Carbon dioxide data from 2002 to present derived from satellite observations

This dataset provides observations of atmospheric carbon dioxide (CO₂) amounts obtained from observations collected by several current and historical satellite instruments.
Carbon dioxide is a naturally occurring Greenhouse Gas (GHG), but one whose abundance has been increased substantially above its pre-industrial value of some 280 ppm by human activities, primarily because of emissions from combustion of fossil fuels, deforestation and other land-use change.
The annual cycle (especially in the northern hemisphere) is primarily due to seasonal uptake and release of atmospheric CO2 by terrestrial vegetation.
Atmospheric carbon dioxide abundance is indirectly observed by various satellite instruments.
These instruments measure spectrally resolved near-infrared and/or infrared radiation reflected or emitted by the Earth and its atmosphere.
In the measured signal, molecular absorption signatures from carbon dioxide and other constituent gasses can be identified.
It is through analysis of those absorption lines in these radiance observations that the averaged carbon dioxide abundance in the sampled atmospheric column can be determined.
The software used to analyse the absorption lines and determine the carbon dioxide concentration in the sampled atmospheric column is referred to as the retrieval algorithm.
For this dataset, carbon dioxide abundances have been determined by applying several algorithms to different satellite instruments.
Typically, different algorithms have different strengths and weaknesses and therefore, which product to use for a given application typically depends on the application.
The data set consists of 2 types of products:

column-averaged mixing ratios of CO2, denoted XCO2
mid-tropospheric CO2 columns.

The XCO2 products have been retrieved from SCIAMACHY/ENVISAT, TANSO-FTS/GOSAT, TANSO-FTS2/GOSAT2 and OCO-2.
The mid-tropospheric CO2 product has been retrieved from the IASI instruments on-board the Metop satellite series and from AIRS.
The XCO2 products are available as Level 2 (L2) products (satellite orbit tracks) and as Level 3 (L3) product (gridded).
The L2 products are available as individual sensor products (SCIAMACHY: BESD and WFMD algorithms; GOSAT: OCFP and SRFP algorithms) and as a multi-sensor merged product (EMMA algorithm).
The L3 XCO2 product is provided in OBS4MIPS format.
The IASI and AIRS products are available as L2 products generated with the NLIS algorithm.
This data set is updated on a yearly basis, with each update cycle adding (if required) a new data version for the entire period, up to one year behind real time.
This dataset is produced on behalf of C3S with the exception of the SCIAMACHY and AIRS L2 products that were generated in the framework of the GHG-CCI project of the European Space Agency (ESA) Climate Change Initiative (CCI).

本数据集提供了由多台当前和历史卫星仪器收集的关于大气二氧化碳（CO₂）含量的观测记录。二氧化碳是一种自然存在的温室气体（GHG），但其含量因人类活动，尤其是化石燃料燃烧、森林砍伐和其他土地利用变化而显著增加，已超过工业前约280 ppm的数值。大气年循环（尤其在北半球）主要是由陆地植被对大气CO2的吸收和释放所导致。大气二氧化碳含量通过多种卫星仪器进行间接观测。这些仪器测量地球及其大气反射或发射的近红外和/或红外辐射的光谱分辨率。在测量的信号中，可以识别出二氧化碳和其他成分气体的分子吸收特征。通过分析这些辐射观测中的吸收线，可以确定采样大气柱中二氧化碳的平均含量。用于分析吸收线并确定采样大气柱中二氧化碳浓度的软件被称为反演算法。对于本数据集，通过对不同的卫星仪器应用多种算法，确定了二氧化碳含量。通常，不同的算法具有不同的优势和劣势，因此，针对特定应用选择哪个产品通常取决于应用本身。数据集包含两种类型的产品：CO2柱平均混合比，记为XCO2；中纬度大气CO2柱。XCO2产品由SCIAMACHY/ENVISAT、TANSO-FTS/GOSAT、TANSO-FTS2/GOSAT2和OCO-2获取。中纬度大气CO2产品由Metop卫星系列上的IASI仪器和AIRS获取。XCO2产品作为第2级（L2）产品（卫星轨道轨迹）和第3级（L3）产品（网格化）提供。L2产品作为单个传感器产品（SCIAMACHY：BESD和WFMD算法；GOSAT：OCFP和SRFP算法）以及多传感器合并产品（EMMA算法）提供。L3 XCO2产品以OBS4MIPS格式提供。IASI和AIRS产品作为使用NLIS算法生成的L2产品提供。本数据集每年更新一次，每次更新周期会添加（如有必要）整个时期的新数据版本，最多落后实时数据一年。本数据集由C3S代表制作，除了SCIAMACHY和AIRS L2产品是在欧洲空间局（ESA）气候变化倡议（CCI）的GHG-CCI项目中生成的。