AHDC

AHDC General Information

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Hydrographic Surveys and Data Processing
Summary of the hydrographic surveys, the data processing method, and the quality flag definitions for the hydrographic data are described by Uchida et al. (2008) [PDF (0.8MB)]. However, all XCTD data were reprocessed with slight modification for the time lag correction. The conductivity data were advanced by 1.5 scans (about 0.2 m) instead of 2 scans relative to the temperature data to correct for a mismatch in the response time of the sensors (Uchida et al. [submitted manscript PDF (1.8MB)]). The results were improved especially for the XCTD-2 data probably due to slightly slower fall rate than that for the XCTD-1 probe. The cruise BO199805 was added to the dataset after publication. Therefore, the AHDC identification number for the cruises thereafter was changed. Also, the AHDC identification number for the cruises SH199602 and TN199912 was changed to A01 and A02, respectively.
Systematic Bias in the Hydrographic Data
Steric height estimated from the quality controlled hydrographic data agreed well with that estimated from the altimeter data (Uchida and Imawaki, J. Geophys. Res., 113, C09035, doi:10.1029/2008JC004796, 2008 [PDF (1.5MB)]). Therefore, an additional correction won't be necessary for the XBT data, although it is suggested that a systematic bias present in XBT data (Gouretski, V., and K. P. Koltermann, Geophys. Res. Lett., 34, L01610, doi:10.1029/2006GL027834, 2007).
Salinity estimation and salinity bias correction
Salinity profiles for the XBT and DBT measurements, and biases of the salinity profiles for the XCTD measurements were estimated by using mean temperature-salinity relations [one standard deviation from the mean temperature-salinity relation is shown by color shaded area in temperature-salinity plot for each cruise; see Uchida and Imawaki (2008) for detail (PDF, 1.5MB)].
File Name and Data Format
Please see note for AHDC.
Citation for the Dataset
Uchida, H., S. Imawaki, H. Ichikawa, and the ASUKA Group (2008): ASUKA Hydrographic Data Collection, Reports of Research Institute for Applied Mechanics, Kyushu University, 135, 21-31.
[PDF (0.8MB)]
Contact
Hiroshi Uchida
Research Institute for Global Change
Japan Agency for Marine-Earth Science and Technology
e-mail: huchida@jamstec.go.jp
or
Shiro Imawaki
Research Institute for Applied Mechanics, Kyushu University
(Now)
Japan Agency for Marine-Earth Science and Technology
e-mail: imawaki@jamstec.go.jp