Collaborative Research: A Synthesis of Existing and New Observations of Air-Snowpack Exchanges to Assess the Arctic

合作研究：综合现有和新的空气-积雪交换观测来评估北极

• 批准号: 0713943
• 负责人: Detlev Helmig
• 金额: $ 72.29万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0713943&HistoricalAwards=false
• 关键词: Collaborative; Research; Synthesis; Existing; New

Chemical and biological processes occuring within, above, and below snowpacks influence tropospheric ozone. Measurements available to date and simplified modeling studies indicate that the resulting impact on tropospheric O3 is significant, but available measurements and current modeling capabilities are insufficient for a quantitative estimate of its magnitude. It is of particular importance to improve our understanding of snowpack-atmosphere O3 exchanges because of ongoing and expected future alterations in snow, sea-ice and permafrost extent resulting from climate change, which will alter snowpack O3 impacts in the future. This project provides an integrated approach to address this need, using field measurements to fill key gaps in current knowledge and synthesizing the new and existing data into a chemistry-climate model.Air-snow exchange fluxes of O3 and NOx (NO+NO2) will be measured at multiple sites with different snow/land types, each for an extended period to capture effects of changing insolation, snowpack properties and (where applicable) soil temperature and soil NOx emissions. Measurements will include O3 and NOx levels and gradients both within and above the snowpack and eddy-correlation O3 fluxes at two heights above the snowpack; ancillary measurements will characterize atmospheric turbulence, actinic flux, micrometeorological parameters and the snowpack's physical and radiative properties. Field locations include Summit, Greenland (representing glacial snowpack), Toolik Lake, Alaska (representing snowpack above permafrost soil and snowpack over frozen lakes) and the Aspen FACE research site operated by Michigan Tech (representing snowpack above biologically active soil). Additional measurements for instrument shakedown at Table Mountain, Colorado, will provide information on intermittent snowpack.New parameterizations of snowpack processes will be developed and incorporated into single column model (SCM) versions of the global chemistry-climate models ECHAM4 and ECHAM5-MESSy. These parameterizations will be designed to describe the underlying processes and to capture variations among the available and new field measurements, which will be used for model evaluation. The new model system will be used to simulate the impact of air-snow O3 and NOx exchange upon the arctic tropospheric O3 budget.This work will close existing gaps in understanding of snowpack processes affecting O3, including O3 uptake to snow and the role of biological activity below snowpacks, NOx release from snow, and boundary layer O3 production resulting from snowpack emissions of O3 precursors. It will provide the first measurements of snow-air O3 and NOx fluxes for snow over permafrost and snow over frozen lakes, and the most thorough measurements available for snow over non-permafrost soil. The new snowpack-exchange model will be a very significant advancement over current simulations of snowpack impacts in chemistry-climate models, and will allow such models to better describe the connections between changing Arctic climate and environmental systems. Its use will produce the first assessment of the impact of snowpack photochemical processes upon the arctic and subarctic tropospheric O3 budget, and will provide the basis for assessing the expected impact that climate change will exert upon the tropospheric O3 budget through changing snowcover and permafrost extent.

在积雪内部，上方和下方发生的化学和生物过程会影响对流层臭氧。迄今为止可用的测量结果和简化的建模研究表明，对对流层O3的影响很大，但是可用的测量和当前的建模功能不足以对其幅度进行定量估计。由于气候变化导致的雪，海冰和永久性范围的未来变化，我们对积雪 - 大气O3交换的理解尤为重要，这将改变Snowpack O3将来会影响Snowpack O3的影响。该项目提供了一种集成的方法来满足这一需求，使用现场测量结果来填补当前知识中的关键空白，并将新的数据和现有数据综合为化学气候模型。o3和nox的空气传输交换通量（no+no2）将会可以在多个雪/土地类型的多个地点进行测量，每种地点都长时间捕获改变的伤亡，积雪特性以及（如果适用）土壤温度和土壤NOX排放的影响。测量值将包括在积雪的内外和涡流的O3和NOX水平和梯度上，在积雪上方的两个高度上的O3通量；辅助测量将表征大气湍流，光化通量，微量标学参数以及积雪的物理和辐射特性。现场位置包括山顶，格陵兰山（代表冰川积雪），工具湖，阿拉斯加（代表永久冻土土壤上方的积雪，在冷冻湖泊上代表积雪）和密歇根理工学院（Michigan Tech）（代表在生物活跃土壤上方的Snekpack）经营的Aspen Face研究站点。在科罗拉多州桌山上进行的仪器shakingown的其他测量将提供有关间歇性积雪的信息。将开发积雪过程的新参数化，并将其整合到全球化学气候模型echam4和eCham5-Messy的单列模型（SCM）版本中。这些参数化将旨在描述潜在的过程并捕获可用的现场测量和新的现场测量之间的变化，这将用于模型评估。新的模型系统将用于模拟空调O3和NOX交换对北极对流层O3预算的影响。这项工作将弥合现有的差距，以了解影响O3的积雪过程，包括O3吸收雪和生物学的作用积雪下方的活动，NOX从积雪中释放以及由O3前体的积雪排放产生的O3生产。它将提供对雪空的O3和NOX通量的首次测量，以使其在永久冻土上积雪和冷冻湖泊上的雪，以及最彻底的测量值，可用于非层状土壤上的雪。与当前对化学气候模型中的积雪影响的模拟相比，新的Snowpack-Extchange模型将是一个非常重大的进步，并将允许此类模型更好地描述不断变化的北极气候和环境系统之间的联系。它的使用将对积雪光化学过程对北极和亚北极对流层O3预算的影响进行首次评估，并将为评估预期的影响提供基础，以改变气候变化通过改变雪地覆盖范围和永久性冻土范围对对流层O3预算的影响。