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G. David Alexander, James A. Weinman, V. Mohan Karyampudi, William S. Olson, and A. C. L. Lee

of the intensity and precipitation patterns associated with extratropical cyclones (e.g., Manobianco et al. 1994 ; Jones and Macpherson 1997 ). It is challenging, however, particularly over data-sparse regions, to obtain continuous and accurate estimates of instantaneous rain rate. Here, we describe a technique through which data from a variety of sources—passive microwave sensors, infrared sensors, and lightning flash observations—along with a classic image processing technique (digital image

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Stanley Q. Kidder and Kae Shyu

forecast errors are still unacceptablylarge. A primary difficulty is that tropical cyclones and their environments are poorly observed by conventionaldata networks. Satellite sounders, however, routinely provide numerous observations near these storms. Meanlayer temperatures from the Scanning Microwave Spectrometer (SCAMS) on board the Nimbus-6 satelliteare decomposed using empirical orthogonal functions, and the expansion coefficients are related to deviationsfrom persistence track forecasts. Based on

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Clive E. Dorman and Robert H. Bourke

observations taken by ships and relating them to a given amount of precipitation, new estimates of oceanic rainfall for the Pacific Ocean between 30-S and 60-N have been derived.Satellite microwave measurements and Taylor's (1973) island analysis support our findings. Annualand quarterly rainfall maps. drawn from our estimates, agree with other modern, land-derivedvalues, but provide greater detail. Between the equator and 60~N, the annual depth and volume rainfall totals are 1282 mm and 1.16 x 10~ kma

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Zhiquan Liu, Craig S. Schwartz, Chris Snyder, and So-Young Ha

assimilating rain-affected microwave radiances, and the QC procedure prohibits the use of AMSU-A data in the precipitating TC core area. Thus, the improved track forecasts by assimilating AMSU-A radiances are likely due to a better depiction of large-scale environmental flow in the analyses and subsequent forecasts. To test this hypothesis, we verified the forecasts against GPS dropwindsonde observations released from NOAA G-IV aircraft ( Aberson 2010 ). The G-IV dropwindsondes sample the atmosphere below

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Jason E. Nachamkin

forecasts were run to 72 h. The forecasts were verified against the Special Sensor Microwave Imager (SSM/I) winds retrieved using the Goodberlet et al. (1990) regression with the Petty (1993) water vapor correction. In the absence of rain, Goodberlet at al. (1990), Petty (1993) , and Gemmill and Krasnopolsky (1999) found that the retrieved winds estimated the in situ buoy and ship observations at the 19.5- m level with an rms of 2 m s −1 . For this study, all data within 75 km of land and all

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Man Zhang, Milija Zupanski, Min-Jeong Kim, and John A. Knaff

regions at operational NWP centers (e.g., McNally 2009 ; Bauer et al. 2010 ). In this study, the prototype regional hybrid data assimilation system is based on the 2011 version of the NOAA operational HWRF model ( Gopalakrishnan et al. 2011 ), and the maximum likelihood ensemble filter (MLEF; Zupanski 2005 ; Zupanski et al. 2008 ). Specifically, observations from the Advanced Microwave Sounding Unit-A (AMSU-A) ( Robel 2009 ) on board the NOAA-18 satellite and the European Organization for the

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John E. Janowiak, Phillip A. Arkin, and Mark Morrissey

diurnal character of tropicalrainfall (convective and stratiform, collectively), as inferred from microwave data from polar-orbiting satellites, are also discussed. In situ observations of precipitation from ship reports and from optical rain gaugesaboard buoys that are moored in the tropical Pacific arealso analyzed.b. Background The characteristics of the diurnal cycle in tropicalconvective rainfall over land surfaces makes sensefrom atmospheric stability considerations. Intense surface heating

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Jason P. Dunion, Samuel H. Houston, Christopher S. Velden, and Mark D. Powell

Automated Network (C-MAN) stations, ships, meteorological aviation reports (METAR) stations, Global Positioning System (GPS) dropwindsondes (dropsondes), and aircraft flight-level data adjusted to the surface (10 m) based on Powell et al. (1996) . Remotely sensed observations include the Step Frequency Microwave Radiometer (SFMR) aboard NOAA research aircraft and data from polar orbiting microwave satellites [the Special Sensor Microwave/Imager (SSM/I), the Quick Scatterometer (QuikScat), and the TRMM

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Daniel C. Hartung, Jason A. Otkin, Ralph A. Petersen, David D. Turner, and Wayne F. Feltz

1. Introduction A 2009 report issued by the National Research Council (NRC) stressed the importance of establishing a comprehensive and adaptive national strategy for surface-based observations of the planetary boundary layer (PBL). This report concluded that the current observation networks are too sparse and unevenly distributed to adequately detail the thermodynamic structure of the boundary layer at high spatial and temporal resolution, which is needed for a wide variety of applications

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William F. Campbell, Craig H. Bishop, and Daniel Hodyss

microwave temperature sounders such as the Advanced Microwave Sounding Unit-A (AMSU-A).] Understanding some of the limitations of current satellite ensemble DA techniques should aid in the search for techniques that are superior for satellite observations. The theoretical basis for radiance space localization is explored in section 2 , and a conceptual 1D model that exposes its essential limitations is presented in section 3 . In section 4 , a more realistic 1D model is presented, with levels

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