Intersensor calibration of DMSP SSM/I's: F-8 to F-14, 1987-1997
Intersensor calibration of DMSP SSM/I's: F-8 to F-14, 1987-1997
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DOI：
10.1109/36.739079
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
M. Colton;G. Poe
中科院分区：
文献类型：
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作者：
M. Colton;G. Poe
国防气象卫星计划（DMSP）运行特殊传感器微波成像仪（SSM/I）在1987年6月19日第一颗SSM/I （F-8）发射之日庆祝了它的十周年纪念日。在F-8之后，DMSP又发射了五架SSM/I， F-10（1990年12月），F-11（1991年11月），F-12（1994年8月），F-13（1995年3月）和F-14（1997年4月），最后一架SSM/I在1999年作为候选发射。这些仪器由休斯飞机公司制造，已被证明是迄今为止最可靠、校准良好的天基被动微波成像辐射计，可以将数据定量地用于作战和气候应用。SSM/I传感器的显著稳定性也提供了量化SSM/I可以相互校准的增量亮度温级差的机会，从而建立了相互比较的“本底噪声”。本文总结了在校准和验证（cal/val）期间确定的每个新传感器的发射前和发射后性能，从政府和公共机构在海军研究实验室（NRL）的指导下进行的正式的、多年的cal/val工作开始，由空军/海军联合DMSP赞助。对有助于整个系统校准的传感器特定组件、轨道配置和系统相对误差进行了检查。特别是，在数据中观察到SSM/I亮度温度的大（1-3 K）但可校正的左右扫描不对称性，并追溯到航天器（扫描开始）和眩光抑制传感器（扫描结束）的天线视场（FOV）入侵。发现这些影响可以使用像素相关的溢出校正校正到一阶。构建了无雨海洋像元的经验统计分布函数，作为评估传感器间定标的基础。制造商衍生的传感器特定天线方向图校正（APC）系数被发现是多个通道中传感器间较大差异的来源，例如，22v通道的1-2 K。
The Defense Meteorological Satellite Program (DMSP) operational special sensor microwave imager (SSM/I) marked its ten-year anniversary on the launch date of the first SSM/I (F-8), June 19, 1987. After F-8, the DMSP has launched five more SSM/I's, F-10 (December 1990), F-11 (November 1991), F-12 (August 1994), F-13 (March 1995), and F-14 (April 1997), leaving the last SSM/I for a candidate launch in 1999. Built by Hughes Aircraft Co., these instruments have proven to be the most reliable and well-calibrated, space-based, passive microwave imaging radiometers to date, allowing the data to be used quantitatively for both operational and climatological applications. The remarkable stability of the SSM/I sensors also provides the opportunity to quantify the incremental brightness temperature differences to which the SSM/Is can be intercalibrated, thus establishing the "noise floor" for intercomparisons. This paper summarizes the prelaunch and postlaunch performances of each new sensor determined during calibration and validation (cal/val), starting with the formal, multiyear cal/val effort conducted by both government and public institutions under the direction of the Naval Research Laboratory (NRL) and sponsored by the joint Air Force/Navy DMSP. Sensor-specific components, orbital configuration, and systematic relative errors are examined that contribute to the total system calibration. In particular, a large (1-3 K) but correctable left-right scan asymmetry of SSM/I brightness temperatures was observed in the data and traced to an antenna field-of-view (FOV) intrusion by the spacecraft (start of scan) and a glare suppression sensor (end of scan). These effects were found to be correctable to first order using a pixel-dependent spillover correction. Empirical statistical distribution functions for rain-free ocean pixels were constructed for the entire set of SSM/Is and formed the basis for assessing intersensor calibration. Manufacturer-derived sensor-specific antenna pattern correction (APC) coefficients were found to be the source of large intersensor differences for several channels, e.g., 1-2 K for the 22-V channel.