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Non-Uniformity in Annual Rainfall Patterns (50% Falling in Only a Few Wettest Days)

EnolaGaia

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We tend to think of weather patterns as somewhat uniform when viewed in the aggregate over the long term. A new study claims that by and large locations receive at least half their annual rain during the dozen 'wettest' days in a given year. Current climatic trends suggest this number will shrink to The implication is that we shouldn't simply be planning for more precipitation overall due to climate change, but also planning for more concentrated rain events.

Half of the Year's Rain Falls on Earth in Just 12 Days
It takes less than two weeks for half of the planet's annual precipitation to fall.

That is, 50 percent of Earth's rain, snow and ice each year falls in the 12 wettest days, according to a new study. The deluges are likely to become even more concentrated by the end of the century, researchers reported Oct. 19 in the journal Geophysical Research Letters. Researchers already know that climate change will likely lead to an overall increase in precipitation ... The new study suggests that this extra rain will fall in the least helpful way possible. ...

FULL STORY: https://www.livescience.com/64129-earth-rain-12-days.html


PUBLISHED RESEARCH REPORT:
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL080298

Excerpt from the report's introduction:

Plain Language Summary

Rain falls unevenly in time, which can lead to floods and droughts. It is widely known that precipitation is uneven, but it is difficult to quantify. Here we develop a measure for the unevenness of precipitation: the number of the wettest days each year in which half of the annual rain falls. We apply this to rain observed by gauges around the world. At all gauges combined, it takes only 12 days each year for half of the rain to fall. We also apply the measure to climate model simulations, with projections for the rest of the century. In the climate model simulations, the change in future rainfall is even more uneven than rainfall today: In a scenario with high greenhouse‐gas emissions, half of the increase in rainfall happens in the wettest 6 days each year. Rather than assuming more rain in general, society needs to take measures to deal with little change most of the time and a handful of events with much more rain.
 
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