Aquarius CAP Level 3 Sea Surface Salinity Rain Corrected Standard Mapped Image 7-Day Data V5.0

Version 5.0 Aquarius CAP Level 3 products are the fourth release of the AQUARIUS/SAC-D mapped salinity and wind speed data based on the Combined Active Passive (CAP) algorithm. CAP Level 3 standard mapped image products contain gridded 1 degree spatial resolution salinity and wind speed data averaged over 7 day and monthly time scales. This particular dataset is the 7-Day running mean sea surface salinity (SSS) rain corrected V5.0 Aquarius CAP product. CAP is a P.I. produced dataset developed and provided by JPL. The CAP algorithm utilizes data from both the onboard radiometer and scatterometer to simultaneously retrieve salinity, wind speed and direction by minimizing the sum of squared differences between model and observations. The main improvements in CAP V5.0 relative to the previous version include: updates to the Geophysical Model Functions to 4th order harmonics with the inclusion of sea surface temperature (SST) and stability at air-sea interface effects; use of the Canadian Meteorological Center (CMC) SST product as the new source ancillary sea surface temperature data in place of NOAA OI SST. The Aquarius instrument is onboard the AQUARIUS/SAC-D satellite, a collaborative effort between NASA and the Argentinian Space Agency Comision Nacional de Actividades Espaciales (CONAE). The instrument consists of three radiometers in push broom alignment at incidence angles of 29, 38, and 46 degrees incidence angles relative to the shadow side of the orbit. Footprints for the beams are: 76 km (along-track) x 94 km (cross-track), 84 km x 120 km and 96km x 156 km, yielding a total cross-track swath of 370 km. The radiometers measure brightness temperature at 1.413 GHz in their respective horizontal and vertical polarizations (TH and TV). A scatterometer operating at 1.26 GHz measures ocean backscatter in each footprint that is used for surface roughness corrections in the estimation of salinity. The scatterometer has an approximate 390km swath.5.0版Aquarius CAP三级产品（Aquarius CAP Level 3 products）是基于组合主动被动（Combined Active Passive，CAP）算法生成的AQUARIUS/SAC-D卫星绘图式盐度与风速数据的第四次发布版本。CAP三级标准绘图影像产品包含空间分辨率为1度的网格化盐度与风速数据，其时间尺度涵盖7日平均与月均平均。本数据集为经过降雨校正的7日滑动平均海表盐度（sea surface salinity，SSS）V5.0版Aquarius CAP产品。 CAP是由喷气推进实验室（Jet Propulsion Laboratory，JPL）开发并提供的首席研究员（Principal Investigator，PI）产出数据集。CAP算法同时利用星载辐射计与散射计的数据，通过最小化模型与观测值之间的平方差之和，同步反演盐度、风速与风向。 相较于前一版本，CAP V5.0的主要改进包括：将地球物理模型函数（Geophysical Model Functions）更新至四阶谐波形式，并纳入海表温度（sea surface temperature，SST）与气-海界面稳定性效应；采用加拿大气象中心（Canadian Meteorological Center，CMC）海表温度产品作为新的辅助海表温度数据源，替代原有的美国国家海洋和大气管理局最优插值海表温度（NOAA Optimum Interpolation SST，NOAA OI SST）。 Aquarius载荷搭载于AQUARIUS/SAC-D卫星，该卫星是美国国家航空航天局（National Aeronautics and Space Administration，NASA）与阿根廷国家空间活动委员会（Comision Nacional de Actividades Espaciales，CONAE）的合作项目。该载荷包含三台沿推扫式阵列排布的辐射计，其相对于轨道阴影面的入射角分别为29°、38°与46°。各波束的地面足印尺寸为：76 km（沿轨向）×94 km（交轨向）、84 km×120 km以及96 km×156 km，总交轨幅宽达370 km。 各辐射计在1.413 GHz频段下，分别测量水平极化与垂直极化下的亮温（记为TH与TV）。一台工作于1.26 GHz频段的散射计，会测量每个地面足印内的海洋后向散射信号，该信号用于盐度反演过程中的海面粗糙度校正。该散射计的幅宽约为390 km。