## 3 Methods  
### Definition of Extreme Weather Events  
Drought is a natural disaster that causes water shortage and damages agriculture, leading to adverse economic and societal effects [28; 29; 30]. It also severely affects crop growth and causes \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Data**} & \multicolumn{2}{c}{**Spatial**} & \multicolumn{2}{c}{**Temporal**} & \multirow{2}{*}{**Source**} \\  & & **Resolution** & & **Resolution** & \\ \hline \multirow{2}{*}{Cropland} & \multirow{2}{*}{CDL (1)} & 56 m (2006–2009) & \multirow{2}{*}{Yearly} & \multirow{2}{*}{USDA (8)} \\  & & 30 m (2010–2015) & & \\ \hline \multirow{3}{*}{Satellite images} & EVI (2) & 250 m & 16 days & \\  & LAI (3) & 500 m & 8 days & NASA EOSDIS (9) \\ \multirow{3}{*}{Meteorological data} & GPT (5) & & & \\  & TMAX (6) & 4 km & Monthly & PRISM (10) Climate Group \\ \multirow{3}{*}{Hydrological data} & SM (7) & 25 km & Monthly & NASA GES DISC (11) \\ \multirow{3}{*}{Yield statistics} & Corn & County & Yearly & USDA (8) \\ \hline \multicolumn{5}{l}{(1) Cropland Data Layer; (2) Enhanced Vegetation Index; (3) Leaf Area Index; (4) Gross Primary Production; (5) Precipitation; (6) Maximum air temperature; (7) Soil Moisture; (8) United States Department of Agriculture; (9) National Aeronautics and Space Administration’s Earth Observing System Data and Information System; (10) Parameter-elevation Regressions on Independent Slopes Model; (11) NASA’s Goddard Earth Sciences Data and Information Services Center.} \\ \end{tabular}
\end{table} 
Table 1: The data used for corn yield prediction. Figure 3: Concept of the (**a**) temporal aggregation for July–August and the (**b**) spatial aggregation using zonal mean operation for the counties of the study area. considerable reductions in yield. For example, the 2012 US drought influenced at least 60% of the farms and substantially decreased the yields of corn and soybean nationwide [31]. We referred to the National Oceanic and Atmospheric Administration (NOAA) and the National Center for Atmospheric Research (NCAR) for the criteria of drought conditions. The Vegetation Health Index (VHI) [32] provided by NOAA and the Palmer Drought Severity Index (PDSI) [33] provided by NCAR are the mainly used drought indices. The VHI value 0 represents the worst condition, and the VHI value 100 indicates the best situation in terms of vegetation health. PDSI typically shows a range of \(-4\) to \(+4\), with the negative values for dry state and the positive values for wet state. Table 2 shows that the study area suffered a severe drought in July and August (the dominant growth period for corn) in 2012. The mean VHI value for the study area in 2012 was lower than that of the other nine years, and it corresponded to a drought case according to the criteria of NOAA (VHI \(<35\)). The mean PDSI value also satisfied a drought condition in terms of the requirement of NCAR (PDSI \(<-2\)). Hence, we considered the year 2012 as a drought case using both indicators from NOAA and NCAR. Corn yields, PPT, minimum temperature (TMIN), TMAX, mean temperature (TMEAN), VHI, and PDSI in July-August for the period between 2006 and 2015 are summarized in Table 2. The counties with a smaller corn yield accompanied by lower precipitation and higher temperature were observed much more frequently in 2012 than in the other years. High air temperature also significantly affects crop yield, as grains require certain temperatures during the growing season for healthy development. If high temperatures continue for long periods, the crop harvest may be reduced considerably because of weak growth and fruition. [PERSON] at al. [34] used crop growth models with climate data to examine the effects of high-temperature stress on crops; they found that more than 20% of the cultivated area of North America can experience extremely high-temperature stress due to climate change. Climate change would increase thermal stress and damage to crop yields, ultimately affecting the global food supply [5].