Opportunity at National Oceanic & Atmospheric Administration (NOAA)
Investigation of Planetary Boundary Processes for State-of-Science Regional Air Quality Modeling
Oceanic and Atmospheric Research, Air Resources Laboratory
||College Park, MD 20740
Human-health and crop-yield potentials are influenced by the air quality (AQ) in the lowest levels of the atmosphere. The planetary boundary layer (PBL) governs the mixing and removal of air pollutants with rather complicated diurnal and geographical characteristics. The daily evolution of the PBL begins with the growth of the layer after sunrise as the sun begins to warm the Earth’s surface with short wave radiation and decays by sunset. The growth phase corresponds to the rapid increase in surface pollutant concentration as sunlight augments the photolytic reactions responsible for ozone (O3) production, and for particulate matter (PM) formation and growth due to organic compounds that also depend on photolytic production processes. AQ modeling within the PBL involves multiple degrees of non-linear phenomena as emissions are discharged primarily near the Earth’s surface and diluted according to the PBL penetration beyond the nocturnal inversion during the morning hours. Radiative heating also results in the nonlinear emission of reactive organic hydrocarbon molecules from vegetation such as isoprene that subsequently reacts rapidly with O3 and other chemical species. Observed nonlinear AQ conditions Within the PBL are also affected by meteorological forcing driven by synoptic flows, air-surface exchanges governed by land-use land-type, topology and chemical forcing affected by emission sources, and rates subject to modulation by soil moisture and meteorological conditions. Nonlinearity during night time conditions is controlled by other factors. Nocturnal atmospheric stability contributes to stagnant winds and exacerbates the frequent occurrence of high concentrations of air pollutants near the Earth’s surface at night. Extremely low PBL heights often prevail, especially for maritime locations—such as observed near large coastal cities. To sum up, the PBL during the periods associated with the morning rush hours and also after sunset pose important research questions for the air quality measurement and modeling sciences. The candidate should be able to work independently on these aspects of planetary boundary layer physics and chemistry research.
Lee P, Ngan RF: Atmosphere 2: 464, 2011
Planetary boundary layer; O3 production; PM formation and growth; Diurnal characteristics; Radiation forcing; Meteorology; Photolytic rates; Air quality; Natural and anthropogenic;
Open to U.S. citizens, permanent residents and non-U.S. citizens
Open to Postdoctoral and Senior applicants
Postdoctoral and Senior Associates will receive an appropriately higher stipend based on the
number of years of experience past their PhD.