GCOS GOOS WCRP/OOPC IX/3 

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VOSClim Analysis 

The VOSClim dataset is a valuable resource for climate researchers. Its wide use must 

be encouraged. There are three distinct phases in the scientific analysis for VOSClim. Firstly, 

the data collected must be thoroughly assessed, using the metadata to determine bias and 

scatter in the observations and how they depend on observational practice and environmental 

conditions. The second phase will use this information to develop a strategy for the 

production of a high quality dataset from the data collected by the VOSClim ships and 

promote good practice amongst the VOS by feeding back the results to the VOS operators. 

Only then can the third stage, the use of high quality data for climate science, begin. At 

present, the only scientific input has come from the VOSClim Scientific Advisors at the UK 

Southampton Oceanography Centre. It is desirable that a wider range of scientists have input 

at each stage. Expanding the user base should be actively encouraged to promote a diversity 

of research and ensure that this dataset is used to its full potential5. It is further desirable to 

promote the wider analysis of error and bias in historical VOS datasets such as ICOADS 

(Diaz et al. 2002, see Section 7.3 of GCOS 2003). 

Action: AOPC should encourage the wider scientific exploitation of VOSClim dataset. 

VOS Development 

In recent years the practice of making observations has been made easier by the 

introduction of automated reporting software such as TurboWin, SEAS or OBSJMA. This has 

reduced the burden of coding reports on the ships officers and provides help, for example, 

with making cloud reports by including pictures of different types of cloud. This type of 

software should have reduced errors due to the incorrect calculation of true winds from ship 

relative winds. However the use of TurboWin logging software has resulted for the first time 

in the implementation of a WMO directive to correct winds to 10 metres height at source 

(Shearman and Zelenko, 1989). SOT II recognised this as a problem, particularly for climate 

research, as there is no metadata to show which reports have been corrected to 10 metres and 

which have not. SOT II has set in motion the process to revoke the WMO height correction 

directive, and in the shorter term the TurboWin developers will remove the height correction 

from the next version (although leaving height correction for fixed platforms reporting in ship 

code following consultation with representatives of NWP centres). An interim mechanism 

using footnotes in WMO Publication 47 should allow the identification of some of the reports 

that have been height corrected at source from metadata. With pressure of time on ships' 

officers, there has been a move towards fully automated systems by some countries, notably 

Canada and France. A good quality automated system, with the facility for manual input of 

some parameters such as cloud types, has the potential to produce climate quality reports. A 

further advantage is the reliable delivery of frequent observations in severe weather 

conditions. However, care needs to be taken that automatic systems are introduced in line 

with the GCOS Climate Monitoring Principles6 (GCOS, 2003) and ensure that enough ships 

still record the full range of variables required for surface flux calculation.  

5

 Note for the OOSDP: the lack of progress on the SURFA project has removed one potential early 

customer for the data set. 

6

 (attached)