L-band InSAR SWE retrievals over Northern Colorado
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During the NASA SnowEx Time Series campaigns, NASA UAVSAR was tasked to acquire weekly to bi-weekly SAR imagery over the Never Summer Mountains and Medicine Bow Mountains of northern Colorado, near Cameron Pass. In 2020, three InSAR pairs were collected spanning 12 February to 12 March, coinciding with 117 mm of snow water equivalent (SWE) accumulation at the Joe Wright SNOTEL station (ID = 551) or about 18% of peak SWE. In 2021, eight InSAR pairs were collected from 15 January to 22 March, coinciding with 282 mm of SWE accumulation at the SNOTEL station or about 48% of peak SWE. The UAVSAR flightline was ~40 km long with a swath width of 16 km. The primary flight heading was southeast (141°), with a secondary northwest heading (321°) flown when time allowed. To produce this dataset, we used the 141° heading for all InSAR pairs except the 27 January to 3 February 2021 interval, which used the 321° heading. Associated NASA UAVSAR interferograms are archived with the Alaska Satellite Faci..., Detailed methods can be found in the associated publication (Bonnell et al., 2024). Changes in SWE (ÎSWE) were calculated following Guneriussen et al. (2001), which requires phase changes, local incidence angles, and relative permittivity. Phase changes were obtained from the UAVSAR unwrapped interferograms, local incidence angles were calculated in uavsar_pytools from the Copernicus DEM and UAVSAR look vectors, and relative permittivity was calculated from the mean snow surface density measured on snow accumulation boards. Finally, interferograms were calibrated to absoluate ÎSWE by subtracting the median difference between UAVSAR ÎSWE and ÎSWE calculated from a group of ground observations., , # Data from: L-band InSAR SWE retrievals over Northern Colorado [https://doi.org/10.5061/dryad.mkkwh7189](https://doi.org/10.5061/dryad.mkkwh7189) ## Description of the data and file structure Data products contain SWE-changes from NASA UAVSAR flights during the SnowEx 2020 and 2021 Time Series Campaigns. Products are continuous from 12 February to 12 March 2020. The 2021 products are continuous from 15 January to 10 March. The 10â16 March unwrapped InSAR pair yielded no coincident data for phase calibration and thus was not included here. The final interval for 2021 is 16â22 March. The products have not been atmospherically corrected because it was determined in the manuscript ([https://doi.org/10.5194/egusphere-2024-236](https://doi.org/10.5194/egusphere-2024-236)) that an atmospheric correction was not warranted. These products are analysis ready. Most SWE-change products have a temporal baseline of 5â8 days. However, two intervals were longer and may have higher uncertainty: 26 F...
在美国国家航空航天局（NASA）SnowEx时间序列科考任务期间，NASA无人机合成孔径雷达（UAVSAR）被指派于科罗拉多州北部卡梅伦山口附近的永夏山脉（Never Summer Mountains）与医药弓山脉（Medicine Bow Mountains）上空采集每周至每两周一次的合成孔径雷达（SAR）影像。 2020年，共采集了3组合成孔径雷达干涉测量（InSAR）对，时间跨度为2月12日至3月12日，对应乔·赖特雪测站（Snow Telemetry, SNOTEL，ID=551）测得的117毫米雪水当量（Snow Water Equivalent, SWE）累积量，约为峰值雪水当量的18%。 2021年，共采集了8组InSAR对，时间跨度为1月15日至3月22日，对应该雪测站测得的282毫米雪水当量累积量，约为峰值雪水当量的48%。 此次任务的飞行航线总长约40千米，幅宽16千米。主飞行航向为东南方向（141°），时间允许时会辅以西北方向（321°）的飞行航线。 为构建本数据集，除2021年1月27日至2月3日的时段采用321°航向外，其余所有InSAR对均使用141°航向数据。相关NASA UAVSAR干涉图已存档于阿拉斯加卫星设施（Alaska Satellite Facility）……详细的处理方法可参见相关学术论文（Bonnell等，2024）。 雪水当量变化量（ΔSWE）的计算遵循Guneriussen等（2001）提出的方法，该方法需要相位变化量、局部入射角和相对介电常数三类参数。相位变化量由UAVSAR解缠干涉图获取；局部入射角通过uavsar_pytools工具包，基于哥白尼数字高程模型（Copernicus DEM）与UAVSAR观测矢量计算得到；相对介电常数则由积雪积累板测得的平均积雪表面密度计算得出。 最终，通过减去UAVSAR ΔSWE与基于地面观测组计算得到的ΔSWE之间的中位数差值，将干涉图校准为绝对ΔSWE。 # 数据集来源：科罗拉多州北部L波段InSAR雪水当量反演 [https://doi.org/10.5061/dryad.mkkwh7189](https://doi.org/10.5061/dryad.mkkwh7189) ## 数据与文件结构说明 本数据集产品包含SnowEx 2020与2021时间序列科考任务期间NASA UAVSAR飞行获取的雪水当量变化量数据。2020年的产品时间跨度为2月12日至3月12日，数据连续完整；2021年的产品原计划覆盖1月15日至3月10日，但3月10日至16日的解缠InSAR对无匹配的相位校准数据，因此未纳入本数据集，2021年最终有效时段为3月16日至22日。 本数据集未进行大气校正，因为相关论文（https://doi.org/10.5194/egusphere-2024-236）已论证无需开展大气校正。所有产品均已预处理完成，可直接用于分析。 多数雪水当量变化产品的时间基线为5~8天，但有两个时段的基线更长，不确定性可能更高：26日……
