A Climate Quality Data Collection System for Volunteer Observing Ships

Historically there have been two separate paths for collection of meteorological data from ships. The first is the near real time data collected by VOS (Volunteer Observing Ships) and transmission via radio or satellite to weather forecast and safety of life at sea facilities. Traditionally, the bulk of surface marine observations have come from these merchant ships. There have been numerous attempts to make use of these observations to map the air-sea fluxes and understand the ocean's role in climate. However, these shipboard observations have significant errors associated with the sensors, sensor placement, and flow disturbance. Furthermore, few ships are equipped to measure the shortwave and longwave radiative fluxes. The second means for collecting surface marine data has been the collection of data for climate research during various research experiments. These experiments have provided higher quality data and were conducted to gain a better understanding of air-sea interaction processes and to improve atmospheric and coupled models.

National agencies and researchers have more recently turned to surface moorings in order to obtain time series of surface meteorology at fixed locations and to work toward observations that were both more complete and more accurate than those obtained on merchant ships. The time series of accurate surface meteorology and air-sea fluxes acquired by the buoys deployed in research experiments are now providing the most comprehensive means to examine the performance of atmospheric models in reproducing surface meteorology over the ocean, the accuracy of climatological data sets, the calibrations and performance of satellite sensors, and methods used to improve the data on Volunteer Observing Ships (VOS). Taylor and Josey at the Southampton Oceanography Centre in the UK have worked to correct biases and errors in the data from the VOS and a comparison of SOC VOS-based flux data at buoy sites agrees very well with buoy data for the same time periods. Further, such SOC and buoy comparisons indicate the need to make regional choices of the parameterizations used in the bulk formulae. There is both temporal and spatial variability in the fluxes due to things such as atmospheric aerosols that make high quality in-situ observations essential.

Benefiting from experience gained with the surface moorings, we are now working to merge the two paths for shipboard data acquisition so that near real time weather forecasting is supported while at the same time acquiring data of the quality needed for seasonal or decadel climate studies and climate forecast development. Further, a strategy for improving global surface meteorology and air-sea fluxes is now moving toward implementation. The plan is to deploy surface moorings as flux reference sites and to field improved VOS systems to fill in the regions around the reference sites. The flux reference sites provide the regional tie points, and the VOS calibrated by these sites provide the mapping capability. This paper will present a description of the development and testing of the data collection system that has a proven record for collecting climate quality data on research buoys and ships, and is now being tested on VOS.