New Zealand dimming and brightening



[1] Recent papers in the international literature on global dimming found a mixed pattern in data from New Zealand. Closer analysis of pyranometer data from four long-term sites shows a downward trend up to 1990, with a reversal at three of them after that time. How much can be attributed to the direct aerosol effect is uncertain from the pyranometer data, but aerosol optical depth data from Lauder show too little aerosol for this to be a substantial component. A comparison with much longer records of sunshine hours shows that there was a trend of increasing cloudiness to around 1990, and a decline since then, consistent with the global pattern.