High and Low-Latitude Controls on the Mean Position of the Atlantic ITCZ (0-150 ka BP)

高纬度和低纬度对大西洋 ITCZ 平均位置的控制（0-150 ka BP）

• 批准号: 0927247
• 负责人: Peter DeMenocal
• 金额: $ 36.6万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0927247&HistoricalAwards=false
• 关键词: Low; Latitude; Controls; Mean; Position

The ITCZ (Intertropical Convergence Zone) is a geographic band with ascendant air circulation and heavy rain, sometimes referred to as the ?thermal equator?. This zone is a dominant atmospheric and oceanic feature of global climate, and its variability dominates the climate of the tropics and subtropics where most of the global population lives. Over the oceans, where it the ITCZ is narrowest and best developed, the position of the ITCZ moves seasonally between 5°S and 5°N following the maximum summer season radiation. These migrations are responsible for well-known climate phenomenon such as monsoons and seasonal droughts. Recent paleoceanographic and paleoclimate data have documented large excursions of the ITCZ in the past. Over the last 30,000 years the ITCZ has shifted rapidly (within decades to centuries) and dramatically away from its historical mean position. Past ITCZ excursions over these timescales may have been as large as ±10-15° latitude, and the climate changes in the (sub)tropics were very large indeed. The emergence of the modern day Saharan desert roughly 5,000 years age from what was previously a well-watered, lake-filled terrain is one such example. This drying of North African led to the depopulation of North Africa, and the rise of urban, stratified civilizations along the Nile Valley and the emergence of Phaeronic culture.The objective of this work is to determine the relative sensitivity of the ITCZ position to known changes in high-latitude global ice volume and low-latitude orbital radiation forcing. Understanding sensitivity of ITCZ to known, natural climate changes is necessary to estimate possible future climate changes in a warming world. Funding of this project will support a post-doctoral researcher and undergraduate research assistants from underrepresented groups.

ITCZ（自由化收敛区）是一个地理带，具有上升的空气循环和大雨，有时也称为“热方程式？”。该区域是全球气候的主要气氛和海洋特征，其可变性主导着大多数全球人口所居住的热带和亚热带的气候。在海洋中，ITCZ最狭窄且最佳开发，ITCZ的位置在最大夏季辐射后季节性移动在5°S至5°N之间。这些迁移负责众所周知的气候现象，例如季风和季节性干旱。最近的古摩纳学和古气候数据已经记录了过去的大量ITCZ。在过去的30，000年中，ITCZ迅速转移（几十年来），并远离其历史平均地位。过去的ITCZ游览可能是纬度±10-15°的大小，并且（子）热带地区的气候变化确实很大。现代撒哈拉沙漠的出现大约5，000年了，这是一个这样的例子。北非的这种干燥导致北非的沉积，以及城市沿尼罗河河谷沿线的文明的兴起和辉长岩文化的出现。这项工作的目的是确定ITCZ位置对已知变化的相对敏感性的相对敏感性。了解ITCZ对已知的自然气候变化的敏感性对于估计温暖世界中可能未来的气候变化是必要的。该项目的资金将支持博士后研究人员和本科生的研究助理。