Turn-over Effect of Biogenic HCHO Columns at High Temperatures Seen by TEMPO Satellite

The deployment of spectrometers on geostationary satellites has enabled unprecedented hourly monitoring of trace gases critical for air quality and atmospheric research. As the dominant species of global BVOC emissions, isoprene has significant implications for health, weather and climate. Field studies have shown that isoprene emission rates increase with temperature until reaching a peak and subsequently decrease. Using TEMPO’s hourly HCHO columns with ERA5 temperature data, we investigate the temperature dependency of HCHO, a proxy for isoprene emissions, across vegetated regions of North America. After accounting for confounding variables such as biomass burning and soil moisture, we apply Pettitt’s test to detect the change-point where correlation between HCHO concentration and temperature shifts from positive to negative. We find distinct turn-over behavior of HCHO columns across diverse regions with different dominant vegetation types, including broadleaf evergreen trees, broadleaf deciduous trees, needleleaf evergreen trees and crops with corresponding temperature thresholds (most significant) of approximately 305.5 K, 306.1 K, 305.6 K and 303.7K, respectively. To ensure statistical robustness, we perform a bootstrap-based Pettitt’s test approach to quantify the uncertainty of these thresholds. The resulting 95% confidence intervals (CI) are [305.97, 306.37] K for broadleaf evergreen trees, [305.49, 306.28] K for broadleaf deciduous trees, [305.60, 305.70] K for needleleaf evergreen trees, and [302.33, 303.06] K for crops, respectively. This marks the first satellite-based detection of such a phenomenon. Our study demonstrates the exceptional potential of Geo-Ring observations, particularly TEMPO’s diurnal sampling, in detecting and constraining biogenic emissions. These findings underscore the value of geostationary data for refining emission models and enhancing predictions of atmospheric composition under a changing climate.