Observational requirements for climate monitoring of upper-air temperature

Climate monitoring of upper-air temperature variations and long-term change is currently done using observations from measurement systems that were not designed for this purpose. The result is large uncertainties in estimates of climate change signals. Efforts within the climate community to improve observations for climate monitoring are underway, and they require a well-defined set of requirements to address climate science priorities. These include the spatial and temporal resolution of the observations, and their accuracy, precision, and long-term stability. To address these issues requires an understanding of the expected future variations in temperature, the types of climate statistics that will be required from the observations, and the way in which individual observations will be assembled to develop those statistics.

Using a reanalysis of the climate of the past half century as a model of temperature variations over the next half century, we have tested various data collection protocols to develop recommendations for observing system requirements for monitoring upper-air temperature. The analysis focuses on accurately estimating monthly climatic data (specifically, monthly average temperature and its standard deviation) and multi-decadal trends in monthly temperatures, at specified locations. We will present specific recommendations regarding data precision, long-term measurement stability, temporal sampling (number of observations per day and per month), and upper-air network size. We will also briefly summarize the broader recommendations of the February 2005 NOAA/GCOS Workshop to Define Climate Requirements for Upper Air Observations.