[1] Sea ice freeboard heights in the Weddell Sea of Antarctica are derived from the Ice, Cloud, and Land Elevation Satellite (ICESat) laser altimeter measurements, which have a unique range precision to flat surfaces of 2 cm within 70 m footprints spaced at 172 m along track. Although elevations of flat surfaces can be obtained to an accuracy of $10 cm (1s) per footprint, direct determination of freeboard heights is precluded by errors in knowledge of the geoid and temporal variability of the ocean surface.

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Abstract. Wavelet analysis of NASA scatterometer (NSCAT) backscatter and DMSP special sensor microwave imager (SSM/I) radiance data can be used to obtain daily sea ice drift information for the Arctic region. This technique provides improved spatial coverage over the existing array of Arctic Ocean buoys and better temporal resolution over techniques utilizing data from satellite synthetic aperture radars. Comparisons with ice motion derived from ocean buoys give good quantitative agreement. Both comparison results from NSCAT and SSM/I are compatible, and the results from NSCAT can definitely complement that from SSM/I when there are cloud or surface effects. Then, three sea ice drift daily results from NSCAT, SSM/I, and buoy data can be merged as a composite map by some data fusion techniques. The ice flow streamlines are highly correlated with surface air pressure contours. Examples of derived ice drift maps in December 1996 illustrate large-scale circulation reversals over a period of 4 days. These calibrated/validated results indicate that NSCAT, SSM/I merged daily ice motions are suitably accurate to identify and closely locate sea ice processes and to improve our current knowledge of sea ice drift and related processes through the data assimilation of ocean-ice numerical model. IntroductionIn 1996 the NASA scatterometer (NSCAT) rode into orbit on the Japanese satellite Advanced Earth Observing System (ADEOS) and gathered 8.5 months of valuable wind data.

We demonstrate the fabrication of long-period fiber gratings (LPFGs) written in the two-mode fiber (TMF) by CO₂ laser. Both uniform and tilted LPFGs were fabricated to provide the light coupling between LP₀₁ mode and LP₁₁ mode with a coupling efficiency of more than 99%. The writing efficiency and the bandwidth of the LPFG mode converter can be adjusted by changing the tilt angle of the tilted TMF-LPFGs. The torsion sensitivity of conventional and tilted LPFG mode converters were measured to be 0.37 nm/(rad/m) and 0.50 nm/(rad/m), respectively. Two orthogonal vector modes (the HEeven 21and HEodd 21 modes) and corresponding orbital angular momentum state were successfully obtained at the resonance wavelength. The proposed LPFG mode converter could be used as not only a high efficiency wavelength tunable mode converter in the mode division multiplexing system but also a high sensitive torsion sensor in the field of optical sensing.

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Synthetic aperture radar (SAR) sensors aboard polar-orbiting satellites have the abilities to acquire high spatial resolution images of the Earth's surface under all weather conditions, but their temporal sampling intervals are long. However, currently two SAR sensors aboard the European remote sensing satellite-2 (ERS-2) and the environment satellite (ENVISAT) have almost the same flight paths with ERS-2 following ENVISAT by approximately 28 minutes. Thus, high spatial resolution images from these two SAR can be jointly used to achieve a high temporal sampling interval for ocean feature monitoring and tracking. This approach has been used to track internal wave refraction along Dong-Sha Atoll in the South China Sea (SCS) on 16 April 2003. On that same day, the moderate resolution imaging spectro-radiometer (MODIS) aboard Terra passed though the same location 28 minutes after ERS-2 and collected data under almost no cloud condition. Therefore, Terra MODIS images provide another source for monitoring the wave refraction and validating the internal wave speed around Dong-Sha Atoll.

In this paper, we propose an algorithms for finding a common fixed point of an infinite family of multi-valued generalized nonexpansive mappings in uniformly convex Banach spaces. Under suitable conditions some strong and weak convergence theorems for such mappings are proved. The results presented in the paper improve and extend the corresponding results of Suzuki (

We present a refractometer with main- and vernier-scale to measure the refractive index (RI) of liquids with high precision by using the fine spectrum structure of a tilted fiber Bragg grating (TFBG). The absolute RI values are determined by the accurate wavelength of cut-off mode resonances. The main- and vernier-scale are calibrated by measuring large groups of fine spectra at different cut-off mode resonances in a small RI range, and the use of vernier-scale certainly reduces the RI measurement uncertainty resulted from the discrete cladding mode resonances. The performance of the TFBG-based vernier refractometer is experimentally verified by exploring the temperature dependence of RI of anhydrous ethanol in a near infrared region, showing an enhanced accuracy to the order of 10, high repeatability and temperature self-calibration capability.