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Rich F. Coleman, James F. Drake, Michael D. McAtee, and Leslie O. Belsma

mechanisms as natural precipitation. If the quantities of water involved are similar to natural precipitation amounts, then similar mesoscale weather effects will result. Preliminary screening of the various types of human activity that add water to the environment identified three types that add water in amounts comparable to natural precipitation in the forecast area. As a result, it was hypothesized that the observed warm bias was a result of neglecting these sources of anthropogenic moisture, which

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Ming Cai, Chul-Su Shin, H. M. van den Dool, Wanqiu Wang, S. Saha, and A. Kumar

available would allow us to, as did Doblas-Reyes et al. (2006) and Liniger et al. (2007) , compare model states with and without GHG increases. Instead, we compare reality (subject to GHG increases) to model states with constant GHGs but realistic initial states. Our analysis can also be considered as an alternate way to reveal the effects of anthropogenic GHGs. The advantage of this alternative method is that, by virtue of including the warming signal in the initial conditions, this approach could

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Andrew W. Ellis and Daniel J. Leathers

1. Introduction At its peak in winter, snow covers approximately 46% of the land surface in the Northern Hemisphere, or about 46 million km 2 ( Robinson et al. 1995b ). Large changes in snow cover extent can modify atmospheric conditions through much of the earth’s troposphere due to the radiative effects of snow. Studies have indicated that snow cover can lower surface air temperatures over timescales of days to months by increasing the surface albedo and through the latent heat of melting (e

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Seungkyu K. Hong, Sang-Boom Ryoo, Jinwon Kim, and Sang-Sam Lee

are generally larger than in other regions due to the effects of anthropogenic aerosols from industrial sources. Although anthropogenic aerosols are screened using the PM 10 –PM 2.5 threshold, as shown in Plaza et al. (2011) , nitrates, one of the major anthropogenic aerosols, sometimes occur in the range 3.2–5.6 μ m, leading to overestimation of Asian dust days for the heavily industrialized four provinces in the Huabei Plain. Similar to the observation, the simulation shows ( Fig. 4b ) a

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Min Li, Ting Zhang, Jianzhu Li, and Ping Feng

standardized precipitation index (SPI) concept and has the same advantages as the SPI in practical applications. Numerous studies have documented that both large-scale oceanic–atmospheric circulation patterns and human activities have significant effects on hydrological drought in China ( Hao et al. 2008 ; Li et al. 2012 ; Zhan et al. 2013 ; Wang et al. 2009 ; Lin et al. 2012 ). Li et al. (2014) quantified the influence of land use change on runoff decreases in the Panjiakou reservoir basin (in the

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Mark P. DeLisi, Alan M. Cope, and Jason K. Franklin

1. Introduction Numerous investigators have examined day-of-the-week weather variations as a means of gauging anthropogenic influence on climate. Their results appear to give a rather mixed message. Rainfall data presented by Nicholson (1965) seemed to indicate that Thursday is the wettest day of the week in parts of England. On the other hand, Cehak (1982) found no significant weekday–weekend variation in rainfall over central Europe. Simmonds and Kaval (1986) looked at 26 yr of data for

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R. Hamdi, Daan Degrauwe, and P. Termonia

effort to properly drive the atmospheric boundary layer. LSMs have tended to concentrate on the processing of water and energy balance by vegetative, water, and soil surfaces, as these land-class types represent the majority of land cover. As a result, most NWP models ignore urban land use, or simply use modified values for a number of surface-characterizing variables without any modification due to the 3D effects, high roughness, and anthropogenic influence. This failure would be expected to have

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Jianping Huang, Jeffery McQueen, James Wilczak, Irina Djalalova, Ivanka Stajner, Perry Shafran, Dave Allured, Pius Lee, Li Pan, Daniel Tong, Ho-Chun Huang, Geoffrey DiMego, Sikchya Upadhayay, and Luca Delle Monache

/Chem) modeling system are used to generate lateral boundary conditions of gas-phase and other aerosol-phase chemical species to the CMAQ. The emission inputs for NAQFC are processed in two different ways, depending on the nature of the emission sources and their sensitivity to meteorology ( Pan et al . 2014 ; Tong et al. 2015 ). Anthropogenic sources including area, mobile, and point sources are obtained from North American environmental agencies. The U.S. emission sources are based on a mixture of the EPA

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David J. Kellenbenz, Thomas J. Grafenauer, and Jonathan M. Davies

evapotranspiration (ET; Holt et al. 2006 ). These observations motivated a study of the synoptic and mesoscale environment associated with this event, which is presented in this paper. The following section is a brief documentation of the tornadoes that occurred on 18 July 2004. An analysis of the associated synoptic and mesoscale environment over eastern North Dakota, including common parameters used in supercell tornado forecasting, will then be presented. The possible effects of ET on boundary layer moisture

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Ernest Agee and Erin Jones

favorable sources for eventual concentration of vorticity into the developing tornado (see Houston and Wilhelmson 2007 ); and the effects of frictionally induced convergence. The intent here is to not explain the variety of intricate details in the evolution of a type I tornado, but to present the infrastructure or boilerplate format for identification (and thus classification). In summary, the type I tornado is produced by a discrete mesocyclonic supercell storm with an SLU that interacts favorably

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