Analysis of global trends of total column water vapour from multiple years of OMI observations

Abstract

<p>Atmospheric water plays a key role for the Earth’s energy budget and temperature distribution via radiative effects (clouds and vapour) and latent heat transport. Thus, the distribution and transport of water vapour are closely linked to atmospheric dynamics on different spatiotemporal scales. In this context, global monitoring of the water vapour distribution is essential for numerical weather prediction, climate modelling, and a better understanding of climate feedbacks.</p><p>Total column water vapour (TCWV), or integrated water vapour, can be retrieved from satellite spectra in the visible “blue” spectral range (430-450nm) using Differential Optical Absorption Spectroscopy (DOAS). The UV-vis spectral range offers several advantages for monitoring the global water vapour distribution: for instance, it allows for accurate, straightforward and consistent retrievals over ocean and land surface even under partly-cloudy conditions.</p><p>To investigate changes in the TCWV distribution from space, the Ozone Monitoring Instrument (OMI) on board NASA’s Aura satellite is particularly promising as it provides long-term measurements (late 2004-ongoing) with daily global coverage.</p><p>Here, we present a global analysis of trends of total column water vapour retrieved from multiple years of OMI observations (2005-2021) and put our results in context to TCWV trends from other climate data records (e.g. reanalysis models or satellite measurements). Additionally, we investigate if the assumption of constant relative humidity over climatological time periods is fulfilled.</p><p>Furthermore, we demonstrate that it is possible to infer changes in the global atmospheric circulation directly from the global TCWV distribution: More precisely, we show that trends in changes in the location of the Hadley cell as well as its poleward expansion can be determined from the latitudinal TCWV distribution using a simple, straightforward and robust methodology.</p>