## 2 Materials
### MODIS Data  
The 8-day 500 m MODIS leaf area index (LAI) Version 6 products (MOD15A2H; [36]), the 8-day 500 m MODIS surface reflectance Version 6 products (MOD9A1; [37]), and the yearly 500 m MODIS Land Cover type Version 5 products (MCD12Q1; [38]) were downloaded from the Land Processes Distributed Active Archive Center ([[https://lpdaac.usgs.gov/](https://lpdaac.usgs.gov/)]([https://lpdaac.usgs.gov/](https://lpdaac.usgs.gov/))). Both MOD15A2H and MOD09A1 were used to derive necessary inputs for model simulation and MCD12Q1 was used to obtain areas of deciduous broadleaf forests. The satellite-derived LAI in MOD15A2H could fluctuate unrealistically in the time series due to cloud and/or aerosol contamination [39]. To produce a reasonable LAI time series, we first replaced poor-quality LAI data as derived based on the Quality Control data in MOD15A2H using the median value of a three-point moving window and then filled the gap, if any, using the autoregressive modeling approach [40]. Spikes in the gap-filled time series due to possible outliers were removed using the Hampel filter and then a Savitzky-Golay filter was applied to produce smoothed time series of canopy LAI on an 8-day basis, which were further linearly interpolated to daily time series [41]. The processed 500 m MODIS LAI time series were resampled to match the 1000 m climate datasets based on the averaging method for the pixels that are classified as deciduous broadleaf forests in the MODIS land cover product. The satellite-based LAI time series were extracted for the pixel containing the corresponding flux tower site. The surface reflectance data in MOD09A1 were processed in the same manner as the LAI data and were further used to derive satellite indices such as enhanced vegetation index (EVI; [42]) and land surface water index (LSWI; [43]). The MODIS land cover product of MCD12Q1 was resampled from 500 m to 1000 m resolution based on the majority approach using the Geospatial Data Abstraction Library (GDAL) and was then used to mask out pixels  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Site Code** & **Site Name** & **Lat (\({}^{\circ}\)N)** & **Lon (\({}^{\circ}\)W)** & **Elev (m)** & **Years** & **Reference** \\ \hline US-Bar & Bartlett Experimental Forest & 44.0646 & \(-\)71.2881 & 272 & 2004–2006 & [PERSON] et al. [27] \\ \hline US-Dk2 & Duke Forest Hardwoods & 35.9736 & \(-\)79.1004 & 168 & 2001–2005 & [PERSON] et al. [28] \\ \hline US-Ha1 & Harvard Forest Environmental & 42.5378 & \(-\)72.1715 & 340 & 2001–2012 & [PERSON] et al. [29] \\ \hline US-MMS & Morgan Monroe State Forest & 39.3231 & \(-\)86.4131 & 275 & 2001–2012 & [PERSON] et al. [30] \\ \hline US-MOz & Missouri Ozark & 38.7441 & \(-\)92.2000 & 219 & 2005–2007 & [PERSON] et al. [31] \\ \hline US-Oho & Oak Openings & 41.5545 & \(-\)83.8438 & 230 & 2005 & [PERSON] et al. [32] \\ \hline US-UMB & Univ. of Mich. Biological Station & 45.5598 & \(-\)84.7138 & 234 & 2001–2006 & [PERSON] et al. [33] \\ \hline US-UMd & Univ. of Mich. Biological Station Disturbance & 45.5625 & \(-\)84.6975 & 239 & 2008–2012 & [PERSON] et al. [33] \\ \hline US-WCr & Willow Creek & 45.8060 & \(-\)90.0798 & 515 & 2001–2012 & [PERSON] et al. [34] \\ \hline \end{tabular}
\end{table}
Table 1: Site information for the flux towers of deciduous broadleaf forests.  
that are not deciduous broadleaf forests. Details on the processing of both climate and MODIS data can also be found in [11].