| << | Profiling of Water Vapour and Temperature | >> |
Abstract
Water vapour is a fundamental driver of weather and climate. Most of the water vapour data used in global weather forecasting is measured by radiosondes launched twice-daily. However, these soundings are insufficient for capturing the spatial and temporal variations. Consequently, the use of newly developed instruments, able to provide water vapour data with a high temporal frequency, should be evaluated to determine if they provide more information in the context of statistical parametrization of tropospheric water vapour.
A dataset gathered over 369 days in various midlatitude sites with a multifrequency microwave radiometric profiler is used to perform a statistical comparison between radiometer retrieved water vapour profiles and those provided by an operational radiosonde sounding dataset. The microwave profiler is automated, providing atmospheric sounding up to 10 km height. It observes brightness temperature at twelve frequencies. Atmospheric profiles are retrieved using a neural network based on historical local radiosondes. Results show a good agreement for the mean water vapour content profiles. The water vapour content distribution for radiometric and radiosounding data are weibull distributed with two parameters scale and shape. The scale parameters in the two cases are very similar. The shape parameter from radiosounding is, as the radiometric one, almost constant and close to the radiometric values for T < 5°C. For T > 5°C it is lower than the radiometric values. Another evaluation is performed by comparing integrated water vapour distribution retrieved from the microwave radiometric profiler and the one calculated from the European reanalysis meteorological database ERA 15. The results show a good agreement.