## 1 Introduction
\begin{table}
\begin{tabular}{c c c c c} \hline
**Satellite** & **Sensor** & **Spatial Resolution** & **Revisit Cycle** & **Operational Period** \\ \hline NOAA & AVHRR & 1.1 km & 12 h & From 1978 \\ \hline \multirow{3}{*}{Terra/Aqua} & \multirow{3}{*}{MODIS} & Band 1-2 250 m & \multirow{3}{*}{1 day} & \multirow{3}{*}{From 2000} \\  & & Band 3-7: 500 m & & \\  & & Band 8–36: 1000 m & & \\ \hline \multirow{3}{*}{Terra} & \multirow{3}{*}{ASTER} & VNIR: 15 m & \multirow{3}{*}{16 days} & \multirow{3}{*}{From Dec-1999} \\  & & SWIR: 30 m & & \\  & & TIR: 90 m & & \\ \hline \multirow{3}{*}{Landsat} & MSS (Landsat 1-3) & 79 m & 18 days & From 1972 to 1983 \\  & \multirow{3}{*}{MSS+TM(Landsat5)} & VNIR: 30 m & 16 days & From 1984 to 2013 \\  & & TIR: 120 m & & \\  & & VNIR: 30 m & & \\  & & TIR: 60 m & & \\  & OLI(Landsat-8) & VNIR: 30 m & 16 days & From 2013 \\ \hline OrbView-2 & \multirow{3}{*}{Sealifts} & 1 km & 1 day & From 1997 \\ \hline \multirow{3}{*}{SPOT} & HRV(SPOT1–3) & 20 m & \multirow{3}{*}{26 days (VGT 1 day)} & \multirow{3}{*}{From 1986} \\  & VGT(SPOT-4) & 1.15 km & & \\  & HRG/HRS/VGT(SPOT-5) & HRG-VNIR: 10 m & & \\ \hline ENVISAT & MERIS & 300 m & 35 days & From 2002 to 2012 \\ \hline \multirow{3}{*}{Sentinel-2} & \multirow{3}{*}{MSI} & 10 m: (VNIR) B2,3,4,8 & 10 days with one & \multirow{3}{*}{From Jun-2015} \\  & & 20 m: B5,6,7,8,A1,11,2 & satellite and 5 days & From Jun-2015 \\  & & 60 m: B1,9,10 & with 2 satellites & \\ \hline HJ-1A/1B & Multi-spectral sensor & 30 m & 31 days & From 2009 \\ \hline TH-1 & Multi-spectral sensor & 10 m & 58 days & From Aug-2010 \\ \hline BJ-1 & Multi-spectral sensor & 32 m & \multirow{3}{*}{From Oct-2005} \\ \hline CBERS-01/02 & Multi-spectral sensor & Multi-spectral-CCD: 19.5 m & 26 days & \multirow{3}{*}{CBERS-01: From 1999} \\  & & Multi-spectral-IRMSS: & 26 days & \multirow{3}{*}{CBERS-02: From Oct-2003} \\  & & 78 m/156 m & & \\ \hline ZY-1 02B & Multi-spectral sensor & 20 m & 26 days & From Sep-2007 \\ \hline ZY-1 02C & Multi-spectral sensor & 10 m & 55 days & From Apr-2012 \\ \hline SI-9A & Multi-spectral sensor & 10 m & 69 days & From Oct-2012 \\ \hline ALOS & AVNIR-2 & 10 m & 46 days & From 2006 to 2011 \\ \hline ADEOS & Multi-spectral sensor & 700 m & 41 days & From 1996 to 1997 \\ \hline JERS-1 & OPS & 18 m & 44 days & From 1992 to 1998 \\ \hline \multirow{3}{*}{IRS-1A/1B} & LISS-1/LISS-A/ & 72.5 m(LISS-I); & \multirow{3}{*}{22 days} & \multirow{3}{*}{From 1988} \\  & LISS-B & 36 m(LISS-II) & & \\ \hline IRS-1C/1D & LISS-III & 23.5 m; 70 m & 24 days & From 1995 to 2010 \\ \hline \multirow{3}{*}{IRS-P3} & \multirow{3}{*}{WiFS/MOS} & 188 m(WiFS); & \multirow{3}{*}{5 days} & \multirow{3}{*}{From 1996 to 2004} \\  & & 1500 m/520 m/ & & \\  & & 550 m/MOS & & \\ \hline \multirow{3}{*}{IRS-P6} & LISS-IV/LISS-III/AWiFS &
\begin{tabular}{c} 5.8 m(LISS-IV)/23.5 m \\ (LISS-III)/70 m(AWiFS) \\ \end{tabular} & 24 days & From 2003 \\ \hline THEOS & Multi-spectral sensor & 15 m & 26 days & From Oct-2008 \\ \hline \end{tabular}
\end{table} 
Table 1: Existing satellite sensors collecting multispectral images with spatial resolution larger than 10 m.  
to our knowledge there is no thorough review article to summarize the progress on this topic. [PERSON] et al. generalized the spatiotemporal data fusion methods developed up to November 2014 [12]. [PERSON] et al. did a comparison among four spatiotemporal data fusion methods [13]. [PERSON] et al. reviewed STARFM and two extended methods as well as their applications in vegetation monitoring [14]. It is urgent to survey the current literature to guide future research on this topic. This review investigates literature on current spatiotemporal data fusion methods, categorizes existing methods, discusses the principal laws underlying these methods, summarizes their applications, presents the key issues, and proposes possible directions of future studies on this topic.