Precise remote sounding for better climate models

September 9, 2013
The ISOWAT spectrometer developed by IMK was operated on board of the CASA C-212 of the Spanish National Institute for Aerospace Technology (INTA). Credit: Christoph Dyroff, IMK

The water budget of the troposphere, the bottom layer of the Earth's atmosphere, determines the weather and plays a central role in climate change. The isotope composition of water vapor, i.e. the ratio of light and heavy water molecules, provides insight into underlying mechanisms. Climate researchers of Karlsruhe Institute of Technology (KIT) gather the data required by in-situ measurements as well as by using remote sounding instruments, e.g. on board of satellites. In a recent campaign, they combined both methods and proved the precision of remote sounding measurements for the first time.

"Water evaporation and condensation processes as well as the strong of water vapor and clouds decisively influence the energy balance of the atmosphere and the entire planet," says Matthias Schneider from the KIT Institute of Meteorology and Climate Research (IMK). "The complex water cycle has to be known better to understand our climate and to reliably estimate its development." Global analysis requires reliable remote sounding measurements. The data measured will then help improve the reliability of .

During a campaign above the sea near the Canary Island of Tenerife, the scientists conducted six measurement flights to determine the isotope composition of water vapor up to 7 km height. For this purpose, they used the ISOWAT diode laser spectrometer specially developed by IMK for use on aircraft. This spectrometer ensures a high accuracy and temporal resolution under dry as well as under humid conditions. In parallel, measurements were carried out at 2370 and 3550 m height on Tenerife in cooperation with the Spanish weather service (AEMET). Two commercial in-situ instruments and an infrared instrument of the worldwide measurement network NDACC (Network for the Detection of Atmospheric Composition Change) were applied for this purpose. In addition, the data of the infrared instrument IASI (Infrared Atmospheric Sounding Interferometer) operated on board of the METOP European weather satellite were used. The flights of the research aircraft were coordinated with the ground-based and satellite measurements.

"For this campaign, the IMK measurement methods for ground- and satellite-based remote sounding were combined with IMK's aircraft-based in-situ measurement methods," Matthias Schneider says. "We found good agreement between the datasets. This means that the precision of the remote sounding instruments, that is the quality of the data supplied by them, was confirmed." For the first time, the researchers have proved that both the worldwide measurement network NDACC with its ground stations and modern weather satellites provide reliable global data for the isotope composition of tropospheric water vapor.

Better understanding of the mechanisms associated with the atmospheric based on isotope composition is the objective of the MUSICA project coordinated by Schneider at IMK. MUSICA stands for "MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water". MUSICA is funded with EUR 1.5 million by the European Research Council (ERC). The project has a duration of five years.

Explore further: Measuring isotope variability in water vapor over Southern California

Related Stories

Volcanoes cause climate gas concentrations to vary

May 22, 2013

Trace gases and aerosols are major factors influencing the climate. With the help of highly complex installations, such as MIPAS on board of the ENVISAT satellite, researchers try to better understand the processes in the ...

Water isotopes leave fingerprints for climate scientists

June 25, 2013

University of Colorado meteorologist David Noone and his team are working to understand how water moves around the planet. With support from the National Science Foundation (NSF), the project team observes and analyzes the ...

Airlines help researchers understand global climate change

June 21, 2013

Commercial aircraft are now being used to collect data which helps scientists to measure greenhouse gases, aerosols and cloud particles. This allows the collection of observational data on a scale and in numbers impossible ...

Recommended for you

Mountain glaciers shrinking across the West

October 22, 2017

Until recently, glaciers in the United States have been measured in two ways: placing stakes in the snow, as federal scientists have done each year since 1957 at South Cascade Glacier in Washington state; or tracking glacier ...

Carbon coating gives biochar its garden-greening power

October 20, 2017

For more than 100 years, biochar, a carbon-rich, charcoal-like substance made from oxygen-deprived plant or other organic matter, has both delighted and puzzled scientists. As a soil additive, biochar can store carbon and ...

Cool roofs have water saving benefits too

October 20, 2017

The energy and climate benefits of cool roofs have been well established: By reflecting rather than absorbing the sun's energy, light-colored roofs keep buildings, cities, and even the entire planet cooler. Now a new study ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.