Improved understanding of Arctic atmospheric composition and climate through exploitation of satellite observations

主管：史蒂夫·阿诺德（SEE），安娜琼斯（BAS），理查德·波普（NCEO/SEE）北极正在经历快速的环境变化，近几十年来变暖的速度大约是全球平均速度的两倍。来自大气CO2增加的辐射强迫（RF）和有效的高纬度气候反馈是北极变暖的主要原因。然而，变暖的一个重要部分是由于大气中短寿命气候强迫因子（SLCFs）浓度变化的影响，如气溶胶颗粒和对流层臭氧。SLCFs通过其北极分布变化产生的局部RF影响北极温度，但也通过其在低纬度的丰度变化以及随后的向极热输送变化产生的RF影响北极温度。北极臭氧和气溶胶因自然反馈而发生的变化也可能很重要，例如，海洋和陆地排放源会对温度和冰雪覆盖的快速变化作出反应。预计经过北极的航运量将增加，这将是该区域气溶胶的又一个直接来源。在将北极对流层组成和气候的变化归因于人为和自然排放源的远程和本地影响方面的一个主要挑战是，对痕量气体和气溶胶的现场观测极为缺乏，特别是长期观测和垂直剖面观测。该项目将利用卫星对对流层组成的观测来限制近几十年来北极地区人为和自然影响的变化。该项目将利用来自天底观测和临边探测器的多个数据集，并将侧重于提供高纬度地区近地表和对流层上层组成的评价数据。将这种数据合成与飞机和表面数据和建模相结合，将对多年观测到的北极快速环境变化的驱动因素产生新的限制。具体调查领域可包括：发展北极对流层组成卫星数据长期综合，通过利用过去25年来的多个传感器。利用飞机上的现有现场数据集评估这种长期数据合成。使用卫星数据时间序列评估北极痕量气体和气溶胶的长期化学-气候模型模拟。结合卫星数据和化学-气候模拟，对北极臭氧和气溶胶辐射效应进行新的估计。使用卫星数据，提高对北极臭氧和气溶胶自然排放影响的认识。使用卫星数据，提高对北极长期化学-气候模型模拟的认识。从中纬度到北极的痕量气体和气溶胶的范围传输，并在模型中评估这些传输路径。使用卫星观测来检测影响北极地区的高纬度局部痕量气体排放的时间和空间变化。学生将加入利兹和BAS的活跃研究团队，专注于大气化学建模和卫星和飞机数据分析。学生将受益于大型地球物理数据集和遥感技术分析方面的专业知识培训，以及数值大气化学-气候建模。预计学生将延长对英国南极调查的合作访问（至少3 /年，1-2周持续时间）。

Supervisors: Steve Arnold (SEE), Anna Jones (BAS), Richard Pope (NCEO/SEE)The Arctic is undergoing rapid environmental change, and in recent decades has warmed at approximately twice the global mean rate. Radiative forcing (RF) from atmospheric CO2 increases and efficient high latitude climate feedbacks are responsible for the majority of Arctic warming. However, a significant part of the warming has been attributed to effects of changes in atmospheric concentrations of short-lived climate forcers (SLCFs), such as aerosol particles and tropospheric ozone. SLCFs affect Arctic temperatures via local RF produced by changes in their Arctic distributions, but also through RF imposed by changes in their abundances at lower latitudes, and subsequent changes in poleward heat transport. Arctic ozone and aerosol changes in response to natural feedbacks may also be important, for example as oceanic and terrestrial emission sources respond to rapid changes in temperature and ice & snow cover. Anticipated increases in shipping transiting the Arctic pose a further, direct, source of aerosols to the region. A major challenge in attributing changes in Arctic tropospheric composition and climate to remote and local influences from anthropogenic and natural emission sources is a severe paucity of in-situ observations of trace gas and aerosol, particularly over the long-term and through the vertical profile. This project will use satellite observations of tropospheric composition to constrain changes in these anthropogenic and natural influences on the Arctic over recent decades. The project will exploit multiple datasets from both nadir-viewing and limb sounders, and will focus on providing evaluation data for near-surface and upper troposphere composition in the high latitude region. Combining this data synthesis with aircraft & surface data and modeling, will allow new constraints on drivers of multi-annual observed rapid Arctic environmental change. Specific areas of investigation may include:Development of a long-term synthesis of satellite data on Arctic tropospheric composition, through exploitation of multiple sensors over the past 25 years.Evaluation of this long-term data synthesis with available in-situ datasets from aircraft.Use of satellite data time-series in evaluation of long-term chemistry-climate model simulations of Arctic trace gas and aerosol.Combining satellite data and chemistry-climate modeling to produce new estimates of ozone and aerosol radiative effects in the Arctic.Using satellite data to improve understanding of natural emission influences on ozone and aerosol in the Arctic.Using satellite data to improve understanding of long-range transport of trace gases and aerosol from mid-latitudes to the Arctic, and to evaluate these transport pathways in models.Using satellite observations to detect temporal and spatial changes in high latitude local emissions of trace gases influencing the Arctic region.The student will join active research teams in Leeds and BAS, focused on atmospheric chemistry modeling and analysis of satellite and aircraft data. The student will benefit from training in expertise in analysis of large geophysical datasets and remote sensing techniques, as well as numerical atmospheric chemistry-climate modelling. Extended collaborative visits for the student to the British Antarctic Survey will be expected (minimum 3 / yr, 1-2 weeks duration).