117
Spatiotemporal Interactions among Ecohydrological Factors
principal means for earth observations. Infrared remote sensing imaging detects the
temperature difference between a target and the surrounding environment. The biggest advantage of infrared remote sensing is that the image can be obtained without
lighting or under cloud cover.
Microwave remote sensing, with a wavelength of 1–1000 mm, detects microwave
radiation, reflection, or scattering from a ground target and can be divided into active
and passive microwave remote sensing. Active microwave remote sensing consists of
imaging radar, microwave scatterometer, and microwave altimeter; passive microwave remote sensing refers mainly to various microwave radiometers that measure
weak microwave radiation emitted from various objects in nature to measure a target’s radiation properties and actual temperature. Passive microwave systems have
been widely used as a direct remote sensing method to explore the capability of
remotely measuring soil moisture (O’Neill et al. 1996; Njoku and Entekhabi 1996;
Burke et al. 2001) and groundwater recharge (Jackson 2002). Later, active microwave
systems were developed and combined with passive remote sensing for earth observations (Moran et al. 1997; Kustas et al. 1998; Glenn and Carr 2003). Remarkable
progress has been made in the use of spectral images from active or passive satellite
sensors for surface soil moisture mapping, where surface soil moisture is the average
moisture in the top few centimeters of soil layer (Grayson et al. 1997; Western and
Grayson 1998; Wilson et al. 2003, 2004; Makkeasorn et al. 2006).
The processing procedure of microwave remote sensing is time consuming and
labor intensive due to its fine resolution. More recent soil moisture studies tend to use
multispectral remote sensing for relatively large areas (Wang et al. 2007; Casper and
Vohland 2008; Merlin et al. 2010). The MODIS sensor is an advanced multipurpose
sensor and is a key instrument aboard the Terra (Earth Observing System [EOS]–
AM) and Aqua (Earth Observing System [EOS]–PM) satellites operated by the
National Aeronautics and Space Administration (NASA). Surface reflectance, LST/
emissivity, and vegetation indices of MODIS satellite data are available from NASA.
6.2.2.2 Urban Environment and Ground-Truth Data Collection
The Tampa Bay urban region mainly includes the Hillsborough, Manatee, and Alafia
River Basins. There are 16 standard land use classes as classified by the United
States Geological Survey (USGS) in the land use and land cover (LULC) map shown
in Figure 6.1a. They include open water, barren land, cultivated crops, deciduous
forest, developed area with high intensity, developed area with medium intensity,
developed area with low intensity, developed area with open space, emergent herbaceous wetlands, evergreen forest, hay/pasture, herbaceous land, mixed forest, perennial snow and ice, shrub/scrub, and woody wetlands. The urban and developed areas
are mainly distributed at north Tampa Bay and lower south Tampa Bay. Most of
the grassland (herbaceous land) is located at upstream the Hillsborough and Alafia
catchments.
Remote sensing methods can achieve indirect measurements for extracting largescale areal estimates of soil moisture. Yet, in situ measurements of soil moisture that
provide exact values limited as point observations are still needed as ground truth for
remote sensing image processing. The in situ soil moisture sampling was launched
in the Tampa Bay watershed on 29 December 2009 (Figure 6.1b). All ground-truth
Spatiotemporal Interactions among Ecohydrological Factors
principal means for earth observations. Infrared remote sensing imaging detects the
temperature difference between a target and the surrounding environment. The biggest advantage of infrared remote sensing is that the image can be obtained without
lighting or under cloud cover.
Microwave remote sensing, with a wavelength of 1–1000 mm, detects microwave
radiation, reflection, or scattering from a ground target and can be divided into active
and passive microwave remote sensing. Active microwave remote sensing consists of
imaging radar, microwave scatterometer, and microwave altimeter; passive microwave remote sensing refers mainly to various microwave radiometers that measure
weak microwave radiation emitted from various objects in nature to measure a target’s radiation properties and actual temperature. Passive microwave systems have
been widely used as a direct remote sensing method to explore the capability of
remotely measuring soil moisture (O’Neill et al. 1996; Njoku and Entekhabi 1996;
Burke et al. 2001) and groundwater recharge (Jackson 2002). Later, active microwave
systems were developed and combined with passive remote sensing for earth observations (Moran et al. 1997; Kustas et al. 1998; Glenn and Carr 2003). Remarkable
progress has been made in the use of spectral images from active or passive satellite
sensors for surface soil moisture mapping, where surface soil moisture is the average
moisture in the top few centimeters of soil layer (Grayson et al. 1997; Western and
Grayson 1998; Wilson et al. 2003, 2004; Makkeasorn et al. 2006).
The processing procedure of microwave remote sensing is time consuming and
labor intensive due to its fine resolution. More recent soil moisture studies tend to use
multispectral remote sensing for relatively large areas (Wang et al. 2007; Casper and
Vohland 2008; Merlin et al. 2010). The MODIS sensor is an advanced multipurpose
sensor and is a key instrument aboard the Terra (Earth Observing System [EOS]–
AM) and Aqua (Earth Observing System [EOS]–PM) satellites operated by the
National Aeronautics and Space Administration (NASA). Surface reflectance, LST/
emissivity, and vegetation indices of MODIS satellite data are available from NASA.
6.2.2.2 Urban Environment and Ground-Truth Data Collection
The Tampa Bay urban region mainly includes the Hillsborough, Manatee, and Alafia
River Basins. There are 16 standard land use classes as classified by the United
States Geological Survey (USGS) in the land use and land cover (LULC) map shown
in Figure 6.1a. They include open water, barren land, cultivated crops, deciduous
forest, developed area with high intensity, developed area with medium intensity,
developed area with low intensity, developed area with open space, emergent herbaceous wetlands, evergreen forest, hay/pasture, herbaceous land, mixed forest, perennial snow and ice, shrub/scrub, and woody wetlands. The urban and developed areas
are mainly distributed at north Tampa Bay and lower south Tampa Bay. Most of
the grassland (herbaceous land) is located at upstream the Hillsborough and Alafia
catchments.
Remote sensing methods can achieve indirect measurements for extracting largescale areal estimates of soil moisture. Yet, in situ measurements of soil moisture that
provide exact values limited as point observations are still needed as ground truth for
remote sensing image processing. The in situ soil moisture sampling was launched
in the Tampa Bay watershed on 29 December 2009 (Figure 6.1b). All ground-truth