þ7#$#s\¾¾.!!!! !$!4!4"!Vx<Þ!Î !î"ñ*#"ñ"í"ñ"ñ#:9"ñ"ñ"ñ"ñ"ñ"ñ uthe selected desert test site. c) To obtain multi-frequency, multi-polarization, multi-look angle SAR images of the desert test site covering several surface types, to investigate the surface and subsurface features and properties which can be measur¾ÁÇÊâäåío‚ÅÏÒ¥§¹»¼âjq³ÅÇâãøúZmo´µúúùøòìæìòìæòìæòìæòæìæòæòàòìæòæìæòìæòÚòæ ü @ € €  À @(ÈÉÊäåîï  :;Rno‚ ¬ ­ Ò ú ! K r s ?ÄÅÑÒ˜™ûõïïææØʾÊææ²²²²²æææ©       —Ž…æææwi !À ˆûxÐ@ !À ˆûxÐ@!À Ð !À Ð!À Ð!À Ð!À Ð !À Ðý0@ !À Ðý0@ !À Ðý0Ð@ !À Ðý0Ð@!À !À !À$:ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿNew York 10 point,timesCourier ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ,ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ óôöÞ.c.Safsaf Titles of Investigations: I. SIR-C Surface and Subsurface Responses from Documented Test Site Localities in the Sahara, Namib, and Kalahari Deserts, Africa and the Jornada del Muerto, New Mexico II. Multifrequency Imaging Radar Polarimetry: Geophysical Factors from Penetration Phenomena Principal Investigators: I. Dr. Gerald Schaber U. S. Geological Survey II. Dr. Howard Zebker Jet Propulsion Laboratory Site Description: The Safsaf area is part of a flat plain, mostly mantled by sand sheet, that extends from south-central Egypt into northwest Sudan. This plain is also known as the Selima Sand Sheet or the Misaha surface. The bounding coordinates of the coverage required for this experiment are (approximately): N 21¡, E 27¡ N 25¡15', E 32¡15' N 26¡, E 30¡40' N 24¡30', E 33¡25' N 25¡30', E 30¡30' N 15¡, E 26¡30' N 27¡45', E 33¡15' N 15¡40', E 25¡15' N 27¡30', E 33¡45' N 20¡, E 28¡30' This rectangular area has one "leg" (part of one pass) extending across the Nile and the Red Sea Hills to the coast; this extra leg covers localities for contingency deployment of the radar reflectors. The Safsaf area lies along the SIR-A swath on which the penetration of dry surficial sands by the L-band signal, and our consequent delineation of subjacent materials and paleodrainage patterns, were first demonstrated. More than 100 pits were dug in the Safsaf area by hand and by backhoe in 1982, 1983, and 1984. This field work confirmed the shallow subsurface geologic units defined on the SIR-A images and provided data for models to explain the radar response of the calcareous duricrust (calcrete or caliche) in which paleodrainage patterns were preserved. Other sand-buried, subjacent materials whose radar responses can be studied are several types of bedrock, including a metamorphic core complex, limestone, sandstone, and a wide range of sediments. In terms of its radar characteristics, Safsaf is the best-known area in the hyperarid core of the Sahara. It is the classic locality in which to test the radar responses to be recorded by the SIR-C/X-SAR sensors. Additional science in the Safsaf area include penetration studies to quantify the depth to which radar sensors can image subsurface features. Since SIR-A images have already illustrated sand-buried targets in the region, Safsaf is a good candidate for additional investigations by SIR-C/X-SAR. During SIR-C/X-SAR, ground field equipment will be deployed as part of a quantitative experiment to characterize the penetration depth. Objectives: I. a) Determine the optimum SAR sensor configuration for detection of desert duricrust and to use this understanding to reconstruct the paleoclimatic history of two large desert regions in Africa. II. a) Model, characterize, and verify penetration phenomena in hyperarid and vegetated regions using the SIR-C multiparameter radar system and ground based receivers. b) Invert measured radar backscatter as a function of frequency and polarization in terms of geophysical parameters of the surface, subsurface, and vegetation canopy such as surface roughness, subsurface geomorphology, tree height and density. c) Display subsurface and within-canopy features in an image format facilitating result interpretability. Field Measurements: Schaber, please provide if applicable II. a) Deploy ground receivers during the experiment to measure field strengths at both vertical and horizontal polarizations. These in situ measurements will constrain and confirm our theoretical models. Crew Observations: 1) Crew Journal: Document dust storms and weather conditions at the site. Note and sketch presence of subtle relict drainage patterns and aeolian sand transport pathways. 2) Cameras: Hercules and Hasselblad will be used to obtain low sun angle stereo photographs of the desert. Coverage Requirements: The minimum coverage requirements for the Safsaf site are three (3) passes, preferably ²48¡. Anticipated Results: I. a) An improved understanding of radar backscatter and penetration in hyperarid-to-semiarid terrains that was initiated during our SIR-A/B investigations (Elachi, Roth and Schaber, 1984; Schaber et al., 1986); b) Refinement of synergistic remote methods to identify various types and stages of datable, authigenic CaCO3 deposits related to successive changes in climate and surface geologic processes during the Quaternary; c) Improved models of geometric scattering effects on SIR signal penetration; and d) Significant new data on the spatial and chronological distribution of semiarid paleoclimatic zones in Africa. II. a) An increased understanding of penetration phenomena in scattering; b) Identification of sources for backscatter in hyperarid subsurface imaging, and quantitative assessment of the relative contribution of canopy top, volume, and ground surface scattering components to the return signal from vegetation canopies; and c) Solutions for descriptive geophysical parameters in the supersites studied. These results would be of great use to any investigators interpreting images acquired over similar targets by SIR-C/X-SAR or any other radar system. „ü| h„ì $ „ü|hì $ „ü|hì $ „F @ $ „F @ „F @ $  h„ì $ „ü|hì $ „ü|hì6™BC9:¦§»¼âã³´ÇÈvwâãúûYZopEFstçè3401òäÖäòÍÍÍÍÍ¿ÍÍͶ­¶ÍÍͤÍÍÍ¿–ˆ–––z–––l–¿Í !À 8ûÈÐ@ !À 8ûÈÐ@ ÿ!À%8ûÈÐ@ !À 8ûÈÐ@!À Ð!À Ðý0!À Ðý0 !À 8ûÈÐ@!À  !À ˆûxÐ@ !À ˆûxÐ@ !À ˆûxÐ@&\@ v\ÿÿÿÿüÿÿ &'ÑÒ01JKb|}”°±ÃÄîï<c´µU     Ú Û „ … { | è é ý þ $ % õ ö  ¸¹$%<=›œ±²‡ˆ`aµ¶)*uvrsZ[\!À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À !À ÿ!À%!À !À !À !À !À !À !À !À !À !À !À !À™ !€È ÓHHÚ(ÿáÿâùFG(üHHÚ(d'@=à/Р ÐRBH -:LaserWriter ChicagoNew YorkGenevaMonaco San Francisco Zapf DingbatsBookmanPalatino Zapf ChanceryTimes HelveticaCourierSymbol! Avant Garde€FloralCapsNouveauÈJPLogo ÓMT Extra€[[€€[(Õüàü[\¾9Mission SummarySIR-CED Karl Erickson Karl Erickson