Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Columbia Engineering team makes major step in improving forecasts of weather extremes

06.06.2011
Observations major step in improving forecasts of weather extremes such as floods and droughts

Moisture and heat fluctuations from the land surface to the atmosphere form a critical nexus between surface hydrology and atmospheric processes, especially those relevant to rainfall.

While current theory has suggested that soil moisture has had a positive impact on precipitation, there have been very few large-scale observations of this.

A team of researchers from Columbia Engineering, Geophysical Fluid Dynamics Laboratory, and Rutgers University has now demonstrated that evaporation from the land surface is able to modify summertime rainfall east of the Mississippi and in the monsoonal region in the southern U.S. and Mexico. One of their main findings is that evaporation from the land is, however, only able to modify the frequency of summertime rainfall, not its quantity.

"This is a major shift in our understanding of the coupling between the land surface and the atmosphere, and fundamental for our understanding of the prolongation of hydrological extremes like floods and droughts," said Pierre Gentine, Assistant Professor of Applied Mathematics at The Fu Foundation School for Engineering and Applied Science at Columbia University, and co-author of the paper "Probability of Afternoon Precipitation in eastern United States and Mexico Enhanced by High Evaporation," published in the June 5th online edition of Nature Geoscience. The other co-authors are Kirsten Findell (Geophysical Fluid Dynamics Laboratory), Benjamin Lintner (Rutgers University), and Christopher Kerr (Geophysical Fluid Dynamics Laboratory).

The researchers used data from the National Centers for Environmental Prediction (NCEP) to quantify the impacts of continental evaporation on the frequency and intensity of summertime rainfall over North America. They discovered that higher evaporation increases the probability of afternoon rainfall east of the Mississippi and in Mexico, while it has no influence on rainfall over the Western U.S. The difference is due to the humidity present in the atmosphere. The atmosphere over the western regions is so dry that no matter what the input of moisture via evaporation is from the surface, an added source of moisture will not trigger any rain since it will instantaneously dissipate into the atmosphere. The atmosphere over the eastern regions is sufficiently wet so that the added moisture from the surface evaporation will make it rain.

"If it starts getting really wet in the east," noted Gentine, "then the surface will trigger more rain so it becomes even moister, and this sets up a vicious cycle for floods and droughts. Nature — i.e. the land surface and the vegetation — cannot control the rainfall process in the west but it can in the east and in the south. This is really important in our understanding of the persistence of floods and droughts."

Consequently, once a flood or a drought is triggered by large-scale processes, such as sea surface temperature anomalies, the flood/drought conditions are most likely to persist in the eastern and southern U.S. But in the West, the duration and frequency of floods/droughts are controlled only by oceanic processes: the surface cannot modify the rainfall process. Whether the soil is dry or wet doesn't change subsequent rainfalls: consequently the surface will not help hydrological extremes persist (e.g. floods/droughts).

Gentine is developing a theoretical framework to understand the precipitation and cloud formation over land and says this should be an important breakthrough in our understanding of how soil moisture and vegetation controls cloud formation and the precipitation process. "I find this work fascinating because it's a great blend of theoretical research — understanding how nature works — and practical applications that affect our world —like flood/drought/water management. My lab is right outside: observing clouds and precipitation!"

The study was funded by the National Science Foundation (NSF).

Columbia Engineering

Columbia University's Fu Foundation School of Engineering and Applied Science, founded in 1864, offers programs in nine departments to both undergraduate and graduate students. With facilities specifically designed and equipped to meet the laboratory and research needs of faculty and students, Columbia Engineering is home to NSF- and NIH-funded centers in genomic science, molecular nanostructures, materials science, and energy, as well as one of the world's leading programs in financial engineering. These interdisciplinary centers are leading the way in their respective fields while individual groups of engineers and scientists collaborate to solve some of society's more vexing challenges. http://www.engineering.columbia.edu/

Holly Evarts | EurekAlert!
Further information:
http://www.columbia.edu

More articles from Earth Sciences:

nachricht Water - as the underlying driver of the Earth’s carbon cycle
17.01.2017 | Max-Planck-Institut für Biogeochemie

nachricht Modeling magma to find copper
13.01.2017 | Université de Genève

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Explaining how 2-D materials break at the atomic level

18.01.2017 | Materials Sciences

Data analysis optimizes cyber-physical systems in telecommunications and building automation

18.01.2017 | Information Technology

Reducing household waste with less energy

18.01.2017 | Ecology, The Environment and Conservation

VideoLinks
B2B-VideoLinks
More VideoLinks >>>