Researchers improve simulations of deep moist convection to accurately predict effects of climate change

Nov 08, 2013
Figure 1: The global Nonhydrostatic ICosahedral Atmospheric Model, when run with a 0.87-kilometer grid size, simulates realistic features of major weather structures. Credit: American Geophysical Union

Simulations of deep moist convection need to be run at grid resolutions finer than 2 kilometers to accurately predict the effects of climate change.

Deep moist atmospheric convection controls the development of major weather systems like hurricanes, drives the global transport of energy within the system and strongly influences the uncertainty of projected climate change. As computational power advances, the direct simulation of cloud processes within models is on the horizon. Yoshiaki Miyamoto, Hirofumi Tomita and their colleagues from the RIKEN Advanced Institute for Computational Science reveal that in order to realistically simulate the critical features of cloud convection, models will ultimately need to be run at a grid resolution no coarser than 2 kilometers.

Unless cloud simulations improve, uncertainties will remain unacceptably high for many pressing topics, such as the response of regional precipitation and global mean temperature to increases in greenhouse gas concentrations. Yet despite decades of research, the role of clouds in a changing climate remains unclear, largely reflecting a disconnect between cloud processes operating at the scale of individual water droplets and the 50- to 100-kilometer resolution used in many simulations of future climate.

Miyamoto and his colleagues showed that an intermediate resolution can be used to drive deep moist convection, thus providing a clear target for future climate model development. The team simulated 12 hours of global cloud processes with the Nonhydrostatic ICosahedral Atmospheric Model (NICAM) at a range of grid spacings of 0.87 to 14 kilometers. They found that simulations at 0.87 kilometers resolved deep moist convective processes ranging from individual subkilometer convective cells to the detail of tropical cyclones spanning hundreds of kilometers (Fig. 1).

At resolutions coarser than 2 kilometers, crucial cloud features were lost. "In the real world, convection is intensely variable and clouds have wide gradients in water vapor density and vertical velocity," says Miyamoto. "Coarser grids create unrealistically sharp transitions in cloud properties, with negative consequences for the realistic representation of related processes like condensation and precipitation."

New theoretical insights could also arise from the team's work. "Our finding that convective features change drastically at resolutions of 2 kilometers or more opens up new avenues for research into the interactions between convection and global atmospheric circulation that would have been invisible at coarser resolutions."

Hitting the 2-kilometer target will be a challenge. Even with ever-expanding computational power, 2-kilometer simulations of climate for a period of a few years, let alone the next century, are probably a decade or more away. Another option, according to Miyamoto, would be to simulate a limited area at a 2-kilometer spacing within a coarser global grid.

Explore further: NASA sees Hurricane Edouard far from US, but creating rough surf

More information: Miyamoto, Y., Kajikawa, Y., Yoshida, R., Yamaura, T., Yashiro, H. & Tomita, H. Deep moist atmospheric convection in a subkilometer global simulation. Geophysical Research Letters 40, 4922–4926 (2013). dx.doi.org/10.1002/grl.50944

add to favorites email to friend print save as pdf

Related Stories

Taming uncertainty in climate prediction

Mar 23, 2012

(PhysOrg.com) -- Uncertainty just became more certain. Atmospheric and computational researchers at Pacific Northwest National Laboratory used a new scientific approach called "uncertainty quantification," ...

Recommended for you

Tree rings and arroyos

1 hour ago

A new GSA Bulletin study uses tree rings to document arroyo evolution along the lower Rio Puerco and Chaco Wash in northern New Mexico, USA. By determining burial dates in tree rings from salt cedar and wi ...

NASA image: Agricultural fires in the Ukraine

2 hours ago

Numerous fires (marked with red dots) are burning in Eastern Europe, likely as a result of regional agricultural practices. The body of water at the lower left of this true-color Moderate Resolution Imaging ...

NASA marks Polo for a hurricane

3 hours ago

Hurricane Polo still appears rounded in imagery from NOAA's GOES-West satellite, but forecasters at the National Hurricane Center expect that to change.

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

Egleton
1 / 5 (9) Nov 08, 2013
Nik?
The Alchemist
1 / 5 (8) Nov 14, 2013
I've been predicting climate and macro-weather perfectly for years. It doesn't take any kind of resolution, just an understanding of weather systems, local terrain effects, will and...
https://www
.facebook.com/#!/groups/454689344557455/
Note artificial carriage return. Here it is for the clickers:

https://www.faceb...4557455/