High-Resolution Atmospheric Water Vapor Fields by Spaceborne Geodetic Sensing, Tomographic Fusion, and Atmospheric Modeling

Project Description



The AtmoWater project, High-Resolution Atmospheric Water Vapor Fields by Spaceborne Geodetic Sensing, Tomographic Fusion, and Atmospheric Modeling is an international collaboration consisting of four institutes of Karlsruhe Institute of Technology (KIT) and ETH Zurich.

The project is coordinated by the Geodetic Institute of KIT and funded by German Research Foundation (DFG, project number: 321886779) and Swiss National Science Foundation (SNSF) for the duration of three years (2018-2021).


Project Description

Although the atmosphere contains only up to 4% water vapor by volume, water vapor is one of the central atmospheric gases. Water vapor is a highly effective greenhouse gas that is directly intertwined with global climate change and its implications for natural disasters such as floods, droughts, deluge or glacier melting.

As a vital component of the hydrological cycle, water vapor represents a main driver for the generation and spatio-temporal distribution of clouds and precipitation. The quantification of water vapor remains a challenge: while regional atmospheric models (Limited Area Model, LAM) in general allow to simulate the distribution of hydro-meteorological variables in space and time in high resolution, their performance in reproducing in detail their high spatio-temporal variability remains still limited.

At the same time only limited high resolution atmospheric water vapor validation records exist. Acting as an important signal in meteorology and climate research, water vapor principally is regarded as a source of noise in Geodesy and Remote Sensing applications. The humidity of the Earth's atmosphere induces delays and distortions of high temporal and spatial fluctuations in microwave signals, which cannot be eliminated by multi-frequency measurements and have to be quantified during the data processing. Thus observations of Global Navigation Satellite Systems (GNSS: high temporal resolution) and Interferometric Synthetic Aperture Radar (InSAR: high spatial resolution) provide valuable contributions for reconstructing the integrated water vapor along the path from the satellites to the observation site on the Earth's surface.

In addition, the sophisticated tomography-based evaluation of these data even allows generating 3D fields of the water vapor distribution in space and time. By using GNSS and InSAR based techniques in combination with high resolution regional atmospheric weather models and geostatistical data merging techniques, the proposed project aims at developing and evaluating new approaches to derive improved spatio-temporal estimates of the atmospheric water vapor distribution. In particular, tomography-based approaches in the evaluation of geodetic and remote sensing data will be further developed to improve the vertical and horizontal resolution of the atmospheric state variable under research. The generated products are used for comparison and assimilation with atmospheric model-based information to finally get an optimal estimation of the atmospheric water vapor distribution.

  Above figure taken from: Heublein M, Alshawaf F, Mayer, M, Hinz S, Heck B (2014): Towards a rigorous fusion of GNSS and InSAR observations for the purpose of water vapor retrieval. KIT Scientific Publishing Karlsruhe, Schriftenreihe des Studiengangs Geodäsie und Geoinformatik / Karlsruher Institut für Technologie, Studiengang Geodäsie und Geoinformatik; 2014,1. Link: http://dx.doi.org/10.5445/KSP/1000043259 External Link  



1. Geodetic Institute (GIK), KIT (Coordinator)
  Leader (since 1/2019): Prof. Dr.-Ing. Hansjörg Kutterer
  Former Leader (until 12/2018): Prof. Dr.-Ing. Bernhard Heck
  Contact person: Dr. Peng Yuan
  Other members: Dr. rer. nat. Malte Westerhaus
Dr.-Ing. Hael Sumaya
2. Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), KIT
  Leader: Prof. Dr. Harald Kunstmann
  Contact person: Dr. Andreas Wagner
  Other member: Dr. Benjamin Fersch
  Extended Link  
3. Institute of Photogrammetry and Remote Sensing (IPF), KIT
  Leader: Prof. Dr.-Ing. Stefan Hinz
  Contact persons: Dr.-Ing. Andreas Schenk
M.Sc. Bettina Raible
4. Institute of Geodesy and Photogrammetry, ETH Zurich
  Leader (since 09/2019): Prof. Dr. Markus Rothacher
  Former Leader (until 08/2019): Prof. Dr. Alain Geiger
  Contact person: M.Sc. Endrit Shehaj



Wagner et al. Assimilation of GNSS water vapour in WRF: a case study for Southern Germany. EGU General Assembly 2019, 7–12 April 2019, Vienna, Austria. (Poster)



News for the 5th meeting of the AtmoWater Project

Date: October 23rd, 2019
Author: Peng Yuan

On October 23rd, 2019, the 5th meeting of the AtmoWater Project 'AtmoWater: High-Resolution Atmospheric Water Vapor Fields by Spaceborne Geodetic Sensing, Tomographic Fusion, and Atmospheric Modeling' took place at Karlsruhe Institute of Technology (KIT) in Karlsruhe.

The meeting was hosted by the geodetic institute of KIT and the following collaborators from the four working groups attended the meeting: (1) KIT IMK-IFU: Dr. Andreas Wagner; (2) Prof. Dr. Hansjörg Kutterer; Dr. Peng Yuan; Dr. Hael Sumaya; (3) Dr. Andreas Schenk; Msc. Bettina Raible; (4) ETH Zürich IGP-MPG: Msc. Endrit Shehaj.

The meeting started at 1:30 p.m. with a warm welcome by Prof. Kutterer. Then, each group gave a 15 minutes presentation to show their progress related to the project. Wagner from IMK-IFU presented the improvements of WRF-derived precipitation caused by assimilating GPS and InSAR tropospheric delay measurements. Peng from GIK assessed the accuracy of newly released EWMWF reanalysis product, ERA5, and investigated its influences on GPS PWV retrieving. Bettina form IPF showed InSAR tropospheric delay images over a region at Freiburg in the Black Forest. Finally, Endrit from IGP-MPG compared different mapping functions showed refractivity and ZTD obtained by tomography. Although pertinent questions were put forward and concise answers were given after each presentation, the delegates had a further discussion for more than two hours. Several crucial technical problems were discussed in detail, including the slant delay and zenith delay of InSAR. At last, the exchange of results between the four groups was clarified.

The meeting ended at 5:15 p.m. The delegates reached agreement that the next meeting will be hosted by IMK-IFU at Augsburg around February and March 2020. IMK-IFU will prepare a vote to determine the specific meeting time.


News for the 4th meeting of the AtmoWater Project

Date: May 15th, 2019
Author: Endrit Shehaj

The 4th meeting of the AtmoWater Project 'AtmoWater: High-Resolution Atmospheric Water Vapor Fields by Spaceborne Geodetic Sensing, Tomographic Fusion, and Atmospheric Modeling' took place in Zurich at ETH Hönggerberg, 13:15-16:15pm, May 15th, 2019.

In this meeting, the following collaborators from the four groups working were present: 1) Dr. Andreas Wagner, Dr. Benjamin Fersch and Roya Mousavian from IMK-Ifu, 2) Prof. Hansjörg Kutterer and Dr. Peng Yuan from GIK, 3) Dr. Andreas Schenk and Prof. Stefan Hinz from IPF and 4) Prof. Alain Geiger, Endrit Shehaj, Dr. Karina Wilgan.

Each group presented its advances related to the project, which was followed by respective discussions about problematic that need to still be solved and future work. IMK-Ifu presented the impact of assimilating ZTD and PWV in their forecasting model. GIK focused its talk on the impact of weighted mean temperature on precipitable water vapor. IPF their advancement in processing of InSAR acquisitions using PSI and updated on the GLORIA experiment. Finally, ETH-IGP presented the impact of different slant models in their 'tomographic ' combination of GNSS and InSAR measurements.

It was decided that the next AtmoWater meeting will take place the 23 October 2019 at 13:00pm in Karlsruhe and will be hosted by GIK.