Sentinel 2 L1C products with simulated methane plumes (S2CH4)

<p>This dataset presents simulated Sentinel 2 L1C products that include methane plumes. </p>
<p>The product name follows the Sentinel 2 L1C naming convention but the initial tag has been replaced by "S2A/B_MSICH4" and at the end the tag "_plumeX_QY" has been added. Here "X" is a number from 0 to 4 that refers to the 5 different plume shapes modeled and "Y" is the methane flux rate in kg/h.</p>
<p>Simulations include three sites representative of typical oil and gas field areas with heterogeneous and homogeneous conditions for the detection of methane emissions.</p>
<li><b>Korpeje (Turkmenistan)</b> @ latlon= (38.49392º, 54.21655º)</li>
<li><b>Permian basin (USA)</b> @ latlon= (31.72070º, -102.28663º)</li>
<li><b>Hassi Messaoud (Algeria)</b> @ latlon= (31.82652º, 6.15011º)</li><br>

<p>The NetCDF product includes the following fields: </p>
<li><b>S2TOA</b> float64 ('xdim', 'ydim', 'num_bands') Sentinel 2 TOA reflectance for the 13 bands at 20m spatial resolution for an area of 1500x1500m.</li>
<li><b>lat</b> float32 ('xdim', 'ydim') Latitude per pixel [degrees]</li>
<li><b>lon</b> float32 ('xdim', 'ydim') Longitude per pixel [degrees]</li>
<li><b>xch4</b> float64 ('xdim', 'ydim') Methane column-averaged dry molar mixing ratio used as an input reference. If multiplied by 1000000 that represents ppm units. </li>
<li><b>SZA</b> float32 Mean sun zenith angle in the region of interest [degrees]</li>
<li><b>VZA</b> float32 Mean viewing zenith angle in the region of interest [degrees]</li>
<li><b>U10</b> float32 10-minute-average wind at an altitude of 10 metres above the surface of the ground [m/s]</li><br>

<p>These products can be used to test your retrieval against the reference enhancement map ("xch4" field).
From this reference enhancement map, the IME can be also compared as well as the flux rate Q [kg/h].
A manuscript with the detailed methodology is under preparation.</p>
<p>This second version of the products has undergone an extensive refinement and validation; however, if you find any issue please contact us.
You can also contact us if more information is needed and, of course, tell us about your results!</p>

<p>Contact email: [e-mail]</p>

本数据集包含含甲烷羽流的模拟哨兵二号（Sentinel 2）L1C级产品。

产品命名遵循哨兵二号L1C级产品的命名规范，但初始标签已替换为"S2A/B_MSICH4"，并在末尾新增了"_plumeX_QY"标签。其中"X"为0至4的整数，对应5种建模得到的不同羽流形态；"Y"为甲烷排放通量，单位为kg/h。

模拟场景涵盖3个典型油气田区域，分别设置了非均质性与均质性条件，用于甲烷排放检测任务：
- **科佩杰（土库曼斯坦）**：坐标为(38.49392°，54.21655°)
- **二叠纪盆地（美国）**：坐标为(31.72070°，-102.28663°)
- **哈西迈萨乌德（阿尔及利亚）**：坐标为(31.82652°，6.15011°)

该NetCDF产品包含以下字段：
- **S2TOA**：float64类型，维度为('xdim', 'ydim', 'num_bands')，对应1500×1500米区域内13个波段的哨兵二号大气顶层反射率（Top-of-Atmosphere Reflectance, TOA），空间分辨率为20m。
- **lat**：float32类型，维度为('xdim', 'ydim')，存储每个像素的纬度信息，单位为度。
- **lon**：float32类型，维度为('xdim', 'ydim')，存储每个像素的经度信息，单位为度。
- **xch4**：float64类型，维度为('xdim', 'ydim')，为作为参考输入的甲烷柱平均干摩尔混合比；将其数值乘以1000000即可转换为ppm单位的浓度值。
- **SZA**：float32类型，为感兴趣区域的平均太阳天顶角（Solar Zenith Angle, SZA），单位为度。
- **VZA**：float32类型，为感兴趣区域的平均观测天顶角（Viewing Zenith Angle, VZA），单位为度。
- **U10**：float32类型，为地表以上10米高度处的10分钟平均风速，单位为m/s。

本产品可基于参考增强图（即"xch4"字段）开展反演结果验证；同时还可对比反演得到的反演模型误差（Inverse Modeling Error, IME）与实际甲烷通量Q（单位：kg/h）。目前包含详细研究方法的学术论文正在筹备中。

本数据集的第二版产品经过了全面的优化与验证；若您在使用过程中发现任何问题，或需要更多相关信息，均可与我们联系，同时也欢迎您分享研究成果！

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