Comparison with observations shows cloud simulations improving

Aug 08, 2012

Climate projections, such as those used by the Intergovernmental Panel on Climate Change, rely on models that simulate physical properties that affect climate, including clouds and water vapor content. Clouds and water vapor are difficult to simulate in global climate models because they are affected by small-scale physical processes, and cloud feedback on climate is therefore a large source of uncertainty in climate predictions.

A new study finds that of vertically averaged cloud water amount have improved in recent years. Jiang et al. develop a quantitative scoring method to evaluate the accuracy of 19 climate models at various vertical heights between the surface and the tropopause (16 to 18 kilometers (10 to 11 miles) in altitude) over the tropical oceans (30 degrees North to 30 degrees South). They compare the models’ simulated multiyear mean of cloud water content and water vapor with observations made using several NASA satellites.

Many of the new models, which were submitted to phase 5 of the Coupled Model Intercomparison Project (CMIP5), have attempted to improve representation of clouds using finer-scale simulations. The authors find that more than half of the models did show improvement over previous models from CMIP3 in simulating the amount and distribution of clouds and water vapor over the tropical oceans. In addition, they find that the models simulated boundary layer water vapor amounts accurately. However, there are large differences among the models and between the models and observations at high altitudes in the upper troposphere.

Explore further: Invisible helpers of the sea: Marine bacteria boost growth of tiny ocean algae

More information: “Evaluation of cloud and water vapor simulations in CMIP5 climate models using NASA "A-Train" satellite observations” Journal of Geophysical Research-Atmospheres, doi:10.1029/2011JD017237, 2012

Related Stories

New tool clears the air on cloud simulations

Oct 26, 2011

(PhysOrg.com) -- Climate models have a hard time representing clouds accurately because they lack the spatial resolution necessary to accurately simulate the billowy air masses.

Ice heating up cold clouds

Sep 21, 2011

In the Arctic, competition within clouds is hot. The small amount of heat released when water vapor condenses on ice crystals in Arctic clouds, which contain both water and ice, determines the cloud's survival, ...

Tropical clouds hold clues for the global water cycle

Jan 16, 2012

(PhysOrg.com) -- To study the wellspring of atmospheric water, you have to start with tropical clouds. Scientists at Pacific Northwest National Laboratory showed that global climate models are not accurately ...

The insides of clouds may be the key to climate change

Feb 17, 2007

As climate change scientists develop ever more sophisticated climate models to project an expected path of temperature change, it is becoming increasingly important to include the effects of aerosols on clouds, according ...

Water vapor confirmed as major player in climate change

Nov 17, 2008

(PhysOrg.com) -- Water vapor is known to be Earth's most abundant greenhouse gas, but the extent of its contribution to global warming has been debated. Using recent NASA satellite data, researchers have estimated ...

Recommended for you

Satellites catch the birth of two volcanic islands

6 hours ago

The birth of a volcanic island is a potent and beautiful reminder of our dynamic planet's ability to make new land. Given the destruction we've seen following natural events like earthquakes and tsunamis in t ...

Uncovering diversity in an invisible ocean world

7 hours ago

Plankton are vital to life on Earth—they absorb carbon dioxide, generate nearly half of the oxygen we breathe, break down waste, and are a cornerstone of the marine food chain. Now, new research indicates ...

Evolution of the Antarctic ice sheet

8 hours ago

ULB study sheds a new light on the stability of the Antarctic ice sheet. It shows for the first time that ice rises (pinning points that keep the floating parts of ice sheets in place) are formed during the transition between ...

User comments : 0

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.