The atlas displays the planned route as a yellow line on the laptop screen; the car's location (calculated by satellite readings) is depicted as a bright green dot.

One way to assure even greater accuracy, Mr. Washburn said, was for someone to invent a lightweight radio receiver so climbers could get satellite readings at the top of the peaks.

Every year or so, the positions of the survey points will be recalculated through new satellite readings.

The New York show will display the latest in Global Postioning Systems, electronic hand-held units that use satellite readings for navigation.

In an announcement by NASA and the atmospheric administration, the satellite readings at the end of September and in early October showed values of less than 100 Dobson units.

Since 1998 and continuing through 2007, the Omega Foundation has placed a GPS receiver on the summit for a suitable period of time to obtain accurate satellite readings.

Other scientists on shore have studied satellite readings to track the movements of elephant seals tagged with tiny radio transmitters.

These units have the capability to average a series of individual satellite readings, making them more accurate than single reading machines.

The data mesh with recent satellite readings showing that the ice can lurch toward the sea during the melting season.

"Last year going into the winter," he said, "we had the second most extensive snow cover over the Northern Hemisphere" since the satellite readings began.