For the first time, it will be possible to determine the daily cycles in total ozone, aerosols, and column water vapor at high temporal and spatial resolution. Ten global spectral images of the sunlit side of the Earth will be acquired within 2 minutes with a spatial resolution of roughly 8 km at nadir.
Ozone anomalies arising from a variety of sources can be tracked with much improved accuracy and related to their meteorological environment. This new knowledge should greatly enhance our basic understanding of ozone processing in the atmosphere and permit more accurate modeling and prediction of ozone variations. The ozone data, in combination with data-assimilation modeling, will also be used to study wave motions, including gravity waves, in the stratosphere much better than previously possible. Other dynamical processes such as the polar vortex structure, near-tropopause circulations, and jet stream winds can be observed. Arctic ozone depletion events can also be detected to assess their ecological threats through enhanced UV radiation. The Triana ozone, cloud, and aerosol data can be used to compute surface UV irradiance each hour so that exposures and health risks can be more accurately determined.
Aerosols will be monitored hourly during the day using combinations of UV and visible wavelengths. The new combination of wavelengths allows determination of optical depth, single scattering albedo, and particle size. Previous use of visible wavelengths for aerosols has been limited to water or forest backgrounds. This new information, provided at high spatial and temporal resolution, will be extremely useful for understanding and modeling the processes that disperse and deplete aerosols, allowing for better assessment and prediction of their chemical, cloud, and radiative impacts. Detection of aerosols in the Arctic Basin, where anthropogenic haze (Arctic Haze) is a significant factor, permits a more accurate determination of the aerosol impact in this extremely sensitive part of the world. The ability to detect aerosols each hour at high spatial resolution will be exploited to provide timely warnings of volcanic ash events and visibility anomalies (smoke and dust plumes) to the air transportation industry (through the FAA), the US Park Service, and the EPA.
EPIC data will also be used to develop valuable new information about cloud, water vapor, and surface properties. Since LEO/GEO satellites are being used to develop comprehensive climatologies of cloud properties at high spatial and temporal resolution, the unique viewing geometry of EPIC can be exploited in conjunction with these other satellites to determine cloud phase and particle shape. Cloud particle habit (shape) is an assumed parameter in current retrieval methods and in mesoscale models and GCMs. Retrieval of this parameter on a global basis will reduce the uncertainties in cloud and radiation modeling as well as in the retrievals of cloud particle size and ice water path. The atmospheric column water vapor will also be derived from reflected measurements over all surfaces on an hourly basis that will complement similar estimates from infrared retrievals of upper tropospheric water vapor column. The near retro-reflection geometry of the EPIC view can also be used to determine anisotropic reflectance properties of various types of vegetation and to improve characterization of canopy structure and plant condition. Diurnal variations of surface spectral albedo will also be derived to provide more accurate models for radiation calculations in GCMs and other atmospheric models.
Triana is a valuable platform for half of a multi-angle remote sensing program because its EPIC images can be collocated with those from any other satellite with close temporal and spatial tolerances. Although only one multi-angle application has been noted, it is expected that the ease of matching EPIC and other satellite data will be an extremely valuable resource for remote sensing and, ultimately, climate modeling, especially in the area of validation. Conversely, other satellite and ground-based measurements taken at sparse temporal or spatial resolution will serve to verify Triana's hourly retrievals.
Triana's use of the "far side" of the Moon as a calibration reference can also help to assess the calibration of other satellite sensors through matching of co-angled collocated pixels. It is expected that the data will be used to characterize the spectral response of the lunar surface.
The global, high-resolution monitoring of the Earth with EPIC's unique spectral complement will also be valuable for scientific field missions. Phenomena such as aerosol plumes that were only detectable with once-per-day satellite observations can be compared in the field each hour. Mission guidance can be provided for aircraft observations of aerosol plumes or ozone changes. Thus, large-scale context can be characterized more accurately and more information can be provided to mission planners.