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  • Author or Editor: H. H. Shih x
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David L. Portep and H. H. Shih

Abstract

The National Oceanic and Atmospheric Administration collects tide and water-level data by using an acoustic tide gauge in its Next Generation Water Level Measurement System (NGWLMS). The elevation of the water is calculated from the round-trip travel time of an acoustic wave generated from a source mounted above the water. At some, sites, solar radiation on the tide well can set up a nonuniform temperature structure in the well. This temperature effect can modify the travel time of the sound pulse, thereby introducing an offset into the estimate of the water level and hence into the computation of datums, such as mean sea level, which is a significant global change index. This diurnal temperature effect was quantified by computing day and night datums for tide stations located at La Jolla, California, and Baltimore, Maryland. By employing the difference in these datums, a method of delineating and removing this temperature effect was developed. This analysis resulted in 1) a quantifiable method for determining the need for maintaining temperature sensors at NGWLMS locations, 2) an optimized temperature correction formula, and 3) an important finding that in most cams the temperature effect will have little impact on significant global change indices such as the, yearly mean sea level.

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Norden E. Huang, Hsing H. Shih, Zheng Shen, Steven R. Long, and Kuang L. Fan

Abstract

Using a process denoted here as the empirical mode decomposition and the Hilbert spectral analysis, the ages of the seiches on the Caribbean coast of Puerto Rico are determined from their dispersion characteristics with respect to time. The ages deduced from this method are less than a day; therefore, the seiches could be locally generated.

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D. H. Bromwich, A. B. Wilson, L. Bai, Z. Liu, M. Barlage, C.-F. Shih, S. Maldonado, K. M. Hines, S.-H. Wang, J. Woollen, B. Kuo, H.-C. Lin, T.-K. Wee, M. C. Serreze, and J. E. Walsh

Abstract

The Arctic is a vital component of the global climate, and its rapid environmental evolution is an important element of climate change around the world. To detect and diagnose the changes occurring to the coupled Arctic climate system, a state-of-the-art synthesis for assessment and monitoring is imperative. This paper presents the Arctic System Reanalysis, version 2 (ASRv2), a multiagency, university-led retrospective analysis (reanalysis) of the greater Arctic region using blends of the polar-optimized version of the Weather Research and Forecasting (Polar WRF) Model and WRF three-dimensional variational data assimilated observations for a comprehensive integration of the regional climate of the Arctic for 2000–12. New features in ASRv2 compared to version 1 (ASRv1) include 1) higher-resolution depiction in space (15-km horizontal resolution), 2) updated model physics including subgrid-scale cloud fraction interaction with radiation, and 3) a dual outer-loop routine for more accurate data assimilation. ASRv2 surface and pressure-level products are available at 3-hourly and monthly mean time scales at the National Center for Atmospheric Research (NCAR). Analysis of ASRv2 reveals superior reproduction of near-surface and tropospheric variables. Broadscale analysis of forecast precipitation and site-specific comparisons of downward radiative fluxes demonstrate significant improvement over ASRv1. The high-resolution topography and land surface, including weekly updated vegetation and realistic sea ice fraction, sea ice thickness, and snow-cover depth on sea ice, resolve finescale processes such as topographically forced winds. Thus, ASRv2 permits a reconstruction of the rapid change in the Arctic since the beginning of the twenty-first century–complementing global reanalyses. ASRv2 products will be useful for environmental models, verification of regional processes, or siting of future observation networks.

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T. H. Vonder Haar, C. F. Shih, D. L. Randel, J. J. Toth, D. N. Allen, R. A. Pielke, and R. Green

A new weather laboratory for teaching and applied research has been developed at Colorado State University (CSU). The laboratory uses DEC workstations and also hosts various microcomputers via a local area network to interface with the Cooperative Institute for Research in the Atmosphere (CIRA) computer system shared by the Department of Atmospheric Science. This computer system centers on a cluster of VAX 700-class computers and includes several user-interactive subsystems, such as the Interactive Research Imaging System (IRIS), Direct Readout Satellite Earth Station (DRSES), and a weather display system (using General Meteorological Software Package [GEMPAK]). Through direct communication lines, the VAX 700-class computer cluster is linked to the mainframe computers of CSU, National Center for Atmospheric Research (NCAR), and National Oceanic and Atmospheric Administration/Environmental Research Laboratory (NOAA/ERL). Since the computer system has such broad interface with other computer systems, a unique feature of the new weather laboratory is its capability to provide not only current weather data but also real-time satellite, radar, mesonet, and profiler data. Examples of the products of the new weather laboratory are presented. Options and trade-offs encountered in the design of the new weather laboratory are discussed.

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Andrew R. Friedman, Gabriele C. Hegerl, Andrew P. Schurer, Shih-Yu Lee, Wenwen Kong, Wei Cheng, and John C. H. Chiang

Abstract

The sea surface temperature (SST) contrast between the Northern Hemisphere (NH) and Southern Hemisphere (SH) influences the location of the intertropical convergence zone (ITCZ) and the intensity of the monsoon systems. This study examines the contributions of external forcing and unforced internal variability to the interhemispheric SST contrast in HadSST3 and ERSSTv5 observations, and 10 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) from 1881 to 2012. Using multimodel mean fingerprints, a significant influence of anthropogenic, but not natural, forcing is detected in the interhemispheric SST contrast, with the observed response larger than that of the model mean in ERSSTv5. The forced response consists of asymmetric NH–SH SST cooling from the mid-twentieth century to around 1980, followed by opposite NH–SH SST warming. The remaining best-estimate residual or unforced component is marked by NH–SH SST maxima in the 1930s and mid-1960s, and a rapid NH–SH SST decrease around 1970. Examination of decadal shifts in the observed interhemispheric SST contrast highlights the shift around 1970 as the most prominent from 1881 to 2012. Both NH and SH SST variability contributed to the shift, which appears not to be attributable to external forcings. Most models examined fail to capture such large-magnitude shifts in their control simulations, although some models with high interhemispheric SST variability are able to produce them. Large-magnitude shifts produced by the control simulations feature disparate spatial SST patterns, some of which are consistent with changes typically associated with the Atlantic meridional overturning circulation (AMOC).

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