Articles | Volume 10, issue 11
Atmos. Meas. Tech., 10, 4521–4536, 2017

Special issue: Twenty-five years of operations of the Network for the Detection...

Atmos. Meas. Tech., 10, 4521–4536, 2017

Research article 22 Nov 2017

Research article | 22 Nov 2017

Quality assessment of integrated water vapour measurements at the St. Petersburg site, Russia: FTIR vs. MW and GPS techniques

Yana A. Virolainen1, Yury M. Timofeyev1, Vladimir S. Kostsov1, Dmitry V. Ionov1, Vladislav V. Kalinnikov2, Maria V. Makarova1, Anatoly V. Poberovsky1, Nikita A. Zaitsev1, Hamud H. Imhasin1, Alexander V. Polyakov1, Matthias Schneider3, Frank Hase3, Sabine Barthlott3, and Thomas Blumenstock3 Yana A. Virolainen et al.
  • 1Atmospheric Physics Department, St. Petersburg State University, Saint Petersburg, 199034, Russia
  • 2Kazan (Volga Region) Federal University, 420008, Kazan, Russia
  • 3Institute of Meteorology and Climate Research (IMK-ASF), Karlsruhe Institute of Technology, Karlsruhe, Germany

Abstract. The cross-comparison of different techniques for atmospheric integrated water vapour (IWV) measurements is the essential part of their quality assessment protocol. We inter-compare the synchronised data sets of IWV values measured by the Bruker 125 HR Fourier-transform infrared spectrometer (FTIR), RPG-HATPRO microwave radiometer (MW), and Novatel ProPak-V3 global navigation satellite system receiver (GPS) at the St. Petersburg site between August 2014 and October 2016. As the result of accurate spatial and temporal matching of different IWV measurements, all three techniques agree well with each other except for small IWV values. We show that GPS and MW data quality depends on the atmospheric conditions; in dry atmosphere (IWV smaller than 6 mm), these techniques are less reliable at the St. Petersburg site than the FTIR method. We evaluate the upper bound of statistical measurement errors for clear-sky conditions as 0.29 ± 0.02 mm (1.6 ± 0.3 %), 0.55 ± 0.02 mm (4.7 ± 0.4 %), and 0.76 ± 0.04 mm (6.3 ± 0.8 %) for FTIR, GPS, and MW methods, respectively. We propose the use of FTIR as a reference method under clear-sky conditions since it is reliable on all scales of IWV variability.

Short summary
Water vapour is one of the most important gases in the Earth’s atmosphere and plays a unique role in climate and weather forming. Cross-comparison of different systems for monitoring the atmospheric integrated water vapour (IWV) measurements is an essential part of their testing and validation protocol. We compare coincident measurements of IWV by different techniques over Saint Petersburg (Russia), assess their quality in various atmospheric conditions, and give recommendation for data users.