The Impact of the Chesapeake Bay Climate and Boundary Layer Dynamics on Air Pollutant Concentrations during Smog Episodes

Transcription

1 The Impact of the Chesapeake Bay Climate and Boundary Layer Dynamics on Air Pollutant Concentrations during Smog Episodes Presentation by: Dan Goldberg, PhD Candidate Co-authors: Chris Loughner, Maria Tzortziou, Jeff Stehr, Tim Canty, Tim Vinciguerra, Ross Salawitch, Ken Pickering & Russ Dickerson Presented at: AMS Annual Meeting 2015 Monday January 5, 2015

2 July 2011 DISCOVER-AQ: Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality Three major observational components: NASA UC-12 (Remote sensing) Continuous mapping of aerosols with HSRL and trace gas columns with ACAM NASA P-3B (in situ meas.) In situ profiling of aerosols and trace gases over surface measurement sites Ground sites In situ trace gases and aerosols Remote sensing of trace gas and aerosol columns Ozonesondes Aerosol lidar observations 1

3 P-3B flights spiral over surface sites (typically 3 times per day, 2 hours apart) 12 Pandoras 40 AERONET sunphotometers 5 MPLs EPA NO2 COMMIT NATIVE; ozonesondes Millersville U. tethersonde EPA NO2 NOAA ship PSU tethersonde Howard U. ozonesondes 2

4 NOAA SRVx (Small Research Vessel) 10-day boat campaign in Chesapeake Bay from July 11 20, 2011 Measured O 3 & NO y Researchgrade NO / NOy Analyzer Picture Courtesy: Maria A. Tzortziou, NASA Ozone Analyzer Inside cabin Picture Courtesy: Chris Loughner, NASA 3

5 Surface O 3 over the Bay vs. Land 8-hour maximum surface O 3 is consistently ppb higher at the surface of the Chesapeake Bay than the closest upwind ground site 8-hr Max Surface O 3 Goldberg et al Scale: 20 km 4

6 Late Afternoon High Anomaly Remarkably similar in the AM and early afternoon At 3 PM, there is a noticeable split in the 2 lines By 6 PM, on average, there is a 20 ppb difference Goldberg et al

7 What are the potential reasons for more ozone over the Chesapeake Bay: 1. Fewer fair-weather cumulus clouds over the Bay allowing for increased photolysis 2. Slower O 3 dry deposition rates over water 3. Shallower boundary layer causing emissions to be trapped close to the surface 4. Decreased boundary layer venting due to meso-high pressure over the Bay Goldberg et al

8 July 20, 2011: MODIS Imagery No clouds over the Chesapeake & Delaware Bays! MODIS imagery from the AQUA satellite at 1:30 PM on July 20, 2011 Increased photolysis over the Bay! 7

9 Differences in Dry Deposition Rates Dry deposition of O 3 over water is up to 10 times slower! When air is stagnant, there can be a significant accumulation of pollutants over the Chesapeake Bay Ozone Dry Deposition rates for Forested, Coastal and Oceanic areas from various literature sources 8

10 Measurements of Boundary Layer height using HSRL from aircraft Goldberg et al Aerosol-based boundary layer: Over land: ~1000 m Over bay: ~500 m Thanks to Rich Ferrare & Chris Hostetler for the HSRL measurements and Amy Jo Scarino for the mixed layer heights 9

11 Impact of the Chesapeake Bay breeze July 2, :00 AM Local time Loughner et al W B Temperatures: Between C (57 68 F) Wind Speed & Direction: Light and from the southwest 10

12 Impact of the Chesapeake Bay breeze July 2, :00 PM Local time Loughner et al W B Temperatures: Between C (88 99 F) Wind Speed & Direction: Southwesterly over land Easterly over the Bay and Ocean! 11

13 Surface O 3 at Edgewood, MD Maryland Monitoring(Location 2011(Design( Projected(2018( Value Design(Value Edgewood Aldino Red Indicates above the 75 ppb National Ambient Air Quality Standard (NAAQS) Projections using CAMx v6.10 and 2018 NEI v1 emissions There s an observed 10 ppb Chesapeake Bay penalty factor 12

14 Where is this O 3 coming from? Along the Chesapeake Bay Modeling domain 30% within Maryland, but the majority from out-of-state! 13

15 Where is this O 3 coming from? Inland Modeling domain These results suggest a large emission source in/near the Bay: Shipping emissions! (Montgomery et al., in prep) When the Bay influence is diminished the amount of O 3 attributed to Maryland decreases dramatically! 14

16 Ozone from Shipping Emissions in the Chesapeake Bay Baseline No Ship Emissions Average Surface O 3 for 2 PM during month of August 2007 See Lynn Montgomery Poster 752, Hall 4, Wednesday 2:30 4:00 PM 15

17 Conclusions Higher concentrations of surface ozone over the Chesapeake Bay have been confirmed. Likely reasons for this high anomaly: 1. Higher photolysis rates 2. Slower dry deposition rates 3. Shallower PBL 4. Decreased PBL venting 5. Shipping emissions Pollutants are advected in the Bay breeze to shoreline communities causing poor air quality in locations popular for summertime activities. 16

18 For more information please see: 17

19 EXTRA MATERIAL 18

20 MODIS Imagery from Other Days 19

21 Near surface nitrate aerosols in the 1-km CMAQ Air Quality model Mean nitrogen aerosol concentration from 9 AM June 28, 2011 through July 5, AM Higher total nitrogen aerosol over the Bays, perhaps from shipping emissions Observations from the CASTNET sites do not pick up on this fine spatial gradient! 20

22 Deposition in the 12-km CAMx Air Quality model l Total NO 3 Wet deposition during July 2011 Observations of wet deposition from the NTN NADP Network are overlaid Also, a local maximum in wet deposition at the bay breeze convergence zone! 21