Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Summer Rain More Likely over Drier Soils

13.09.2012
Where does it rain on a hot day’s afternoon? New satellite data show that soil moisture plays an important role. It influences precipitation in a way which is quite different from what models have predicted so far.

Summer rain is more likely over drier soil – this is the conclusion scientists have drawn from a detailed analysis of satellite data. State-of-the-art computer models predict the opposite effect; these models must now be reconsidered, says the study published in the journal “Nature”.


A storm is brewing (Mali, Sahel)

"F. Guichard & L. Kergoat, AMMA project, CNRS" copyright

Several international research groups were involved in the project: The Centre for Ecology and Hydrology (Wallingford, UK), the VU University Amsterdam, the Center of Meteorology CNRM in Toulouse, and the Vienna University of Technology.

Convective Showers: Hot Air Moves Up

Frontal rain systems, moving from the ocean across the land, can lead to rain over large areas. Summer showers, which frequently occur at the end of a hot day, are often restricted to a rather small region. This kind of rain is a completely different phenomenon. Instead of moving across the land, the air moves from the hot ground upwards, forming clouds high up in the air, and finally leading to rain. This is called “convective precipitation”.
Does Soil Moisture Lead to More Rain?

“It’s tempting to assume that moist soils lead to higher evaporation, which in turn stimulates more precipitation”, says Wouter Dorigo (Vienna University of Technology), one of the authors of the study. “This would imply that there is a positive feedback loop: moist soils lead to even more rain, whereas dry regions tend to remain dry.” But observations suggest otherwise: “We have analyzed data from different satellites measuring soil moisture and precipitation all over the globe, with a resolution of 50 to 100 kilometers. These data show that convective precipitation is more likely over drier soils”, says Wouter Dorigo.

The new data contradicts established computer models. A conclusive explanation for this effect has yet to be found. “The air over dry soils heats up more easily. This could lead to a more intense vertical draft”, Dorigo suspects. However, this cannot yet be described at a sufficient level of detail with today’s computer simulations.

Microwaves from Space

Soil moisture can be measured with satellites using microwave radiation. Unlike visible light, microwaves can penetrate clouds. Satellites can either measure the Earth's natural microwave radiation to calculate the local soil moisture (passive measurement) or the satellite sends out microwave pulses and measures how strongly the pulse is reflected by the surface (active measurement). From this data, the soil moisture can be calculated.

Picture Download:
http://www.tuwien.ac.at/dle/pr/aktuelles/downloads/2012/sommerregen/

Further information:
Dr. Wouter Dorigo
Institute for Photogrammetry and Remote Sensing
Vienna University of Technology
Gusshausstraße 25-29, 1040 Wien
T: +43-1-58801-12243
Mobile: +43-650-7426622
wouter.dorigo@tuwien.ac.at

Dr. Florian Aigner | Technische Universität Wien
Further information:
http://www.tuwien.ac.at

More articles from Earth Sciences:

nachricht NASA examines newly formed Tropical Depression 3W in 3-D
26.04.2017 | NASA/Goddard Space Flight Center

nachricht Early organic carbon got deep burial in mantle
25.04.2017 | Rice University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Millions through license revenues

27.04.2017 | Health and Medicine

The TU Ilmenau develops tomorrow’s chip technology today

27.04.2017 | Information Technology

Scientist invents way to trigger artificial photosynthesis to clean air

26.04.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>