRT is used to calculate thermal stress indices, i.e. For a human located in a given environment with a given posture and clothing, the MRT is defined as “that uniform temperature of a fictive black-body radiation enclosure (emission coefficient ε = 1) which would result in the same net radiation energy exchange with the subject as the actual, more complex radiation environment” (Kántor and Unger 2011).Īs a critical physical quantity representing how human beings experience radiation, the MRT has been the subject of studies in a variety of disciplines, from urban planning to public health and climate change (Lindberg and Grimmond 2011 Lindberg et al. the amount of radiation incident on a surface, it is converted into a temperature via the Stefan–Boltzmann equation. Rather than expressing this measure as a flux density, i.e. The MRT is a measure of the total radiation from the atmosphere and the ground ( radiant environment) incident on an object from all directions. Nevertheless, together with air temperature, humidity and wind speed, it is essential to describe the thermo-physiological effects of the outdoor environment on the human heat balance and comfort. ![]() The mean radiant temperature (MRT) is considered the most problematic variable to estimate in the assessment of human biometeorological comfort (Kántor and Unger 2011). Comparison against measurements from radiation monitoring stations showed a good agreement with NWP-based MRT (coefficient of determination greater than 0.88 average bias equal to 0.42 ☌) suggesting its potential as a proxy for observations in application studies. Mapped distributions of MRT were correspondingly computed at the global scale. The applicability of the framework was demonstrated using NWP reanalysis radiation data from the European Centre for Medium-Range Weather Forecasts. It also considers changes in the Sun’s position affecting radiation components when these are stored by NWP models as an accumulated-over-time quantity. The proposed framework requires as input radiation fluxes computed by numerical weather prediction (NWP) models and generates as output gridded globe-wide maps of MRT. This work presents a general framework to compute the MRT at the global scale for a human subject placed in an outdoor environment and irradiated by solar and thermal radiation both directly and diffusely. In human biometeorology, the estimation of mean radiant temperature (MRT) is generally considered challenging. ![]()
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