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Importance of marine gases and particles for tropospheric chemistry

海洋气体和颗粒对对流层化学的重要性

基本信息

批准号：
NE/L005271/1
负责人：
Claire Reeves
金额：
$ 33.5万
依托单位：
University of East Anglia
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%2FL005271%2F1
关键词：
Importance marine gases particles tropospheric

项目摘要

The oceans cover ~70% of the Earth's surface. The lowest part of the atmosphere over the oceans, the marine boundary layer (MBL), is subject to fluxes of sea spray aerosol and gases from the ocean and is linked to the free troposphere (FT) by vertical mixing in convective events but also by large scale mixing events such as frontal passages or tropical easterly waves. Most greenhouse gases (such as carbon dioxide, CO2, nitrous oxide, N2O) have atmospheric lifetimes of hundreds or thousands of years but others, notably methane, CH4, and tropospheric ozone, O3, have much shorter lifetimes (~9 years and weeks, respectively), largely because they have chemical sinks in the troposphere. Together they account for about 30% of the global radiative forcing of all greenhouse gases. Under most conditions, the MBL acts as a sink for O3 due to the low concentrations of NOx; furthermore about 25% of the tropospheric CH4 destruction occurs in the tropical MBL and a further 35% in the tropical marine free troposphere, hence the atmosphere above the (tropical) oceans is a very important region for atmospheric chemistry. The atmospheric oxidation capacity ("self-cleansing" capacity) is to a large extent determined by the hydroxyl radical (OH), O3 and their budgets and cycling; globally most tropospheric OH is found in the tropics. Therefore a quantitative understanding of the composition and chemistry of the marine atmosphere is crucial to examine the atmospheric oxidative capacity and climate forcing.This project will use a regional three-dimensional model (WRF-Chem) to study meteorological and chemical processes in the marine atmosphere. The model results will be compared to data from recent field campaigns in the East Pacific (TORERO, EqPOS) and from the North Atlantic (Cape Verde Atmospheric Observatory and Bermuda). By comparing model results with field data we will be able to see if the processes, sources and chemical reactions that are included in the model are sufficient to explain the data or if modifications and improvements to the reaction mechanism, emissions inventories or details of physical parameterisations will have to be made. Once these improvements have been made and the model is capable of reproducing the data, we will then be able to quantify lifetimes and budgets of important compounds such as ozone and the toxic mercury and to transfer our results to other ocean regions and to inform global models including Earth System models. This project aims to quantitatively describe the underlying processes and not to simply optimise the fit to observational data by unphysical adjustments in the model.

海洋覆盖了地球表面的70%。海洋边界层（MBL）是海洋上空大气的最低部分，它受到来自海洋的海雾气溶胶和气体通量的影响，并通过对流事件中的垂直混合以及大尺度混合事件（如锋面通道或热带东风波）与自由对流层（FT）联系在一起。大多数温室气体（如二氧化碳，CO2，一氧化二氮，N2 O）的大气寿命为数百年或数千年，但其他气体，特别是甲烷，CH 4和对流层臭氧，O3的寿命要短得多（分别为9年和9周），主要是因为它们在对流层中有化学汇。它们加起来约占全球所有温室气体辐射强迫的30%。在大多数情况下，MBL作为一个汇的O3由于低浓度的氮氧化物;此外，约25%的对流层CH 4破坏发生在热带MBL和热带海洋自由对流层的进一步35%，因此（热带）海洋上空的大气是一个非常重要的区域大气化学。大气的氧化能力（“自我净化”能力）在很大程度上取决于羟基自由基（OH）、O3及其收支和循环;全球大多数对流层OH都存在于热带地区。因此，定量了解海洋大气的组成和化学性质对于研究大气氧化能力和气候强迫作用至关重要，本项目将使用区域三维模式（WRF-Chem）研究海洋大气中的气象和化学过程。将把模型结果与最近在东太平洋（TORERO、EqPOS）和北大西洋（佛得角大气观测站和百慕大）进行的实地活动的数据进行比较。通过将模型结果与现场数据进行比较，我们将能够了解模型中包含的过程、来源和化学反应是否足以解释数据，或者是否必须对反应机制、排放清单或物理参数化的细节进行修改和改进。一旦做出这些改进，模型能够重现数据，我们就能够量化臭氧和有毒汞等重要化合物的寿命和预算，并将我们的结果转移到其他海洋区域，并为包括地球系统模型在内的全球模型提供信息。该项目旨在定量描述基本过程，而不是简单地通过模型中的非物理调整来优化与观测数据的拟合。