%0 Journal Article %1 Pater2001 %A de Pater, I. %A Dunn, D. %A Romani, P. %A Zahnle, K. %D 2001 %J Icarus %K ATMOSPHERE; BELT; CLOUD EQUATORIAL GAS-COMPOSITION; LABORATORY MEASUREMENTS; NEPTUNE; NORTH ORIGIN PLANETS; SPECTRUM; STRUCTURE; TROPOSPHERIC WAVELENGTHS; %N 1 %P 66--78 %T Reconciling Galileo probe data and ground-based radio observations of ammonia on Jupiter %V 149 %X Prior to the Galileo probe entry in Jupiter's atmosphere, the ammonia abundance in the planet's deep atmosphere as deduced from microwave observations was thought to be close to the solar N value at P > 3 bar and subsolar at P < 2 bar, Analysis of the attenuation of the probe radio signal during its descent in Jupiter's atmosphere suggested NH3 to be 3.6 +/- 0.5 times solar N at P > 8 bar (Folkner er al 1998). Assuming this high value is globally representative of the NH3 abundance in Jupiter's deep atmosphere, we show in this article that to match Jupiter's microwave spectrum the ammonia abundance must, globally, decrease at pressures P less than or similar to4 bar, and reach subsolar (less than or similar to0.5) values at P less than or similar to2 bar, We confirm earlier analysis of the 1.3-cm wavelength region indicating that the disk-averaged relative humidity must be of the order of 10% at P < 0.55 bar. We discuss various ways in which NH3 could decrease globally at altitudes well below the level where the NH3-ice clouds form, We also present radio images of Jupiter taken with the VLA at 2, 3.6, and 6 cm wavelength in November/December 1995 and January 1996. The Galileo probe entered Jupiter's atmosphere on 7 December 1995, at a latitude of 6.5<degrees>N, i.e., at the southern edge of the north equatorial belt (NEE), Simulations of our data suggest that the longitude-averaged NH3 abundance in the NEB at the time of the Galileo probe entry is of the order of 50-70% of the value in the equatorial zone (EZ), while the NH3 abundance in the EZ is about less than or similar to0.5 x solar N, This low ammonia abundance in the NEB must exten down to the similar to4- to 6-bar level. (C) 2000 Academic Press..

@article{Pater2001, abstract = {Prior to the Galileo probe entry in Jupiter's atmosphere, the ammonia abundance in the planet's deep atmosphere as deduced from microwave observations was thought to be close to the solar N value at P > 3 bar and subsolar at P < 2 bar, Analysis of the attenuation of the probe radio signal during its descent in Jupiter's atmosphere suggested NH3 to be 3.6 +/- 0.5 times solar N at P > 8 bar (Folkner er al 1998). Assuming this high value is globally representative of the NH3 abundance in Jupiter's deep atmosphere, we show in this article that to match Jupiter's microwave spectrum the ammonia abundance must, globally, decrease at pressures P less than or similar to4 bar, and reach subsolar (less than or similar to0.5) values at P less than or similar to2 bar, We confirm earlier analysis of the 1.3-cm wavelength region indicating that the disk-averaged relative humidity must be of the order of 10% at P < 0.55 bar. We discuss various ways in which NH3 could decrease globally at altitudes well below the level where the NH3-ice clouds form, We also present radio images of Jupiter taken with the VLA at 2, 3.6, and 6 cm wavelength in November/December 1995 and January 1996. The Galileo probe entered Jupiter's atmosphere on 7 December 1995, at a latitude of 6.5<degrees>N, i.e., at the southern edge of the north equatorial belt (NEE), Simulations of our data suggest that the longitude-averaged NH3 abundance in the NEB at the time of the Galileo probe entry is of the order of 50-70% of the value in the equatorial zone (EZ), while the NH3 abundance in the EZ is about less than or similar to0.5 x solar N, This low ammonia abundance in the NEB must exten down to the similar to4- to 6-bar level. (C) 2000 Academic Press..}, added-at = {2009-11-03T20:21:25.000+0100}, author = {de Pater, I. and Dunn, D. and Romani, P. and Zahnle, K.}, biburl = {https://www.bibsonomy.org/bibtex/227269744ccb92a28f44c7fdb9c287347/svance}, citedreferences = {1928, INT CRITICAL TABLES ; ANDERS E, 1989, GEOCHIM COSMOCHIM AC, V53, P197 ; ATREYA SK, 1985, PLANETARY METEOROLOG, P17 ; ATREYA SK, 1999, PLANET SPACE SCI, V47, P1243 ; BAARS JWM, 1977, ASTRON ASTROPHYS, V61, P99 ; BERGE GL, 1976, JUPITER, P621 ; BJORAKER GL, 1986, Icarus, V66, P579 ; BRANSON NJB, 1968, MON NOT R ASTRON SOC, V139, P155 ; CARLSON BE, 1993, J GEOPHYS RES-PLANET, V98, P5251 ; CORNWELL T, 1989, NRAO WORKSH, V21, P185 ; DEBOER DR, 1994, Icarus, V109, P352 ; DEPATER I, 1985, Icarus, V62, P143 ; DEPATER I, 1986, ASTROPHYS J, V308, P459 ; DEPATER I, 1986, Icarus, V68, P344 ; DEPATER I, 1989, COMETS POST HALLEY E, P175 ; DEPATER I, 1991, Icarus, V91, P220 ; DEPATER I, 1993, J GEOPHYS RES-PLANET, V98, P5471 ; DEPATER I, 1998, ASTRON J, V116, P987 ; ENCRENAZ T, 1978, ASTRON ASTROPHYS, V70, P29 ; FOLKNER WM, 1998, J GEOPHYS RES-PLANET, V103, P22847 ; FOUCHET T, 2000, Icarus, V143, P223 ; FRIEDSON AJ, 1999, B AM ASTRON SOC, V31, P1155 ; GREVESSE N, 1991, ASTRON ASTROPHYS, V242, P482 ; HOFFMAN JP, 1999, Icarus, V140, P235 ; ISAMBERT, 1881, COMPT REND, V92, P919 ; ISAMBERT, 1982, COMPT REND, V94, P958 ; KLEIN MJ, 1978, Icarus, V35, P44 ; KUNDE V, 1982, ASTROPHYS J, V263, P443 ; LINDAL GF, 1981, J GEO R-S P, V86, P8721 ; LINDAL GF, 1992, ASTRON J, V103, P967 ; MAGNUSSON JP, 1907, J PHYS CHEM-US, V2, P21 ; MAHAFFY PR, 1999, B AM ASTRON SOC, V31, P5205 ; MOLNAR LA, 2000, UNPUB Icarus ; NIEMANN HB, 1998, J GEOPHYS RES-PLANET, V103, P22831 ; ORTON GS, 1998, J GEOPHYS RES-PLANET, V103, P22791 ; OWEN T, 1999, Nature, V402, P269 ; RAGENT B, 1998, J GEOPHYS RES-PLANET, V103, P22891 ; ROBERTS JA, 1984, ASTROPHYS J, V282, P345 ; ROMANI PN, 1995, B AM ASTRON SOC, V27, P81 ; SHOWMAN AP, 1998, Icarus, V132, P205 ; SPILKER TR, 1990, THESIS STANFORD U ; SPILKER TR, 1993, J GEOPHYS RES-PLANET, V98, P5539 ; SROMOVSKY LA, 1998, J GEOPHYS RES-PLANET, V103, P22929 ; ULABY FR, 1981, MICROWAVE REMOTE SEN ; WEIDENSCHILLING SJ, 1973, Icarus, V20, P465}, interhash = {d49c258241988d5e7419b03ea80600d9}, intrahash = {27269744ccb92a28f44c7fdb9c287347}, journal = {Icarus}, keywords = {ATMOSPHERE; BELT; CLOUD EQUATORIAL GAS-COMPOSITION; LABORATORY MEASUREMENTS; NEPTUNE; NORTH ORIGIN PLANETS; SPECTRUM; STRUCTURE; TROPOSPHERIC WAVELENGTHS;}, number = 1, owner = {svance}, pages = {66--78}, timestamp = {2009-11-03T20:22:09.000+0100}, title = {Reconciling Galileo probe data and ground-based radio observations of ammonia on Jupiter}, volume = 149, year = 2001 }