These are some of the storm tracks produced by Wise and Dannenberg’s study. And using other paleoclimate records-such as coral skeletons from the Pacific or ice cores from the Andes-they could augment their local tree ring data with knowledge of when a broader El Niño or La Niña event was convulsing the Pacific. They estimated years of storm tracks from the additional 275 years of data in the tree rings. Using the correlations observed from those 50 years of known meteorological data matched to tree rings, they were able to back-track. This is when low-pressure storms tumble out of the Pacific, delivering Oregon and Washington most of their annual rainfall.) (They also focused their analysis on storm tracks measured during the October to March rainy period. By matching this data to the geocoded tree rings, Wise and Dannenberg could learn what kinds of storms soak a certain valley and what kinds leave them dry. People have been recording storm tracks in the region since the 1950s. Then, the authors collated this tree-ring data with the past 50 years of observational measurements for the region. They also merged this new data with a broader, older library of tree-ring chronologies recorded across the Pacific Northwest. Every ring in this mean tree is associated with a year, and researchers can tell whether the year was wet or dry, depending on the thickness of the ring. Once enough samples have been collected per stand, then a kind of average tree ring history emerges for the site. From each stand, she or her colleagues would sample 25 or 30 different trees, taking two cores per tree. Six years ago, Wise began going out in the field, collecting data from dozens of stands of trees across the Pacific Northwest. Like many other trees, too, ponderosa pines mark wetter years-which often boost their growth-as a thicker splotch. Every year, like all trees, a pine inscribes the outside perimeter of its bark into its heartwood as a ring. They form stands in valleys, on ridge lines, and on the lee sides of mountains. Ponderosa pines are nestled across this crucial region. But if they come at a slight angle, there’s less of a shadow, and the eastern side is a little bit wetter compared to the west side.” “If storms come west to east, there’s a big rain shadow. How so? “The storm track really affects the water on the eastern side of the Cascades,” says Wise. All three create and respond to the annual storm track: the average of all the paths taken by winter storms within a year. The paper relies on the relationship between the Cascades, the Pacific, and thousands of ponderosa pines. And ponderosa pines scattered across the two states absorb the moisture, thriving in wet years and adding thin growth layers in dry years. The direction of a storm’s path makes a big difference in the precipitation each valley and ridge in the region receives. From every October to March, storms roll in from the Pacific and break across the Cascades mountain range in Washington and Oregon. Their finding will resonate beyond the Cascades: Because that region is so important to how moisture enters and fans across North America, the study helps answer important questions about how climate change will roil the United States.Īt the center of the paper is an especially sensitive species nestled across an especially ecologically diverse region. In a paper published this month in Science Advances, Erika Wise and Matthew Dannenberg, both paleoclimatologists at the University of North Carolina, teased three centuries of local climate history out of the ponderosa pine trees that dot the Pacific Northwest. Now, two scientists may have found a way to track a storm-or, at least, track the average of all storms across the season-325 years in the past. A weather historian can track a storm from a century ago using records-watching it crawl across the plains through the precipitation totals of yellowed farm journals and log books. A meteorologist can track a storm today using satellite or pulse-Doppler radar data.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |