Trajectory mapping of middle atmospheric water vapor by a mini network of NDACC instruments

Abstract

Abstract.The important task to observe the global coverage of middle atmospheric trace gases like water vapor or ozone usually is accomplished by satellites. Climate and atmospheric studies rely upon the knowledge of trace gas distributions throughout the stratosphere and mesosphere. Many of these gases are currently measured from satellites, but it is not clear whether this capability will be maintained in the future. This could lead to a significant knowledge gap of the state of the atmosphere. We explore the possibilities of mapping middle atmospheric water vapor in the Northern Hemisphere by using Lagrangian trajectory calculations and water vapor profile data from a small network of five ground-based microwave radiometers. Four of them are operated within the frame of NDACC (Network for the Detection of Atmospheric Composition Change). Keeping in mind that the instruments are based on different hardware and calibration setups, a height-dependent bias of the retrieved water vapor profiles has to be expected among the microwave radiometers. In order to correct and harmonize the different data sets, the Microwave Limb Sounder (MLS) on the Aura satellite is used to serve as a kind of traveling standard. A domain-averaging TM (trajectory mapping) method is applied which simplifies the subsequent validation of the quality of the trajectory-mapped water vapor distribution towards direct satellite observations. Trajectories are calculated forwards and backwards in time for up to 10 days using 6 hourly meteorological wind analysis fields. Overall, a total of four case studies of trajectory mapping in different meteorological regimes are discussed. One of the case studies takes place during a major sudden stratospheric warming (SSW) accompanied by the polar vortex breakdown; a second takes place after the reformation of stable circulation system. TM cases close to the fall equinox and June solstice event from the year 2012 complete the study, showing the high potential of a network of ground-based remote sensing instruments to synthesize hemispheric maps of water vapor.

The SPARC water vapor assessment II: intercomparison of satellite and ground-based microwave measurements

“…Only the Mauna Loa and Lauder measurements performed well in the upper stratosphere (Haefele et al, 2009). There have since been efforts to extend the useful lower altitude of some of these measurements (Nedoluha et al, 2011;Lainer et al, 2015) …”

Significant decline of mesospheric water vapor at the NDACC site near Bern in the period 2007 to 2018

“…In recent years, data from the MIAWARA radiometer have been used to detect a solar-induced variability of mesospheric H 2 O (Lainer et al, 2016); further they have been used to investigate planetary 16 d, subdiurnal and 2 d atmospheric wave activities by using H 2 O as a dynamical tracer (Scheiben et al, 2014;Lainer et al, 2017Lainer et al, , 2018.…”

The SPARC water vapor assessment II: intercomparison of satellite and ground-based microwave measurements

“…Only the Mauna Loa and Lauder measurements performed well in the upper stratosphere (Haefele et al, 2009). There have since been efforts to extend the useful lower altitude of some of these measurements (Nedoluha et al, 2011;Lainer et al, 2015)…”

“…In the stratosphere H 2 O increases with altitude as CH 4 is oxidized (Le Texier et al, 1988;Wrotny et al, 2010). As this oxidation occurs gradually, the amount of H 2 O that has been produced by this process in the stratosphere depends upon the age of the parcel, and this is affected by variations in dynamics.…”