A data system employed by the Department of Defense and the U.S. Air Force’s Air Weather Service was recently made public. While certain aspects of this data system remain classified, all meteorological and environmental data that are gathered from space and all specifications necessary to make full use of the imagery are now available. This system became widely known as the Data Acquisition and Processing Program (DAPP), but its name was changed to Defense Meteorological Satellite Program (DMSP), effective 13 December 1973. Images captured by the low-light sensor in this system are discussed in this article. These nighttime images in the visible and near-infrared not only have enhanced operational meteorological support but also provide a promising new research tool with civil as well as military potential.

The accompanying illustrations provide graphic examples of nighttime images taken near local midnight in different areas of the world. City lights, auroral displays, volcanoes, oil and gas fields, and forest fires are some of the phenomena detected by one of the radiometric sensors of the DAPP. This high-resolution 2.0 nautical-miles radiometer of the DAPP system “sees” in the spectral interval from .4 to 1.1 microns. Therefore, the information displayed in the images provides an added bonus in that important subvisual and supervisual events occurring below the satellite are detected in addition to that detected in the visual range (.5 to .7 microns). With this sun-synchronous satellite system, nighttime coverage of the same location can usually be achieved twice each night. These DAPP satellites record imagery at a map scale of 1:7,500,000 or 1:15,000,000 from a viewing platform 450 nautical miles high.

One such “bird’s-eye view” shows the lights of many North American cities and the aurora borealis or northern lights.(Figure 1) The mapping and study of this important space phenomenon have been a challenge since first observed from the ground. Now this mapping and research can be done routinely by a system already in-being. Such broad-scale depictions of the aurora are a first by DAPP. As mentioned earlier, the human eye only senses energy in the spectral interval from .5 to .7 microns while the low-light sensor of DAPP records energy emissions out to 1.1 microns. Since important emission lines of the aurora extend out to 1.08 microns, the broader spectral interval captured by DAPP results in the very bright scene displayed on the imagery. That is, the sensor has processed the emissions from a wider viewing band and presented it to our eyes as a very intense auroral display.

Knowledge of the aurora is important for many reasons. By analysis of aircraft and ground laboratory data and their correlation with the DAPP imagery, it was found that the location of the auroral-produced D, E, and F ionization layers, could be determined and the occurrence of polar magnetic substorms observed.¹ This technique will permit real-time observations of the extremely complex and variable polar ionosphere. These imagery observations, in turn, promise to provide data crucial to the operation of over-the-horizon detection systems and high-frequency radios. In addition, this DAPP correlation provides information on refraction and range errors to SPACE TRACK radars, as well as information on local density variations that relate to drag on orbiting satellites. These near real-time observations are already operationally available to the large computer complex at the Air Force Global Weather Central at Offutt Air Force Base, Nebraska. The world energy crisis suggests yet another use for DAPP data.

Further examination of Figure 1 shows the brightness (i.e., intensity) of the illumination from all major and minor cities in North America. The large cities forming the megalopolis of the northeast, Chicago along the shore of Lake Michigan, and the far western population centers of Los Angeles and San Francisco are all shown under no-moonlight conditions. Miami and the “Gold Coast” of southern Florida are equally bright. During our present energy crisis, the DAPP nighttime low-light sensor could monitor city light intensities. According to 1970 General Electric surveys, direct energy consumption from lighting accounts for about 20 percent of the country’s electric power consumption or between 4 and 5 percent of the total energy consumption.² In some of the larger cities, consumption is even higher. New York City’s Consolidated Edison reports 40 percent of its power goes for lighting. In addition to providing information on energy consumption, these “lights” aid the tactical meteorologist in his efforts to accurately place “weather” phenomena such as clouds.

Geographical location and gridding of real-time meteorological satellite systems of the Department of Defense, the National Oceanic and Atmospheric Administration, and the National Aeronautics and Space Administration comprise a difficult task. The importance of putting latitude and longitude lines on satellite imagery cannot be stressed enough, yet difficulties do exist in computer mapping. At this stage of development, without sufficient human quality control, great errors in computer gridding can occur. If a photo is not gridded properly, the location of all information derived from it is unreliable. Figure 1 presents no problems in geographical interpretation to a human observer. However, another tactic for solving the difficult gridding problem presents itself here with the storage in a computer of this city light location and intensity much like a stellar background used for space navigation. In this manner, the simultaneous, three-dimensional, infrared imagery could be accurately gridded. Also, spurious lighting could be studied for other physical events such as forest fires.

Figure 1. A nightime montage of North America depicts city lights and the aurora borealis, from a DAPP high-resolution sensor on two revolutions of a synchronous satellite.

Figure 1. A nightime montage of North America depicts city lights and the aurora borealis, from a DAPP high-resolution sensor on two revolutions of a synchronous satellite. Besides enabling new research on the aurora and its effects, information can be gleaned from such imagery for use in geographical gridding, forest fire detection, light pollution, energy evaluation, electrical storm detection, volcanic location, oil field intelligence, and many other areas of investigation.

The United States and Canada spend untold numbers of dollars for forest fire detection in remote areas of North America. The low-moonlight DAPP sensor, as well as other sensors of the DAPP system such as the .3NM-resolution infrared 8-13 micron radiometer, could be of great assistance in locating forest fires. The normal DAPP configuration, in which two operational satellites produce imagery over a particular area every six hours, is certainly capable of performing such a task. A computer-stored city illumination map, as mentioned earlier, could aid in the location of new forest fires by sounding an alarm when a “light” cannot be identified. It must be noted, however, that not all spurious light sources are forest fires.

An unusual amount of light is seen emanating from Cuba in Figure 1. City lights? These numerous bright spots are probably sugarcane fields being burned. This agricultural event is similar to the rice paddy burnings in Southeast Asia. These events can be of extreme importance militarily. Coupled with other meteorological parameters, reduction to visibility from smoke and haze could be easily predicted. In addition, targeting “visibility” is enhanced by these burning lights. The oil fields of Ploesti during the Second World War would have easily been seen on DAPP nighttime visual imagery.

Figures 2 and 3 are also nighttime imagery, with and without moonlight, over southern Europe and North Africa. Well-lighted oil fields can be readily detected in the North African desert. Halos appear around some of the light sources, along with short black lines parallel to the radiometer scan lines. The black lines appear to originate at the brightest sources of light. This sensor or atmospheric phenomenon will be discussed in the next section on volcanoes.

Figure 4 imagery was taken over the Hawaiian Islands in the central Pacific before a new-moon phase. The bright “light” with the haloed rings around it is the erupting volcano of Kilauea. This ringed pattern could be a halo formed by ice crystal clouds, volcanic smoke particles, or even an out-of-focus mirror in the radiometric sensor. The geometry of this halo is similar to the rings occasionally seen around the sun or moon caused by ice-crystal cirrus clouds. These ringed patterns are also seen around oil and gas fields, except over the United States and other industrial nations where the oil and gas fields are capped. Volcanic eruptions, both explosive and effusive, can easily be seen in remote areas with this nighttime visual and near infrared sensor. On the island of Oahu, Honolulu and Waikiki Beach stand out as the large elongated bright spot on the photo. A careful check of current events is important for the DAPP analyst, lest bright apparitions like nuclear explosions escape his examination of the images.

Any other bright spot on the nighttime images not accounted for could be nuclear tests, missile launches, nose cone re-entry, electrical storms, etc. Lightning activity in intense storm areas is clearly captured on these brief views of the earth by the DAPP sensors. (Figure 5)

The aurora, city light intensity, nighttime gridding, forest fires, lightning, volcanoes, and oil and gas fields are only a few of the many spectacular intelligence yields available from the low-light visible sensor of the Defense Meteorological Satellite Program. Other sensor applications, particularly in the field of meteorology, will no doubt be presented in many scientific journals and symposiums in the near future. Perhaps the knowledge of this unique system and some of the applications presented here will stimulate the reader to think of other uses for the DMSP.

1. Air Force Cambridge Research Laboratories Newsletter no. 444, 6 April 1973.

Major Henry W. Brandli (M.S., Massachusetts Institute of Technology) is a staff meteorologist at the Air Force Eastern Test Range, Florida. He has been assigned to special projects and aerospace science positions in Southeast Asia, Hawaii, Illinois, and the Washington area. His primary concern is with operational satellite meteorology, currently with such test projects as space shuttle and Trident programs. Major Brandli has published technical articles in domestic and foreign meteorological journals.

The conclusions and opinions expressed in this document are those of the author cultivated in the freedom of expression, academic environment of Air University. They do not reflect the official position of the U.S. Government, Department of Defense, the United States Air Force or the Air University.

U.S. Air Force/Air Weather Service Nighttime Spectacular

U.S. Air Force/Air Weather Service
Nighttime Spectacular