KEYWORDS: Satellites, Remote sensing, Temporal resolution, Data analysis, Temperature metrology, Data storage, Earth observing sensors, Data integration, Thermal effects, Tongue
Previous studies of the Mediterranean outflow and meddies (O&M) were limited by poor spatial and temporal resolution of the conventional observations. Little is known about meddies formation and transport, and the spatial and temporal variation of its trajectories. Generally speaking, most of the satellite observations are confined to the ocean's surface or its surface layer, while meddies were located, on an average, at a depth of 1000m. We developed a new remote sensing method to observe and study the O&M through unique approaches in satellite multi-sensor data integration analyses. Satellite altimeter, scatterometer, SST and XBT data were used to detect and calculate the trajectories and the relative transport of the O&M. We found that more northwestward meddies occurred in the spring and more southward meddies occurred in the fall than previously thought. Since the O&M play a significant role in carrying salty water from the Mediterranean into the Atlantic and contribute to the North Atlantic Deep Water (NADW) formation, such new knowledge about their trajectories, transport and life histories is important to understand their mixing and interaction with the North Atlantic water, adn hence, to lead to a better understanding of the global ocean circulation and the global change.
A microwave scatterometer of the National Aeronautics and Space Administration (NASA) of the United States, SeaWinds, was launched on the second Advanced Earth Observing System (ADEOS-II) of the Japanese Space Agency (NASDA) in December 2002. A preliminary data set was released to the Ocean Vector Wind Science Team (OVWST) for calibration/validation on July 15, 2003. A comparison of this data set with ocean buoy measurements was performed and the quality of the data was found to be very similar to that from an identical scatterometer deployed on NASA QuikSCAT mission. An overview of potential unique impact of SeaWinds on ADEOS-2 is also presented.
A revised geophysical model function for applications of QuikSCAT data to tropical cyclones is described. An analysis of QuikSCAT σ0s from the fore- and aft-beams indicates a directional dependence of about 0.5-1 dB for above 40 m/s wind speeds. The differences between QuikSCAT fore- and aft-beam σ0s were used to estimate the second harmonics coefficients, characterizing the upwind and crosswind asymmetry. The results show that the QuikSCAT σ0s have a peak-to-peak wind direction modulation of ~1 dB at 35 m/s wind speed, and the amplitude of modulation decreases with wind speed. The trend agrees well with the QSCAT1 model function at near 20 m/s. A simple analytic correction of the QSCAT1 model function is presented. We explored two microwave radiative transfer models to account for the attenuation and scattering effects of rain. One is derived from the collocated QuikSCAT and SSM/I data set, and the other one is a published parametric model developed for precipitation radars. The comparison of these two radiative transfer models indicates the relative significance of volume scattering, scattering from rain-roughened surfaces and rain attenuation. The models suggest that the σ0s of wind-induced surfaces at 40-50 m/s are comparable to the contributions of rain for up to 10-20 mm/h. The radiative transfer models have been used to retrieve the ocean wind vectors from the collocated QuikSCAT and SSM/I rain rate data for several tropical cyclones. The resulting wind speed estimates of these tropical cyclones show improved agreement with the expected wind fields derived from the best track analysis and Holland's model for up to about 15 mm/h rain rate.
The high spatial resolution and global coverage of a spaceborne microwave scatterometer make it a powerful instrument to study phenomena ranging from typhoons to El Nino Southern Oscillations which have regional and short term economic and ecological impacts as well as effects on long term and global climate changes. In this report, the application of scatterometer data, by itself, to study the intensity and the evolution of a typhoon is demonstrated. The potential of combining wind vector and precipitable water derived from two spaceborne sensors to study the hydrologic balance in the tropics is discussed. The role of westerly wind bursts as a precursor of anomalous warming in the equatorial Pacific is investigated with coincident data from microwave scatterometer, altimeter, and radiometer.
NIRSPEC is a recently funded, high-resolution, 1 - 5 micrometers cryogenic spectrograph for the Keck II telescope. The design of this new instrument is based on 1024 X 1024 InSb arrays and provides resolving powers of R equals 2,000 in non-cross-dispersed mode and R equals 25,000 in echelle mode with typically 5 to 6 orders on the array covering 60 - 90% of the selected waveband, J, H, K, or L, in a single observation. Later, even higher resolution can be achieved by using the proposed adaptive optics facility at Keck II and replacing some of the internal modules of NIRSPEC. This paper gives a brief description of the proposed design concepts, and a discussion of the detector and system constraints required to achieve the scientific goals of the instrument.
This paper describes the performance of a unique new IR array camera system which provides simultaneous imaging at two wavelengths in the near IR. Two-color imaging is achieved with a dichroic beam splitter which yields two independent beams, one short-wave (SW) from 1 to 2.5 micrometers and one long-wave (LW) from 2 to 5 micrometers . A Rockwell NICMOS 3 256 by 256 HgCdTe array is used in the SW channel and the LW channel has an InSb 256 by 256 array from SBRC. The instrument, which is designed for the University of California's Lick Observatory 3-m telescope and for the f/15 focus of the 10-m W.M. Keck telescope, employs a closed cycle refrigerator and a compact array control/data acquisition system based on transputers with a host 486 PC. On the Lick 3-m telescope the pixel size is 0.7' which gives a field of view of about 180' by 180'. Facilities are also provided for spectroscopy and polarimetry. Recent observational results are reported to illustrate the performance of this system.
This paper describes a new infrared imaging system being developed at UCLA for use on both the Lick Observatory 3-m telescope and the W.M. Keck 10-m telescope. The instrument has a relatively wide field of view on each telescope and is intended for infrared surveys and deep imaging. To enhance efficiency, the new instrument incorporates a dichroic beam splitter to provide two simultaneous imaging systems, one short-wave (SW) from 1 - 2.5 micrometers and one long-wave (LW) from 2 - 5 micrometers . Each wavelength channel is independently optimized. The SW channel contains a Rockwell NICMOS3 256 X 256 HgCdTe array and the LW channel has an SBRC 256 X 256 InSb array. The thermal design employs a closed cycle cooler. A control and data acquisition system based on transputers and high speed analog electronics is being developed to handle the high data rates.
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