A 20 Year Record of Satellite-Derived Winds over the Polar Regions for Climate Studies

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: the ones generated by the National Centers for Environmental Prediction/National Center for; Arctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.523.4810

Recent studies have shown that the Arctic climate has changed markedly over the past 25 years. Unfortunately, two major reanalysis products that can be used for studying recent changes exhibit relatively large errors in the wind field over the Arctic where there is little radiosonde data available for assimilation. At least ten numerical weather prediction centers worldwide have demonstrated that satellite-derived polar winds have a positive impact on global weather forecasts. The impact on reanalyses should be similar. Therefore, a polar wind data set spanning more than 20 years was generated using Advanced Very High Resolution Radiometer (AVHRR) data. This paper focuses on the winds generated over the Arctic. Comparisons with winds from collocated radiosondes show good agreement over the Arctic, with relatively small biases in the AVHRR-derived winds of 0.1 – 0.8 m s-1, depending on the level. In addition, AVHRR polar winds have lower speed root-mean-squared errors and speed biases than reanalysis winds when compared to rawinsondes that were not assimilated into the reanalysis. We also show that frequently the AVHRR winds are faster in jet streams than what the reanalysis depicts. The results from this study could lead to a better dynamical understanding of the deficiencies on the reanalysis products over the Arctic region. It is recommended that the historical AVHRR polar winds dataset be included in future reanalysis efforts.