MOLA reference DTM and aligned HRSC DTM mosaic at the Martian South Pole

Datasets from Xiao et al. (2022, in revision with Planetary and Space Science) titled "Prospects for Mapping Temporal Height Variations of the Seasonal CO2 Snow/Ice Caps at the Martian Poles by Co-registration of MOLA Profiles". An initial version of the manuscript can be accessed at https://arxiv.org/abs/2109.04899.

## abbreviations
Mars Orbiter Laser Altimeter (MOLA)
Digital Terrain Model (DTM)
University College London (UCL)
High-Resolution Stereo Camera (HRSC)

MOLA_reference_DTM_from_self_registration.tif is the reference DTM generated from self-registration of the reprocessed MOLA profiles. The heights are references to a Martian sphere of 3396 km. It covers the region poleward of 78°S with a resolution of 500 m/pixel. Projection is polar stereographic centered at the South Pole. Number_footprints_per_pixel_MOLA_reference_DTM.tif is the map that demonstrates the number of available MOLA footprints (after reprocessing and self-registration) within each of the grid element for the generation of MOLA_reference_DTM_from_self_registration.tif.

The original UCL HRSC DTMs at the Martian South Pole, with a gridding resolution of 50 m/pixel, can be accessed at https://www.cosmos.esa.int/web/psa/UCL-MSSL_iMars_HRSC_v1.0. Please also refer to Putri, A. R. D., Sidiropoulos, P., Muller, J. P., Walter, S. H., & Michael, G. G. (2019). A New South Polar Digital Terrain Model of Mars from the High-Resolution Stereo Camera (HRSC) onboard the ESA Mars Express. Planetary and Space Science, 174, 43-55.

UCL_HRSC_DTMs_mosaic_after_alignment_to_MOLA_reference.tif is the mosaic of these UCL HRSC DTMs after being aligned to the self-registered MOLA profiles, which are used to generate MOLA_reference_DTM_from_self_registration.tif. Grid size is 50 m/pixel with a stereographic projection centered at South Pole.

Height_difference_before_alignment.tif and Height_difference_after_alignment.tif show the relative height differences between these HRSC DTMs and the self-registered MOLA profiles before and after the alignment, respectively. Grid size is 170 m/pixel with a stereographic projection centered at South Pole. Relative tilts of magnitudes up to ~10 m are ubiquitous before the alignment. Meanwhile, after the alignment, height differences are homogeneous with magnitudes typically less than 2 m.

本数据集源自Xiao等人（2022年，投稿于《行星与空间科学（Planetary and Space Science）》并处于审稿阶段）的研究，论文标题为《利用MOLA剖面共配准测绘火星极地季节性CO₂雪/冰盖时间高度变化的前景（Prospects for Mapping Temporal Height Variations of the Seasonal CO2 Snow/Ice Caps at the Martian Poles by Co-registration of MOLA Profiles）》，手稿初稿可于https://arxiv.org/abs/2109.04899获取。

本次研究涉及的缩写术语如下：火星轨道器激光高度计（Mars Orbiter Laser Altimeter, MOLA）、数字地形模型（Digital Terrain Model, DTM）、伦敦大学学院（University College London, UCL）、高分辨率立体相机（High-Resolution Stereo Camera, HRSC）。

MOLA_reference_DTM_from_self_registration.tif为经重处理后的MOLA剖面自配准生成的参考DTM，其高程以半径3396 km的火星球体为基准，覆盖南纬78°以南区域，分辨率为500 m/像素，投影方式为以南极为中心的极球面投影。Number_footprints_per_pixel_MOLA_reference_DTM.tif为用于展示生成上述MOLA_reference_DTM_from_self_registration.tif时，每个网格单元内经重处理与自配准后的可用MOLA足迹数量的分布图。

火星南极原始UCL HRSC DTM，网格分辨率为50 m/像素，可于https://www.cosmos.esa.int/web/psa/UCL-MSSL_iMars_HRSC_v1.0获取，相关参考文献为Putri等（2019）发表于《行星与空间科学（Planetary and Space Science）》174卷第43-55页的《基于欧空局火星快车号搭载高分辨率立体相机（HRSC）构建火星南极新数字地形模型（A New South Polar Digital Terrain Model of Mars from the High-Resolution Stereo Camera (HRSC) onboard the ESA Mars Express）》。

UCL_HRSC_DTMs_mosaic_after_alignment_to_MOLA_reference.tif为配准至上述自配准MOLA剖面后的UCL HRSC DTM拼接图，该拼接图用于生成MOLA_reference_DTM_from_self_registration.tif，网格尺寸为50 m/像素，投影方式为以南极为中心的极球面投影。

Height_difference_before_alignment.tif与Height_difference_after_alignment.tif分别展示配准前后HRSC DTM与自配准MOLA剖面之间的相对高程差。二者网格尺寸均为170 m/像素，投影方式为以南极为中心的极球面投影。配准前，普遍存在幅值可达约10 m的相对倾斜；配准后，高程差分布均匀，幅值通常小于2 m。