VOSClimElizabeth Kent1, Sarah North2,

Scott Woodruff3 and David Berry1

1: National Oceanography Centre, Southampton, UK2: Met Office, Exeter, UK

3: Earth System Research Laboratory, NOAA/OAR, Boulder CO, USA

VOSClim: Talk Outline

o What is VOSClim?

o How does it work?

o Why do we need it?

o What have we learnt?

o What about the future?

What is VOSClim?

o VOSClim is a JCOMM pilot project aiming to improve the quality of marine meteorological observations from Voluntary Observing Ships (VOS)

o VOSClim aims to produce a high quality dataset from a subset of VOS which can be used in climate research

o VOSClim ships are standard VOS, which happen to provide good quality reports, we are not equipping them with higher quality instruments

What is VOSClim?

o 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

o Archiving the ship report with co-located forecast model output

o Reporting extra parameters to try and understand the data

How does VOSClim work?

o 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

o 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

o 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

Why do we need VOSClim?

o 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

o But the ships still provide information we cannot currently get in any other way

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.

High-quality surface fluxes from VOS

o VOS are are only source of in situ flux data distributed over the ocean.

o In well sampled regions (typically northern mid-latitudes and major shipping lanes) we can make daily estimates of air-sea exchange.

o We need to make sure we have both the QUALITY and QUANTITY of data we need.

VOSClim and VOSo Numbers of ships with > 10 SST

reports in 2004

• VOS: 2300 (or 500 > 360 obs)

• VOSClim: 100

o VOS and VOSClim ships are similar ships using the same instrumentation

o VOSClim ships selected for their good reporting record

o VOSClim has recruited about 20% of the ships which report regularly

o VOS and VOSClim are converging as VOS numbers decline

o The total number of reports is becoming a major issue

Ship Reporting: 1980 and 2004

o In 1980 there are many more ships making a relatively small number of observations than in 2004

o In 2004 we have fewer ships overall, but a higher proportion make more reports, often hourly

o A higher proportion of ships have associated metadata in 2004 than in 1980

What Have We Learnt?

o 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

o There have also been problems with the data flow and archival

o The transmission formats necessary to transfer the additional parameters have only just been ratified by JCOMM-II

o 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

Air Temperature Sensor ExposurePaper:

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.

What about the future?

o 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

o 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

VOSClim needs your help

o The early years of VOSClim have been taken up in getting the project set up and the data flowing

o But VOSClim now needs to produce scientific results

o 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