VOSClim: Talk Outline

1. VOSClimElizabeth Kent1, Sarah North2,Scott Woodruff3 and David Berry11: National Oceanography Centre, Southampton, UK2: Met Office, Exeter, UK3: Earth System Research Laboratory, NOAA/OAR, Boulder CO, USA

2. VOSClim: Talk Outline • What is VOSClim? • How does it work? • Why do we need it? • What have we learnt? • What about the future?

3. What is VOSClim? • VOSClim is a JCOMM pilot project aiming to improve the quality of marine meteorological observations from Voluntary Observing Ships (VOS) • VOSClim aims to produce a high quality dataset from a subset of VOS which can be used in climate research • VOSClim ships are standard VOS, which happen to provide good quality reports, we are not equipping them with higher quality instruments

4. What is VOSClim? • VOSClim tries to do this by: • Recruiting ships with good reporting records • Asking Port Meteorological Officers (PMOs) to visit the VOSClim ships more frequently • Getting the full Pub. 47 metadata • Asking for pictures of the ship and instruments • Monitoring the data received to higher standards • Archiving the ship report with co-located forecast model output • Reporting extra parameters to try and understand the data

5. How does VOSClim work? • The participating countries recruit their best VOS to VOSClim • A detailed survey of the ship and its instruments is made, photos taken and metadata collected • The reports from the VOSClim ships are extracted by the Met Office from the GTS datastream • The Met Office append co-located forecast model output to the report • VOSClim ships have tighter monitoring limits • The reports are sent to NCDC for archive • NCDC maintain the archive of VOSClim reports/model output/additional parameters and maintain the VOSClim website • www.ncdc.noaa.gov/oa/climate/vosclim/vosclim.html

6. Why do we need VOSClim? • Some of the problems with VOS meteorological reports are well known. • Bucket SSTs are usually too cold • Historically Engine Intake SSTs were too warm • Visual winds need adjustment • Screen humidities are too high • Daytime air temperatures are too warm • But the ships still provide information we cannot currently get in any other way

7. The importance of ship data Data Requirement: Monthly mean heat flux to 10Wm-2 (WGASF, 2000). Air temperature, humidity and winds all inadequate. SST adequate in most regions, but other requirements, for example for high resolution products, will probably show SST data also inadequate.

8. High-quality surface fluxes from VOS • VOS are are only source of in situ flux data distributed over the ocean. • In well sampled regions (typically northern mid-latitudes and major shipping lanes) we can make daily estimates of air-sea exchange. • We need to make sure we have both the QUALITY and QUANTITY of data we need.

9. VOSClim and VOS • Numbers of ships with > 10 SST reports in 2004 • VOS: 2300 (or 500 > 360 obs) • VOSClim: 100 • VOS and VOSClim ships are similar ships using the same instrumentation • VOSClim ships selected for their good reporting record • VOSClim has recruited about 20% of the ships which report regularly • VOS and VOSClim are converging as VOS numbers decline • The total number of reports is becoming a major issue

10. Ship Reporting: 1980 and 2004 • In 1980 there are many more ships making a relatively small number of observations than in 2004 • In 2004 we have fewer ships overall, but a higher proportion make more reports, often hourly • A higher proportion of ships have associated metadata in 2004 than in 1980

11. What Have We Learnt? • The number of ships participating in VOSClim is smaller than we had hoped (about half the target minimum of 200) .... • The VOSClim analysis data is fairly small • There have also been problems with the data flow and archival • The transmission formats necessary to transfer the additional parameters have only just been ratified by JCOMM-II • But a paper has been published in the CLIMAR-II special issue of Int. J. Climatology on the effect of instrument exposure on VOS air temperature measurements

12. Air Temperature Sensor Exposure Paper: Berry, D. I. and E. C. Kent, 2005: The Effect of Instrument Exposure on Marine Air Temperatures: An Assessment Using VOSClim Data International Journal of Climatology (CLIMAR-II Special Issue), 25(7), 1007-1022.

13. What about the future? • For VOSClim to succeed we need to recruit more ships • But the pool of VOS available is shrinking, in 2004 2300 ships made identifiable SST reports, and of these only about 500 made a substantial contribution • The adequacy analysis shows our knowledge of most in situ marine meteorological fields is declining • The dataset must be analysed • Identify and promote good observing practice • Develop corrections to data where necessary • Produce estimates of data requirements (quantity and quality) for VOSClim and VOS

14. VOSClim needs your help • The early years of VOSClim have been taken up in getting the project set up and the data flowing • But VOSClim now needs to produce scientific results • We are looking for people to join a "VOSClim Scientific Users Group" • Minimum required input is to participate in email discussions on scientific issues for VOSClim (and VOS) • But more involvement is encouraged, and necessary, if VOS and VOSClim datasets are to meet the needs of marine climatology