scholarly journals Review of acp-2016-981, “WRF-Chem simulation of aerosol seasonal variability in the San Joaquin Valley” by Longtao Wu et al.

2017 ◽  
Author(s):  
Anonymous
2016 ◽  
Author(s):  
Longtao Wu ◽  
Hui Su ◽  
Olga V. Kalashnikova ◽  
Jonathan H. Jiang ◽  
Chun Zhao ◽  
...  

2016 ◽  
Author(s):  
Longtao Wu ◽  
Hui Su ◽  
Olga V. Kalashnikova ◽  
Jonathan H. Jiang ◽  
Chun Zhao ◽  
...  

Abstract. WRF-Chem simulations of aerosol seasonal variability in the San Joaquin Valley (SJV), California are evaluated by satellite and in-situ observations. Results show that the WRF-Chem model successfully captures the distribution, magnitude and variation of SJV aerosols in cold season. However, the aerosols are not well represented in warm season. Aerosol simulations in urban areas during the cold season are sensitive to model horizontal resolution, with better simulations at 4 km resolution than at 20 km resolution, mainly due to inhomogeneous distribution of anthropogenic emissions. In rural areas, the model sensitivity to grid size is rather small. Our observational analysis show that dust is a primary contributor to aerosols in the SJV, especially in the warm season. Aerosol simulations in the warm season are sensitive to parameterization of dust emission in the WRF-Chem model. The GOCART (Goddard Global Ozone Chemistry Aerosol Radiation and Transport) dust scheme produces very little dust in the SJV while the DUSTRAN (DUST TRANsport model) scheme overestimates dust emission. Vertical mixing of aerosols is not adequately represented in the model comparing to CALIPSO (Cloud-Aerosol Lidar and Infrared pathfinder Satellite Observation) aerosol extinction profiles. Improved representation of dust emission and vertical mixing are needed for better simulations of aerosols in warm season in the SJV. Aerosols generated by wild fires are not captured in the simulations with climatological fire emissions, underscoring the need of fire emission observations for operational usage.


2017 ◽  
Vol 17 (12) ◽  
pp. 7291-7309 ◽  
Author(s):  
Longtao Wu ◽  
Hui Su ◽  
Olga V. Kalashnikova ◽  
Jonathan H. Jiang ◽  
Chun Zhao ◽  
...  

Abstract. WRF-Chem simulations of aerosol seasonal variability in the San Joaquin Valley (SJV), California, are evaluated by satellite and in situ observations. Results show that the WRF-Chem model successfully captures the distribution and magnitude of and variation in SJV aerosols during the cold season. However, aerosols are not well represented in the warm season. Aerosol simulations in urban areas during the cold season are sensitive to model horizontal resolution, with better simulations at 4 km resolution than at 20 km resolution, mainly due to inhomogeneous distribution of anthropogenic emissions and precipitation that is represented better in the 4 km simulation. In rural areas, the model sensitivity to grid size is rather small. Our observational analysis reveals that dust is a primary contributor to aerosols in the SJV, especially during the warm season. Aerosol simulations in the warm season are sensitive to the parameterization of dust emission in WRF-Chem. The GOCART (Goddard Global Ozone Chemistry Aerosol Radiation and Transport) dust scheme produces very little dust in the SJV, while the DUSTRAN (DUST TRANsport model) scheme overestimates dust emission. Vertical mixing of aerosols is not adequately represented in the model based on CALIPSO (Cloud-Aerosol Lidar and Infrared pathfinder Satellite Observation) aerosol extinction profiles. Improved representation of dust emission and vertical mixing in the boundary layer is needed for better simulations of aerosols during the warm season in the SJV.


1992 ◽  
Vol 5 (4) ◽  
pp. 299-305 ◽  
Author(s):  
lonan Marigómez ◽  
Manu Soto ◽  
Eduardo Angulo

2017 ◽  
Vol 94 (3) ◽  
pp. 37-61
Author(s):  
Douglas R. Littlefield

Some histories of California describe nineteenth-century efforts to reclaim the extensive swamplands and shallow lakes in the southern part of California's San Joaquin Valley – then the largest natural wetlands habitat west of the Mississippi River – as a herculean venture to tame a boggy wilderness and turn the region into an agricultural paradise. Yet an 1850s proposition for draining those marshes and lakes primarily was a scheme to improve the state's transportation. Swampland reclamation was a secondary goal. Transport around the time of statehood in 1850 was severely lacking in California. Only a handful of steamboats plied a few of the state's larger rivers, and compared to the eastern United States, roads and railroads were nearly non-existent. Few of these modes of transportation reached into the isolated San Joaquin Valley. As a result, in 1857 the California legislature granted an exclusive franchise to the Tulare Canal and Land Company (sometimes known as the Montgomery franchise, after two of the firm's founders). The company's purpose was to connect navigable canals from the southern San Joaquin Valley to the San Joaquin River, which entered from the Sierra Nevada about half way up the valley. That stream, in turn, joined with San Francisco Bay, and thus the canals would open the entire San Joaquin Valley to world-wide commerce. In exchange for building the canals, the Montgomery franchise could collect tolls for twenty years and sell half the drained swamplands (the other half was to be sold by the state). Land sales were contingent upon the Montgomery franchise reclaiming the marshes. Wetlands in the mid-nineteenth century were not viewed as they are today as fragile wildlife habitats but instead as impediments to advancing American ideals and homesteads across the continent. Moreover, marshy areas were seen as major health menaces, with the prevailing view being that swampy regions’ air carried infectious diseases.


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