11 Snow and Ice
243
for snow mapping on small basins. As the nighttime pass of NOAA-A VHRR cannot
be used for snow mapping in the visible spectrum, only one-half of the overflights can
be used. However, several NOAA satellites may pass overhead at different times on
a given day in specific locations.
Despite the various problems mentioned, visible aircraft and satellite imagery have
been found to be very useful for monitoring both the buildup of snow cover in a
drainage basin and, even more importantly, the disappearance of the snow covered
area in the spring. This disappearance or depletion of the snow cover is important to
monitor for snowmelt runoff forecasting purposes. It has been recommended (Rango,
1985) that the optimum frequency of observation of the snow cover during depletion
would be once a week. Depending on the remote sensing data used, it could be very
difficult to obtain this frequency. Certain snowmelt-runoff applications have been
possible with as few as two to three observations during the entire snowmelt season
(Rango, 1985).
In cryospheric applications other than snow cover, Landsat images have proved to
be very useful for collecting certain basic data from glaciers including long-term
surface velocities determined by comparison of displacement on different image dates
and short-term high flow rates of surging glaciers. Perhaps the easiest remote observation to make, if the data are available, is the location of the snow line on a glacier
at the end of the melt season which can be related to the annual net mass balance
(Braslau & Bussom, 1979).
Formation and dissipation of river ice on the Ottawa River was monitored daily
using visible imagery from NOAA satellites. The break-up of 14 ice-covered reaches
was observed during the melt period (McGinnis & Schneider, 1978). Both Landsat
and NOAA satellite data were used to study the ice break-up on the Mackenzie River
in the Canadian Arctic (Dey et aI., 1977). These satellite observations are adequate
to detect patterns of river ice break-up in these remote regions at much less the cost
of conventionally collecting the necessary hydrological data in the Arctic environment.
Lake ice studies using visible and infrared remote sensing data have primarily been
made for increasing the length of the navigation season on major lakes. Borodulin and
Prokacheva (1985) combined aircraft and satellite observations of ice to provide a 35year data set. They were able to develop regression relations between remote sensing
ice-covered area on 15 April and the ice cover thickness and the duration of the ice
melting period.
Advantages. There are several advantages to using visible satellite data for snow and
ice applications. First, the data are relatively easy to interpret, and it is also relatively
easy to distinguish snow from snow-free areas (as well as ice from ice-free areas). If
necessary, the analysis of visible satellite data for snow mapping can be accomplished
on microcomputer-based systems (Baumgartner and Rango, 1995). The visible
satellite data is available in a range of resolutions from 20 m resolution (SPOT) to 8
km resolution (NOAA satellites) which allows applications on small basins up to
applications on continental size areas. Because these data have progressed to an
243
for snow mapping on small basins. As the nighttime pass of NOAA-A VHRR cannot
be used for snow mapping in the visible spectrum, only one-half of the overflights can
be used. However, several NOAA satellites may pass overhead at different times on
a given day in specific locations.
Despite the various problems mentioned, visible aircraft and satellite imagery have
been found to be very useful for monitoring both the buildup of snow cover in a
drainage basin and, even more importantly, the disappearance of the snow covered
area in the spring. This disappearance or depletion of the snow cover is important to
monitor for snowmelt runoff forecasting purposes. It has been recommended (Rango,
1985) that the optimum frequency of observation of the snow cover during depletion
would be once a week. Depending on the remote sensing data used, it could be very
difficult to obtain this frequency. Certain snowmelt-runoff applications have been
possible with as few as two to three observations during the entire snowmelt season
(Rango, 1985).
In cryospheric applications other than snow cover, Landsat images have proved to
be very useful for collecting certain basic data from glaciers including long-term
surface velocities determined by comparison of displacement on different image dates
and short-term high flow rates of surging glaciers. Perhaps the easiest remote observation to make, if the data are available, is the location of the snow line on a glacier
at the end of the melt season which can be related to the annual net mass balance
(Braslau & Bussom, 1979).
Formation and dissipation of river ice on the Ottawa River was monitored daily
using visible imagery from NOAA satellites. The break-up of 14 ice-covered reaches
was observed during the melt period (McGinnis & Schneider, 1978). Both Landsat
and NOAA satellite data were used to study the ice break-up on the Mackenzie River
in the Canadian Arctic (Dey et aI., 1977). These satellite observations are adequate
to detect patterns of river ice break-up in these remote regions at much less the cost
of conventionally collecting the necessary hydrological data in the Arctic environment.
Lake ice studies using visible and infrared remote sensing data have primarily been
made for increasing the length of the navigation season on major lakes. Borodulin and
Prokacheva (1985) combined aircraft and satellite observations of ice to provide a 35year data set. They were able to develop regression relations between remote sensing
ice-covered area on 15 April and the ice cover thickness and the duration of the ice
melting period.
Advantages. There are several advantages to using visible satellite data for snow and
ice applications. First, the data are relatively easy to interpret, and it is also relatively
easy to distinguish snow from snow-free areas (as well as ice from ice-free areas). If
necessary, the analysis of visible satellite data for snow mapping can be accomplished
on microcomputer-based systems (Baumgartner and Rango, 1995). The visible
satellite data is available in a range of resolutions from 20 m resolution (SPOT) to 8
km resolution (NOAA satellites) which allows applications on small basins up to
applications on continental size areas. Because these data have progressed to an