Surface and Tropospheric Water Vapor Variability and Decadal Trends at Two Supersites of CO-PDD (Cézeaux and Puy de Dôme) in Central France

Dani Hadad,Valentin Duflot,Jean-Luc Baray,Jean-Marc Pichon,Nadège Montoux,Michel Ramonet,Camille Yver Kwok,Joël Van Baelen,Patrick Fréville,Nelson Bègue,Pierre Bosser

doi:10.3390/atmos9080302

Abstract

We present an analysis of decadal in situ and remote sensing observations of water vapor over the Cézeaux and puy de Dôme, located in central France (45° N, 3° E), in order to document the variability, cycles and trends of surface and tropospheric water vapor at different time scales and the geophysical processes responsible for the water vapor distributions. We use meteorological stations, GPS (Global Positioning System), and lidar datasets, supplemented with three remote sources of water vapor (COSMIC-radio-occultation, ERA-interim-ECMWF numerical model, and AIRS-satellite). The annual cycle of water vapor is clearly established for the two sites of different altitudes and for all types of measurement. Cezeaux and puy de Dôme present almost no diurnal cycle, suggesting that the variability of surface water vapor at this site is more influenced by a sporadic meteorological system than by regular diurnal variations. The lidar dataset shows a greater monthly variability of the vertical distribution than the COSMIC and AIRS satellite products. The Cézeaux site presents a positive trend for the GPS water vapor total column (0.42 ± 0.45 g·kg−1/decade during 2006–2017) and a significant negative trend for the surface water vapor mixing ratio (−0.16 ± 0.09 mm/decade during 2002–2017). The multi-linear regression analysis shows that continental forcings (East Atlantic Pattern and East Atlantic-West Russia Pattern) have a greater influence than oceanic forcing (North Atlantic Oscillation) on the water vapor variations.

Highlights

Water under its three phases is a key element of the atmosphere
That suggests that the variability of surface water water vapor at this site is more influenced by sporadic meteorological systems than by regular vapor at this site is more influenced by sporadic meteorological systems than by regular diurnal diurnal variations
In this study we presented an analysis of a long data set of lidar, GPS, CRDS, and meteorological observations at the sites of puy de Dôme and Cezeaux

Summary

Introduction

Water under its three phases is a key element of the atmosphere. Atmospheric icing occurs in high altitude clouds, like cirrus, which have been recognized as important regulators of the radiative balance of the earth’s atmosphere system [1], and at the top of convective clouds with important issuesAtmosphere 2018, 9, 302; doi:10.3390/atmos9080302 www.mdpi.com/journal/atmosphereAtmosphere 2018, 9, 302 for aircraft security [2]. Water under its three phases is a key element of the atmosphere. Atmospheric icing occurs in high altitude clouds, like cirrus, which have been recognized as important regulators of the radiative balance of the earth’s atmosphere system [1], and at the top of convective clouds with important issues. Clouds and precipitation are important components in the Earth’s energy budget and water cycle, the Earth’s climate, and climate variability [3]. Anomalously dry layers can be interpreted as small-scale features of stratospheric intrusions [5,6]. For these reasons, water vapor is an Essential Climate Variable (ECV) of the Global

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