16 August :A small investment in cloud and climate research begun in 1983 has paid big dividends for NASA scientists and their colleagues around the world.
At a time when an international satellite collaboration of this sort had never existed, the cautious step made by NASA management to fund the core of the International Satellite Cloud Climatology Project (ISCCP) was a risk. But the project that was planned to last for five to seven years of data collecting operations is celebrating its 25th anniversary this summer, proving the investment risk was worth the research payoff.
ISCCP was developed as the first project of the World Climate Research Program to study the role that clouds play in the climate, a topic identified as one of the two leading obstacles to progress in understanding the climate.
"We envisioned a data collecting project to create a data set of global cloud physical properties," said Bill Rossow, head of the ISCCP Global Processing Center and former senior research scientist at NASA’s Goddard Institute for Space Studies, now a Distinguished Professor of Remote Sensing at The City College of New York.
Rossow and ISCCP Project Manager Robert Schiffer and a group of their colleagues saw a need for quantitative data describing the physical properties of clouds around the globe. These properties, such as height, density and reflectance, were not available from meteorological observations. This group formed an international collaboration to use the infrared and visible radiance data obtained from the imagers on polar and geostationary meteorological satellites to produce the required data sets of global cloud cover and cloud radiative properties.
ISCCP Total cloud amount 1983 to 1990. This data image, compiled using data from ISCCP shows the total fractional cloud cover annual averaged from 1983-1990. Image credit: NASA The project began with two goals related to climate: first to understand how clouds affect Earth’s radiation budget and second to understand how clouds affect the global water cycle.
One of the biggest dividends to come from ISCCP investment is a breakthrough in the ability to calculate surface and top-of-atmosphere radiative fluxes almost as well as if they were measured directly. ISCCP data results quantitatively determine the effect of clouds on the radiation budget, making it such that clouds are no longer the leading uncertainty in climate change research.
A further reward from ISCCP is one that was unintended. As time passed and the project grew, the team learned to incorporate advances in cloud analysis to reprocess the data so that they can be used for other research purposes.
"As the record kept getting longer and longer, we started thinking about making a climate data record, which was not the original goal" said Rossow. "ISCCP is the only data set with enough time resolution to answer important questions about the dynamics of cloud processes in our climate."
The National Academies of Science state that time resolution, or highly accurate long-term measurements of key variables are required to uncover slowly evolving dynamics or long-term climate changes. While Rossow admits that there are some limitations in the ISCCP climate record analysis that the team is now working to reduce or fix, he asserts that the added benefit of a cloud climate data record truly shows that the initial investment was worthwhile.
NASA scientists are studying the role that clouds play in the climate. NASA scientists are studying the role that clouds play in the climate. This photo of clouds was taken at Inks Lake in Burnet, Texas. Image credit: Janni Boehme. "ISCCP is well beyond just a dataset," said Don Anderson, NASA Headquarters program manager. "A whole structure has been developed, which not only ingests and cross calibrates [geosynchronous] satellite clouds data, but also develops tools for Web access to information that streamlines the ability of the climate research community to utilize these data to evaluate climate models and improve the characterization of clouds in Earth System Models."
ISCCP is truly an international project and is used in the science community around the world.
"Right now, ISCCP is being very widely used," said Rossow. "The total number of citations as of the end of 2006 was 1300 papers. That number is still growing exponentially and I would estimate that it’s over 1500 papers now."
Key partners in the project include the National Oceanic and Atmospheric Administration (NOAA), the European Space Agency and the EUMETSAT, the Meterological Services of Canada, Colorado State University, the Japan Meteorological Agency, University of Wisconsin, NASA Langley’s Atmospheric Science Data Center, Centre de Meteorologie Spatiale, the China Meteorological Administration and the Brazilian Space Agency.
ISCCP is currently funded to continue data collection and processing until the end of 2012. NASA and NOAA have now provided funding to work towards improving the ISCCP climate record to continue beyond 2012.