How to apply the XBT DEPTH bias correction: 1) compute elapse time (t) for each reported depth by using the original drop-rate equation. 2) compute depth biases by a linear function of (t) with coefficients listed in the table below. 3) The coefficients are defined at the middle of year. The users are recommended to interpolate yearly coefficients to dates for individual XBT observations. Example: In case of XBT probe T7 (Sippican; b=6.691, a=-2.25*0.001), the elapse time is given by t = 1486.89 - sqrt(2210838.568-444.444*d), where d is a reported depth. When d is 500 meters, the elapse time becomes 76.7 seconds. Assuming that the observation was made at the center of 1971, the depth biase is finally computed as d = 0.143 * 76.7 = 10.97. That is, the reported depth is larger by 10.97 meters than expected. Note: 1) Please refer to the following manuscript for further details of our XBT-depth-bias correction scheme: Ishii, M. and M. Kimoto, 2008: Reevaluation of Historical Ocean Heat Content Variations With Time-Varying XBT and MBT depth bias Corrections. J. Oceanogr. (in press). [available from http://atm-phys.nies.go.jp/~ism/pub/ProjD/doc/Ishii-Kimoto-2008_rev2.pdf] 2) The correction depends on the observational data base, WOD05 and GTSPP (the latest as of July 2008), used for the estimation of the coefficients. Table: This is the same as Table 2 of Ishii and Kimoto (2008). Sippican Tsurumi Sparton Year T7 T4 T6 T5 T10 D.BLUE T4 T6 T7 XBT-7 Unknown 1966 0.061 0.175 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.181 1967 0.061 0.175 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.181 1968 0.061 0.074 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.184 1969 0.061 0.090 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.176 1970 0.062 0.102 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.035 1971 0.143 0.190 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.093 1972 0.167 0.206 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.118 1973 0.200 0.228 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.217 1974 0.177 0.266 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.184 1975 0.194 0.263 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.205 1976 0.211 0.305 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.176 1977 0.234 0.322 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.333 1978 0.222 0.319 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.245 1979 0.224 0.319 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.239 1980 0.217 0.259 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.197 1981 0.198 0.164 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.075 1982 0.138 0.124 -0.178 0.067 0.059 0.037 0.051 0.014 0.055 -0.317 0.006 1983 0.136 0.133 -0.178 0.068 0.059 0.037 0.051 0.014 0.055 -0.317 0.046 1984 0.083 0.072 -0.178 0.109 0.059 0.037 0.051 0.014 0.055 -0.317 0.044 1985 0.065 0.081 -0.178 0.109 0.059 0.037 0.051 0.014 0.055 -0.317 0.034 1986 0.036 0.053 -0.178 0.109 0.059 0.037 0.051 0.014 0.055 -0.317 -0.015 1987 0.011 0.063 -0.178 0.109 0.055 0.037 0.051 0.014 0.055 -0.317 -0.019 1988 0.064 0.046 -0.178 0.109 0.056 0.037 0.051 0.014 0.055 -0.317 0.003 1989 0.097 0.022 -0.178 0.109 0.081 0.037 0.051 0.014 0.055 -0.318 0.057 1990 0.105 -0.016 -0.178 0.109 0.082 0.037 0.051 0.014 0.055 -0.318 0.059 1991 0.087 -0.022 -0.178 0.106 0.082 0.037 0.051 0.014 0.055 -0.318 0.060 1992 0.130 -0.040 -0.178 0.127 0.082 0.037 0.051 0.014 0.055 -0.317 0.066 1993 0.128 0.078 -0.178 0.136 0.082 0.031 0.051 0.014 0.055 -0.286 0.074 1994 0.109 0.089 -0.179 0.167 0.089 0.074 0.051 0.014 0.055 -0.258 0.074 1995 0.086 0.101 -0.255 0.095 0.090 0.016 0.051 0.014 0.055 -0.247 0.056 1996 0.061 0.100 -0.244 0.121 0.090 0.032 0.051 0.015 0.055 -0.171 0.033 1997 0.073 0.106 -0.240 0.143 0.100 0.036 0.051 0.015 0.064 -0.171 0.036 1998 0.038 0.121 -0.238 0.170 0.086 0.093 0.051 0.009 0.064 -0.171 0.057 1999 0.057 0.180 -0.239 0.130 0.086 0.128 0.051 -0.004 0.064 -0.171 0.053 2000 0.065 0.183 -0.235 0.142 0.083 0.120 0.051 -0.009 0.065 -0.171 0.123 2001 0.085 0.183 -0.233 0.108 0.055 0.100 0.051 -0.011 0.049 -0.171 0.120 2002 0.098 0.183 -0.233 0.021 0.054 0.095 0.051 0.001 0.039 -0.171 0.120 2003 0.156 0.183 -0.233 0.014 0.054 0.094 0.051 -0.018 0.038 -0.171 0.120 2004 0.172 0.183 -0.233 0.032 0.054 0.086 0.051 -0.017 0.038 -0.171 0.120 2005 0.180 0.183 -0.233 0.032 0.054 0.087 0.051 -0.017 0.038 -0.171 0.120 2006 0.180 0.183 -0.233 0.032 0.054 0.083 0.051 -0.017 0.038 -0.171 0.120