Silva Fennica

Fig. 1. Land surface temperature (LST) values plotted against a vegetation index (VI), forming a theoretical triangle model.

Fig. 2. The study area, located in the southeastern United States.

Table 1. Beginning and ending times of data collection by MODIS satellite during each of the eleven 16-day periods considered in this study.
Period	Beginning date (time 00:00:00)	Ending date (time 23:59:59)
1	22-Mar-2009	6-April-2009
2	7-April-2009	22-April-2009
3	23-April-2009	8-May-2009
4	9-May-2009	24-May-2009
5	25-May-2009	9-June-2009
6	10-June-2009	25-June-2009
7	26-June-2009	11-July-2009
8	12-July-2009	27-July-2009
9	28-July-2009	12-August-2009
10	13-August-2009	28-August-2009
11	29-August-2009	13-September-2009

Fig. 3. Locations and names of the in situ moisture measurement stations in the study area.

Table 2. Names of in situ moisture measurement stations, their networks, and geographic coordinates, for the analyzed data.
Station number	Station name	Latitude, Longitude	Network	Vegetation type ^a
1	Little River	31°30´N, 83°30´W	SCAN	Agriculture
2	Pee Dee	34°18´N, 79°44´W	SCAN	Agriculture, young pine plantation, old deciduous forest
3	Wakulla	30°18´N, 84°25´W	SCAN	Middle-aged pine plantation
4	Watkinsville	33°53´N, 83°26´W	SCAN	Agriculture, developed areas
5	Youmans Farm	32°40´N, 81°12´W	SCAN	Agriculture, old pine forest
6	Blackville	33°21´N, 81°20´W	USCRN	Agriculture
7	McClellanville	33°09´N, 79°22´W	USCRN	Agriculture, deciduous forest
^a Vegetation types in the immediate area (100 m) around each measurement point.

Table 3. Statistical summary of the in situ moisture data used for parameterization into moisture units (m³ m^–3).
Soil depth	Parameter	Little River	Pee Dee	Wakulla	Watkinsville	Youmans Farm	Blackville	McClellanville
cm	-	m³ m^–3	m³ m^–3	m³ m^–3	m³ m^–3	m³ m^–3	m³ m^–3	m³ m^–3
5	Minimum	0.037	0.063	0.014	0.111	0.027	0.034	0.022
	Maximum	0.338	0.296	0.140	0.405	0.327	0.213	0.110
	Mean	0.103	0.189	0.066	0.204	0.123	0.103	0.052
	Std. Dev.	0.038	0.055	0.029	0.069	0.058	0.055	0.017
10	Minimum	0.047	0.051	0.029	0.054	0.038	0.047	0.019
	Maximum	0.369	0.251	0.144	0.327	0.304	0.171	0.111
	Mean	0.102	0.162	0.077	0.121	0.142	0.089	0.063
	Std. Dev.	0.035	0.046	0.025	0.052	0.058	0.038	0.022
20	Minimum	0.056	0.048	0.010	0.067	0.030	0.210	0.012
	Maximum	0.229	0.209	0.103	0.331	0.288	0.290	0.133
	Mean	0.116	0.137	0.060	0.128	0.137	0.240	0.076
	Std. Dev.	0.036	0.039	0.022	0.054	0.061	0.025	0.028

Table 4. Parameters for dry and wet edges of the calculated “triangles” for each of the analyzed eleven 16-day periods.
Period	TVDI(NDVI)				TVDI(EVI)
	Wet edge		Dry edge		Wet edge		Dry edge
	a_min	b_min	a_max	b_max	a_min	b_min	a_max	b_max
1	264.0	33.0	315.2	–19.2	279.0	19.1	310.0	–19.0
2	273.0	20.5	318.0	–23.0	283.1	13.8	311.2	–22.5
3	272.8	24.6	338.0	–40.0	284.0	16.3	325.0	–34.0
4	278.0	10.0	337.2	–38.0	282.0	8.0	324.8	–32.0
5	267.0	26.0	340.6	–39.0	280.6	16.0	324.0	–28.0
6	289.8	3.0	330.8	–25.5	291.4	1.9	333.0	–38.0
7	297.0	–7.4	351.2	–49.0	286.2	6.0	340.0	–49.0
8	268.2	22.6	341.2	–40.0	267.4	30.8	326.0	–29.5
9	253.8	42.0	343.0	–42.5	260.0	42.0	323.4	–26.8
10	237.0	59.0	340.0	–41.0	246.0	62.0	320.0	–22.4
11	247.0	44.0	346.0	–47.0	249.1	60.5	313.0	–12.0
Average	268.0	25.2	336.5	–36.7	273.5	25.1	322.8	–28.5
a_max, b_max = linear regression parameters for the dry edge a_min, b_min = linear regression parameters for the wet edge TVDI – Temperature Vegetation Dryness Index NDVI – Normalized Difference Vegetation Index EVI – Enhanced Vegetation Index

Fig. 4. Triangular relationships developed for the study area through the use of land surface temperature (LST) and Temperature Vegetation Dryness Index (TVDI) based on the Normalized Difference Vegetation Dryness index (NDVI).

Fig. 5. Scatterplots with regression lines for in situ soil moisture content at three depths a) 5 cm; b) 10 cm; and c) 20 cm predicted from Temperature Vegetation Dryness Index (TVDI) values. P-values for each regression model are also shown. View larger in new window/tab.

Fig. 6. Map of soil moisture values calculated from the MODIS based on Temperature Vegetation Dryness Index calculated using Normalized Difference Vegetation Index TVDI(NDVI) (left) and Temperature Vegetation Dryness Index calculated using Enhanced Vegetation Dryness Index TVDI(EVI) (right) for three depth measurements during the second study measurement period (April 7–22, 2009): a) 5 cm; b) 10 cm; and c) 20 cm. View larger in new window/tab.