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John E. Janowiak, Valery J. Dagostaro, Vernon E. Kousky, and Robert J. Joyce

1. Introduction Precipitation is a fundamental element of the earth’s weather, water, and climate system, and is a primary link in the transfer of mass and energy between the atmosphere and ocean. Because of that, it is important to monitor variations in precipitation, yet it remains a challenge to quantify precipitation over all regions of the planet and even more of a challenge to forecast it correctly. Furthermore, even where rain gauge density is relatively dense, such as over the United

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Kingtse C. Mo, Eric Rogers, Wesley Ebisuzaki, R. Wayne Higgins, J. Woollen, and M. L. Carrera

assimilation and SSTs in the Gulf of California and address the uncertainties in the analyses. The impact studies are based on three of NCEP’s data assimilation systems: one global and two regional systems. The global system is the Climate Data Assimilation System (CDAS). During the EOP, data from the operational Global Data Assimilation System (GDAS) forecast system were also archived. The GDAS products serve as a reference because it has higher resolution and captures the monsoon-related features better

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Wanqiu Wang and Pingping Xie

. (2005) showed that the simulated NAM rainfall from the PSU–NCAR MM5 was sensitive to the specified SSTs. In addition, accurate estimate of SSTs are also found to be important in the monitoring and forecast of hurricane activities in the Gulf of Mexico and the western Atlantic ( Bender and Ginis 2000 ), which have strong potential impacts over North America. Results from these studies indicate that an accurate SST analysis is essential for understanding the mechanisms of the NAM variability and for

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Katrina Grantz, Balaji Rajagopalan, Martyn Clark, and Edith Zagona

–ocean temperature gradient, consequently delaying the summer monsoon. It is reasoned that the wetter winter and spring conditions in the southwestern United States are largely driven by winter oceanic–atmospheric conditions, especially Pacific SSTs, the PDO–ENSO pattern, and the observed increase in ENSO activity in recent decades ( Trenberth and Hoar 1996 ; Rajagopalan et al. 1997 ). Links to the antecedent land, ocean, and atmosphere conditions offer hope for long-lead forecasts of the summer monsoon. This

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Richard H. Johnson, Paul E. Ciesielski, Brian D. McNoldy, Peter J. Rogers, and Richard K. Taft

reviews by Douglas et al. 1993 ; Adams and Comrie 1997 ; Higgins et al. 2003 ) and these features are critical for precipitation forecasting and water resource management in this part of North America. The purpose of this paper is to document the summer 2004 mean flow characteristics and multiscale variability over the NAME domain using data from the NAME sounding network. Particular attention will be given to the kinematic and thermodynamic properties, as well as the apparent heat and moisture

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Michelle Hallack-Alegria and David W. Watkins Jr.

very different, seasonal rainfall totals tend to be uncorrelated with each other, and thus separate cold season drought frequency analysis is warranted. Details of drought frequency analysis for the cold season may be found in Hallack-Alegria (2005) , who also investigated the potential for cold season precipitation forecasting. Preliminary analysis showed significant correlation between warm season ENSO phenomena and winter precipitation, with La Niña events consistently leading drier

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Mekonnen Gebremichael, Enrique R. Vivoni, Christopher J. Watts, and Julio C. Rodríguez

Satellites- Infrared (GOES-IR). These sensors have complementary features that allowed us to look at different aspects of the temporal and spatial variability of rainfall using a multitude of techniques, and also to perform a limited validation assessment. This paper is organized as follows. Section 2 presents the regional topographical and meteorological features. Section 3 describes the study area and the different datasets used. The spatial variability of marginal statistics, joint statistics, the

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J. Craig Collier and Guang J. Zhang

Mexico by the NCEP Global Forecast System (GFS) were analyzed. They showed that the model’s simulation of precipitation over the U.S. southwest and northwestern Mexico is improved when increasing the resolution from T62 to T126. The present study measures the sensitivity to horizontal resolution of CAM3 simulations of the warm-season rainfall associated with the North American monsoon system. It identifies any improvements or degradations in the simulation of the precipitation and upper-level height

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Myong-In Lee, Siegfried D. Schubert, Max J. Suarez, Isaac M. Held, Arun Kumar, Thomas L. Bell, Jae-Kyung E. Schemm, Ngar-Cheung Lau, Jeffrey J. Ploshay, Hyun-Kyung Kim, and Soo-Hyun Yoo

[GFDL Global Atmosphere Model (AM2); Anderson et al. (2004) ], and NCEP [Global Forecasting System (GFS) version 2]. The dynamical and physical schemes of the models are described in detail in Lee et al. (2007) . As in Lee et al. (2007) , we again focus on simulations of the diurnal cycle carried out with prescribed climatological-mean monthly sea surface temperature (SST) forcing, which was obtained from a 20-yr (1983–2002) average of the Reynolds et al. (2002) optimum interpolation (OI) SST

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David J. Gochis, Christopher J. Watts, Jaime Garatuza-Payan, and Julio Cesar-Rodriguez

USW, and C 1 (=0.00145) and C 2 [set equal to 1.0 in accordance with Duchon and Essenberg (2001) ] are regression parameters found using a least squares fitting technique and the experimental controlled flow rate data. This functional form, whose resulting bias-corrected values are shown as open circles in Fig. 2a , permits the correction for larger errors at higher flow rates while providing negligible correction at rates approaching zero. As shown in Fig. 2b , the bias in TE525USW

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