# Presentation: 802933

## VOSClimElizabeth Kent1,  Sarah North2,Scott Woodruff3 and David Berry11: National Oceanography Centre, Southampton,  UK2: Met Office, Exeter, UK3: Earth System Research Laboratory, NOAA/OAR, Boulder CO, USA

## VOSClim:  Talk Outline

- What is VOSClim?
- How does it work?
- Why do we need it?
- What have we learnt?
- What about the future?

## 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

## 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

## 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](http://www.ncdc.noaa.gov/oa/climate/vosclim/vosclim.html)_

## 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

## 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

- 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.

## 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

## 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

## 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

## 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.

## 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

## 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