Improved Database of Historical Ocean Subsurface Temperature Observations

We have started to reassemble historical expendable bathythermograph (XBT) data in order to improve an ocean subsurface database in the North Pacific. In the 1980s and early 1990s temperature observed by XBT were reported at the standard depths or inflection depths because temperature profile was recorded on strip chart so that temperature and depth were digitized by hand. We therefore discovered and collected several thousand of existing XBT strip charts, and traced a recorded temperature profile at a higher resolution for every chart. The traced XBT data compare with CTD data at the same or neighborhood time and position in order to estimate their systematic errors or uncertainties before replacing data. The related information such as probe type, fall rate, type of recorder or converter are also included in database as metadata. The improved database will be used to assess the climate change and the sea level rise in the North Pacific.