BST/NOAA PSL Level 2 UAS Soil Moisture, Digital Elevation, Normalized Difference Vegetative Index, and Surface Temperature for SPLASH

This dataset contains uncrewed aircraft systems (UAS) high-resolution data of soil moisture at the 0-5 cm soil depth, normalized difference vegetation index (NDVI), surface temperature, and digital elevation for the Study of Precipitation, the Lower Atmosphere, and Surface for Hydrology (SPLASH) campaign sponsored by the National Oceanic and Atmospheric Administration (NOAA).  These data were collected near Avery Picnic (38.972425 degrees N,106.996855 degrees W) and Kettle Ponds (38.942005 degrees N,106.973006 degrees W) in the East River Watershed in Colorado from a series of flights starting on June 1st, 2022 and ending October 18th, 2023.  Soil moisture measurements were retrieved using the Lobe Differencing Correlation Radiometer (LDCR) which is a L-Band (1-2 GHz) microwave radiometer and was flown on the E2 and S2 aerial platforms operated by Black Swift Technologies LLC.  

Each zip file contains a set of four Level 2 NetCDF files which provides the highest spatial resolution available for each of four products for a given flight location.  With the Level 2 data, each flight location and variable can have different spatial resolutions depending on the sensor type, retrieval algorithm, and flight altitude.  The file name convention for the zip files is as follows.

uas_L2_yyyymmdd_hhmmss_vX.X.zip 

where

L2 = Level 2 data 

yyyymmdd = year,month,day

hhmmss = hour,minute,second

vX.X = version number

Time is the flight start time in UTC.

The NetCDF file format contained in the zip files has a similar format to the zip files with convention

uas__L2_yyyymmdd_hhmmss.nc 

where

= vsm, dem, ndvi, or stmp

vsm = volumetric soil moisture

dem = digital elevation

ndvi = normalized difference vegetation index

stmp = surface temperature

Note that each flight location using the E2 aerial platform required two flights so starting flight times for the soil moisture NetCDF files are different from the other three products.

November 2023 update: Version 2.0 added flight data from 2023. Version 2.0 includes an updated calibration of the soil moisture retrieval that has been applied to 2023 data, and a mask was applied to the soil moisture retrieval over water surfaces for both 2022 and 2023 data.

December 2023 update: Version 2.1 updated soil moisture data with a wet bias in v2.0 for flights #2 (17:40:35 UTC) and #3 (19:24:45 UTC) on July 27, 2022.

本数据集包含由美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）资助的降水、低层大气与水文地表研究（SPLASH）项目所需的无人机系统（Uncrewed Aircraft Systems, UAS）高分辨率数据，涵盖0-5厘米土层土壤湿度、归一化差分植被指数（Normalized Difference Vegetation Index, NDVI）、地表温度及数字高程数据。

这些数据采集于科罗拉多州东河流域的埃弗里野餐地（北纬38.972425°，西经106.996855°）与凯特尔池塘（北纬38.942005°，西经106.973006°），采集时段为2022年6月1日至2023年10月18日的一系列无人机飞行任务。

土壤湿度数据通过瓣差分相关辐射计（Lobe Differencing Correlation Radiometer, LDCR）反演获取，该设备属于L波段（1-2 GHz）微波辐射计，搭载于黑斯威夫特技术有限责任公司（Black Swift Technologies LLC）运营的E2与S2航空平台上。

每个ZIP压缩包包含4个二级NetCDF（Level 2 NetCDF）文件，对应单次飞行地点下4种产品的最高空间分辨率数据。二级数据中，单次飞行地点与各变量的空间分辨率可因传感器类型、反演算法及飞行高度而异。压缩包的命名规则如下：
"uas_L2_yyyymmdd_hhmmss_vX.X.zip"
其中：
- L2 代表二级数据
- yyyymmdd 为年、月、日
- hhmmss 为时、分、秒
- vX.X 为版本号
此处的时间为飞行的协调世界时（UTC）起始时间。

压缩包内的NetCDF文件命名规则类似，格式为：
"uas__L2_yyyymmdd_hhmmss.nc"
其中对应位置为"vsm"、"dem"、"ndvi"或"stmp"，分别对应：
- vsm：体积土壤含水量
- dem：数字高程
- ndvi：归一化差分植被指数
- stmp：地表温度

需注意，使用E2航空平台的每个飞行地点均需执行两次飞行任务，因此土壤湿度NetCDF文件的飞行起始时间与其余三类产品的起始时间存在差异。

2023年11月更新：2.0版本新增了2023年的飞行数据。该版本对2023年的土壤湿度反演结果进行了校准更新，并为2022年与2023年的土壤湿度反演结果添加了水面掩膜。

2023年12月更新：2.1版本修正了2.0版本中2022年7月27日第2次（UTC时间17:40:35）与第3次（UTC时间19:24:45）飞行任务的土壤湿度数据湿偏差问题。