Using OCO-2 and AIRS to quantify water vapor in the Planetary Boundary Layer

Accurate quantification of water vapor in the lower troposphere is critical for numerical weather prediction and climate studies. Water vapor is the most important greenhouse gas in the atmosphere with respect to radiative forcing feedback. Water vapor's natural regulation and large variability with space and time makes it difficult to quantify on a global scale. Ground-based in-situ measurements of water vapor are historically accurate, however, lack the global coverage needed to fully understand water vapor's role in the overarching climate system. Space-based satellite observations of water vapor in the lower atmosphere have the potential to improve temporal and spatial resolution of water vapor measurements, allowing for a deeper understanding of its role in Earth's mechanisms of radiative forcing. This study combines water vapor products from the Atmospheric Infrared Sounder (AIRS) and the Orbiting Carbon Observatory-2 (OCO-2) using a differencing formula to quantify water vapor in the lowermost portion of the troposphere; the planetary boundary layer. These calculations are then validated against radiosonde-based mergesonde products sourced from the Atmospheric Radiation Measurement (ARM) user facilities at the Southern Great Plains (SGP) site. Quantification of water vapor from space will be vital for improving numerical weather prediction models and understanding Earth's mechanisms of heat and energy transfer.