Remote sensing-based evapotranspiration algorithm: a case study of all sky conditions on a regional scale

Figures & data

Figure 1. Geographic location of the study area. For full color versions of the figures in this paper, please see the online version.

Table 1. Site descriptions.

ID	Seolmacheon site (SMC)	Cheongmicheon site (CFC)
Latitude	37.94° N	37.16° N
Longitude	126.95° E	126.65° E
Altitude (m)	293	141
Terrain	Mountainous	Flat
Land cover	Mixed forest	Rice paddy
Canopy height (m)	15	1
Vegetation age (years)	20–40	Annual plant

Table 2. The MODIS data used in this study.

Product ID	Product	Spatial resolution (km)	Temporal resolution (days)	Parameters used
MOD06	Cloud product	1	3–7	Cloud optical depth
		5	3–7	Cloud emissivity, cloud fraction, and cloud top temperature
MOD07	Atmospheric product	5	3–7	Latitude, longitude, air and dew-point temperature, air pressure, precipitable water content, and solar zenith angle
MOD11	Land surface temperature	1	1	Land surface temperature
MOD13	Vegetation indices	1	16	Normalized difference vegetation index (NDVI) Enhanced vegetation index (EVI)
MOD15	Leaf area index	1	8	Leaf area index (LAI)
MOD43	Albedo	1	8	White sky albedo

Figure 2. Flowchart to estimate ET from the MODIS data for all sky conditions.

Figure 3. Temporal variations of daily estimated ET in 2012.

Table 3. Statistic comparing observed and estimated ET.

Site	Average (mm day^−1)	Bias (mm day^−1)	RMSE (mm day^−1)	Regression slope	Correlation coefficient
SMC	2.96	−0.18	1.42	1.03	0.85
SMCBR	4.42	−0.03	0.90	0.97	0.97
CFC	4.69	−0.14	1.26	1.02	0.87
CFCBR	4.94	0.01	1.24	0.98	0.91

Note: Data points in SMC = 142 and CFC = 128. Bias = ET_Fluxtower  – ET_MODIS.

Figure 4. Comparison between observed and estimated ET.

Figure 5. Spatial distribution of monthly estimated ET under all sky conditions in 2012. For full color versions of the figures in this paper, please see the online version.