Synchronous Changes of Surface and Near‐Surface Air Temperature: Insights From a Field‐Scale Experiment

ABSTRACT

Surface temperature ( T _s ) and the thermal state of air immediately above urban surfaces are strongly coupled. This study used a 12‐day field campaign over a homogeneous 100 × 60 m artificial‐turf football field to examine the covariation among radiation, T _s , and a shaded near‐surface temperature proxy at 0.5 m height. Incident shortwave ( I ), reflected shortwave ( R ), downward longwave ( D ), and upward longwave ( U ) radiation were recorded every 10 s with a four‐component net radiometer and aggregated to hourly values. T _s was derived from longwave radiation using the Stefan–Boltzmann law with an emissivity of 0.95 and correction for reflected downward longwave radiation. The field exhibited a low effective albedo under high‐irradiance conditions, while the ratio U/D generally ranged from 1.1 to 1.6. T _s consistently exceeded the shaded near‐surface temperature proxy by about 5°C–30°C during daytime, and both variables covaried with incoming shortwave and net radiation. Linear associations were evident at the daily scale, although the explained variance differed among metrics, indicating modulation by atmospheric conditions. These results quantify the radiation‐temperature behavior of a homogeneous artificial‐turf surface and support the interpretation that low‐albedo surfaces can intensify near‐surface warming under sunny conditions.