Slide 1

Active Remote Sensing in the Baltimore-Washington DC Metropolitan Area: UMBC Monitoring of Atmospheric Pollution (UMAP)Ruben Delgado, Jaime Compton, Daniel Orozco,Patricia Sawamura, Kevin Majewski, Timothy Berkoff, Kevin J. McCann, and Raymond M. Hoff

Atmospheric Lidar GroupUniversity of Maryland-Baltimore County

2011 National Air Quality Conference, San Diego, CA1Remote sensing studies of the atmosphere with lidar measurements to determine the vertical distribution of aerosols (natural and anthropogenic) and water vapor.

Lidar activities at UMBC support NOAA CREST Lidar Network, WMO-GALION, Maryland Department of the Environment and NASA and NOAA satellite calibration/validation measurements.

Understanding optical, chemical and physical properties of atmospheric aerosols and gases.

The integration of atmospheric aerosol measurements into practical tools contributes to informed policymaking on issues of air quality, long-range transport of pollutants and climate change .UMBC Atmospheric Lidar Group

Profiling Air Quality over BaltimoreUMBC Monitoring of Atmospheric Pollution (UMAP)http://alg.umbc.edu/umapLidar (light detection and ranging)

4Air Quality: Pollutant TransportDifficulty to determine sources contributing to local pollution. Aerosols remain in the environment for long periods and can be transported by winds globally. The air we breathe is strongly affected by local-to-regional-to-global pollution sources.

Atmospheric and pollution dynamics aloft are missed by surface instruments. Insight into processes influencing the fate of pollutants in the atmosphere.

Transport aloft is important during pollution events: pollutants aloft mix down increasing surface concentrations.

5For air quality concerns, the most important aspect of the LLJ is that it forms in the residual layer. The residual layer contains the remnants of the well mixed boundary layer from the previous afternoon. The well-mixed residual layer is homogenous, retaining the structure and air mass characteristics of the previous day. As the atmosphere exhibits no boundaries in space or time, interstate pollutant transport occurs continuously throughout the diurnal cycle. During the daytime when the atmospheric column is well mixed, it is difficult to apportion the relative impact of long-range emissions versus local emissions. However, during the night when the atmosphere stratifies, pollutant concentrations can sometimes become isolated in the residual layer. The residual layer creates an opportunity to observe interstate transport before local emissions contribute to the total pollutant load. The obstacle is finding a way to take measurements from within the residual layer, which is typically 300-600m above the surface of the ground. All types of transport move an elevated reservoir of ozone and ozone precursors into the Washington region.Planetary Boundary LayerParticle pollution and gases are primarily trapped within the PBL.Aerosols can be used as tracer of height and dynamics within PBL.

Planetary Boundary LayerDiagnostic variable atmospheric transport and dispersion forecasting models.

Without realistic PBL heights models have large errors that result in inadequate public protection against unhealthy air quality.

National Research Council has recommended a network of networks1After 60 years of remote sensing research, it is astounding that the PBL is not measured regularly throughout its diurnal cycle

1- NRC. 2009. Observing Weather and Climate from the Ground Up: A Nationwide Network of Networks. Washington, DC: National Academy Press.

7

Strong winds, associated to frontal activity, provide a mechanism of injection of soil (sand) from the Gobi and Taklimakan deserts into troposphere [Merrill et al., 1989].

Asian dust contributes 0.2-1.0 g m-3 of the total PM2.5 mass concentration in North America, with higher frequency of transport during spring (March-May) [VanCuren and Cahill, 2002].

Dust particles affect the concentration of gaseous pollutants and secondary aerosols components by acting as condensation surfaces and catalysts in heterogeneous reactions [Dentener et al., 1996; Wang et al., 2007].Trans-Pacific Transport of Asian Dust

OMI Aerosol Index

AIRS Infrared Dust Flag Product April 2006DeSouza-Machado et al., GRL, 33, L03801, 2006.

DateDateDate

BaltimoreApr 17Apr 20Apr 23PM2.55.104.839.37PM1012.2016.7012.90PM coarse7.1011.873.53PM2.5 dust0.971.810.53Ca0.060.140.03IMPROVEAerosol Monitoring NetworkPM2.5 dust = 2.2[Al] + 2.49[Si] + 1.63[Ca] + 2.42 [Fe] + 1.94[Ti].Malm et al., J. Geophys. Res. 1994, 99, 13471370.Ca: April 20, 2006

SmokeJune 13June 11June 12June 10North Carolina Wildfireshttp://rapidfire.sci.gsfc.nasa.gov/subsets/16Smoke from biomass burning:

Increase PM2.5 directly by injecting carbonaceous aerosols into the atmosphere.

Increase ozone indirectly by increasing carbon monoxide (CO), nitrogen oxides (NOx), and volatile organic compounds (VOCs).

McKeen et al. (2002): J. Geophys. Res., 107, D14, 4192. Ozone enhancements (20-30 ppb) due to wildfire emissions. Increase due to the transport of NOx and ozone formed in the plume.

June 13, 200818Nocturnal Low Level Jets (NNLJ)The NLLJ occurs between 00:00 and 7:00 AM and has the following characteristics:- Generally located between 300 and 1000 m in altitude- S-SW wind maximum in the residual layer of 1020 m/s.- Veering winds (turning from S to W) from the surface up through the NLLJ core.

The turbulence generated by this wind shear can induce nocturnal mixing events and enhance surface-atmosphere exchange, thereby influencing the dispersion of pollutants near the surface.

Taubman et al., J. Atmos. Sci., 61, 1781-1793, 2004.Delgado et. al., Atmos. Chem. Phys., 2010.19Efficiently transports moisture, momentum, and air pollutants throughout the Great Plains in USA. The Southern Great Plains (SGP) region of the United Statesis one such region where the LLJ has been studied extensively because of its impact on the development of nocturnal severe storms and role in precipitation In situations with surface winds of less than 5 m/s, wind speeds at altitudes of 100m due to the nocturnal LLJ can be greater than 20 m/s.

A transport mechanism created by mesoscale meteorological conditions also has a significant impact on poor air quality episodesin Maryland. This mechanism is the nocturnal low-level jet (NLLJ) which flow from SW to NE in the Mid-Atlantic region, parallel to and on the lee-side of the Appalachian Mountains.Taubman25 describes the NLLJ in simple terms:

The NLLJ occurs between 12:00 AM and 6:00 AM EST and has the following characteristics: Generally located between 300 and 1000 m in altitude South-Southwesterly wind maximum in the residual layer of 1020 m/s NLLJ core with wind speed maximum greater than those in the underlying nocturnalboundary layer and those just above, but still in the jet Veering winds (turning from S to W) from the surface up through the NLLJ coreThe nocturnal boundary layer provides a low-friction surface over which the jet can travel. Thisphenomenon also seems to be orographically derived, possibly resulting from the differentialheating and pressure gradients associated with sloping terrain on the lee-side of the AppalachianMountains. Pollutant transport via the NLLJ is disproportionately important during periods ofstagnation when geostrophic winds are light.

NLLJ FormationForms between the Appalachian Mountains & Atlantic Ocean.Sunset: ground cools/air poor conductor of heat/air close to ground cools too (~100 meters).Air over mountains cools more than air at same elevation near coast.Temperature gradient induces a southerly wind a few hundred meters above the ground.

Cool AirWarm Air20LLJs tend to occur as part of the standard high O3 weather pattern because diffuse high pressure near the surface means that synoptic scale winds will be light, often variable, so that weaker effects, such as terrain-induced temperature gradients, can determine local wind speed and direction. For forecasting these events, the development of the standard high O3 weather pattern is also a good indicator of the expected presence of a LLJ. Standard features include an upper air ridge with its axis over or west of the region; diffuse surface high pressure straddling the region with the center of high pressure typically over the Appalachians. Subsidence east of the ridge induces clear skies, high temperatures, atmospheric stability, and stagnant winds. These factors enhance photochemistry and inhibit vertical mixing, thereby contributing to increased local concentrations of ozone.

21

The transport of the smoke to the US Mid-Atlantic States caused 24-hour PM2.5 concentrations to reach 2008 US National Ambient Air Quality Standards (NAAQS) exceedance levels (>35 mg/m3).WRF June 14 07:00 UTCChemical Analysis of 24-hour PM2.5 (mg m-3) in MarylandJune 11June 14June 17Nitrate (NO3-)0.360.940.42Sulfate (SO42-)3.675.474.27Ammonium (NH4+)1.272.291.50Organic Carbon (OC)2.8711.432.20ElementalCarbon (EC)0.240.380.28Potassium (K)0.060.130.03Crustal Material0.610.470.30Other8.6610.061.73PM2.517.7531.4410.74Organic Carbon and Potassium are markers for Biomass Burning.

Winter Pollution Events-Surface temperature inversions play a major role in air quality, especially during the winter.

-The warm air aloft on top of cooler air acts like a lid, suppressing vertical mixing and trapping the cooler air at the surface.

-Inversion traps pollutants near the ground, leading to poor air quality.

Non-spherical particles

Size Distribution: Coarse Particle Component Single Scattering Albedo: Aerosols/Dust like signature

PM2.5 [mg m-3]Baltimore PM2.5 Hourly Timeseries

Morphology and Elemental CompositionSEM @ UMBCPIXE @ Univ. of Sao Paulo

DustApril 17-20, 2006UrbanAerosolsForest firesJune 14, 2008P.B. Russell et al., Atmos. Chem. Phys., 10, 1155-1169, 2010.SummaryVertical and temporal resolution of lidar allows:-Assessment of long range transport of natural and anthropogenic aerosols vs. local sources to local air quality.

-Aid source allocation of particle pollution for during Air Quality Action Days. Evidence for Exclusion of Air Quality Exceedance due to Exceptional Events.

-Continuous monitoring of PBL verification and validation of forecasts and models.

Lidar + real time ground monitoring of pollutants: Characterization of temporal and spatial changes ofparticle pollution, oxidants, and precursors.

AcknowledgementsMaryland Department of the Environment (U00R6200819)Measurement of Nocturnal Low Level Jets with UMBC Lidars

NOAA CCNY Foundation CREST (NA06OAR4810162)

NASA Cooperative Agreement (NNH04ZYO010C)"Three Dimensional Air Quality System (3D-AQS)

NASA (NNX08AO93G)"Profiling Air Quality over Baltimore

http://alg.umbc.edu/usaqhttp://alg.umbc.edu/umap

*The statements contained within the presentation are not the opinions of the funding agencies or the U.S. government, but reflect the authors opinions. 30

Madison, WIhttp://lidar.ssec.wisc.edu/

CALIPSO April 17, 2010 07:30 UTC

Hampton, VA

CALIPSO April 19, 2010 06:00 UTCBaltimore, MD

PM2.5 in Baltimorehttp://www.epa.gov/ttn/airs/airsaqs/detaildata/downloadaqsdata.htm