Search

The NOAA 2 environmental satellite and subsequent environmental satellites provide daily coverage of the earth in the visible (0.6–0.7 μm) and thermal (10.5–12.5 μm) spectral bands. The ground resolution of the very high resolution radiometer is 1 km at nadir. This improved resolution in the visible spectral band permits more detailed observations of snow features than were possible with the previous operational satellites. A visible band image from February 11, 1973, depicts the heavy snow cover in considerable detail in areas from Alabama to North Carolina. Digitized reflectance data from the study area have been compared with prestorm bare ground digitized reflectance data of February 6, 1973, to examine the relation of snow reflectivity to snow depths. A regression analysis of greatest brightness versus greatest snow depth for 201 data pairs produced a power correlation coefficient of 0.86. Reflectance values from snow deeper than 30 cm tended to be uniformly high; values from snow less than 30 cm tended to increase rapidly as snow depth increased.

The Antarctic mosaic project is a joint National Oceanic and Atmospheric Administration/United States Geological Survey (NOAA/USGS) project to produce a photomosaic map at 1:5 000 000 scale. The mosaic will be made as a collage of rectified images from the polar-orbiting NOAA-6 satellite. The near-infrared wavelength band of 0.725 to 1.10 μm, with a spatial resolution of 1.1 km, will be used. The NOAA-6 data are obtained from the McMurdo station receiving facility and from the archive of recorded data. Examples of imagery from both sources are presented. The operational plan including the processing flow chart, rectification process, progress to date, and problems to be faced are discussed. Applications of the mosaic are discussed as well as possible NOAA-6 applications to Antarctic investigators.

Winter season snow and ice charts of the Northern Hemisphere based on satellite data from 1966 through 1975 were examined to determine the extent and area of snow cover in Eurasia and North America Graphical analysis indicates no significant overall increase in North American winter snow cover for the 9-year period of data, whereas over the same period a large fluctuation occurred in Eurasia. Regression analysis yielded several equations with correlation coefficients significant enough to have possible applications for 30-, 60-, and 90-day forecasting of seasonal, hemispheric, and continental snow cover.

Since the winter of 1972–73, NOAA visible and thermal images of North America have been available for the study of ice on the Great Lakes. The shallowest of the Great Lakes is Lake Erie, on which ice occurs from December usually through April. The NOAA series of polar-orbiting satellites collect two thermal and one visible image per day; the Geostationary Observational Environmental Satellites (GOES) collect visible and infrared images every 30 min. NASA’s Landsat satellite has an 18 d revisit cycle (a 9 d cycle when two are operating), with superb ground resolution (79 m). Satellite images from all three satellites were used in this study. Ice formation, movement, and break-up in Lake Erie are different in each sub-basin, Western, Central, and Eastern, owing to the variation in depth of water, geomorphology, and meteorologic factors. Ice movement after initial break-up in 1974–77 resulted in the accumulation of ice at the entrance of the Niagara River at the eastern end of the lake. In 1973, satellite images show the unusual development of an ice dam across the entire width of Lake Erie and the “ice plug” at the mouth of the Niagara did not form. The effect of wind direction on break-up patterns is seen to be critical to any attempt at forecasting date of complete ice melt as well as day-to-day distribution of ice. Satellite observation of ice in Lake Erie—and in all large lakes—provides information regularly, routinely, and synoptically from a point in space. These data are useful for the study of ice formation, movement, and break-up, and they provide an unrivaled and unprecedented data set of historical records.

The thickness and extent of the sediment cover in the Patuxent Estuary has been determined using a high-frequency, high-spatial resolution, shallow penetration, continuous seismic profiling system. From these data, an isopachous map was prepared The isopachous map provides the subbottom information required to determine optimum locations for placing test equipment on the river bottom Mud filled depressions, acoustically transparent to 12-kHz sound pulses, occur mainly to the north of Half Pone Point, and east of the present channel Based on the identification of first subbottom reflectors, these depressions are as much as 16 feet thick The dominance of the thicker deposits east of the channel and evidence of a submerged terrace indicates that either the channel has migrated to the west, or that the channel of the Patuxent River at this location was larger in the past and has subsequently filled in much of the material in the eastern edge Maximum penetration at the scarp of the submerged terrace was 36 feet beneath the water-sediment interface This study demonstrates the use of seismic profiling techniques for collecting and presenting data required for coastal engineering applications.

During recent winters the news media frequently reported very large snowfalls in the midwestern and northeastern states coincident with greatly reduced snowfalls in the Rocky Mountain and western states. The dangers of large snowmelt floods and restricted transportation in the Midwest and Northeast and the water management problems arising from the extended drought in the West brought national attention to the economic importance of the seasonal snow cover. Although we cannot eliminate the immediate problems of heavy snowfalls in areas such as Buffalo, New York, or water shortages in California, as snow hydrologists we should reconsider our research objectives in view of these serious national problems. In this article we outline our ideas about the current status and needs in snow hydrology in order to provide some guidance for the multitude of national and local organizations that are affected by these problems.