Meteorological Controls on Dust Emission and Transport in a Closed Basin

按质量计算，尘埃是地球大气层中最普遍的气溶胶。尘埃在地球的天气和气候中扮演着重要的角色，因为矿物气溶胶影响着水循环、海洋和陆地的营养平衡以及辐射能量平衡。大气总沙尘负荷的很大一部分是由封闭的地形凹陷(封闭盆地)排放的，但人们对控制这种地形特征的沙尘排放的气象过程知之甚少。该项目旨在通过对起源于加利福尼亚州最东南部的封闭海平面下盆地Salton盆地的沙尘暴进行观测和数值分析，阐明对封闭盆地中沙尘排放和输送的气象控制，以解决这一认识上的差距。以前的实地研究侧重于阐明撒哈拉沙漠最大沙尘源内沙尘排放和输送的气象控制，然而这里提出的初步结果表明，封闭盆地中沙尘排放和输送的基本气象过程与撒哈拉沙漠广阔来源地区的沙尘排放和输送的气象过程非常不同。本项目将重点研究暖风事件对沙尘排放的作用。索尔顿海是一个巨大的浅水湖，填满了索尔顿盆地的最低部分，该盆地是1905年由工程师意外地创造出来的，当时工程师们试图灌溉帝国谷。2017年颁布的新立法导致索尔顿海的淡水输入大幅减少，预计未来十年，索尔顿海的水位将大幅下降，其表面积可能会缩小100至200平方英里。该项目还将阐明海洋干燥对导致沙尘排放的气象过程的影响，并估计不断扩大的干旱天气将如何影响盆地的总沙尘负荷。该研究中心将利用新的科学发现为政策提供信息，并改善受影响地区25万人因暴露于空气中的沙尘而产生的人类健康后果。科学成果将通过该州的索尔顿海管理计划(SSMP)与利益攸关方进行沟通，以便为政策决策提供信息，特别是在旨在减少干球粉尘排放的管理活动方面。此外，将开发和验证WRF-Chem预报版本，以便提供该区域5天的沙尘浓度预报。这些预测的主要目标将是为弱势群体、卫生保健提供者和急救人员提供机会，以减轻与当地沙尘暴相关的不利的人类健康和安全风险。首席调查员(PI)将与SSMP的公共推广委员会合作，以接触到相关的利益相关者，并提高预测产品的实用性。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

By mass, dust is the most pervasive aerosol in the Earth's atmosphere. Dust plays an important role in the Earth's weather and climate since mineral aerosols affect the hydrological cycle, oceanic and terrestrial nutrient budget, and radiative energy budget. A large fraction of the total atmospheric dust load is due to emission from closed topographic depressions (closed basins), yet little is known about the meteorological processes controlling dust emission from such topographic features. The project aims to address this gap in understanding by elucidating the meteorological controls on dust emission and transport in a closed basin via observational and numerical analysis of dust storms originating in the Salton Basin, a closed sub-sea level basin in extreme southeastern California that experiences frequent dust storms.Previous field studies have focused on elucidating the meteorological controls on dust emission and transport within the largest dust sources in the Sahara, yet the initial results presented here suggest that the meteorological processes fundamental to dust emission and transport in a closed basin are very different from those over the expansive source regions in the Sahara. This project will focus on the role of warm Foehn events on dust emission. The Salton Sea is the large shallow lake that fills the lowest portions of the Salton Basin, which was accidentally created in 1905 by engineers attempting to irrigate the Imperial Valley. New legislation enacted in 2017 is resulting in a massive reduction in freshwater input to the Salton Sea and it is expected that the level of the Salton will drop so much over the next decade that its surface area may shrink by 100 to 200 square miles. This project will also elucidate the effect of the drying of the Sea on the meteorological processes responsible for dust emission and estimate how the expanding dry playa will influence the total dust burden for the basin.The Broader Impacts of this research center on using the new scientific findings to inform policy and improve human health outcomes from exposure to airborne dust for the quarter-million people living and working in the affected area. Scientific results will be communicated with stakeholders via the state's Salton Sea Management Program (SSMP) in order to inform policy decisions, particularly in terms of those management activities aimed at reducing dust emission from the dry playa. Additionally, a forecast version of WRF-Chem will be developed and validated in order to provide 5-day forecasts of dust concentrations for the region. The main goal of these forecasts will be to afford vulnerable groups, health care providers and first responders an opportunity to mitigate adverse human health and safety risks associated with local dust storms. The Principal Investigator (PI) will work with the SSMP's Public Outreach Committee in order to reach relevant stakeholders and improve the utility of the forecast products.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.