Byron L. Wood

Estimating high mosquito-producing rice fields using spectral and spatial data

Abstract The cultivation of irrigated rice provides ideal larval habitat for a number of anopheline vcclors of malaria throughout the world. Anopheles freeborni, a potential vector of human malaria, is associated with the nearly 240 000 hectares of irrigalcd rice grown annually in Northern and Central California; therefore, this species can serve as a model for the study of rice field anopheline population dynamics. Analysis of field dala revealed that rice fields with early season canopy development, that are located near bloodmcal sources (i.e., pastures with livestock) were more likely to produce anopheline larvae than fields with less developed canopies located further from pastures. Remote sensing reflectance measurements of early-season canopy development and geographic information system (GIS) measurements of distances between rice fields and pastures with livestock were combined to distinguish between high and low mosquito-producing rice fields. Using spectral and distance measures in cither a dis...

Distinguishing high and low anopheline-producing rice fields using remote sensing and GIS technologies

Abstract Worldwide, 140 million ha are devoted to rice cultivation, mostly in developing countries of the tropics and subtropics where malaria still constitutes a serious human health problem. Because rice fields are flood-irrigated on a semi-permanent basis during each growing season, they provide an ideal breeding habitat for a number of potential mosquito vectors of malaria. One of these vectors, Anopheles freeborni , is distributed throughout nearly 240 000 ha of irrigated rice in northern and central California, and may serve as a model for the study of rice field mosquito population dynamics using spectral and spatial information. Analysis of field data revealed that rice fields with rapid early season vegetation canopy development, located near livestock pastures (i.e. bloodmeal sources), had greater mosquito larval populations than fields with more slowly developing vegetation canopies located further from pastures. Remote sensing reflectance measurements of early season rice canopy development and geographic information system (GIS) measurements of distance to livestock pasture were combined to distinguish between high and low mosquito-producing rice fields. These distinctions were made with 90% accuracy nearly 2 months before anopheline larval populations peaked.

Spectral and spatial characterization of rice field mosquito habitat

Abstract Irrigated rice provides an ideal breeding habitat for Anopheles freeborni, the western malaria mosquito, throughout California. In a 1985 study, it was determined that early-season rice canopy development, as monitored using remotely sensed data, could be used to distinguish between high and low mosquito producing rice fields. This distinction could be made over two months prior to peak mosquito production. It was also found that high-producing fields were located in an area characterized by a diversity of land use, including livestock pastures, whereas the low-producing fields were in an area devoted almost exclusively to the cultivation of rice. The ability to distinguish between high and low mosquito producing fields prior to peak mosquito production is important in terms of mosquito habitat surveillance and control.

Use of spacecraft data to derive regions on Mars where liquid water would be stable.

Combining Viking pressure and temperature data with Mars Orbital Laser Altimeter topography data, we have computed the fraction of the martian year during which pressure and temperature allow for liquid water to be stable on the martian surface. We find that liquid water would be stable within the Hellas and Argyre basin and over the northern lowlands equatorward of about 40°. The location with the maximum period of stable conditions for liquid water is in the southeastern portion of Utopia Planitia, where 34% of the year liquid water would be stable if it were present. Locations of stability appear to correlate with the distribution of valley networks.

Education, outreach and the future of remote sensing in human health

The human health community has been slow to adopt remote sensing technology for research, surveillance, or control activities. This chapter presents a brief history of the National Aeronautics and Space Administrations experiences in the use of remotely sensed data for health applications, and explores some of the obstacles, both real and perceived, that have slowed the transfer of this technology to the health community. These obstacles include the lack of awareness, which must be overcome through outreach and proper training in remote sensing, and inadequate spatial, spectral and temporal data resolutions, which are being addressed as new sensor systems are launched and currently overlooked (and underutilized) sensors are newly discovered by the health community. A basic training outline is presented, along with general considerations for selecting training candidates. The chapter concludes with a brief discussion of some current and future sensors that show promise for health applications.

Overview of field studies for the application of remote sensing to the study of malaria transmission in Tapachula, Mexico

Abstract A National Aeronautics and Space Administration (NASA) sponsored project to use remote sensing technology in a predictive model of vector population dynamics and malaria transmission potential for the coastal plain of Chiapas, Mexico, is described. Included are the results of recent studies to characterize vector habitats and an assessment of the kinds of information that will be required for developing the predictive model within a geographic information system.

A remote sensing and geographic information system approach to sampling malaria vector habitats in Chiapas, Mexico

This paper describes a procedure whereby remote sensing and geographic information system (GIS) technologies are used in a sample design to study the habitat of Anopheles albimanus, one of the principle vectors of malaria in Central America. This procedure incorporates Landsat‐derived land cover maps with digital elevation and road network data to identify a random selection of larval habitats accessible for field sampling. At the conclusion of the sampling season, the larval counts will be used to determine habitat productivity, and then integrated with information on human settlement to assess where people are at high risk of malaria. This aproach would be appropriate in areas where land cover information is lacking and problems of access constrain field sampling. The use of a GIS also permits other data (such as insecticide spraying data) to the incorporated in the sample design as they arise. This approach would also be pertinent for other tropical vector‐borne diseases, particularly where human activ...

Medsat: A satellite system for surveillance of tropical vector‐borne diseases

In this paper, the authors describe the need for, and preliminary student design of, a research satellite system (Medsat) devoted to the surveillance of environmental and epidemiological factors that influence the patterns and dynamics of tropical vector‐borne diseases.

MEDSAT: a small satellite for malaria early warning and control

This paper presents the design for a low cost, light satellite used to aid in the control of vector-borne diseases like malaria. The 340 kg satellite contains both a synthetic aperture radar and a visual/infrared multispectral scanner for remotely sensing the region of interest. Most of the design incorporates well established technology, but innovative features indude the Pegasus launch vehicle, low mass and volume SAR and VISfR sensors, integrated design, low power SAR operation, microprocessor power system control, and advanced data compression and storage. This paper describes the main design considerations of the project which include the remote sensing task, implementation for malaria control, launch yehide, orbit, satellite bus, and satellite subsystems.

Simultaneous Image Data Acquired By A Multispectral Scanner And A Polarimetric, Multifrequency Synthetic Aperture Radar Over A Wetland Site In Colusa County, California: A Comparative Analysis

In studies of cultural wetlands (e.g., rice) or natural wetlands (e.g., marshes), scientists may be interested in using remotely-sensed data to map certain wetland features. In our studies, we considered visible and infrared scanners (VIRS) and synthetic aperture radar (SAR). In support of our investigation, NASA acquired, from aircraft platforms ,VIRS data [in the Thematic Mapper (TM) bands] and full-polarimetric, multifrequency SAR data over a wetland area in Colusa County, California, on the same day and at nearly the same time. The SAR measured the backscattering properties of the surface at three frequencies, C-band (6-cm wavelength), L-band (24 cm), and P-band (68 cm), and included full polarization properties (backscatteringmagnitudes and phase-angle differences). The two data sets were acquired at mid-day on May 27, 1988, over rice fields and natural wetlands (e.g., bullrushes) managed for duck hunting and other wildlife. The date was early in the rice growing season after fields had been flooded and rice had emerged in some fields. These data presented a unique opportunity for us to compare broad-band VIRS data to full polarimetric, multifrequency SAR data.