AERONET Activities and Future Plans

David Giles1,2, Brent Holben2, Thomas Eck2,3,

Joel Schafer1,2, Alexander Smirnov1,2, Ilya Slutsker1,2,

Aliaksandr Sinyuk1,2,Mikhail Sorokin1,2,Jason Kraft2,4,

and Daniel Meiselman2,4

1 Science Systems and Applications, Inc.2 NASA Goddard Space Flight Center

3 Universities Space Research Association 4 Fibertek, Inc.

SPARTAN 3rd Annual MeetingApril 19, 2018

• Aerosol Remote Sensing Using Sun/Sky Scanning Radiometers• Measure light intensity from UV to Vis to NIR (8-10 wavelengths)• Aerosol Optical Depth (Direct Sun or Direct Moon)• Inferred Aerosol Properties (Direct Sun and Sky Radiances)

• Widely Used by the Aerosol Community• Aerosol Characterization and Climatology• Satellite and Model Evaluation• Model Assimilation• Synergism with other Earth Science data sets

Aerosol Robotic Network (AERONET)http://aeronet.gsfc.nasa.gov

AERONET V3 L2

2

Cimel Sun/Sky Radiometer2016

V3 AOD Data Quality LevelsLevel 1.0 – Minimally screenedLevel 1.5 – Cloud Screened & Quality ControlledLevel 2.0 – Quality assured

Vo

V m~1/cosθz

TOA

StandardizationMeasurements

• Cimel radiometers

• Direct sun measurements (every 3 to 15 minutes)

• Sky scans performed hourly (e.g., almucantar, principal plane)

Calibration

• Langley calibration technique for reference instruments

• Calibration transfer from reference to field instruments

• Integrating sphere calibrated by NIST light source for sky measurements

Processing

• Known techniques for computing aerosol properties

• Implementing EOS data sets (e.g., NCEP reanalysis fields, OMI NO2, TOMS O3)

• Processed and freely available on web site in near real time

AERONET Version 3: AOD• V3 Level 1.0: Unscreened data (NRT)

• Applies new temperature characterizations

• Updated coordinates and elevation

• Applies NO2 OMI L3 climatology (2004-2013)

• Applies updated absorption coefficients (Literature/HITRAN)

• V3 Level 1.5: Based on Level 1.0 (NRT)

• Improved cloud screening

• New quality controls applied

• V3 Level 2.0: Based on Level 1.5 with pre- and post-calibration and temperature characterization applied

• Level 2.0 data quality confirmed during post-field calibration evaluation and released 30 days afterwards to allow for updates to ancillary databases

• Significantly improves timeliness of Level 2.0 data availability

AOD and Principal Plane sky radianceindicate obstruction affecting measurement

Anomalous temperatures

NCEP

Giles et al. 2018, in preparation AERONET Version 3 AOD Algorithm Quality Control

Technical Description (2018), in preparation

ARCTAS

SCAR-B ZIBBEE

SAFARI 2000

INDOEX

TIGERZBASE-Asia

SEAC4RS-SEUS

DRAGONs7-SEAS

KORUS-AQ

ORACLES

UAE2

Distributed Regional Aerosol Gridded Observation Network (DRAGON)

• DRAGON Objectives• Multidimensional validation

data set for satellite remote sensing of aerosol properties

• Comparison to related surface and airborne in situmeasurements

• Assessment of the evolution of aerosol properties from transported particulates

• Method• Deploy up to 40 Sun/sky

radiometers

Holben et al, 2018, An overview of meso-scale aerosol processes, comparison and validation studies from DRAGON networks

Eck et al, 2014, Observations of rapid aerosol optical depth enhancements in the vicinity of polluted cumulus clouds

Radius (µm)

Deer Park, TX

Radius (µm)

ManvelCroix, TX

• LARGE in situ air craft measurements:

• Ultra high sensitivity aerosol spectrometer (UHSAS)<0.1-0.5 µm

• Dry Sample

• AERONET – Ambient measurement

DRAGON-TX/DISCOVER-AQ

• AERONET and LARGE fine mode volume concentration peaks match after growthfactor applied to LARGE data set• AERONET coincident within ±60 minutes

of LARGE spiral• No adjustment is made to LARGE

concentration when applying growth factor Schafer et al, in preparation

Aerosol Volume Concentration

DRAGON and DISCOVER-AQ

Schafer et al, in preparation

• Comparison of peak volume concentration radius for coincident measurements for DISCOVER-AQ and AERONET DRAGON

• More agreement (~0.02µm) with AERONET on average when applying the growth factor to the LARGE data at MD, CA and TX

• Note: GF factor calculations provided by LARGE -0.04

-0.02

0

0.02

0.04

0.1 0.15 0.2 0.25 0.3 0.35

MDCATXCOMD GFCA GFTX GF

AE

RO

NE

T-L

AR

GE

Pe

ak R

adiu

s D

iffe

rence

(

m)

AERONET Peak Radius Mean (m)

N

3

36

27

28

3

36

27

AERONETNew Instrumentation/Enhancements

• Improved solar tracking reducing triplet variance

• Greater control over instrument measurement scenarios (e.g., CCS and Hybrid)

• Lunar measurements• 1st to 3rd quarter lunar phase (waxing to

waning gibbous)• Processing for lunar measurements (e.g., ROLO,

Tom Stone)

• Development toward attachment for CO2 measurements (Emily Wilson)

• Synergism with MPLNET, PANDORA, SPARTAN, and in situ measurements

Cimel Sun/Sky/Lunar Radiometer

Hybrid Scan results in many more retrievals at AOD> 2 at 440 nm since Hybrid scans can be made at mid-day with low Solar Zenith Angle (SZA). Almucantar scans require SZA > 50 degrees – this results in insufficient signal to measure 440 nm AOD when AOD is very high

Hybrid and Almucantar Sky Scan Retrievals

Eck et al. 2018, in preparation

Provisional Lunar AODKanpur, India 22–23 February 2016

0

0.1

0.2

0.3

0.4

0.5

53.4 53.6 53.8 54.0 54.2 54.4 54.6 54.8 55.0

AOD 440nm

AOD 500nm

AOD 675nm

AOD 870nm

AOD 1020nm

AOD 1640nm

Aero

so

l O

ptical D

epth

Day of Year

Day Night Day

• Under evaluation

• Instrument nighttime performance

• Lunar calibration and corrections

• Cloud screening and quality controls

Aerosols and More

Ocean Color Solar FluxPARUV-AUV-B

Maritime AOD Cloud Mode

Zibordi et al. [2009], JAOT

Smirnov et al. [2009], JGR Chiu et al. [2010], JGR

Schafer et al. [2004], JGR

Summary

• Version 3 solar AOD and almucantar sky scan inversions now available as of January 2018

• Hybrid sky scans provide additional retrievals near satellite overpass time and for high aerosol loading

• Version 3 lunar AOD can provide periodic 24-hour AOD

• Many AERONET sites already exist in densely populated regions and can potentially be collocated with SPARTAN instrumentation