Many researchers have begun to study Urban Heat Islands, or cities that get hotter than nearby rural areas. Often, scientists rely on satellite data for air temperatures.
New research cautions against relying exclusively on satellite data for urban heat risk assessments, arguing that citizen weather stations produced more accurate data.
From the paper, published in Science Advances:
Spatially explicit LST data from satellites are gaining popularity and are being increasingly applied, either directly or for predicting air temperature, to public health risk studies (35, 36). In doing so, researchers run the risk of overestimating the magnitude of temperature exposure as well as the contribution of urbanization to the local temperature. This is particularly concerning given that the upward bias of satellite-based measures of UHI was greatest during conditions that are most relevant to heat risk epidemiology (daytime, low cloud cover, high diurnal temperature ranges, and low wind speeds). Proper quantification of the public health implications of UHI requires dense monitoring networks in cities, and in the absence of these monitoring networks, crowdsourced air temperature measurements can be a reasonable alternative, as we demonstrate in the present study.
Crowdsourced weather data are now widely available (44), with dense CWS networks in major urban centers globally (https://weathermap.netatmo.com). Although data quality is a concern, it does not preclude the use of these data in urban climatology studies. Data quality control procedures used in the present study (fig. S9) are open source (28, 45) and significantly reduce risk of including statistically implausible Tair due to misplacement of sensors, solar exposition (radiative errors), inconsistent metadata, and device malfunctions.