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;
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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.
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National Air Quality Forecast over Hawaii
A suite of reactive gases and aerosols emitted from the Ocean:

Isoprene;

Dimethyl Sulfide (DMS);
Organic Aerosols;

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Algae Bloom and Ocean Cloudiness
(Meskhidze and Nenes, Science, 2006)
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A Review of Approaches for Marine Isoprene Emissions
Eiso - Isoprene emission;
 Shaw et al. (2003):
[Chl-a] - Isoprene emission;
Eiso = [Chl - a] *V * EF
V – euphotic water volume;
 Palmer & Shaw (2005):
EF – Emission factor;
Eiso = KAS * (CW - H * CA)
P - CW (ki * CXi + kbio + kAS / ZML) - LMIX = 0
ki – chemical reaction rate for oxidant i;
kbio – bacterial loss rate;
CW – isop. conc. in water
CA – isop. conc. in the air
H – Henry’s law constant;
LMIX – loss due to downward mixing;
P – isoprene production;
 Gantt et al. (2009):
Eiso = SA * H max *[Chl - a] * Fiso * ò
H max
0
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kAS – exchange coeff.;
Air Resources Laboratory
Pdh
Hmax – euphotic zone height;
ZML – mixing layer height;
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JPSS marine Isoprene algorithm (V1.0)
 Built upon several pioneering works:
JPSS Products Used:
 [Chl-a]
N
F = a ´[Chl]´ å(EFi ´ fi )´ H max ´ g
i=1
 Kd490
 PAR
Euphotic zone height (Gantt et al., 2009)
2.5
H max = (- ln( ) / K 490 )
I0
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
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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

Chlorophyll-a
Kd(490)
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Global Distribution of Marine Isoprene
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:
Eiso  KAS * (CW  H * CA)
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:
KAS  0.31  U 2 (( 3913.15  162.13T  2.67T 2  0.012T 3 ) / 660) 0.5
U – surface wind speed;
T – Sea surface Temperature
(Wanninkhof et al., 2004)
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Isoprene applications:
National and regional air quality forecasting
Global
Isoprene
(April 2014)
Isoprene into
CMAQ
domains
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: [email protected]
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Summary & Future Plan

Derived global high-resolution marine isoprene emissions;

The emission data validated with ship measurements;

Data will be made available to CMAQ users;

Future plans include adding additional trace gases and organic
aerosol emissions to better capture ocean emissions into the air.
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