Reconstructions of North Pacific atmospheric circulation since 1500 AD based on soil moisture, air temperature, and precipitation in Southwest US and output of paleoclimate simulations Wahl, E.R.; Zorita, E.; Trouet, V.; Taylor, A.H. Wahl, E.R. Zorita, E. Trouet, V. Taylor, A.H. Atmospheric and Oceanic Circulation Patterns Reconstruction earth science/paleoclimate/reconstructions (Pacific Ocean and American continents>LATITUDE >LONGITUDE ) Moisture delivery in California is largely regulated by the strength and position of the North Pacific jet stream (NPJ), winter high-altitude winds that influence regional hydroclimate and forest fire during the following warm season. We use climate model simulations and paleoclimate data to reconstruct winter NPJ characteristics back to 1600 CE to identify the influence of NPJ behavior on moisture and forest fire extremes in California before and during the more recent period of fire suppression. Maximum zonal NPJ velocity is lower and northward shifted and has a larger latitudinal spread during presuppression dry and high-fire extremes. Conversely, maximum zonal NPJ is higher and southward shifted, with narrower latitudinal spread during wet and low-fire extremes. These NPJ, precipitation, and fire associations hold across pre–20th-century socioecological fire regimes, including Native American burning, postcontact disruption and native population decline, and intensification of forest use during the later 19th century. Precipitation extremes and NPJ behavior remain closely linked in the 20th and 21st centuries, but fire extremes become uncoupled due to fire suppression after 1900. Simulated future conditions in California include more wet-season moisture as rain (and less as snow), a longer fire season, and higher temperatures, leading to drier fire-season conditions independent of 21st-century precipitation changes. Assuming continuation of current fire management practices, thermodynamic warming is expected to override the dynamical influence of the NPJ on climate–fire relationships controlling fire extremes in California. Recent widespread fires in California in association with wet NPJ extremes may be early evidence of this change. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Wahl, E.R. Investigator : Zorita, E. Investigator : Trouet, V. Investigator : Taylor, A.H. 2019-02-07 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/26030 https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2019/ https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2019/wahl2019-readme.txt https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2019/ https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2019/wahl2019-readme.txt English https://www.ncdc.noaa.gov/paleo/study/26030 https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2019/ https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2019/wahl2019-readme.txt Wahl, Eugene R., Eduardo Zorita, Valerie Trouet, and Alan H. Taylor2019Jet stream dynamics, hydroclimate, and fire in California: 1600 CE to presentProceedings of the National Academy of Sciences START YEAR: 1500 AD * END YEAR: 1980 AD 120 -60 -60 70