黑河生态水文遥感试验：黑河流域中游盈科绿洲与花寨子荒漠机载PLMR地面同步观测数据集（2012年7月10日）

2012年7月10日在盈科绿洲与花寨子荒漠PLMR样方进行了机载飞行地面同步观测。PLMR（Polarimetric L-band Multibeam Radiometer）是双极化（H/V）的L波段微波辐射计，中心频率1.413 GHz，带宽24 MHz，分辨率1 km （相对航高3 km），有6个beam同时观测，入射角为±7º，±21.5º，±38.5º，灵敏度<1K。飞行主要覆盖中游人工绿洲生态水文试验区。本地面同步数据集可为发展和验证被动微波遥感反演土壤水分算法提供基本地面数据集。
样方及采样策略：
观测区位于张掖绿洲南缘-安阳滩荒漠过渡带，张（张掖）-大（大满）公路西侧，南北跨龙渠干渠，分为两部分，西南方向为1 km×1 km的荒漠样方，由于荒漠较为均质，在此1 km样方内采集5个点（四周各1点及中心点，实际测量过程中，可在沿路行走过程中多测几个点）的土壤水分，四个角点除对角线方向外，互相间隔600 m，西南角角点为花寨子荒漠站，便于与气象站数据比较。在东北侧，选择了面积1.6 km×1.6 km的大样方针对绿洲下垫面开展同步观测。样方的选择依据主要是考虑地表覆盖代表性、尽量避开民居和大棚、穿越绿洲农田以及南边的部分荒漠、可达性、观测（路途消耗）时间，以期获得与PLMR观测的亮度温度的比较。
考虑到PLMR观测的分辨率，同步观测中，东西方向以160 m为间隔，采集了11条样线（东西分布），每条线80 m间隔共21个点（南北方向），使用4台Hydraprobe Data Acquisition System （HDAS，参考文献2）同时测量。
测量内容：
获取了样方上约230个点，每个点2次观测，即对覆膜玉米地，在每个采样点进行2次观测，1次膜内（数据记录中标记为a），1次膜外（数据记录中标记为b）。由于HDAS系统采用POGO便携式土壤传感器，观测获得土壤温度、土壤水分（体积含水量）、损耗正切、土壤电导率、土壤复介电实部及虚部。当日未开展专门的植被同步采样。
数据：
本数据集包括土壤水分观测和植被观测两部分，前者保存数据格式为矢量文件，空间位置即为各采样点位置（WGS84+UTM 47N），土壤水分等测量信息记录在属性文件中。

Airborne flight and ground synchronous observations were conducted at the Yingke Oasis and Huazhaizi Desert PLMR plots on July 10, 2012. PLMR (Polarimetric L-band Multibeam Radiometer) is a dual-polarization (H/V) L-band microwave radiometer, with a central frequency of 1.413 GHz, bandwidth of 24 MHz, spatial resolution of 1 km (at a relative flight altitude of 3 km), supporting simultaneous observation with 6 beams, with incidence angles of ±7°, ±21.5°, and ±38.5°, and a sensitivity of less than 1 K. The flight mainly covered the middle-reach artificial oasis eco-hydrological experimental area. This ground synchronous dataset can provide fundamental ground reference data for developing and validating passive microwave remote sensing soil moisture retrieval algorithms.

Plot and Sampling Strategy:
The observation area is located at the southern margin of Zhangye Oasis - Anyantan Desert transition zone, west of the Zhangye-Daman Highway, spanning the Longqu Canal from north to south, and is divided into two parts. The southwest part is a 1 km×1 km desert plot. As the desert is relatively homogeneous, soil moisture measurements were taken at 5 points within this 1 km plot: one at each corner and one at the center; additional points can be measured while walking along the road during actual fieldwork. The four corner points are 600 m apart except along the diagonal direction, and the southwest corner is the Huazhaizi Desert Station, facilitating comparison with meteorological station data. On the northeast side, a large 1.6 km×1.6 km plot was selected for synchronous observations targeting the oasis underlying surface. The plot selection criteria mainly include representativeness of surface cover, avoidance of residential buildings and greenhouses as much as possible, coverage of oasis farmland and part of the southern desert, accessibility, and observation travel time costs, aiming to enable comparison with the brightness temperature observed by PLMR. Considering the observation resolution of PLMR, in the synchronous observations, 11 east-west transects were deployed at 160 m intervals in the east-west direction, with a total of 21 points per transect at 80 m intervals in the north-south direction, measured simultaneously using 4 Hydraprobe Data Acquisition Systems (HDAS, Reference 2).

Measurement Contents:
Approximately 230 points were measured across the plots, with two observations per point. For plastic-film mulched corn fields, two observations were conducted at each sampling point: one inside the film (marked as 'a' in the data records) and one outside the film (marked as 'b' in the data records). The HDAS system uses POGO portable soil sensors, which measure soil temperature, soil moisture (volumetric water content), loss tangent, soil electrical conductivity, and the real and imaginary parts of soil complex dielectric permittivity. No dedicated synchronous vegetation sampling was conducted on that day.

Data:
This dataset includes two parts: soil moisture observations and vegetation observations. The former is stored as vector files, where the spatial positions correspond to the locations of each sampling point (WGS84+UTM 47N), and measurement information such as soil moisture is recorded in the attribute files.