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Inter-comparison of AIRS temperature and relative humidity profiles with AMMA and DACCIWA radiosonde observations over West Africa
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  • Marian Amoakowaah Osei,
  • Leonard K Amekudzi,
  • Craig R. Ferguson,
  • Sylvester Kojo Danuor
Marian Amoakowaah Osei
Kwame Nkrumah University of Science and Technology

Corresponding Author:[email protected]

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Leonard K Amekudzi
Department of Physics, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi-Ghana
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Craig R. Ferguson
Atmospheric Sciences Research Center
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Sylvester Kojo Danuor
University of Science and Technology
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Abstract

The vertical profiles of temperature and water vapour from the Atmospheric InfraRed Sounder (AIRS) have been validated across various regions of the globe as an effort to provide a substitute for radiosonde observations. But there is a paucity of inter-comparisons over West Africa where local convective processes dominate and RAOBs are limited. This study validates AIRS temperature and relative humidity profiles for selected radiosonde stations in West Africa. Radiosonde data was obtained from the AMMA and DACCIWA campaigns which spanned 2006 - 2008 and June-July 2016 respectively and offered a period of prolonged radiosonde observations in West Africa. AIRS performance was evaluated with the bias and root mean square difference (RMSD) at seven RAOB stations which were grouped into coastal and inland. Evaluation was performed on diurnal and seasonal timescales, cloud screening conditions and derived thunderstorm instability indices. At all timescales, the temperature RMSD was higher than the AIRS accuracy mission goal of ±1 K. Relative humidity RMSD was satisfactory for the entire troposphere with deviations < 20% and < 50% respectively. AIRS retrieval of water vapour under cloudy and cloud-free conditions had no significant difference whereas cloud-free temperature was found to be more accurate. The seasonal evolution of some thunderstorm convective indices were also found to be comparable for AIRS and RAOB. The ability of AIRS to capture the evolution of these indices imply its applicability for determining the thunderstorm probability over West Africa under the Global Challenges Research Fund African Science for Weather Information and Forecasting Techniques project.