Modeling of Mountain-Valley Wind Fields in the Southern San Joaquin Valley, California

Moore, G.E.; Daly, Christopher; Liu, Mei-Kao; Huang, Shi-Jian

doi:10.1175/1520-0450(1987)026<1230:momvwf>2.0.co;2

Cited by 15 publications

(6 citation statements)

References 12 publications

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“…Previous studies have shown that the prevailing summertime wind pattern is dominated by marine air that penetrates through the Carquinez Strait and splits into two currents when entering the Central Valley, one flowing northeastward toward Sacramento and one flowing southeastward toward San Joaquin Valley [ Moore et al , 1987; Zaremba and Carroll , 1999; Zhong et al , 2004]. Figure 1 shows an analysis of back trajectories during the measurements in this study obtained using NOAA's Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model with meteorological data sets from Eta Data Assimilation System (EDAS40).…”

Section: Site and Methodsmentioning

confidence: 99%

Formation and growth of ultrafine particles from secondary sources in Bakersfield, California

Ahlm¹,

Liu²,

Day³

et al. 2012

J. Geophys. Res.

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[1] In this study, physical and chemical properties of ultrafine aerosol particles are investigated at an urban site in Bakersfield, California, during the CalNex 2010 (California Research at the Nexus of Air Quality and Climate Change) campaign in May and June. Ultrafine particle measurements include particle number size distributions by a scanning Differential Mobility Analyzer (DMA) and size resolved aerosol chemical composition determined with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). Growth events of ultrafine particles were observed on most days and had a very regular pattern. A nucleation mode centered at $20 nm appeared in the morning and grew to 40-100 nm throughout the day. Microphysical modeling and size-resolved HR-ToF-AMS concentrations showed that organic components provided most of the particle growth in the ultrafine mode, and sulfate provided on most days only a minor contribution to the mass of this mode. The ultrafine particle mass was largely dominated by organics (77%), and was at maximum during the afternoon. Elemental carbon (EC) and the AMS tracer C 4 H 9 + for hydrocarbon-like organic aerosol (HOA) peaked in the early morning during rush hour, indicative of primary emissions. The fact that the particle number concentration peaked in the afternoon, when EC was at minimum, indicates that the midday increase in number concentration was likely due to new particle formation. The potential importance of solar radiation, the condensation sink of vapor on existing particles, concentrations of OH, O 3 , SO 2 , NH 3 , and VOCs for both condensational growth and new particle formation is evaluated based on the covariation of these parameters with ultrafine mass. The results suggest that the ultrafine particles are from secondary sources that are co-emitted or co-produced with glyoxal and formaldehyde.

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Section: Site and Methodsmentioning

confidence: 99%

Formation and growth of ultrafine particles from secondary sources in Bakersfield, California

Ahlm¹,

Liu²,

Day³

et al. 2012

J. Geophys. Res.

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“…The topography is of critical importance to the airflow pattern present in the valley. According to previous studies (Schultz et al 1961;Frenzel 1962;Hays et al 1984;Moore et al 1987;Zaremba and Carroll 1999;Zhong et al 2004), the prevailing summertime wind pattern is dominated by a flow of marine air into the Central Valley through a gap in the Coastal Range east of the San Francisco Bay Area. This flow moves into the Delta Region and splits into two currents curving north into the Sacramento Valley and south into the San Joaquin Valley.…”

Section: Measurement Sites and Area Of Interestmentioning

confidence: 99%

Diurnal Evolution and Annual Variability of Boundary-Layer Height and Its Correlation to Other Meteorological Variables in California’s Central Valley

Bianco

Djalalova

King

et al. 2011

Boundary-Layer Meteorol

109

111

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One year of observations from a network of five 915-MHz boundary-layer radar wind profilers equipped with radio acoustic sounding systems located in California's Central Valley are used to investigate the annual variability of convective boundary-layer depth and its correlation to meteorological parameters and conditions. Results from the analysis show that at four of the sites, the boundary-layer height reaches its maximum in the late-spring months then surprisingly decreases during the summer months, with mean July depths almost identical to those for December. The temporal decrease in boundary-layer depth, as well as its spatial variation, is found to be consistent with the nocturnal low-level lapse rate observed at each site. Multiple forcing mechanisms that could explain the unexpected seasonal behaviour of boundary-layer depth are investigated, including solar radiation, precipitation, boundary-layer mesoscale convergence, low-level cold-air advection, local surface characteristics and irrigation patterns and synoptic-scale subsidence. Variations in solar radiation, precipitation and synoptic-scale subsidence do not explain the shallow summertime convective boundary-layer depths observed. Topographically forced cold-air advection and local land-use characteristics can help explain the shallow CBL depths at the four sites, while topographically forced low-level convergence helps maintain larger CBL depths at the fifth site near the southern end of the valley.

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“…Because the synopticscale flows are usually weak, the primary flows in the region are produced by differential heating between water and land and between the valley and surrounding mountain ranges. According to previous studies (Schultz et al 1961;Frenzel 1962;Hays et al 1984;Moore et al 1987;Zaremba and Carroll 1999), the prevailing summertime wind pattern is dominated by marine air that penetrates through the Carquinez Strait, moves through the delta region, and splits into two currents flowing north and south into the Sacramento and San Joaquin Valleys, respectively. Superimposed on this dominant flow pattern are diurnally varying, thermally driven local circulations that flow up the mountain slopes during the day and down the slopes at night.…”

Section: Topography and Summer Climate In Central Californiamentioning

confidence: 99%

Diurnal Evolution of Three-Dimensional Wind and Temperature Structure in California's Central Valley

Zhong

Whiteman

Bian³

2004

Journal of Applied Meteorology

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The diurnal evolution of the three-dimensional summer-season mean wind and temperature structure in California's Sacramento and San Joaquin Valleys (collectively called the Central Valley) is investigated using data from 22 radar wind profiler/radio acoustic sounding systems (RASS) operated as part of the Central California Ozone Study in 2000. The profiler network revealed, for the first time, that the persistent summer-season flow pattern documented by surface observations extends 800-1000 m above the surface. At most locations, upvalley winds persist during both day and night except at the upper ends of the valleys and close to the valley sidewalls where diurnal wind reversals occur. Wind speeds exhibit pronounced diurnal oscillations, with amplitudes decreasing with height. A low-level wind maximum occurs in the lowest 300 m, with a sharp decrease in speed above the maximum. Especially well defined nocturnal low-level jets occur at sites in the southern San Joaquin Valley, where maximum speeds of 10 m s Ϫ1 or more occur 1-2 h before midnight at heights near 300 m. The afternoon mixed layer, generally deeper than 1000 m, increases in depth with up-valley distance in both valleys. At night, temperature inversions develop in the lowest several hundred meters with near-isothermal layers above. Mean temperatures in the lowest 500 m of the valleys are always warmer than at the same altitude over the coast, and temperature increases from the lower to upper valleys. The diurnal oscillations of the coastvalley and along-valley temperature and pressure difference reach a maximum in late afternoon and a minimum in early morning. These oscillations are in phase with the diurnal variation of westerly onshore flows. The alongvalley wind maxima, however, occur 1-2 h before midnight, whereas the along-valley pressure gradient maxima are usually found just before sunset.

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Modeling of Mountain-Valley Wind Fields in the Southern San Joaquin Valley, California

Cited by 15 publications

References 12 publications

Formation and growth of ultrafine particles from secondary sources in Bakersfield, California

Formation and growth of ultrafine particles from secondary sources in Bakersfield, California

Diurnal Evolution and Annual Variability of Boundary-Layer Height and Its Correlation to Other Meteorological Variables in California’s Central Valley

Diurnal Evolution of Three-Dimensional Wind and Temperature Structure in California's Central Valley

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