CO2 Mofetta - monitoring of natural carbon dioxide emissions using a network of low-cost sensors

在拟议的项目中，对德国北部黑森林霍布和罗滕堡之间的Eyach山谷的自然二氧化碳(CO2)排放进行了观测和分析。二氧化碳可能会积聚在地表附近，对动物和人类构成危险。此外，二氧化碳是一种气候活跃的温室气体，对气候变化起到了促进作用。Eyach山谷的二氧化碳浓度从来没有用科学方法量化过。类似的、更大的二氧化碳莫菲塔区域存在于世界不同的地区，而且没有量化。因此，地质来源的天然二氧化碳排放对大气气体收支的贡献是完全未知的。该项目的目标是监测Eyach山谷及其周围低层大气中的地质二氧化碳排放。实验收集的数据将被用来量化二氧化碳的排放量，并确定水平和垂直气体通量，包括时间(日变化和季节变化)。为了实现这一目标，将安装一个由单一涡旋协方差(EC)站支持的低成本传感器网络。单个传感器的低成本允许部署更多的传感器。该网络既提供水平分辨率的数据，又提供(整合后)区域代表性数字，包括高时间分辨率。在过去的几年里，图宾根大学的环境物理学小组开发了适合该项目的低成本传感器。与高级传感器相比，低成本设备通常的缺点是绝对精度降低。因此，传感器网络将得到EC站的补充，该站不仅为网络的校准提供更高的精度，而且至少在一个单一位置提供直接测量的湍流气体和热通量。因此，EC站是校准、确定湍流交换系数和网络长期稳定性的参考。除了二氧化碳测量，低成本传感器还将配备空气温度和空气湿度传感器。在该项目中，必须获得所有传感器，但不能提供资金：拟议项目的整个设备已经由阿尔弗雷德-特费尔基金会提供资金。最后，测量的数据将被添加到数据库中，并通过互联网接口提供给科学界。该项目分为两个阶段，每个阶段为期三年。这里只申请第一阶段。在第二阶段，测量数据用于数值弥散模型的初始化和验证。此外，开发的方法还将出口到其他有地质二氧化碳排放的地区。

The natural carbon dioxide (CO2) emission of the Eyach valley (between Horb and Rottenburg, Northern Black Forest, Germany) is observed and analysed in the proposed project. CO2 can accumulate near the surface and become hazardous for animals and humans. Also, CO2 is a climate-active greenhouse gas and contributes to the climate change. The CO2 concentrations in the Eyach valley have never been quantified with scientific methods. Similar and much larger areas with CO2 mofetta exist in various regions of the world and are not quantified. Thus the contribution of natural CO2 emission from geological sources to the atmospheric gas budget is entirely unknown.Goal of the project is the monitoring of the geological CO2 emission into the lower atmosphere in the Eyach valley and its surrounding. The experimentally gathered data will be used to quantify the amount of emitted CO2 and to specify the horizontal and the vertical gas fluxes, including temporal (diurnal and seasonal) variations. In order to reach this goal, a network of low-cost sensors will be installed, supported by a single eddy-covariance (EC) station. The low costs of a single sensor allow for the deployment of a larger number of sensors. The network gives both data with horizontal resolution and (after integration) area-representative numbers, including high temporal resolution. During the last years, the environmental-physics group at the University of Tübingen developed the suited type of low-cost sensors for this project. The usual disadvantage of low-cost equipment compared to high-grade sensors is a reduced absolute accuracy. Therefore, the sensor network will be complemented by an EC station that does not only deliver higher accuracy for the calibration of the network, but also the directly measured turbulent gas and heat fluxes, at least at one single location. The EC station is thus the reference for the calibration, for the determination of the turbulent exchange coefficients and for the long-term stability of the network. In addition to the CO2 measurement, the low-cost sensors will also be equipped with air temperature and air humidity sensors. Within the project, all sensors have to be obtained, but not financed: the entire equipment for the proposed project is already funded by the Alfred-Teufel foundation. Finally, the measured data will be added to a data base and offered to the science community via an internet interface.The project is structured in two phases of three years duration each. Here only the first phase is applied for. During the second phase, the measured data are used for the initialisation and verification of a numerical dispersion model. Furthermore, the developed methods will be exported to other regions with geological CO2 emission.