In his new paper in the Proceedings of the National Academy of Sciences, he uses a procedure known as «downscaling» — combining together global climate models with a much higher
resolution hurricane model — to show that hurricanes may be both more numerous and also more intense going forward.
Meanwhile, high -
resolution hurricane models can forecast the growth and path of tropical storms, but would require much greater computer power or eons of time to simulate the large samples of storms required for climate - change studies.
Here's why: One of our most accurate, highest -
resolution hurricane models — the Hurricane Weather Research and Forecast system — has been strongly hinting that nothing much will happen with 99L until late Saturday or early Sunday, at which point a period of rapid intensification could make the storm blossom quickly into a hurricane.
Not exact matches
«In the low -
resolution models,
hurricanes were far too infrequent,» Wehner said.
What he found was that not only were the simulations much closer to actual observations, but the high -
resolution models were far better at reproducing intense storms, such as
hurricanes and cyclones.
Emanuel and his colleagues had previously devised a technique to simulate
hurricane development in a changing climate, using a specialized computational
model they developed that simulates
hurricanes at high spatial
resolutions.
But there, challenges also arise, as
models that simulate changing climate at a global scale do so at relatively coarse
resolution, of around hundreds of kilometers, while
hurricanes require
resolutions of a few kilometers.
But last year, the team was able to improve the
resolution on its
hurricane model, which helped improve the intensity predictions.
«We tried to simulate the fundamental fluid dynamics and thermodynamics that control
hurricane genesis in the Atlantic in a numerical
model to a very high
resolution.»
Higher
resolution models tended to get more
hurricane formation (perhaps unsurprisingly), with quarter - degree
models parameterized using observed SSTs generally capturing historical
hurricane formation rates fairly accurately.
# 34 Steve With regard to the
hurricanes, how can the
models predict an increase and measure the rate of that increase if the
resolution is insufficient or if the absolute SST is not taken into account?
But the GFDL study is based on a state - of - the - art high -
resolution model that is more appropriate for
hurricane studies and provides important evidence suggesting that climate change may have an effect on the TCs.
What he found was that not only were the simulations much closer to actual observations, but the high -
resolution models were far better at reproducing intense storms, such as
hurricanes and cyclones.
For example, the two
models with the highest
resolution (FLOR and HiFLOR) show increased extreme precipitation during the Atlantic
hurricane season in the U.S. southeast.
With respect to
hurricane intensity, there are observed trends indicating this and
model results predicting this, and while there are problems in each (data problems with
hurricanes, coarse
resolution in global
models, etc.), theoretical arguments also make clear that there will be more energy and water vapor available in the atmosphere to cause more intense
hurricanes, so a very strong case can be made for this happening.
«Changes in extreme wind conditions related to small scale
hurricane - type storms can not be skillfully detected in
models that have a
resolution to [o] coarse to resolve th [ese] storms»
* Changes in extreme wind conditions related to small scale
hurricane - type storms can not be skillfully detected in
models that have a
resolution to coarse to resolve this storms.
Haarsma et al (http://onlinelibrary.wiley.com/doi/10.1002/grl.50360/abstract;jsessionid=885F86BAD593643C939DBD1032EC4B01.d04t02) use a high
resolution model to make projections of changes in
hurricanes reaching the European coast.
Remember, for these «
hurricane models», you are trying to deal with a much higher
resolution (or more regional effects which are more weakly
modeled so far) than «climate
models» which deal with easier - to -
model larger affects... ie.
As noted above, there is some indication from high
resolution models of substantial increases in the numbers of the most intense
hurricanes even if the overall number of tropical storms or
hurricanes decreases.
The GFDL
hurricane model used for the study is an enhanced
resolution version of the
model used to predict
hurricanes operationally at NOAA's National Centers for Environmental Prediction.
The average intensity of the storms that do occur increases by a few percent (Figure 6), in general agreement with previous studies using other relatively high
resolution models, as well as with
hurricane potential intensity theory (Emanuel 1987).
Our 2015 study examines the impact of 21st - century projected climate changes (CMIP5, RCP4.5 scenario) on a number of tropical cyclone metrics, using the GFDL
hurricane model to downscale storms in all basins from one of the lower
resolution global atmospheric
models mentioned above.
Most climate
models available to scientists like Emanuel are too coarse in
resolution to simulate the formation of
hurricanes.
But Emanuel and his team developed one that can
model hurricanes at high spatial
resolutions within a changing climate.