1. XBT fall rate corrections Summary of pre-meeting discussions Step 1: Making recommendations for future XBT data collection Step 2: Correction of the historical records for climate applications Step 3: Publications and the future Email discussion summary0 |

2. Step 1: making recommendations for future XBT data collection: We should NOT recommend new fall rate coefficients for the collection of data. – Only Hanawa and Sippican coefficients should be used for data collection. – Any corrections should be applied separately, the original data retained. Metadata collection needs to be improved and defined. We should recommend the required metadata. – Do we need to recommend a format to hold the data (GTSPP netcdf format?) The Sippican pressure switch option – we prefer the company to implement tighter weight controls and better thermistor calibrations. The form of the fall rate equation requires more investigation. Eg including an offset term requires a physical reason. We require ongoing and more side-by-side data sets – TSK, cold water, changing fall rate. Email discussion summary1 |

3. Step 2: Recommending a correction for historical data for climate applications We want to make recommendations for all probe types (if we decide to make a recommendation) We will recommend that any fall rate corrections used should be acknowledged in publications. Email discussion summary2 |

4. Step 2 continued: Recommending a correction for historical data for climate applications Do we agree that we need to recommend a correction for climate applications? A mix of opinions – A recommendation can be made, but it is only a recommendation and is subject to review – Scientists should read the literature and make their own decisions on how to correct the data. – We should publish a summary of all the corrections currently available. Who needs a correction – only those working in climate change field. Email discussion summary3 |

5. How do we decide on a recommendation? Comparison of the schemes to find a ‘best’ outcome – How do we do an unbiased comparison? – Is the best solution a mix of corrections based on best performances for each probe type, time period etc? – We need to provide uncertainties for any recommended correction scheme. The minimum requirements for a correction: time variable fall rate, offset, temperature bias. Do we need the geographical/temperature correction? Can any schemes be eliminated? Email discussion summary4 | Step 2 continued: Recommending a correction for historical data for climate applications

6. Step 3: Publications and the future We should produce a white paper with the goals, recommendations and outcomes from the meeting. Recommendations can be part of the IODE/JCOMM Ocean Data Standards and Best Practices Project (ODSBP) (Charles Sun) The organization of the next fall rate workshop needs to include key members, list these members. Currently have some exciting ongoing research – more publications coming. Email discussion summary5 |

7. Step 3 continued: Ongoing research The fall rate in the first part of the water column and how it relates to the offsets found in several studies. – Deployment height and water temperatures Recording system issues: – thermistor constant, recorder hardware/software issues (precisions, offsets in different recorders) – Why is the temperature bias higher in strip chart recorders? Aerial XBTs – is there someone who can work with the US Navy on this dataset? Email discussion summary6 |