# Flow Duration Curves from Surface Reflectance in the Near Infrared Band
## 2 Materials and Methods
### Study Area and Datasets
#### 2.1.2 Satellite Dataset  
MODIS is a multispectral sensor observing the Earth in 36 spectral bands ranging from 405 nm to 14,385 nm. The spatial resolution at the ground depends on the bands: 250 m for band 1 and 2500 m for bands from 3 to 7, and 1 km for the bands from 8 to 36. Here, the MYD09A1 Version 6 product in Near Infrared in band 2 (841-876 nm) is collected, which provides an estimate of the surface spectral reflectance of Aqua MODIS atmospherically  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Station** & **USGS ID** & **Lat.** & **Lon.** & **A\({}_{\text{b}}\)****** & **Missing Data** & **Qmax** & **Qmin** & **Qmean** \\  & & & **[km\({}^{2}\)]** & **[\%]** & **[\%]** & **[m\({}^{3}\)/s]** & **[m\({}^{3}\)/s]** & **[m\({}^{3}\)/s]** \\ \hline St. Cloud & 5270700 & 45.547 & \(-94.147\) & 34,498 & 0 & 10,333 & 277 & 2040 \\ \hline St. Paul & 5331000 & 44.945 & \(-93.084\) & 95,311 & 0 & 35,052 & 622 & 5847 \\ \hline Prescott & 5344500 & 44.746 & \(-92.800\) & 116,031 & 12.0 & 4049 & 108 & 705 \\ \hline Winona & 5378500 & 44.056 & \(-91.638\) & 153,327 & 0.3 & 5040 & 173 & 1076 \\ \hline McGregor & 5389500 & 43.027 & \(-91.171\) & 174,823 & 48.1 & 55,169 & 2213 & 12,333 \\ \hline Clinton & 5420500 & 41.781 & \(-90.252\) & 221,702 & 0 & 6654 & 238 & 1771 \\ \hline Keokuk & 5474500 & 40.394 & \(-91.374\) & 308,207 & 0 & 15,121 & 229 & 2635 \\ \hline Below Grafton & 5587455 & 38.951 & \(-90.373\) & 443,663 & 10.2 & 159,106 & 4084 & 43,651 \\ \hline St. Louis & 7010000 & 38.628 & \(-90.181\) & 1,805,213 & 0 & 283,769 & 16,459 & 74,299 \\ \hline Chester & 7020500 & 37.901 & \(-89.830\) & 1,835,256 & 0 & 27,014 & 1620 & 7202 \\ \hline Thebes & 7022000 & 37.220 & \(-89.467\) & 1,847,170 & 0 & 295,961 & 19,050 & 80,995 \\ \hline Memphis & 7032000 & 35.127 & \(-90.079\) & 2,415,929 & 75.0 & 48,988 & 5097 & 20,250 \\ \hline Vicksburg & 7289000 & 32.315 & \(-90.906\) & 2,964,227 & 35.3 & 65,412 & 5409 & 21,415 \\ \hline \end{tabular}
\end{table}
Table 1: List of the in-situ gauged stations along the Mississippi River selected for the analysis (latitude, Lat.; longitude, Lon.; basin area, A\({}_{\text{b}}\)) and their characteristics (percent of missing data; minimum, maximum and mean river discharge: Qmin, Qmax, and Qmean, respectively) extracted for the period January 2003 to December 2019.  
Figure 2: River discharge hydrogen (**a**) and reflectance ratio C/M (**b**) for the selected in-situ gauged stations.  
corrected every 8 days at 500 m resolution [17]. It is a level-3 composite in which the product pixel contains the best possible Level-2 observation during an 8-day period as selected on the basis of high observation coverage, low view angle, absence of clouds or cloud shadow, and aerosol loading [18]. This product can be considered sufficiently accurate to avoid the presence of the clouds and to investigate most of the selected sites, whose widths exceed 500 m. Only the most upstream stations, St. Cloud and St. Paul, have widths of approximately 180-200 m. For these two stations, the analysis is useful to investigate the limits of applicability of the procedure.