Establishing the GCOS
Reference Upper Air Network

Background

The assessment of global climate research carried out in the 3rd IPCC assessment report (Climate Change 2001: The Scientific Basis), highlighted a deficiency in the global climate observing system. This deficiency has compromised efforts to reliably and accurately attribute observed changes in global climate to human activities. Specifically, disagreements between measured and modelled trends in temperatures in the region between about 3 and 15 km in altitude, cast doubt on the attribution of observed changes in temperatures to human-induced emissions of greenhouse gases. This issue was further clouded by the fact that the quality of temperature measurements in this region of the atmosphere was inadequate for the detection of long-term temperature trends.

This is because such measurements are made primarily for use as input to models used by weather forecasters to make forecasts over periods of up to one week into the future. The measurements are made using balloon-borne instruments called radiosondes which make vertical profile measurements of temperature, pressure and humidity. It was never intended that these radiosonde measurements would be used to detect multi-decadal trends in temperature.

To address this short-fall in high precision measurements of essential climate variables in the upper atmosphere, the World Meteorological Organization (WMO) and the Global Climate Observing System (GCOS) called for the establishment of a new state-of-the-art global climate monitoring network. This network would be tasked with making high quality measurements in the upper atmosphere that would be suitable for the detection of multi-decadal trends.

Sites within the network would not operate under the short-term requirements for weather forecasting but would rather focus on making very precise measurements, stable over many decades, to detect climate trends in the upper atmosphere. Participation in this elite set of sites would be by invitation only, and, as the crème-de-la-crème of climate monitoring stations, would be expected to operate under the most exacting international standards. The establishment of this GRUAN (GCOS Reference Upper Air Network) was needed.

Bodeker Scientific in GRUAN

Bodeker Scientific is involved in the operation of GRUAN through:

• Greg Bodeker is one of two co-chairs of GRUAN.

• Greg Bodeker is the chair of the Scientific Organizing Committee for the GRUAN Workshop to Develop Network Design and Expansion Criteria. More information is available on that workshop here.

• Bodeker Scientific has been contracted by the German Weather Service to develop the Manual of Operations for GRUAN that will establish the operational philosophy under which GRUAN will operate and to inform current and future GRUAN sites of the expected modus operandi for GRUAN. It defines the requirements for GRUAN site operations, including requirements on expected accuracy, long-term stability, and uncertainty measures. Rather than prescribing the methods, techniques and processes that should be employed in GRUAN, it provides higher level principles that are intended to direct the development of the methods, techniques and processes needed to achieve the stated goals of GRUAN.

For more information on the involvement of Bodeker Scientific in GRUAN, please contact Greg Bodeker.

More information on GRUAN is available here.