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Saharan - West African Monsoon Multi-scale Analysis (SWAMMA)

撒哈拉 - 西非季风多尺度分析 (SWAMMA)

基本信息

批准号：
NE/L004836/1
负责人：
Eleanor Highwood
金额：
$ 26.04万
依托单位：
University of Reading
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FL004836%2F1
关键词：
Saharan West African Monsoon Multi

项目摘要

The West African Monsoon is critical to the livelihoods of millions, but remains a major challenge for weather and climate prediction. The monsoon provides moisture for large systems of thunderstorms that provide the annual rainfall in the Sahel. The monsoon is driven by the summertime heating over the continent. The Sahara exhibits the highest summertime temperatures and it is known that the monsoon is sensitive to the heating in the Sahara and the Sahel. The heating in the Sahara is controlled by dust, cloud and ventilation by colder air from the Sahara's margins. It is known that models exhibit major differences in this region, which is for example important for monsoon onset, but historically there has been an absence of data with which to evaluate models. Recent research has shown that the monsoon, dust and the storm-systems form a fully coupled system and that global models exhibit major biases in the couplings within this system. Operational models fail to capture the organisation, location and timing of the monsoon rains and this leads to incorrect coupling between the storm systems and the monsoon. Operational models also fail to represent the haboob dust storms generated by the storm systems, which are likely the main driver of dust emission in the summer. This means that even operational models which include dust fail to accurately capture the impacts of the dust on the meteorology, since a major dust emission mechanism is missing in the models. Recent research has also shown the existence of larger dust particles over the Sahara than previously observed, which will affect heating rates, feeding back on to the meteorology. SWAMMA will bring together a recently-developed model that can for the first time capture these couplings with recently-acquired data from this highly data-sparse region (collected during the NERC-funded AMMA and Fennec projects). SWAMMA will therefore combine for the first time a model that should be able to represent the key features of the summertime energy budget of the monsoon system with the first data sufficient to evaluate such a model. SWAMMA will evaluate the new model, quantifying the winds that generate dust uplift in the Sahara and Sahel. It will use the new data to analyse the impacts of variations in the sizes of dust particles. SWAMMA will evaluate the energy budgets of the monsoon system using both models and observations from AMMA and Fennec. SWAMMA will quantify how the coupled processes of the monsoon system respond to the seasonal evolution of the monsoon's boundary conditions to control the seasonal stability of the monsoon rainfall and its variability. By bringing together the recently-acquired data and the new model with existing weather and climate models the project will evaluate how process errors in operational models lead to systematic errors in predictions, both over West Africa and globally. The project will provide metrics for the processes that must be captured by operational models for them to capture the key processes and couplings in the West African monsoon system.

西非季风对数百万人的生计至关重要，但仍然是天气和气候预测的重大挑战。季风为大型雷暴系统提供水分，从而为萨赫勒地区提供年降雨量。季风是由夏季大陆上空的高温驱动的。撒哈拉沙漠夏季气温最高，众所周知，季风对撒哈拉和萨赫勒地区的加热很敏感。撒哈拉沙漠的加热是由灰尘、云和来自撒哈拉边缘的冷空气的通风控制的。众所周知，该地区的模型表现出重大差异，这对于季风爆发很重要，但历史上一直缺乏用于评估模型的数据。最近的研究表明，季风、沙尘和风暴系统形成了一个完全耦合的系统，并且全球模型在该系统内的耦合方面表现出重大偏差。业务模型无法捕捉季风降雨的组织、位置和时间，这导致风暴系统和季风之间的耦合不正确。运行模型也无法代表风暴系统产生的哈布沙尘暴，这可能是夏季沙尘排放的主要驱动因素。这意味着即使包含灰尘的运行模型也无法准确捕捉灰尘对气象的影响，因为模型中缺少主要的灰尘排放机制。最近的研究还表明，撒哈拉沙漠上空存在比之前观察到的更大的尘埃颗粒，这将影响加热速率，从而反馈给气象。 SWAMMA 将汇集一个最近开发的模型，该模型可以首次捕获这些耦合与最近从这个数据高度稀疏地区获取的数据（在 NERC 资助的 AMMA 和 Fennec 项目期间收集）。因此，SWAMMA 将首次将能够代表季风系统夏季能源收支关键特征的模型与足以评估该模型的第一批数据相结合。 SWAMMA 将评估新模型，量化撒哈拉和萨赫勒地区产生尘埃上升的风。它将使用新数据来分析灰尘颗粒尺寸变化的影响。 SWAMMA 将使用 AMMA 和 Fennec 的模型和观测数据来评估季风系统的能量预算。 SWAMMA 将量化季风系统的耦合过程如何响应季风边界条件的季节性演变，以控制季风降雨的季节性稳定性及其变化。通过将最近获得的数据和新模型与现有的天气和气候模型结合起来，该项目将评估业务模型中的过程错误如何导致西非和全球预测的系统性错误。该项目将为运营模型必须捕获的过程提供指标，以便他们捕获西非季风系统的关键过程和耦合。