Radiative Exchanges during the Buildup of the Surface Based Temperature Inversion: Analysis of IGAC-ALPACA-PBL Intensive Field Experiment

In high latitudes during extreme winters, an anticyclonic meteorological feature triggers intense surface radiative cooling. Consequently, a surface-based temperature inversion layer (SBI) forms altering vertical radiative flux divergence. The initial shallow SBI instigates a change in surface cooling rate to then effectively decoupling it from the rest of the troposphere. Moreover, in the cold and dark polar atmospheric conditions such meteorological feature can extend its lifespan by several days. Through that time the surface radiative cooling excess deepens the SBI into the troposphere.

In this study, we thoroughly analyzed vertical radiative exchanges during the buildup of the SBI. This involved merging high-resolution thermodynamic profiles obtained from high resolution microwave radiometer observations with the vertically resolved MODTRAN model. To validate the radiative transfer model output, surface observations of turbulent and radiative fluxes were taken into account.

Multiple instances of SBI buildup were documented during the IGAC-ALPACA field experiment in the winter of 2022. This study illustrates the SBI's formation cycle, calculates cooling rates and radiative flux divergence time series, and is complemented by a thorough synoptic meteorological framework analysis. Gaining insight into the SBI buildup is crucial for mesoscale parameterization refinements. Accurate parameterization is essential to compute air pollution mixing and dispersion in constrained stratified layers and better delineate the radiative feedback components in Earth system models.