Ryan Harp, an Ubben Postdoctoral Research Fellow at the Institute for Sustainability and Energy at Northwestern, is the paper's first author. Horton is an assistant professor of Earth and planetary sciences in Northwestern's Weinberg College of Arts and Sciences, where he also leads the Climate Change Research Group. What we found is pretty simple: When it rains now, it rains more."
"For this particular study, we wanted to look at the non-extreme events, which are, by definition, much more common. "When people study how climate change has affected weather, they often look at extreme weather events like floods, heatwaves and droughts," said Northwestern's Daniel Horton, the study's senior author. The study was published in Geophysical Research Letters. Climate model simulations have previously predicted increases in precipitation intensity, particularly during extreme events, but the Northwestern study examined historically observed precipitation data across all intensities-and found a systematic shift in precipitation intensity in many parts of the country. When it rained over the Pacific Coast or Rocky Mountains, however, no intensity changes were observed. When it rained east of the Rocky Mountains in recent decades, about 5% more precipitation fell.
In most regions, the intensity of the rainfall has shifted from lighter to more moderate and often heavy deluges. They found that when it's rained in recent decades, it's rained more. In a new study, researchers compared observed rainfall from two climatologically distinct time periods and across 17 different climate regions in the U.S. Early visible and infrared satellites provided information on cloud tops and their horizontal extent however, wide-band microwave frequencies proved extremely useful for probing into the precipitating liquid and ice layers of clouds.That turns out to be increasingly true for much of the United States, according to Northwestern University researchers.
Historical, multi-decadal measurements of precipitation from surface-based rain gauges are available over continents, but oceans remained largely unobserved prior to the beginning of the satellite era. These factors together make precipitation difficult to quantify, yet measurements at such local scales are needed for many hydrometeorological applications such as flood and landslide forecasting. It is not uncommon to see a wide range of rain amounts over a small area and in any given area, the amount of rain can vary significantly over a short time span. However, rainfall is difficult to measure because precipitation systems tend to be random in character and also evolve and dissipate very rapidly. Accurate and comprehensive information on precipitation is essential for understanding the global water/energy cycle and for a wide range of research and applications with practical benefits to society. Precipitation is also a fundamental component of the weather/climate system for it regulates the global energy and radiation balance through coupling to clouds, water vapor, global winds and atmospheric transport. Water cycling and the future availability of fresh water resources are immense societal concerns that impact all nations on Earth as it affects virtually every environmental issue.
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