Adding the dimension of time Geographic information system

the condition of earth s surface, atmosphere, , subsurface can examined feeding satellite data gis. gis technology gives researchers ability examine variations in earth processes on days, months, , years. example, changes in vegetation vigor through growing season can animated determine when drought extensive in particular region. resulting graphic represents rough measure of plant health. working 2 variables on time allow researchers detect regional differences in lag between decline in rainfall , effect on vegetation.

gis technology , availability of digital data on regional , global scales enable such analyses. satellite sensor output used generate vegetation graphic produced example advanced very-high-resolution radiometer (avhrr). sensor system detects amounts of energy reflected earth s surface across various bands of spectrum surface areas of 1 square kilometer. satellite sensor produces images of particular location on earth twice day. avhrr , more moderate-resolution imaging spectroradiometer (modis) 2 of many sensor systems used earth surface analysis.

in addition integration of time in environmental studies, gis being explored ability track , model progress of humans throughout daily routines. concrete example of progress in area recent release of time-specific population data u.s. census. in data set, populations of cities shown daytime , evening hours highlighting pattern of concentration , dispersion generated north american commuting patterns. manipulation , generation of data required produce data not have been possible without gis.

using models project data held gis forward in time have enabled planners test policy decisions using spatial decision support systems.