Delayed-Mode Calibration of Hydrographic Data Obtained from Animal-Borne Satellite Relay Data Loggers
Delayed-Mode Calibration of Hydrographic Data Obtained from Animal-Borne Satellite Relay Data Loggers
复制标题
DOI：
10.1175/2010jtecho801.1
复制
发表时间：
2011-06-01
影响因子：
2.2
通讯作者：
Guinet, Christophe
中科院分区：
文献类型：
--
作者：
Roquet, Fabien;Charrassin, Jean-Benoit;Guinet, Christophe
为了提高部署在象海豹上的CTD-卫星中继数据记录仪（CTD-SRDL）的水文数据质量，提出了一种延迟模式校准方法。这一程序适用于2007年在凯尔盖朗群岛部署的10个CTD-SRDL获得的数据集。首先对CTD-SRDL与船基CTD系统进行了比较。一个压力效应校正，与压力成线性关系，推导出温度和盐度测量。电导率传感器上的外场效应也被检测到，引起额外的盐度偏移。盐度偏移不能直接从基于船的CTD比较中估计，因为密封头上CTD-SRDL的附件修改了外场效应的大小。提出了两种后验盐度偏移估计方法。第一种方法使用稳定的盐度最大特征较低的绕极深水（LCDW），采样海豹觅食南部南极绕极流锋。如果这种方法是不可能的，CTD-SRDLs表面盐度测量的交叉比较的统计方法是使用在缓慢的北方凯尔盖朗高原。在没有校正的情况下，温度的准确度分别估计为+/- 0.02摄氏度，盐度的准确度估计为+/- 0.1摄氏度。延迟模式校准显著改善了CTD-SRDL数据，分别将精度提高到+/- 0.01摄氏度和+/- 0.03摄氏度。当可以使用LCDW方法时，实现了更好的盐度精度+/- 0.02。对于无法进行船基CTD比较的CTD-SRDL，温度的预期准确度为+/- 0.02摄氏度，得出的盐度的预期准确度为+/- 0.04。
A delayed-mode calibration procedure is presented to improve the quality of hydrographic data from CTD-Satellite Relay Data Loggers (CTD-SRDL) deployed on elephant seals. This procedure is applied on a dataset obtained with 10 CTD-SRDLs deployed at Kerguelen Islands in 2007. A comparison of CTD-SRDLs with a ship-based CTD system is first presented. A pressure-effect correction, linear with pressure, is deduced for both temperature and salinity measurements. An external field effect on the conductivity sensor is also detected, inducing an additional salinity offset. The salinity offset cannot be estimated directly from the ship-based CTD comparisons, because the attachment of the CTD-SRDL on the seal head modifies the magnitude of the external field effect. Two methods are proposed for estimating a posteriori the salinity offset. The first method uses the stable salinity maximum characterizing the Lower Circumpolar Deep Water (LCDW), sampled by seals foraging south of the Southern Antarctic Circumpolar Current Front. Where this approach is not possible, a statistical method of cross-comparison of CTD-SRDLs surface salinity measurements is used over the sluggish Northern Kerguelen Plateau. Accuracies are respectively estimated as +/- 0.02 degrees C for temperature and +/- 0.1 for derived salinity without corrections. The delayed-mode calibration significantly improves the CTD-SRDL data, improving accuracies to +/- 0.01 degrees C and +/- 0.03, respectively. A better salinity accuracy of +/- 0.02 is achieved when the LCDW method can be used. For CTD-SRDLs where ship-based CTD comparisons are not available, the expected accuracy would be +/- 0.02 degrees C for temperature and +/- 0.04 for the derived salinity.