involving more than a dozen U.S. universities and international collaborations with scientists from Australia, Canada, Denmark, France, Greenland, and the United Kingdom. All data are freely available within 6 months of acquisition through the National Snow and Ice Data Center.

Among the advantages of suborbital efforts like IceBridge are that varied and multiple instruments can be used onboard airborne laboratories, innovative instruments can be tested, and flight patterns can be optimized for specific tasks. However, suborbital platforms can provide observations only at regional scales. In this respect, IceBridge is an ideal example, as it was able to focus on especially sensitive portions of ice sheets and glaciers as its domain. Even in this context, however, it must leave unobserved large portions of the major ice sheets and sea ice, which ICESat-2 will regularly monitor over several years.

1The IceBridge instrument suite currently consists of three lidar systems (Airborne Topographic Mapper, Laser Vegetation Imaging Sensor, and Sigma Space Photon Counting Lidar Prototype), four radar systems (Multi-channel Coherent Depth Sounder, Snow depth radar, Ku-band radar altimeter, and accumulation radar), gravimeter, and high-resolution aerial photography. Platforms include NASA’s airborne laboratories on the DC-8, P-3B, King Air B-200, the Basler BT-67, a Single Engine Otter, and UAVs, including NASA’s Global Hawk and Ikhana (planned).

 

accuracy of this allocation for 2011, stating that funding for mission-enabling activities is just under half of ESD’s total budget.45

Although there are specific NASA budget items titled “research and analysis,” the committee was made aware by NASA officials that the level of integration of R&A activities throughout ESD, and the broad definition used for R&A, make it difficult to quantify the total investment in R&A with a specific number. Nevertheless, the committee concluded that the level of R&A and the manner in which R&A is conducted in ESD are commensurate with the recommendation and intent of the 2007 decadal survey. However, with cost growth in missions and with a lower overall budget, there will be continued pressure to reallocate R&A funds to meet mission needs.

The survey noted that assimilation of satellite data into numerical models, and model-based Observing System Simulation Experiments (OSSEs), are other facets of data integration warranting continued investment by NASA. It also recommended that NASA, NOAA, and the USGS should increase their support for Earth system modeling, including provision of high-performance computing facilities and support for scientists working in the areas of modeling and data assimilation.46 Although significant progress has been made in the area of data assimilation for weather forecasts, much work remains to verify integrated Earth systems models. In particular, Earth observations have to be assimilated into such models to create a consistent and integrated picture of the Earth system, and these observations have to be integrated into a predictive modeling system that can make reliable forecasts far into the future.47

45M. Freilich, Director, Earth Science Division, NASA, presentation to the Committee on the Assessment of NASA’s Earth Science Program, April 27, 2011.

46National Research Council, Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, 2007, p. 15.

47The 2007 decadal survey also discusses the need for data to be acquired and archived in a way that supports future reprocessing, noting its particular importance for the development of climate data records. As stated by the decadal survey’s Panel on Climate Variability and Change: “Reprocessing of data allows the incorporation of gains in knowledge, the correction of errors in preflight and in-flight calibrations, inclusion of changes in instrument function, and the correction of errors in earlier processing algorithms” (National Research Council, Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, 2007, p. 264). For a more detailed discussion of reprocessing and its role in a climate observing system, see K. Trenberth, “The important



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