Response of the North American monsoon to regional changes in ocean surface temperature

摘要: [1] The North American monsoon (NAM), an onshore wind shift occurring between July and September, has evolved in character during the Holocene largely due to changes Northern Hemisphere insolation. Published paleoproxy modeling studies suggest that prior ∼8000 cal years BP, NAM affected a broader region than today, extending westward into Mojave Desert of California. proxy SST records from Gulf California (GoC) adjacent Pacific provide constraints for this changing climatology. Prior lower GoC SSTs would not have fueled northward surges tropical moisture up GoC, which presently contribute most precipitation western region. During early Holocene, High was further north Current off Baja were warmer, allowing monsoonal flow subtropical take more direct, northwesterly trajectory expanded area southwestern U.S. west 114°W. A new upwelling record southwest reveals enhanced beginning at ∼7500 year BP may triggered change climatology, focusing geographic expression USA its modern core east ∼114°W, Arizona New Mexico. northwestern Mexico, including lakes, vegetation/pollen, caves are reviewed found be supportive hypothesis