The NOAA/NASA Polar Pathfinder Program
The NOAA/NASA Pathfinder Program is designed to facilitate user access to earth science data sets which address global change concerns. The Polar Pathfinders, a subgroup of the Pathfinder Program, addresses the comparison of parameters from different data sets with a common projection, file naming conventions, and validation conventions. This ensures that consistently processed data sets are available to the cryospheric science community, for comparing and contrasting.
A History of the Polar Pathfinder Program
The Cryosphere and Global Change
Throughout the past decade, weakened by melting, ice shelves surrounding the Antarctic Peninsula have been in retreat, yielding massive icebergs to the waves and in some cases, disintegrating entirely. The crumbling ice shelves likely reflect increasing temperatures, and perhaps signal global changes ahead.
The ice shelves' behavior is one demonstration of how exquisitely tuned icy regions are to climate. But not only do they reflect varying climate conditions, Earth's ice and snow cover shape daily weather patterns and human activities around the world. Consider: the polar ice sheets act on the solar energy received, inducing moisture fluxes that lead to cloud formation, precipitation, and ultimately, that feed back into global atmospheric and oceanic circulation patterns. The extent and volume of the planet's solid waters change radically season-to-season, and over hundreds of thousands of years, effecting dramatic changes in the planet's albedo, weather, water resources, and global sea level.
Because of the cryosphere's sensitivity, scientists turn to the world's ice sheets, glaciers, snow cover, sea- lake- and river ice, ice caps and frozen ground, to learn more about past climate events, to understand current weather, and to project, on regional and global levels, what the future holds. However, true understanding depends on adequate representation of cryospheric processes and cryosphere-climate interactions in climate and hydrological models, and on our ability to monitor and understand variability exhibited by major ice sheets and hemispheric patterns of snow and sea ice extent. The difficulties inherent in comparing parameters from different data sets hamper even basic studies. To mitigate such obstacles, NASA and NOAA initiated the Pathfinder Program.
The NOAA/NASA Pathfinder Program
Scientists can often experience difficulties when working with large data sets. When using extended time series, researchers face a variety of formats and media, inconsistency in data processing methods, and possible inattention to long time-series data calibration.
In October 1990, NASA and NOAA, through the Earth Observing System (EOS) Program Office, initiated the Pathfinder Program to address these issues and to make existing satellite data sets available to the global change research community. Data sets were selected on the basis of whether or not they provided both a long time-series, and possessed stable calibration capability.
The Pathfinder Program also aimed at developing a protocol for processing and handling large data sets. Accordingly, science working groups for each Pathfinder were formed to define and guide production of appropriate data products. A 20-month benchmark period, from April 1987 to November 1988, was designated to assess program feasibility, and wherever possible, Pathfinder data processing began with this period. Processing has continued to the present on data streams from many of the sensors.
The Polar Pathfinder Program Sensors
The Polar Pathfinder Program involves four primary satellite sensors and their respective products: The Advanced Very High Resolution Radiometer (AVHRR), the Scanning Multichannel Microwave Radiometer (SMMR), the Special Sensor Microwave/Imager (SSM/I), and TIROS Operational Vertical Sounder (TOVS).