KONVEX (KONza Validation EXperiment) summary report

11-18 July 1999

by Jim Conel, MISR Validation Scientist

The MISR validation team participated in the Kansas Bigfoot experiment during the week of 11-18 July (see Bigfoot home page). The "Golden Day" for our measurements was July 13. At approximately 10:30 a.m. local time, AirMISR flew over the target site, and acquired four lines of data, at varying azimuths. During each of these runs, the AirMISR camera was slewed to its nine angles, replicating the nine view angles of its on-orbit counterpart (to be launched later this year). The skies were clear of cloud cover, however a haze was noted indicating high humidity conditions.

The target site (39 04.95N, 096 33.60W) was on the SouthEast corner of the Konza Long Term Ecological Site (LTER). The area used by our team had two adjacent areas, divided by a road. Each was about 100 meters wide by 300 meters long. One site was burned annually, the other was burned biennially (that is once a year, and once every two years).

The MISR team made continual sunphotometer observations during the week from its Reagan, Cimel, and MFRSR instruments. Radiance samples covering both the upwelling and downwelling hemispheres were acquired using the PARABOLA III. The best of these data were acquired co-incident with the AirMISR overpass. The PARABOLA acquired a full days data at the annual burned site. This will provide bi-directional reflectance factor (BRF) of the area through a range of solar zenith angles. PARABOLA data over the biennial burn site were acquired on 7/14/99, however the days prior and following the Golden Day were intermittent with clouds and cirrus. Data from our ASD provide a verification of the PARABOLA data, at a nadir-view angle.

Additional supporting data were acquired over our site, on this date, courtesy of other teams. In particular, the USGS (David Meyer's group) acquired Exotech data, albedo measurements via a Kipp Zonen, and 2 groups made measurements of LAI/ FPAR. A Goddard team acquired additional ASD surface reflectance data (nadir view) to compare to our measured ASD data. The University of Arizona team also made surface reflectance measurements. Finally, GPS data have located our site to within 1 meter.

By comparing BRF retrievals made by the PARABOLA and AirMISR, the MISR surface processing algorithms will be validated (John Marthonchik/ Wedad Abdou JPL team leads). Ranga Myeni will run AirMISR data through his LAI/ FPAR algorithms, and validate with the in-situ observations. (Note, LAI/ FPAR are not currently a MISR standard product, but can be produced from the radiance images). Additionally, data from the AirMISR nadir and 26 degree fore and aft views can be used to retrieve the height of the surface terrain. This will be used to validate MISR algorithms used to retrieve stereo height.