This study is to understand the complex underlying processes in the transitioning of meteorological drought into agricultural drought (i.e., drought propagation) during the entire crop season. For this purpose we identify the correlation between a drought indicator and the crop yield variation using a linear regression model applied for each month of a crop growth season for major crops including corn, soybean, wheat, barley, and hay during the period of 1960 to 2009. The meteorological drought indicator is defined in terms of Standardized Precipitation Evapotranspiration Index (SPEI) at the county level for the Contiguous United States (CONUS), Previous studies analyzed a critical month that has the maximum correlation between drought and yield variation for a specific crop using a fixed crop season. However, the crop growth season for the same crop varies spatially as both planting and harvesting dates are dependent on the non-freezing days. In this study, the crop growth season is not fixed to capture the effect of the varying season in drought propagation. Results indicates that the critical month which has the maximum correlation varies in the crop growth season of the same crop, while different crops exhibit different statistical distributions of the correlation. Future work includes analysis to identify the variation of meteorological drought effects on a crop from crossing counties. This variation can be affected by the distribution of crop growth stages within the season, as well as the climatic properties of particular areas.

Temporal and Spatial Crops Yield Variability Under Droughts in the Contiguous United States

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[Paper Proceedings](https://doi.org/10.1061/9780784483466)

Conference DOI: https://doi.org/10.26226/m.6329c39b68fb0e00131f77d2