ESA Land Surface Temperature Climate Change Initiative (LST_cci): Daily multisensor Infra-Red (IR) Low Earth Orbit (LEO) land surface temperature (LST) time series level 3 supercollated (L3S) global product (1995-2024), version 3.00

This dataset contains land surface temperatures (LSTs) and their uncertainty estimates from multiple Infra-Red (IR) instruments on Low Earth Orbiting (LEO) sun-synchronous (a.k.a. polar orbiting) satellites. Satellite land surface temperatures are skin temperatures, which means, for example, the temperature of the ground surface in bare soil areas, the temperature of the canopy over forests, and a mix of the soil and leaf temperature over sparse vegetation. The skin temperature is an important variable when considering surface fluxes of, for instance, heat and water.

Daytime and night-time temperatures are provided in separate files corresponding to 10:00 and 22:00 local solar time. Per pixel uncertainty estimates are given in two forms, first, an estimate of the total uncertainty for the pixel and second, a breakdown of the uncertainty into components by correlation length. Also provided in the files, on a per pixel basis, are the observation time, the satellite viewing and solar geometry angles, a quality flag, and land cover class.

The dataset is comprised of LSTs from a series of instruments with a common heritage: the Along-Track Scanning Radiometer 2 (ATSR-2); the Advanced Along-Track Scanning Radiometer (AATSR) and the Sea and Land Surface Temperature Radiometer on Sentinel 3B (SLSTRB); and data from the Moderate Imaging Spectroradiometer on Earth Observation System - Terra (MODIS Terra), to fill the gap between AATSR and SLSTR. So, the instruments contributing to the time series are: ATSR-2 from June 1995 to May 2002; AATSR from June 2002 to March 2012; MODIS Terra from April 2012 to November 2018; and SLSTRB from December 2018 to December 2024. Inter-instrument biases are accounted for by cross-calibration with the Infrared Atmospheric Sounding Interferometer (IASI) instruments on Meteorological Operational (METOP) satellites. For consistency, a common algorithm is used for LST retrieval for all instruments. Furthermore, an adjustment is made to the LSTs to account for the half-hour difference between satellite equator crossing times. For consistency through the time series, coverage is restricted to the narrowest instrument swath width.

The dataset coverage is near global over the land surface. During the period covered by ATSR-2, small regions were not covered due to downlinking constraints (most noticeably a track extending southwards across central Asia through India – further details can be found on the ATSR project webpages at https://artefacts.ceda.ac.uk/frozen_sites/www.atsr.rl.ac.uk/documentation/docs/userguide/index.shtml).

LSTs are provided on a global equal angle grid at a resolution of 0.01° longitude and 0.01° latitude. Full Earth coverage is achieved in 3 days so the daily files have gaps where the surface is not covered by the satellite swath on that day. Furthermore, LSTs are not produced where clouds are present since under these circumstances the IR radiometer observes the cloud top which is usually much colder than the surface.

Dataset coverage starts on 1st June 1995 and currently ends on 31st December 2024. There are two gaps of several months in the dataset: no data were acquired from ATSR-2 between 23 December 1995 and 27 June 1996 due to a scan mirror anomaly; and the ERS-2 gyro failed in January 2001, data quality was less good between 17th Jan 2001 and 5th July 2001 and are not used in this dataset. Also, there is a twelve day gap in the dataset due to Envisat mission extension orbital manoeuvres from 21st October 2010 to 1st November 2010. There are minor interruptions (1-10 days) during satellite/instrument maintenance periods or instrument anomalies.

This version of the dataset (Version 3.00) extends the temporal coverage by four years to the end of 2024. This dataset provides a daily product, and a separate monthly averaged product also exists. The temporal coverage of the monthly product will be further extended at 6 monthly intervals through the Copernicus Climate Change Service. Other changes in Version 3.00 include: SLSTR on Sentinel 3A is no longer used, instead data from SLSTR on Sentinel 3B is used from November 2018; the correction for time differences between the sensors is calculated in brightness temperature space using radiative transfer simulations; and the ATSR-2 and AATSR data are from the fourth reprocessing of these datasets.

The dataset was produced by the University of Leicester (UoL) and LSTs were retrieved using a Generalised Split Window retrieval algorithm and data were processed in the UoL processing chain.
The dataset was produced as part of the ESA Land Surface Temperature Climate Change Initiative which strives to improve satellite datasets to Global Climate Observing System (GCOS) standards.

本数据集包含来自近地轨道（Low Earth Orbiting, LEO）太阳同步（亦称极轨）卫星上多台红外（Infra-Red, IR）仪器的陆表温度（Land Surface Temperature, LST）及其不确定性估算值。卫星陆表温度为表层温度，具体而言，裸土区域指地表温度，森林区域指冠层温度，稀疏植被区域则为土壤与叶片温度的混合值。表层温度是研究热、水等地表通量的关键变量。

日间与夜间温度分别存储于对应地方太阳时10:00与22:00的独立文件中。每像素的不确定性估算以两种形式给出：其一为该像素的总不确定性估算值，其二为按相关长度分解的不确定性分量。文件中还按像素提供了观测时间、卫星观测与太阳几何角度、质量标记以及土地覆盖类别。

本数据集的陆表温度数据源自一系列具有共同技术传承的仪器：沿轨扫描辐射计2号（Along-Track Scanning Radiometer 2, ATSR-2）、高级沿轨扫描辐射计（Advanced Along-Track Scanning Radiometer, AATSR）、哨兵3B号上的海表与陆表温度辐射计（Sea and Land Surface Temperature Radiometer on Sentinel 3B, SLSTRB）；以及地球观测系统Terra卫星上的中分辨率成像光谱仪（Moderate Imaging Spectroradiometer on Earth Observation System - Terra, MODIS Terra），用于填补AATSR与SLSTR之间的数据空白。因此，参与时间序列的仪器及其运行时段如下：ATSR-2：1995年6月至2002年5月；AATSR：2002年6月至2012年3月；MODIS Terra：2012年4月至2018年11月；SLSTRB：2018年12月至2024年12月。仪器间的偏差通过与气象业务（Meteorological Operational, METOP）卫星上的红外大气探测干涉仪（Infrared Atmospheric Sounding Interferometer, IASI）进行交叉定标予以校正。为保证一致性，所有仪器的陆表温度反演均采用统一算法。此外，还对陆表温度数据进行了调整，以抵消卫星过赤道时间的半小时时差影响。为保证时间序列的一致性，数据覆盖范围被限制为最窄的仪器刈幅宽度。

本数据集的覆盖范围接近全球陆表区域。在ATSR-2运行时段，受下行链路约束，部分小区域未被覆盖（最显著的是一条横跨中亚至印度的南向轨道，详细信息可参见ATSR项目官网：https://artefacts.ceda.ac.uk/frozen_sites/www.atsr.rl.ac.uk/documentation/docs/userguide/index.shtml）。

陆表温度数据以全球等角网格形式提供，分辨率为经度0.01°、纬度0.01°。每3天可完成一次全球完整覆盖，因此每日文件中存在当日卫星刈幅未覆盖的区域间隙。此外，当有云存在时，不会生成陆表温度数据，因为此时红外辐射计观测的是云顶温度，通常远低于地表温度。

本数据集的时间覆盖范围始于1995年6月1日，当前截至2024年12月31日。数据集存在两处长达数月的间隙：1995年12月23日至1996年6月27日期间，因扫描镜异常，ATSR-2未获取任何数据；2001年1月ERS-2陀螺仪失效，2001年1月17日至7月5日期间的数据质量不佳，未被纳入本数据集。此外，2010年10月21日至11月1日期间，因Envisat任务延伸的轨道机动操作，数据集存在12天的间隙。在卫星/仪器维护期或仪器异常期间，还存在若干次1至10天的小型数据中断。

本数据集版本（3.00版）将时间覆盖范围延长了四年，至2024年底。本数据集提供逐日产品，同时另有独立的月均产品。月均产品的时间覆盖范围将通过哥白尼气候变化服务局每6个月进行一次更新。3.00版的其他变更包括：不再使用哨兵3A号上的SLSTR数据，自2018年11月起改用哨兵3B号上的SLSTR数据；传感器间时间差的校正通过辐射传输模拟在亮温空间中计算；ATSR-2与AATSR的数据源自这两类数据集的第四次再处理。

本数据集由莱斯特大学（University of Leicester, UoL）制作，陆表温度反演采用广义分裂窗反演算法，数据通过UoL处理链完成加工。本数据集作为欧洲空间局陆表温度气候变化倡议的成果之一制作完成，该倡议致力于将卫星数据集提升至全球气候观测系统（Global Climate Observing System, GCOS）标准。