Pineapple express: not just your favorite strain


Utah’s second winter rain system blew into the state on Tuesday, continuing to bring scattered showers and seasonally warm temperatures throughout the state; a moisture conveyer belt with its origin in the tropics is to blame.

Atmospheric rivers are exactly what they sound like: rivers in the sky that ebb and flow, bringing moisture and heat from the equator to the midlatitudes. They have been popularized with colloquial names like “Hawaiian Fire Hose” and “Pineapple Express,” serving as inspiration for the name of a marijuana strain and Seth Rogan’s popular movie.

These events are common and crucial for the transport of tropical moisture to extra-tropical regions around the world. In any season, there are anywhere from 6 to 10 tributaries flowing out of the Earth’s largest atmospheric water source: the equator.

While the appropriate name for these moisture conveyer belts is still under debate, the image provided by the term atmospheric river is useful to think about the quantity of water being transported. A team of atmospheric scientists led by Reginald Newell calculated the volumetric flow of a typical atmospheric river to be comparable to the flow of the Amazon – the most powerful river in the world discharging 8 million gallons of water in a day.

This magnitude of flow can be catastrophic. Zach Johnson, a graduate student studying climate science at Utah State University, has personal experience with atmospheric rivers and the impact they can have on California. “Back where I grew up, we lived on a hill,” Johnson said. “We had mudslide issues, so whenever there was an atmospheric river event it was a cause for concern.”

While Utah’s inland position prevents atmospheric rivers from having extreme impacts, winter rain events can still affect our snowpack. “If there’s already heavy snowpack in the mountain, that snowpack can melt and cause water issues,” Johnson said.

Winter rain events hasten snowmelt, adding to early season runoff and decreasing flows for later in the year when much off the state’s water is needed; galvanizing interest in the scientific community to understand the role of atmospheric rivers in a changing climate.

“Warming waters in the tropics and sub-tropics allow for more latent heat release into the atmosphere, providing more moisture,” Johnson said. “Some research suggests we’ll have wavier upper-air anomalies, and if it’s able to tap into that moisture we could potentially have more atmospheric rivers.”


Total precipitable water (depth of water in a column of the atmosphere) from the National Centers for Environmental Prediction’s Reanalysis II dataset. Animation shows 4 moderate atmospheric rivers extending to the west coast of North America between January 7, 2019 and January 17, 2019.


Comments

Post a Comment

Popular posts from this blog

Water in the West: a future of uncertainty

Utah State University hosted the Spring Runoff Conference on Tuesday, highlighting water challenges in the western United States and the hurdles the region will face. Alan Rhoades, a hydroclimate specialist from the Lawrence Berkeley National Laboratory, spoke at the conference on his work to overcome the uncertainty of the future by assessing the performance of novel climate modeling techniques. For Utah and the West, global climate change is expected to drastically impact our snowpack: the natural water storage reservoir for populations around the Rockies and Sierra Nevadas. One major problem for scientists and stakeholders working to adapt to a new climate is that different carbon emission scenarios and different data analyses techniques provide different projections for the future of snow. “Stakeholders and I are ascending this mountain of information and uncertainty, and we’re trying to do this together,” Rhoades said. There are about 30 global climat...
Read more

What wizards and prophets have to do with climate change

“Outbreaks in nature don’t end well,” said Charles C. Mann, an American journalist and author. In biology, outbreaks occur when a species reaches a population that requires more resources than are naturally available. “We’re reaching the end of the petri dish,” Mann said. For microorganisms, the edges of a petri dish are physical limits to growth. For humans – the natural limit isn’t as clear or tangible. Mann spoke at Utah State University on Thursday to discuss his book, “The Wizard and the Prophet,” a biography of two scientists who Mann said embody competing approaches toward mitigating harmful impacts from population outbreak and climate change. The ideologies of the wizard and the prophet “are less about technology than they are about values,” Mann said. “These are different ideas about what kind of world we want to live in.” In Mann’s example, the wizard tackles challenges with industrial-scale science. Geoengineering, genetically modified a...
Read more

Scientists want action to preserve the Great Salt Lake ecosystem

House Concurrent Resolution 10, calling for more information on the ecological and economic impacts of Bear River development on the Great Salt Lake ecosystem, was met with skepticism from some scientists who believe Utah lawmakers are ignoring the research that already exists — and that the real need isn't more research but action.  Passed on Feb. 15, the resolution is designed to address the dire state of the Great Salt Lake ecosystem, outlining the ecological and economic benefits of the lake and calling for more informed policy and management suggestions. The benefits include the impact of lake effect snow on snowpack accumulation, the preservation of wetland habitat for wildlife, the estimated $1.3 billion annual contribution to Utah’s economy and more. The detailed account of the Great Salt Lake’s ecosystem services paints a picture of a legislature looking to preserve and protect the lake and its habitat. However, the resolution’s call for m...
Read more