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S. C. Ou, K. N. Liou, and J. F. King

Abstract

We have explored the applicability of the differential inversion (DI) method to temperature retrievals in both clear and cloudy atmospheres using red satellite data. The main theme of the DI is that the local Planck intensity can be exactly expressed by a linear combination of the derivatives of radiances in the logarithmic pressure coordinate. The inversion coefficients are obtained by fitting the weighting function to a generalized form. The higher-order derivatives of radiances are determined from polynomial fittings. The satellite dataset used in this work contains collocated brightness temperatures and radiosonde data that have been collected during the period of Baseline Upper Atmospheric Network (BUAN) experiments. These data include both cloudy and clear cases. A multispectral cloud-removal method using the principle of the N * method has been developed. This method uses radiances of High-Resolution Infrared Radiation Sounder channels 6, 7, and 8 to estimate clear radiances of these channels and the surface temperature simultaneously based on radiative transfer simulations. Subsequently, the quantity N * (the ratio of effective cloud cover over adjacent pixels) and the clear radiances of the rest of the channels are evaluated.

Retrieval results are presented in terms of rms temperature differences between retrieved and sounding profiles. Considering all clear and partly cloudy cases, the rms differences in temperature of approximately 2 K for retrievals using the DI are comparable to those using the minimum-variance scheme. The rms differences in temperature for retrievals using the multispectral cloud-removal scheme are slightly larger than those using the BUAN cloud-removal scheme by approximately 0.5 K. Finally, the rms temperature differences are much smaller than those for the first guess of the minimum-variance scheme. These results indicate fire that the DJ can achieve acceptable performance without first-guess or error covariance matrices; second, that the proposed multispectral cloud-removal method is also capable of generating reasonable cloud-removed clear radiances; and finally that the DI can be used as a tool to obtain first guesses in the current operational method and to perform large-volume temperature retrievals for climate studies.

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Oleg Dubovik, Brent Holben, Thomas F. Eck, Alexander Smirnov, Yoram J. Kaufman, Michael D. King, Didier Tanré, and Ilya Slutsker

Abstract

Aerosol radiative forcing is a critical, though variable and uncertain, component of the global climate. Yet climate models rely on sparse information of the aerosol optical properties. In situ measurements, though important in many respects, seldom provide measurements of the undisturbed aerosol in the entire atmospheric column. Here, 8 yr of worldwide distributed data from the AERONET network of ground-based radiometers were used to remotely sense the aerosol absorption and other optical properties in several key locations. Established procedures for maintaining and calibrating the global network of radiometers, cloud screening, and inversion techniques allow for a consistent retrieval of the optical properties of aerosol in locations with varying emission sources and conditions. The multiyear, multi-instrument observations show robust differentiation in both the magnitude and spectral dependence of the absorption—a property driving aerosol climate forcing, for desert dust, biomass burning, urban–industrial, and marine aerosols. Moreover, significant variability of the absorption for the same aerosol type appearing due to different meteorological and source characteristics as well as different emission characteristics are observed. It is expected that this aerosol characterization will help refine aerosol optical models and reduce uncertainties in satellite observations of the global aerosol and in modeling aerosol impacts on climate.

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S. E. Perkins-Kirkpatrick, A. D. King, E. A. Cougnon, N. J. Holbrook, M. R. Grose, E. C. J. Oliver, S. C. Lewis, and F. Pourasghar
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Walter F. Dabberdt, Jeremy Hales, Steven Zubrick, Andrew Crook, Witold Krajewski, J. Christopher Doran, Cynthia Mueller, Clark King, Ronald N. Keener, Robert Bornstein, David Rodenhuis, Paul Kocin, Michael A. Rossetti, Fred Sharrocks, and Ellis M. Stanley Sr.

The 10th Prospectus Development Team (PDT-10) of the U.S. Weather Research Program was charged with identifying research needs and opportunities related to the short-term prediction of weather and air quality in urban forecast zones. Weather has special and significant impacts on large numbers of the U.S. population who live in major urban areas. It is recognized that urban users have different weather information needs than do their rural counterparts. Further, large urban areas can impact local weather and hydrologic processes in various ways. The recommendations of the team emphasize that human life and well-being in urban areas can be protected and enjoyed to a significantly greater degree. In particular, PDT-10 supports the need for 1) improved access to real-time weather information, 2) improved tailoring of weather data to the specific needs of individual user groups, and 3) more user-specific forecasts of weather and air quality. Specific recommendations fall within nine thematic areas: 1) development of a user-oriented weather database; 2) focused research on the impacts of visibility and icing on transportation; 3) improved understanding and forecasting of winter storms; 4) improved understanding and forecasting of convective storms; 5) improved forecasting of intense/severe lightning; 6) further research into the impacts of large urban areas on the location and intensity of urban convection; 7) focused research on the application of mesoscale forecasting in support of emergency response and air quality; 8) quantification and reduction of uncertainty in hydrological, meteorological, and air quality modeling; and 9) the need for improved observing systems. An overarching recommendation of PDT-10 is that research into understanding and predicting weather impacts in urban areas should receive increased emphasis by the atmospheric science community at large, and that urban weather should be a focal point of the U.S. Weather Research Program.

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Allen B. White, Brad Colman, Gary M. Carter, F. Martin Ralph, Robert S. Webb, David G. Brandon, Clark W. King, Paul J. Neiman, Daniel J. Gottas, Isidora Jankov, Keith F. Brill, Yuejian Zhu, Kirby Cook, Henry E. Buehner, Harold Opitz, David W. Reynolds, and Lawrence J. Schick

The Howard A. Hanson Dam (HHD) has brought flood protection to Washington's Green River Valley for more than 40 years and opened the way for increased valley development near Seattle. However, following a record high level of water behind the dam in January 2009 and the discovery of elevated seepage through the dam's abutment, the U.S. Army Corps of Engineers declared the dam “unsafe.” NOAA's Office of Oceanic and Atmospheric Research (OAR) and National Weather Service (NWS) worked together to respond rapidly to this crisis for the 2009/10 winter season, drawing from innovations developed in NWS offices and in NOAA's Hydrometeorology Test-bed (HMT).

New data telemetry was added to 14 existing surface rain gauges, allowing the gauge data to be ingested into the NWS rainfall database. The NWS Seattle Weather Forecast Office produced customized daily forecasts, including longer-lead-time hydrologic outlooks and new decision support services tailored for emergency managers and the public, new capabilities enabled by specialized products from NOAA's National Centers for Environmental Prediction (NCEP) and from HMT. The NOAA Physical Sciences Division (PSD) deployed a group of specialized instruments on the Washington coast and near the HHD that constituted two atmospheric river (AR) observatories (AROs) and conducted special HMT numerical model forecast runs. Atmospheric rivers are narrow corridors of enhanced water vapor transport in extratropical oceanic storms that can produce heavy orographic precipitation and anomalously high snow levels, and thus can trigger flooding. The AROs gave forecasters detailed vertical profile observations of AR conditions aloft, including monitoring of real-time water vapor transport and comparison with model runs.

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J. C. Doran, S. Abbott, J. Archuleta, X. Bian, J. Chow, R. L. Coulter, S. F. J. de Wekker, S. Edgerton, S. Elliott, A. Fernandez, J. D. Fast, J. M. Hubbe, C. King, D. Langley, J. Leach, J. T. Lee, T. J. Martin, D. Martinez, J. L. Martinez, G. Mercado, V. Mora, M. Mulhearn, J. L. Pena, R. Petty, W. Porch, C. Russell, R. Salas, J. D. Shannon, W. J. Shaw, G. Sosa, L. Tellier, B. Templeman, J. G. Watson, R. White, C. D. Whiteman, and D. Wolfe

A boundary layer field experiment in the Mexico City basin during the period 24 February–22 March 1997 is described. A total of six sites were instrumented. At four of the sites, 915-MHz radar wind profilers were deployed and radiosondes were released five times per day. Two of these sites also had sodars collocated with the profilers. Radiosondes were released twice per day at a fifth site to the south of the basin, and rawinsondes were flown from another location to the northeast of the city three times per day. Mixed layers grew to depths of 2500–3500 m, with a rapid period of growth beginning shortly before noon and lasting for several hours. Significant differences between the mixed-layer temperatures in the basin and outside the basin were observed. Three thermally and topographically driven flow patterns were observed that are consistent with previously hypothesized topographical and thermal forcing mechanisms. Despite these features, the circulation patterns in the basin important for the transport and diffusion of air pollutants show less day-to-day regularity than had been anticipated on the basis of Mexico City's tropical location, high altitude and strong insolation, and topographical setting.

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N. L. Miller, A. W. King, M. A. Miller, E. P. Springer, M. L. Wesely, K. E. Bashford, M. E. Conrad, K. Costigan, P. N. Foster, H. K. Gibbs, J. Jin, J. Klazura, B. M. Lesht, M. V. Machavaram, F. Pan, J. Song, D. Troyan, and R. A. Washington-Allen

A Department of Energy (DOE) multilaboratory Water Cycle Pilot Study (WCPS) investigated components of the local water budget at the Walnut River watershed in Kansas to study the relative importance of various processes and to determine the feasibility of observational water budget closure. An extensive database of local meteorological time series and land surface characteristics was compiled. Numerical simulations of water budget components were generated and, to the extent possible, validated for three nested domains within the Southern Great Plains—the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Cloud Atmospheric Radiation Testbed (CART), the Walnut River watershed (WRW), and the Whitewater watershed (WW), in Kansas.

A 2-month intensive observation period (IOP) was conducted to gather extensive observations relevant to specific details of the water budget, including finescale precipitation, streamflow, and soil moisture measurements that were not made routinely by other programs. Event and seasonal water isotope (d18O, dD) sampling in rainwater, streams, soils, lakes, and wells provided a means of tracing sources and sinks within and external to the WW, WRW, and the ARM CART domains. The WCPS measured changes in the leaf area index for several vegetation types, deep groundwater variations at two wells, and meteorological variables at a number of sites in the WRW. Additional activities of the WCPS include code development toward a regional climate model that includes water isotope processes, soil moisture transect measurements, and water-level measurements in groundwater wells.

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A. B. White, M. L. Anderson, M. D. Dettinger, F. M. Ralph, A. Hinojosa, D. R. Cayan, R. K. Hartman, D. W. Reynolds, L. E. Johnson, T. L. Schneider, R. Cifelli, Z. Toth, S. I. Gutman, C. W. King, F. Gehrke, P. E. Johnston, C. Walls, D. Mann, D. J. Gottas, and T. Coleman

Abstract

During Northern Hemisphere winters, the West Coast of North America is battered by extratropical storms. The impact of these storms is of paramount concern to California, where aging water supply and flood protection infrastructures are challenged by increased standards for urban flood protection, an unusually variable weather regime, and projections of climate change. Additionally, there are inherent conflicts between releasing water to provide flood protection and storing water to meet requirements for the water supply, water quality, hydropower generation, water temperature and flow for at-risk species, and recreation. To improve reservoir management and meet the increasing demands on water, improved forecasts of precipitation, especially during extreme events, are required. Here, the authors describe how California is addressing their most important and costliest environmental issue—water management—in part, by installing a state-of-the-art observing system to better track the area’s most severe wintertime storms.

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J. A. Curry, P. V. Hobbs, M. D. King, D. A. Randall, P. Minnis, G. A. Isaac, J. O. Pinto, T. Uttal, A. Bucholtz, D. G. Cripe, H. Gerber, C. W. Fairall, T. J. Garrett, J. Hudson, J. M. Intrieri, C. Jakob, T. Jensen, P. Lawson, D. Marcotte, L. Nguyen, P. Pilewskie, A. Rangno, D. C. Rogers, K. B. Strawbridge, F. P. J. Valero, A. G. Williams, and D. Wylie

An overview is given of the First ISCCP Regional Experiment Arctic Clouds Experiment that was conducted during April–July 1998. The principal goal of the field experiment was to gather the data needed to examine the impact of arctic clouds on the radiation exchange between the surface, atmosphere, and space, and to study how the surface influences the evolution of boundary layer clouds. The observations will be used to evaluate and improve climate model parameterizations of cloud and radiation processes, satellite remote sensing of cloud and surface characteristics, and understanding of cloud–radiation feedbacks in the Arctic. The experiment utilized four research aircraft that flew over surface-based observational sites in the Arctic Ocean and at Barrow, Alaska. This paper describes the programmatic and scientific objectives of the project, the experimental design (including research platforms and instrumentation), the conditions that were encountered during the field experiment, and some highlights of preliminary observations, modeling, and satellite remote sensing studies.

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