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首页> 外文期刊>Paleoceanography >Response of the North American monsoon to regional changes in ocean surface temperature
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Response of the North American monsoon to regional changes in ocean surface temperature

机译：北美季风对海洋表面温度区域变化的响应

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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 in Northern Hemisphere insolation. Published paleoproxy and modeling studies suggest that prior to ?8000 cal years BP, the NAM affected a broader region than today, extending westward into the Mojave Desert of California. Holocene proxy SST records from the Gulf of California(GoC)and the adjacent Pacific provide constraints for this changing NAM climatology. Prior to ?8000 cal years BP, lower GoC SSTs would not have fueled northward surges of tropical moisture up the GoC, which presently contribute most of the monsoon precipitation to the western NAM region. During the early Holocene, the North Pacific High was further north and SSTs in the California Current off Baja California were warmer, allowing monsoonal moisture flow from the subtropical Pacific to take a more direct, northwesterly trajectory into an expanded area of the southwestern U.S. west of 114°W. A new upwelling record off southwest Baja California reveals that enhanced upwelling in the California Current beginning at ?7500 cal year BP may have triggered a change in NAM climatology, focusing the geographic expression of NAM in the southwest USA into its modern core region east of ?114°W, in Arizona and New Mexico. Holocene proxy precipitation records from the southwestern U.S. and northwestern Mexico, including lakes, vegetation/pollen, and caves are reviewed and found to be largely supportive of this hypothesis of changing Holocene NAM climatology.
机译：北美季风（NAM）是发生在7月至9月之间的陆上风变，在全新世期间已经演变成特征，这主要是由于北半球日照的变化。已发表的古过氧化物和模型研究表明，在BP距今8000 cal年之前，NAM的影响范围比今天更广，向西延伸至加利福尼亚的莫哈韦沙漠。来自加利福尼亚湾（GoC）和邻近太平洋的全新世SST记录为这种变化的NAM气候提供了限制。在BP 8000cal年之前，较低的GoC SST不会助长GoC向北的热带湿气激增，目前热带潮气将大部分季风降水贡献给了NAM西部地区。在全新世早期，北太平洋高压带向北，加利福尼亚下加利福尼亚州海流的海温上升，使得亚热带太平洋的季风水分流更直接，向西北移动，进入了美国西南部以西的扩张区域。 114°W。在下加利福尼亚州西南部发生的一次新的上升流记录显示，从BP 7500 cal年开始，加利福尼亚海流的上升流可能触发了NAM气候学的变化，将NAM在美国西南部的地理表达集中到了其东部的现代核心地区。 114°W，亚利桑那州和新墨西哥州。审查了美国西南部和墨西哥西北部的全新世代用降水记录，包括湖泊，植被/花粉和洞穴，并发现在很大程度上支持这种全新世NAM气候学改变的假设。

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