What's the reason for the severe drought in CONUS from 2010-2013?

Monthly mean of Precipitation： ftp://ftp.cdc.noaa.gov/Datasets/cpc_us_precip/precip.V1.0.mon.mean.nc

Monthly mean of Temperature： ftp://ftp.cdc.noaa.gov/Datasets/ghcncams/air.mon.mean.nc

Monthly mean of soil moisture： ftp://ftp.cdc.noaa.gov/Datasets/cpcsoil/soilw.mon.mean.v2.nc

The Palmer Drought Severity Index： ftp://ftp.cdc.noaa.gov/Datasets/dai_pdsi/pdsi.mon.mean.selfcalibrated.nc

CONUS Precent Area： https://droughtmonitor.unl.edu/Data/DataDownload/ComprehensiveStatistics.aspx

Binder link: https://mybinder.org/v2/gh/Steven19970523/final-project.git/master

1. Analyze the current drought condition in CONUS.
2. Analyze the drought anomaly to find out the severest year and compare it with others.
3. Analyze some potential reasons, including temperature, precipitation and soil moisture, to figure out the correlation between those reasons and drought.
4. Analyze the global impact of La NiNa and how it impact US climate.