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Application of corrections to original XBT data based on Cowley, R., S. Wijffels, L. Cheng, T. Boyer, S. Kizu: Biases in Expendable BathyThermograph data: a new view based on historical side-by-side comparisons, accepted by Journal of Atmospheric and Oceanic Technology. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Step 1: Identify appropriate correction Corrections are provided for T4/T6 (Sippican), T7/Deep Blue (Sippican), TSK T6 and TSK T7/Deep Blue. If manufacturer is not given the deploying country and year of deployment and maximum depth should be used to identify probe type. Deploying country: TSK types are applied to: Japan, Taiwan, Korea, Thailand, China. All other countries are designated Sippican. Table 1 contains the information on earliest to market and depth cutoffs for each probe type.
Probes designated TSK T4 use TSK T6 (TSK does not make T4s). All Sparton XBTs use Sippican corrections. In the paper, the following additional corrections were applied to other probe types for the Global Ocean Heat Content (GOHC) calculation: Where a correction was not available for a particular year, T4/T6 corrections were used for T7/DB probes and vice versa for Sippican types. The equivalent Sippican correction was used for TSK types. Sippican T4/T6 corrections were applied to all T10, T11, and unknown types with terminal depth < 550 m. Sippican T7/DB corrections were applied to Sippican Fast Deeps and unknown types with terminal depth = 550 m and < than 1005m. Corrections were not applied to T5s or to probes with depths = 1005m. XBT data from 1996 to the present with no depth equation information were not included in the GOHC calculation. Step 2: Convert to Hanawa (1995) fall rates if required. Step 3: Apply the corrections: Cowley et al Cheng Corrections Back calculate time from depth, t = q - (q2 - z/bh)0.5 Where q = ah/(2 * bh) and time t is in seconds. Z(corrected) = a*t - b*t2 - c T(corrected) = T(original) - Thermal_bias Thermal _bias for Cheng corrections is provided in Table 5. |
Last modified: Thu, 23-Apr-2015 19:57 UTC | NCEI.info@noaa.gov | ||
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