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L. A. Sromovsky, H. E. Revercomb, V. E. Suomi, S. S. Limaye, and R. J. Krauss

Abstract

Previous Voyager 1 and 2 Jovian circulation measurements exhibit a large positive correlation between eddy momentum transports and the meridional shear of the zonal wind component, implying a very large rate of conversion of eddy kinetic energy into kinetic energy of the zonal jets. Examination of the vectors mainly responsible for the correlation in our recent Voyager 2 global measurements indicates that it is probably caused by a biased sampling of prominent cloud features associated with circulating eddies. Intensive diagnostic measurements with more nearly uniform spatial sampling show no significant correlation in regions where our original measurements showed strong correlations. If the sampling bias mechanism is fully accounted for in all Jovian circulation measurements, the estimated eddy-to-mean-flow kinetic energy conversion rate may be reduced significantly.

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L. A. Sromovsky, J. R. Anderson, F. A. Best, J. P. Boyle, C. A. Sisko, and V. E. Suomi

Abstract

An untended instrument to measure ocean surface heat flux has been developed for use in support of field experiments and the investigation of heat flux parameterization techniques. The sensing component of the Skin-Layer Ocean Heat Flux Instrument (SOHFI) consists of two simple thermopile heat flux sensors suspended by a fiberglass mesh mounted inside a ring-shaped surface float. These sensors make direct measurements within the conduction layer, where they are held in place by a balance between surface tension and float buoyancy. The two sensors are designed with differing solar absorption properties so that surface heat flux can be distinguished from direct solar irradiance. Under laboratory conditions, the SOHFI measurements agree well with calorimetric measurements (generally to within 10%). Performance in freshwater and ocean environments is discussed in a companion paper.

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L. A. Sromovsky, J. R. Anderson, F. A. Best, J. P. Boyle, C. A. Sisko, and V. E. Suomi

Abstract

The Skin-Layer Ocean Heat Flux Instrument (SOHFI) described by Sromovsky et al. (Part I, this issue) was field-tested in a combination of freshwater and ocean deployments. Solar irradiance monitoring and field calibration techniques were demonstrated by comparison with independent measurements. Tracking of solar irradiance diurnal variations appears to be accurate to within about 5% of full scale. Preliminary field tests of the SOHFI have shown reasonably close agreement with bulk aerodynamic heat flux estimates in freshwater and ocean environments (generally within about 20%) under low to moderate wind conditions. Performance under heavy weather suggests a need to develop better methods of submergence filtering. Ocean deployments and recoveries of drifting SOHFI-equipped buoys were made during May and June 1995, during the Combined Sensor Program of 1996 in the western tropical Pacific region, and in the Greenland Sea in May 1997. The Gulf Stream and Greenland Sea deployments pointed out the need for design modifications to improve resistance to seabird attacks. Better estimates of performance and limitations of this device require extended intercomparison tests under field conditions.

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S. S. Limaye, H. E. Revercomb, L. A. Sromovsky, R. J. Krauss, D. A. Santek, V. E. Suomi, S. A. Collins, and C. C. Avis

Abstract

Independent measurements of Jovian cloud motions confirm previously published results on the general structure of Jupiter's zonal mean circulation. The new results are based on Voyager 2 images and measurement techniques which are different from those used in previous studies. The latitudes of the zonal jets agree with previous results, but there are some differences in the measured speed of the jets which exceed uncertainty estimates. These differences may be due to differences in sampling strategies. The structure of the zonal mean meridional velocity profile has still not been clearly resolved: mean meridional velocities generally differ from zero by no more than their estimated uncertainty. An analysis of successive measurements of the same cloud targets shows that most of the variance of individual velocity measurements is due to true variability of the winds. In agreement with the previous results the curvature of the zonal velocity profile is consistent with barotropic instability within most easterly jets, although the cloud morphologies visible in the images do not confirm that large-scale instabilities actually exist in these regions. Baroclinic effects may also be important in these regions. Large differences among independent estimates of eddy momentum transport indicate that this quantity has yet to be reliably determined.

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W. L. Smith, H. E. Revercomb, H. B. Howell, H-L. Huang, R. O. Knuteson, E. W. Koenig, D. D. LaPorte, S. Silverman, L. A. Sromovsky, and H. M. Woolf

Abstract

A high spectral resolution interferometer sounder (GHIS) has been designed for flight on future geostationary meteorological satellites. It incorporates the measurement principles of an aircraft prototype instrument, which has demonstrated the capability to observe the earth-emitted radiance spectrum with high accuracy. The aircraft results indicate that the theoretical expectation of 1°C temperature and 2°–3°C dewpoint retrieval accuracy will be achieved. The vertical resolution of the water vapor profile appears good enough to enable moisture tracking in numerous vertical layers thereby providing wind profile information as well as thermodynamic profiles of temperature and water vapor.

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W. L. Smith, V. E. Suomi, W. P. Menzel, H. M. Woolf, L. A. Sromovsky, H. E. Revercomb, C. M. Hayden, D. N. Erickson, and F. R. Mosher

First results are presented from an experiment to sound the atmosphere's temperature and moisture distribution from a geostationary satellite. Sounding inferences in clear and partially cloudy conditions have the anticipated accuracy and horizontal and vertical resolutions. Most important is the preliminary indication that small but significant temporal variations of atmospheric temperature and moisture can be observed by the geostationary satellite sounder. Quantitative assessment of the accuracy and meteorological utility of this new sounding capability must await the accumulation of results over the coming months.

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