Site reflectances extracted from SPOT HRV imagery over FIFE study area

The Thematic Mapper sensor system was used to collect the original data between February 1987 and October 1989 from which this data set was produced. Landsat TM extract data contains the average instrument corrected spectral radiances for each of the seven spectral bands. In addition, the associated view and solar angles are available for each of 39 FIFE ground measurement sites. The Site Reflectances Extracted from Landsat TM Imagery Data Set also contains reflectance values and exoatmospheric reflectance values for these seven spectral bands. These reflectances were derived using the sensor calibrated radiances which were corrected for exoatmospheric effects using atmospheric aerosol optical thickness and gaseous absorption profile measurements, when available. The atmospheric correction algorithm of Fraser et al. (1989) was used to calculate reflectance in the visible and infrared channels. The thermal data were corrected using parameters derived from the Lowtran-7 atmospheric path radiance model (Kneizys et al. 1988).

Site specifice radiance, exoatmospheric reflectance & surface reflectance

Site averaged product of the flux data collected by many PIs during the 1987-1989 FIFE experiment. Data are in 30-minute intervals and include data only for 1988.

This data presented with this data set includes: (a) The position of the satellite in its orbit about the Earth at 200 second intervals in heliocentric ecliptic rectangular coordinates (B1950), where the X axis points to the First Point of Ares. In addition an Earth ephemeris is also included, which was generated by Miles Standish at JPL using the information that was available in 1983 to best approximate the knowledge of the Earth's position that was used in the reduction of the IRAS data. Finally, the geocentric position of the satellite is calculated using the above information. (b) The IRAS Scan History File describes the pointing geometry and length of each survey-mode scan (by SOP OBS) over the entire mission.

Surface reflectance factors, radiances, and temperatures were measured with a Mast-borne Modular Multiband Radiometer (MMR), predominantly in the solar principal plane, with nadir and off-nadir, view-zenith angles. The MMR was mounted on a portable mast in order to achieve a spatial sampling at a variety of sites as well as within each site. The portable mast alignment varied from the solar principal plane, to the azimuthal plane aligned perpendicular to the principal plane and aligned with the satellite azimuthal plane. Measurements were periodically collected with the MMR over a barium sulfate reference panel. Measurements were typically coordinated with aircraft and/or satellite overpasses. Solar radiation data at or near the specific site should be used to screen possible times of variable cloud cover.

This bundle collects data taken at IRTF and associated document files.

The Advanced Very High Resolution Radiometer (AVHRR) is a four- or five-channel scanning radiometer capable of providing global daytime and nighttime sea-surface temperature and information about ice, snow, and clouds. The sensor measures emitted and reflected radiation in five channels (bands) of the electromagnetic spectrum. The Site Average Reflectances Extracted from AVHRR-LAC Imagery Data Set consists of averages of pixel extracts from AVHRR-LAC (1 km resolution) scenes that overlay the FIFE site. Average radiances for dates are available for the five sensor wavebands and average reflectance and exoatmospheric reflectances are available for wavebands 1 and 2. Site averages are clustered in 1987 and during the summer of 1989. Some data are also available for early 1988. The AVHRR is capable of operating in both real-time or recorded modes. Direct readout data were transmitted to ground stations of the automatic picture transmission (APT) class at low-resolution (4x4 km) and to ground stations of the high-resolution picture transmission (HRPT) class at high resolution (1x1 km). Data recorded on board were available for processing in the NOAA Central Computer Facility. They included local area coverage (LAC) data which were from selected portions of each orbit with a 1x1 km resolution. The precision of satellite remote sensing estimates of surface reflectance (Hall et al., 1992), calibrated and corrected for atmospheric effects, was no worse than about 1 percent absolute.

As part of the FIFE staff science data processing effort, the FIFE Information System (FIS) extracted site average radiances from the level-1 NS001-TMS products. Data were collected by the NS001 during each of the FIFE IFC's. Selected flights were processed to level-1. The site averages were extracted from these processed images. Therefore, this data set contains a small number of observation dates for each site, but at the multiple angles provided by the grid pattern used during each flight. The data set can be used for canopy reflectance modeling studies. The site average radiances extracted from the NS001 imagery are instrument-corrected spectral radiances for each of the eight spectral bands. Geographic location and viewing and solar angles for each of 39 FIFE ground measurement sites are also included for each observation. The sensor calibrated radiance values were corrected using atmospheric aerosol optical thickness and gaseous absorption profile measurements, when available. The atmospheric correction algorithm of Fraser et al. (1989) was used to calculate reflectance in the visible and infrared channels. The thermal data are corrected using parameters derived from the Lowtran7 atmospheric path radiance model (Kneizys et al., 1988).

The Surface Temperatures, Reflected and Emitted Radiation, and PAR from UNL Data Set contains surface temperatures at different view zenith and azimuth angles, net radiation, incoming and reflected photosynthetically active radiation, incoming and reflected shortwave radiation, and reflected and emitted longwave radiation. Surface temperatures were measured at a 30 degree view zenith angle with an Everest infrared thermometer (IRT) Model 112C and at approximately a 60 degree view zenith angle with a Scheduler Plant Stress Monitor at 4 view azimuths (predominantly 90 degree increments from the solar azimuth). The Scheduler also measured air temperature, relative humidity, and vapor pressure deficit. Net radiation was measured with a Radiation and Energy Balance Systems (REBS) net radiometer Model Q*3. Incoming shortwave radiation was measured with a horizontally mounted Eppley Precision Pyranometer Model PSP. Reflected shortwave radiation was measured with two (2) Eppley Precision pyranometers Model PSP usually mounted horizontally (at site 966 (2437-PSP) one PSP was mounted horizontally and the other was inclined parallel to the slope). Reflected and emitted longwave radiation were measured with a horizontally mounted Eppley Precision Infrared Radiometer Model PIR.