Emission Inventory Evaluation Using DISCOVER-AQ Aircraft Data

Transcription

1 Emission Inventory Evaluation Using DISCOVER-AQ Aircraft Data Gary McGaughey, David Allen (PI) and Elena McDonald-Buller (co-pi) Center for Energy and Environmental Resources The University of Texas at Austin August 8, 2014

2 DISCOVER-AQ Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality Primary objective of DISCOVER-AQ is to improve the capability of satellite observations to diagnose near-surface air quality. NASA-sponsored flight campaigns Baltimore-Washington, D.C.: late Jun/Jul 2011 San Joaquin Valley, California: Jan/Feb 2013 Houston: Sep 2013 Denver: Jul/Aug 2014

3 DISCOVER-AQ measurement platforms The A-Train of Earth Observing Satellites NASA King Air NASA P-3B Ground sites

4 NASA P-3B Houston flights during September 2013 Flights were flown on nine days (HGB Max 8-hr O 3 in ppbv in red)

5 Example P-3B flight track: Sept 25, 2013, ~8 a.m. to ~4 p.m. CST

6 Detail: Late morning ship channel spirals: Sept 25, 2013

7 Project overview Ambient measurements from DISCOVER-AQ can be used to assess concentrations and ratios of key compounds in the Houston ship channel region. Observations can be compared to predictions from photochemical modeling to assess the emissions inventory. Measurements collected during the spirals when coupled with estimates of mixing heights from radar wind profiles and wind speed/direction may support calculations of horizontal fluxes for the ship channel under prevailing north-south winds.

8 Project overview (continued) Additional DISCOVER-AQ datasets to be leveraged: Measurements from the 915 MHz Radar Wind Profiler (RWP) at LaPorte will provide hourly estimates of mixing height as well as vertical profiles of wind speed and wind direction representative of the ship channel region. These estimates are expected later this year (Clinton MacDonald, Sonoma Technology, Inc.) Community Multi-scale Air Quality (CMAQ) Version photochemical model simulations for the September 2013 DISCOVER-AQ period are currently being developed (Ken Pickering, NASA GSFC) Meteorological inputs will be generated using Weather Research and Forecast (WRF) Version 3.6 Anthropogenic emissions based on TCEQ s 2012 EI Model configuration will consist of nested domains with horizontal spatial resolutions of 36, 12, 4, and 1.33 km [development of the 1.33 km grid funded by an Air Quality Research Program project; PI: Alan Fried]

9 WRF 36, 12, 4 and 1.33 km grid domains The CMAQ modeling domains will be slightly smaller than the WRF modeling domains (grid cells close to the horizontal edge of the WRF domains will not be included in the CMAQ domains).

10 NASA P-3B flight spirals during September 2013 Our focus to-date has been on analysis of measurements collected by the NASA P-3B during the paired sets of spirals flown north of the Houston ship channel (Channelview) and south of the ship channel (Deer Park). The routine daily flight pattern included three paired sets of ship channel spirals flown during the late morning, early afternoon, and late afternoon. The vertical sampling within the spirals typically began a few hundred meters above the ground (AGL) and extended to 3-4 km AGL. To conserve flight hours, individual flights were sometimes shortened or modified if weather conditions were not conducive to the overall sampling strategy.

11 Summary of P-3B spirals Wind direction (WD) and wind speed (WS) shown below were primarily based on measurements at Moody Tower (70 meters AGL) during the time of the spirals WD/WS will likely be available from the La Porte RWP later this year. Late Morning Spirals Early Afternoon Spirals Late Afternoon Spirals

12 P-3B measurements One-second (often preliminary) datasets were downloaded from in Apr/May 2014; the following measurements have been utilized for our analyses to-date: Geographic: altitude, latitude, longitude Meteorology: mixing ratio, relative humidity, static temperature, potential temperature, wind speed, wind direction Trace gases: Carbon Dioxide (CO 2 ), Ozone (O 3 ), Total Reactive Nitrogen (NO y ), Nitrogen Oxide (NO), Nitrogen Dioxide (NO 2 ), Sulfur Dioxide (SO 2 )

13 P-3B measurements (continued) Proton Transfer Reaction Time of Flight Mass Spectrometer (PTRMS) Volatile Organic Compounds (VOCs) Biogenic: Monoterpenes, Isoprene and its oxidation products MVK_MACR_Crotonaldehyde Oxygenated VOCs: acetaldehyde, MEK_butanal, aceticacid_glycoaldehyde, acetone_propanal Aromatics: benzene, toluene, C8-alkylbenzenes, C9-alkylbenzenes Alkenes: propene (ethylene was not measured) Other: acetonitrile Formaldehyde by Difference Frequency Generation Absorption Spectroscopy

14 Average and maximum gas phase concentrations using all spiral measurements collected between 350 and 1000 meters AGL Examination of the vertical profiles of temperature, potential temperature, and water vapor mixing ratio within the ship channel spirals flown across the 9 flight days suggested that the mixing height was often (but not always) > 1 km above ground level. Future analyses will use hourly mixing heights from the La Porte RWP in conjunction with the aircraft meteorological data. The minimum sampling height AGL at Channelview was often ~350 m; the minimum sampling height at Deer Park was often lower. To provide an overview of the magnitude of gas phase concentrations, all measurements collected between meters AGL were used to compute average and maximum concentrations by compound.

15 Average and maximum gas phase concentrations (ppbv) using all m measurements in the ship channel spirals

16 Average and maximum VOC concentrations (ppbv) using all m measurements in the ship channel spirals

17 Comparison of downwind to upwind vertically-averaged concentrations on Sep 24, 25, and 26 Cold fronts moved through southeast Texas on 9/21 and 9/25. Northerly winds in the lower atmosphere on the 9/24 and 9/25 flights placed Deer Park downwind of Channelview. On 9/26, a reversal in wind direction associated with southerly return flow from the Gulf of Mexico placed Channelview downwind of Deer Park. The following slides show results using the m average concentrations within the ship channel spirals flown on 9/24 (3 sets of spirals), 9/25 (3 sets) and 9/26 (2 sets): Ozone NO y SO 2 Propene Benzene

18 Sept 24: Upwind and downwind concentrations (selected compounds) by spiral

19 Sept 25: Upwind and downwind concentrations (selected compounds) by spiral

20 Sept 26: Upwind and downwind concentrations (selected compounds) by spiral

21 Ozone: Downwind to upwind concentration ratios by time of day

22 NOy: Downwind to upwind concentration ratios by time of day

23 SO2: Downwind to upwind concentration ratios by time of day

24 Propene: Downwind to upwind concentration ratios by time of day

25 Benzene: Downwind to upwind concentration ratios by time of day

26 Median downwind to upwind concentration ratios (across 8 spirals flown 9/24-26) for selected compounds

27 Example vertical profiles The measurement data collected in the spirals provide information on the variability of concentrations within and above the mixed layer. Because the spiral pattern consists of circles with diameters of ~10 km, the path sampled by the aircraft inherently captures horizontal spatial variation (at ~10 km distance scale) as well as vertical variability. The data collected within the spirals indicate that concentrations of most compounds typically associated with emissions from industrial sources commonly have substantial variation with respect to height within the mixed layer. The examples presented today are focused on the late afternoon spiral flown on 9/25.

28 Vertical profiles of temperature (left) and mixing ratio (right) during the late afternoon pair of ship channel spirals on 9/25 Channelview (red) is upwind of Deer Park (blue) With respect to height between 2.2 km AGL and 2.5 km AGL, temperatures show a slight increase while water vapor mixing ratio decreases sharply from ~9.5 g/kg to ~1-2 g/kg. The profiles above strongly suggest a mixed layer (ML) height of ~2.2 km AGL.

29 Vertical profiles of ozone (left) and formaldehyde (right) during the late afternoon pair of ship channel spirals on 9/25 Ozone above the ML was similar at both locations at ppbv. Ozone within the ML averaged 107 ppbv at Channelview and 121 ppbv at Deer Park. The vertical increases and decreases with respect to height for formaldehyde are somewhat similar to those for ozone.

30 Vertical profiles of NOy (left) and SO2 (right) during the late afternoon pair of ship channel spirals on 9/25 Concentrations of NOy and SO2 above the ML are low. Multiple increases and decreases of concentrations with respect to height throughout the ML (especially at Deer Park) suggest that the aircraft is flying through one or more emission plumes from nearly industrial sources. The next slide shows a classed post plot of SO2 concentrations over a map of the Houston ship channel to identify the Deer Park locations where SO2 > 5 ppbv were measured.

31 Aircraft-measured SO2 concentrations during the late afternoon on Sept 25, 2013; Concentrations >=5 ppbv shown in red

32 Vertical profiles of propene (left) and benzene (right) during the late afternoon set of ship channel spirals on 9/25 Channelview (upwind) concentrations for propene and benzene are consistently low both within and above the ML. Highest propene concentration at Deer Park is 11.2 ppbv. Highest benzene concentration at Deer Park is 2.1 ppbv.

33 Summary Limited analysis of the spatial variation of highest concentrations collected within individual spirals suggest that the aircraft is flying through distinct plumes associated with emissions from ship channel industrial sources that may or may not be well-mixed within the mixed layer and cover only portions of the spiral. For a given set of paired spirals during 9/24-26, the average lower atmospheric concentrations for compounds typically associated with emissions from industrial sources were highest at the location downwind of the ship channel. Measurements within the spirals commonly showed substantial variation with respect to height AGL especially for the location that is downwind of the ship channel.

34 Future Work Measurements collected within the spirals combined with La Porte RWP estimates of mixing height, wind speed, and wind direction will be used to analyze the local meteorological conditions impacting the ship channel region on each flight day. The P-3B measurements will be used to investigate concentrations and ratios of key compounds on days with favorable (e.g., North/South) winds in the lower atmosphere. Data collected on 9/24, 9/25, and 9/26 are the initial focus. Observations will be compared to predictions from photochemical modeling to assess the emissions inventory. The meteorology used in CMAQ will be specific to September 2013 CMAQ predictions are planned at a relatively fine-scale horizontal grid resolution of 1.33 km