Evidence of a Diurnal Cycle in Precipitation over the Southern Ocean as Observed at Macquarie Island

A diurnal cycle in precipitation over the Southern Ocean has been identified, with maximum rainfall occurring during night and early morning, and minimum in the afternoon. This pattern, observed at Macquarie Island from 1998 to 2016, is most pronounced in summer and suggests a significant contribution of marine boundary layer clouds to total precipitation. The study analyzed surface hourly precipitation data and twice-daily upper air soundings (1995–2011), revealing stronger lower tropospheric inversions at night, consistent with the observed diurnal cycle. These findings challenge the assumption that ERA-Interim precipitation products accurately represent natural variability, as they are dominated by a 12-hourly cycle likely due to twice-daily initialization. The implications for satellite-derived precipitation products, such as those from the A-Train constellation, are also discussed.

Lang, F., Huang, Y., Siems, S. T., & Manton, M. J. (2020). Evidence of a Diurnal Cycle in Precipitation over the Southern Ocean as Observed at Macquarie Island. Atmosphere, 11(2), 181. https://doi.org/10.3390/atmos11020181