Remote sensing & vector-borne diseases
Sensors used in Vector-borne diseases
RADARSAT-2
RADARSAT-2 is an Earth observation satellite that was launched December 14, 2007 for the Canadian Space Agency byStarsem from Kazakhstan's Baikonur Cosmodrome. It has the same orbit as RADARSAT-1 (798 km altitude sun-synchronous orbit with 6 p.m. ascending node and 6 a.m. descending node). Some of the orbit characteristics are 24 days repeat cycle (=343 orbits), 14.29 orbits per day, each orbit being 100.75 minutes duration.
RADARSAT-2 is very useful in Vector-borne disease study. Because many of such infectious diseases are prevalent in tropical areas with significant cloud cover making it difficult for commonly used optical sensors to obtain useful cloud-free satellite data. Radar offers capability to penetrate clouds and haze and to capture image of both day and night thereby making it all-weather capability for surveillance in tropical areas. RADARSAT-2 offers higher spatial and temporal resolution data and fully polarimetric C-band imagery making it capable of monitoring and assessing vector-borne disease
LandSat
Landsat is the longest running enterprise for acquisition of moderate-resolution satellite imagery of Earth. First launched on July 23, 1972, it provides a unique resource for those who work in agriculture, geology, forestry, regional planning, education, mapping, and global change research and more importantly to emergency response and disaster relief. The most recent Landsat is Landsat 8 which was launched on February 11, 2013. Landsat 7 data has eight spectral bands with spatial resolutions ranging from 15 to 60 meters; the temporal resolution is 16 days.
Landsat measures reflected light in both
visible wavelengths and infrared wavelengths which helps scientists see how healthy vegetation is as healthy plants generally absorb red light and reflect infrared light. Identifying the health of plants with Landsat’s 30-meter resolution imagery informs decision makers about habitat conditions for disease-carrying vectors such as mosquito habitats in malaria-stricken areas. Sometimes Scientists combine 30-meter Landsat data with daily satellite data of weather and vegetation to identify conditions conducive to disease outbreaks before an actual outbreak occurs. Landsat also helps to monitor habitat of these vector borne diseases: Rift Valley Fever, Lyme
disease, and dengue fever.
MODIS
MODIS provides time series of various environmental parameters and is a most important payload on the Terra and Aqua NASA satellites. Due to the solar-synchronous time pattern, MODIS data are available four times a day. MODIS is a whisk-broom sensor with 36 channels ranging from visible to thermal-infrared. Data are delivered at 250-meter (Red, Near Infrared: bands 1-2), 500-meter (Mid Infrared: bands 3-7) and 1,000-meter resolution (Thermal Infrared: bands 8-36). NASA produces a series of operational products including Land Surface Temperature and Emissivity products, vegetation indices, snow and ice cover, and surface reflectance which can be used to derive additional environmental parameters such as water indices and drought indicators.
MODIS data are increasingly used in vector-borne disease modeling. At present, the MODIS sensor provides an optimal match of temporal and spatial resolution and have been widely used in vector-borne disease analysis such as Tick-borne disease vectors, Rodent-borne disease vectors, Mosquito-borne disease vectors