Atmospheric evolution: from early Earth to exoplanets

地球上的大气层令人敬畏。它们是地球上所有废气的混合罐，气体来自从微生物到地幔的一切东西，经过光化学和地球化学处理。大气组成在很大程度上决定了什么生命可以生活在地球表面，并通过设定温室效应的强度和吸收多少阳光来控制行星气候。随着我们进入系外行星时代，大气层是我们通向其他世界的窗口；远程大气特征是可以探索系外行星并最终探测生命的手段。*我的研究计划是关于行星大气的演变，对于有人居住的行星(现在就是地球)，比较太阳系中的行星和卫星(金星、火星、土卫六等)，以及越来越多的系外行星。拟议研究的目标是：增进我们对地球历史上气候-地球化学-生物圈耦合演化的理解；在比较行星学框架内发展行星演化理论，将地球与其他类地行星联系起来；并将这一理论应用于制定辨别系外行星是否宜居或可居住的方法学。*我们将研究四个主题：(A)地球大气的演变，模拟氮、碳和氧的循环，以及大气中氮气、氧气、二氧化碳、甲烷、N2O和NH3的清单，将地球化学和气候变化联系起来。我们将研究地球冰川的大氧化和雪球现象，以及整个地球历史上的变化。(B)地球过去深处的气候，使用三维气候模型了解气候系统，特别是云，以及一个项目，以核实这些模型中使用的辐射代码的准确性。(C)其他行星和卫星上的大气演化，研究金星通过失控的温室和土卫六(D)(Exo)行星的奇怪大气层的过渡，发展关于哪些行星可能有生命的理论，以及“宜居带”如何取决于大气组成和水库存。*拟议的工作解决了与之相关的基本的“蓝天”问题，为地球和类地行星是如何进化的贡献了新的理论。它将直接有助于开发系外行星生命探测和表征的方法，这将是一个在未来几十年迅速扩大的领域，并利用加拿大的主要资产。它将被应用于改善对人为气候变化的理解，因为探索地球历史为现代变化提供了背景。我的研究计划的一个特别新颖的方面是跨学科的广度：我们解决气候科学、地球化学和大气化学、地质学、天文学和行星科学中的问题，以了解我们和其他大气的演变。

Terrestrial planet atmospheres are awesome. They are the mixing pot of every waste gas from the planet, gasses from everything from microbes to the mantle, processed by photochemistry and geochemistry. Atmospheric composition largely determines what life can live at the surface and controls planetary climate by setting the strength of the greenhouse effect and how much sunlight is absorbed. As we enter the age of exoplanets, atmospheres are our window to other worlds; remote atmospheric characterization is the means by which exoplanets may be explored and ultimately life may be detected. ******My research program is about the evolution of planetary atmospheres, for inhabited planets (just Earth right now), for comparison planets and moons in the solar system (Venus, Mars, Titan and more) and, increasingly, for exoplanets. The objectives of the proposed research are: to improve our understanding of the coupled climate-geochemical-biosphere evolution of Earth throughout its history; to develop theory of planetary evolution in a comparative planetology framework, linking Earth to the other terrestrial planets; and to apply this theory to developing methodology for discerning whether exoplanets are habitable or inhabited. ******We will research across four themes: (A) Evolution of Earth's atmosphere, modelling cycles of nitrogen, carbon and oxygen and the atmospheric inventories of N2, O2, CO2, CH4, N2O and NH3, linking geochemical and climate changes. We will look at the Great Oxidation and snowball Earth glacials, and change throughout Earth history. (B) Climate of Earth's deep past, using 3-D climate models to understand the climate system and clouds in particular, and a project to verify the accuracy of the radiation codes used in these models. (C) Atmospheric evolution on other planets and moons, studying the transition of Venus through a runaway greenhouse and the weird atmosphere of Titan (D) (Exo)planet habitability, developing theory on which planets could harbour life, and how the "habitable zone" depends on atmospheric composition and water inventory. ******The proposed work addresses fundamental "blue-sky" questions relating, contributing novel theory to how the Earth and terrestrial planets have evolved. It will directly contribute to developing methodology for exoplanet life detection and characterization, which will be a rapidly expanding field over the next few decades and utilize major Canadian assets. It will be applied to improved understanding of anthropogenic climate change, as exploring Earth history provides the context for modern-day changes. A particularly novel aspect of my research program is the interdisciplinary breadth: we tackle problems in climate science, geochemistry and atmospheric chemistry, geology, astronomy and planetary sciences as necessary to understand the evolution of our, and other, atmospheres.