Methane data from 2002 to present derived from satellite observations

This dataset provides observations of atmospheric methane (CH₄) amounts obtained from observations collected by several current and historical satellite instruments.
Methane is a naturally occurring Greenhouse Gas (GHG), but one whose abundance has been increased substantially above its pre-industrial value of some 720 ppb by human activities, primarily because of agricultural emissions (e.g., rice production, ruminants) and fossil fuel production and use. A clear annual cycle is largely due to seasonal wetland emissions.
Atmospheric methane abundance is indirectly observed by various satellite instruments.
These instruments measure spectrally resolved near-infrared and infrared radiation reflected or emitted by the Earth and its atmosphere.
In the measured signal, molecular absorption signatures from methane and constituent gasses can be identified.
It is through analysis of those absorption lines in these radiance observations that the averaged methane abundance in the sampled atmospheric column can be determined.
The software used to analyse the absorption lines and determine the methane concentration in the sampled atmospheric column is referred to as the retrieval algorithm.
For this dataset, methane abundances have been determined by applying several algorithms to different satellite instruments.
The data set consists of 2 types of products:

column-averaged mixing ratios of CH4, denoted XCH4
mid-tropospheric CH4 columns.

The XCH4 products have been retrieved from SCIAMACHY/ENVISAT, TANSO-FTS/GOSA Tand TANSO-FTS-2/GOSAT-2.
The mid-tropospheric CH4 product has been retrieved from the IASI instruments onboard the Metop satellite series.
The XCH4 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: WFMD and IMAP algorithms; GOSAT: OCFP, OCPR, SRFP and SRPR algorithms) and as a multi-sensor merged product (EMMA algorithm).
The L3 XCH4 product is provided in OBS4MIPS format.
The IASI 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 L2 products that were generated in the framework of the GHG-CCI project of the European Space Agency (ESA) Climate Change Initiative (CCI).

本数据集收录了由多台现行及历史卫星仪器收集的大气甲烷（CH₄）含量观测数据。甲烷作为一种自然发生的温室气体（GHG），其含量因人类活动而显著增加，超出了工业前约720 ppb的水平，主要归因于农业排放（如水稻生产、反刍动物）以及化石燃料的生产与利用。其明显的年度周期主要源于季节性湿地排放。大气甲烷含量通过多种卫星仪器间接观测。这些仪器测量地球及其大气反射或辐射的近红外和红外光谱辐射。在测量的信号中，可以识别出甲烷及其组分的分子吸收特征。通过分析这些辐射观测中的吸收线，可以确定样本大气柱的平均甲烷含量。用于分析吸收线并确定样本大气柱中甲烷浓度的软件被称为检索算法。对于本数据集，通过应用多种算法于不同的卫星仪器，确定了甲烷含量。数据集包含两种类型的产品：CH₄的柱平均混合比，记为XCH₄，以及中层大气CH₄柱。XCH₄产品由SCIAMACHY/ENVISAT、TANSO-FTS/GOSA以及TANSO-FTS-2/GOSAT-2获得。中层大气CH₄产品由Metop卫星系列上的IASI仪器获得。XCH₄产品以第2级（L2）产品（卫星轨道轨迹）和第3级（L3）产品（网格化）形式提供。L2产品可作为单个传感器产品（SCIAMACHY：WFMD和IMAP算法；GOSAT：OCFP、OCPR、SRFP和SRPR算法）和多传感器合并产品（EMMA算法）提供。L3 XCH₄产品以OBS4MIPS格式提供。IASI产品以NLIS算法生成的第2级产品形式提供。该数据集每年更新一次，每次更新周期将添加（如有必要）整个周期的新数据版本，最多落后实时数据一年。本数据集由C3S代表生成，但SCIAMACHY L2产品是在欧洲空间局（ESA）气候变化倡议（CCI）的GHG-CCI项目框架内生成的。