Forecasting Andean rainfall and crop yield from the influence of El Nino on Pleiades visibility
Forecasting Andean rainfall and crop yield from the influence of El Nino on Pleiades visibility
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作者：
Orlove, BS;Chiang, JCH;Cane, MA
南美洲安第斯山脉干旱地区的农民在历史上观测了南方冬至前后昂宿星团中恒星视亮度的变化，以预测夏季降雨量和秋季收成的年际变化。他们通过调整最重要的作物土豆的种植日期来减轻降雨量减少的影响（1）。在这里，我们使用的数据从卫星图像，农业数据从安第斯高原和厄尔尼诺变化指数的云量和水蒸气分析这种预测方法。我们发现，在六月的昴宿星能见度差，造成亚视觉高卷云的增加，是一个厄尔尼诺年，这通常是与几个月后的生长季节降雨量减少的指示。我们的研究结果表明，这种古老的方法？季节性降雨预报的基础可能是厄尔尼诺变化的一个简单指标。
Farmers in drought-prone regions of Andean South America have historically made observations of changes in the apparent brightness of stars in the Pleiades around the time of the southern winter solstice in order to forecast interannual variations in summer rainfall and in autumn harvests. They moderate the effect of reduced rainfall by adjusting the planting dates of potatoes, their most important crop(1). Here we use data on cloud cover and water vapour from satellite imagery, agronomic data from the Andean altiplano and an index of El Nino variability to analyse this forecasting method. We find that poor visibility of the Pleiades in June-caused by an increase in subvisual high cirrus clouds-is indicative of an El Nino year, which is usually linked to reduced rainfall during the growing season several months later. Our results suggest that this centuries-old method? of seasonal rainfall forecasting may be based on a simple indicator of El Nino variability.