Daniel Tong, Hang Lei, Li Pan, Pius Lee NOAA Air Resources Laboratory (ARL), College Park, MD

1. Global high-resolution marine isoprene emission derived from VIIRS-SNPP and MODIS-Aqua ocean color observations Daniel Tong, Hang Lei, Li Pan, Pius Lee NOAA Air Resources Laboratory (ARL), College Park, MD Menghua Wang NOAA Center for Satellite Applications and Research (STAR), College Park, MD Brett Gantt and Sarwar Golam US EPA Office of Research and Development Jeff McQueen and Ivanka Stajner NOAA National Weather Services Acknowledge: NOAA Joint Satellite System Proving Ground Program for funding support; Air Resources Laboratory

2.   Marine Isoprene Emission Isoprene (CH2=CH-C(CH3)=CH2) is a biogenic hydrocarbon emitted by trees, grasses and ocean phytoplankton. • Oceans cover 70% of Earth’s surface, but marine emissions are highly certain; • Marine emissions play oversized roles in cloud formation in pristine environment; • Anthropogenic emissions decreasing and ozone standards tightened  marine emissions and chemistry become increasingly important; • Marine chemistry being added to CMAQ  carefully verified emissions; There is a similar need for climate models and Earth System models. 2

3. National Air Quality Forecast over Hawaii A suite of reactive gases and aerosols emitted from the Ocean: • Isoprene; • Dimethyl Sulfide (DMS); • Organic Aerosols; Air Resources Laboratory

4. Algae Bloom and Ocean Cloudiness (Meskhidze and Nenes, Science, 2006) Air Resources Laboratory

5. Eiso - Isoprene emission; • Shaw et al. (2003): [Chl-a] - Isoprene emission; A Review of Approaches for Marine Isoprene Emissions V – euphotic water volume; • Palmer & Shaw (2005): EF – Emission factor; kAS – exchange coeff.; CW – isop. conc. in water ki – chemical reaction rate for oxidant i; CA – isop. conc. in the air kbio – bacterial loss rate; H – Henry’s law constant; LMIX – loss due to downward mixing; P – isoprene production; • Gantt et al. (2009): Hmax – euphotic zone height; ZML – mixing layer height; Air Resources Laboratory

6. Built upon several pioneering works: JPSS Products Used: • [Chl-a] JPSS marine Isoprene algorithm (V1.0) • Kd490 • PAR Euphotic zone height (Gantt et al., 2009) I0 – ground radiation; K490 – defuse attenuation coefficient in water Phytoplankton Functional Types (PFTs) (Arnold et al., 2009) Determine emission factor (EF) and abundance (f); No data available from JPSS, using SeaWiFS climatological data Air Resources Laboratory

7. Chlorophyll-a and Kd(490) • Sensor/Satellite: Visible Infrared Imaging Radiometer Suite (VIIRS) on SNPP • Ocean Color Data Processing: - Multi-Sensor Level-1 to Level-2 (MSL12) is used for VIIRS ocean color data processing - Routine ocean color data production from SDR (Level-1B) to ocean color EDR (Level-2), and to global Level-3 data, including nLw, chlorophyll-a, and Kd(490). - Level 3: Products are mapped to the CoastWatch geographic regions • Algorithms (Ocean Color EDR Team): • Chlorophyll-a concentration: VIIRS OC3 algorithm • Diffuse attenuation coefficient at 490 nm Kd(490): Wang et al. (2009) algorithm 7 Kd(490) Chlorophyll-a

8. Global Distribution of Marine Isoprene

9. Isoprene Observations and Reprocessing Issue: Some data can not be directly used for product validation. Reprocessing Approach: Air-sea mass transfer. Convert seawater conc into flux: kAS – exchange coeff.; CW – isop. conc. in water CA – isop. conc. in the air H – Henry’s law constant; Calculate exchange coeff based on wind speed: U – surface wind speed; T – Sea surface Temperature (Wanninkhof et al., 2004) 1/2/2020 Air Resources Laboratory 9

10. Isoprene applications: National and regional air quality forecasting Global Isoprene (April 2014) Isoprene into CMAQ domains

11. Marine Isoprene Data Spatial coverage: global 4km; Temporal: hourly, daily, weekly, monthly, or yearly; Two products: 1) emission rate with GFS; 2) normalized emission with own met; Data format: 1) netCDF; 2) IOAPI; Data projection: 1) lat-lon; 2) Lambert Conformal Conic Data access Forecasters – Direct data access from NOAA CMAQ and other model users – RSIG(EPA) or CMAS? University users – NSF EarthCube (PI: L. Di) Contact information: Daniel.Tong@noaa.gov

12. Derived global high-resolution marine isoprene emissions; • The emission data validated with ship measurements; • Data will be made available to CMAQ users; Summary & Future Plan • Future plans include adding additional trace gases and organic aerosol emissions to better capture ocean emissions into the air. Air Resources Laboratory