Changes in Non-Extreme Precipitation May Have Not-So-Subtle Consequences Nov 14, 2017

[Low flow in a stream. Non-extreme rainfall is essential for maintaining ecosystem functions. Credit: Praveen Kumar]

From National Science Foundation

Extreme floods and droughts receive a lot of attention. But what happens when precipitation — or lack thereof — occurs in a more measured way?

Researchers have analyzed more than five decades of data from across North America to find that changes in non-extreme precipitation are more significant than previously realized. And the changes are greater than those that have occurred with extreme precipitation.

[Earth’s critical zone: from the base of bedrock to the top of the tree canopy. Credit: NSF]

Non-extreme precipitation can have a strong effect on ecosystems, agriculture, infrastructure design and resource management, the scientists say, pointing to a need to examine precipitation in a more nuanced, multifaceted way.

“This study shows that everyday precipitation events — not just the extremes that have been the focus of most studies — are changing,” said University of Illinois scientist Praveen Kumar, principal investigator of the National Science Foundation’s (NSF) Intensively Managed Landscapes Critical Zone Observatory (CZO), one of nine such NSF CZOs.

[At NSF’s Critical Zone Observatories, scientists study the processes at Earth’s surface. Credit: NSF]

“It’s not just the amount of rainfall that’s important,” said Kumar, “it’s the duration of that rainfall and the amount of time between rainfall and dry periods.”

The study, published today in Nature Scientific Reports, is the most comprehensive of its type, said co-author Susana Roque-Malo, also of the University of Illinois.

“We used data from more than 3,000 weather stations,” said Roque-Malo. “There are a few other studies that use a similar methodology, but they have focused on smaller sections of the continent or parts of Europe.”

[This river ecosystem is maintained by daily rainfall. Credit: Praveen Kumar]

The researchers identified several regions where the microclimate — local climate determined by elevation and ecosystem — appears to have a significant effect on precipitation trends.

“This study confirms that there is more to climate than the number and size of extreme events,” said Richard Yuretich, CZO program director at NSF, which funded the research through its Division of Earth Sciences. “Shifts in the daily patterns of rainfall, sometimes subtle, also occur. These can be very hard to document, but the existence of long-term monitoring sites provides the information needed to recognize trends and plan for the future.”

[Changes in non-extreme rainfall can alter agricultural production in fields such as this one. Credit: Praveen Kumar]

In areas such as Oregon’s Willamette Valley, the researchers observed decreases in the total annual precipitation, the number of days per year with precipitation, and the number of consecutive days with precipitation. The areas immediately surrounding the valley, however, had increases in those measures.

“Examples like this indicate that it may not be the best practice to make broad assumptions like ‘all wet areas are becoming wetter and all dry areas are becoming drier,'” said Roque-Malo.

The observations have important implications for the resilience of ecosystems and for agriculture and water resource planning, the researchers say.

[Researchers at NSF’s Intensively Managed Landscapes CZO investigate human-environment interactions. Credit: Praveen Kumar]

“Successive generations of ecosystems evolve through adaptation to these kinds of changes,” said Kumar. “If the rate of change, however small, exceeds the adaptive capacity, these environments will be susceptible to collapse.”

Added Roque-Malo, “Hydroelectric plants, storm water drainage systems — any structure that relies on an assumption of expected precipitation — could be vulnerable as we look toward becoming more climate-resilient.”

Although current models may not be able to resolve the small but steady changes observed in this study, the researchers hope their work will inform and provide validation criteria for future models and assessments.

Edited for WeatherNation by Meteorologist Mace Michaels

Leave a comment

Your email address will not be published. Required fields are marked *

Tweets

JUST IN - NOAA Weather satellite performance issue being looked into by scientists. READ THE LATEST ->… https://t.co/l9XYF4uf5W

34 minutes ago by WeatherNation

NEW! Severe T-Storm Watch in effect until 9pm MDT . #COwx #NEwx #WYwx #SDwx https://t.co/aQ9786xHYU

41 minutes ago by WeatherNation

NO REST FROM WICKED RAINS IN FLORIDA: Yup, it's going to be a rainy couple of days for the Sunshine State. Check o… https://t.co/JXCv2Ge4bS

3 hours ago by WeatherNation

Stellar time lapse of marching shelf clouds in Southern Maryland. https://t.co/rwcgLV0rer

4 hours ago by WeatherNation

A look at the severe weather forecast across the Upper Midwest and Plains the next few days: https://t.co/89vSHtkcy2 https://t.co/w2yLOHEosb

6 hours ago by WeatherNation

Fog concerns and low visibility this morning for parts of Alabama this morning #WeatherNation #Fog https://t.co/N6sjoa63Gj

6 hours ago by WeatherNation

A broad low pressure center located near the Yucatan Peninsula has a 60% chance to develop into a tropical system,… https://t.co/432lOjiW3Q

6 hours ago by WeatherNation

FLASH FLOOD WARNING in place for Western GA and Eastern AL. Radar has estimated anywhere between 1-6" of rain has f… https://t.co/onzfXQx8yi

6 hours ago by WeatherNation

Relative to the average, what areas have the highest chances for a warm June? The details: https://t.co/860ArInY9I https://t.co/Gwf6cKuSQu

7 hours ago by WeatherNation

#BREAKING: The National Hurricane Center is now calling for a 60% chance of tropical development within the next 5… https://t.co/gYPC7dm2d4

8 hours ago by WeatherNation

Ominous lava landscape on Hawaii's Big Island. https://t.co/fz2MLhuV1B

8 hours ago by WeatherNation

This is stunning. Check out the sunrise from Monument Valley Navajo Tribal Park in Arizona https://t.co/DMPcEuTXzK

8 hours ago by WeatherNation

Fog concerns and reduced visibility this morning across parts of the Great Lakes #WeatherNation #Fog https://t.co/IzUTBmIQn3

8 hours ago by WeatherNation

Swimming in the hail equivalent of dippin' dots. We do not recommend. https://t.co/P8TGK5w5Rx

9 hours ago by WeatherNation

Rain showers and isolated thunderstorms from near Montgomery, AL to central Georgia this morning #WeatherNation https://t.co/4IPrzL6bvY

10 hours ago by WeatherNation

Rain across parts of the Dakotas to Iowa this morning #WeatherNation #Rain https://t.co/HZTGUvK0Gp

10 hours ago by WeatherNation

A look at VIPIR radar across the nation #WeatherNation https://t.co/LiGpRfSK8A

10 hours ago by WeatherNation
Follow Us