As components of the GOES-R ABI Air Quality products, a multi-channel algorithm similar to MODIS/VIIRS for NOAA’s next generation geostationary satellite sensor, GOES-R ABI to retrieve Suspended Matters (SM) and Aerosol Optical Depth (AOD). ABI is a 16-channel Imager with wavelength coverage extending from visible to thermal IR. Its temporal (five minute coverage of the Contiguous United States) and spatial resolution (2 km at nadir) will provide unprecedented monitoring capabilities of short-lived and localized weather and air pollution events that can sometimes be missed by polar-orbiting satellite sensors. The algorithm development for SM/AOD has been completed and tested using three types of proxy data: (1) ABI radiances generated from a simulator using a radiative transfer model and MODIS derived land and atmospheric variables, (2) ABI radiances generated from a simulator using a radiative transfer model and WRF-CHEM model generated land and atmospheric variables, and (3) MODIS radiances. Analysis based on 10 years of ABI AOD retrievals using MODIS radiances shows that the product meets accuracy specifications (±0.06 over land and ±0.02 over water for AODs ranging between 0.04 and 0.8 and for AODs greater than 0.8, ±0.12 and ±0.1 over land and water respectively). Table 1. Channel numbers and wavelengths for the GOES-R ABI. Channels used in both the SM/AOD algorithm are given in the last column.

2. Introduction

3. ABI Aerosol Retrieval algorithm

4. Routine Validations of ABI AOD with MODIS Collection 5 Aerosol Product1. Abstract

In this poster, we present the, (1) introduction on GOES-R ABI SM/AOD Algorithm; (2) routine validation with MODIS collection 5 aerosol product; (3) Validations with ground-based (AERONET) measurements; (4) introduction of simulator of ABI clear-sky radiance , and (5) summary

5. Validations SM/AOD product with ground-based (AERONET) measurements 6. Comparisons with MODIS AOD over ocean

7. Summary

1. Extensive Validations of GOES-R ABI Suspended matter/AOD algorithm indicates that it meets the F&P required accuracy2. Using MODIS gas-absorption corrected and clear sky radiance as proxy, ABI retrievals are evaluated with MODIS aerosol products and ground-based (AERONET)

measurements3. Validation system is operated routinely (two weeks delay for comparison with MODIS aerosol product and 4 month delay from ground-based validations. Results are

archived and accessible through internal website 4. Performance of SM/AOD algorithm is monitored by the time-series of key statistical parameters from the comparison with MODIS AOD.

Summary of GOESR-ABI SM/AOD algorithm: Land algorithm: The land aerosol algorithm is designed to retrieve simultaneously surface reflectance at 2.25um

and aerosol optical depth at 0.55um, and also select aerosol model from 4 predefined land aerosol type that produce the minimum residual between the calculated and observed TOA reflectance at channels used for land aerosol retrievals.

Ocean algorithm: Ocean bidirectional surface reflectance is explicitly calculated according to the state of ocean

(wind speed and wind direction etc.) with Cox and Mon model. A pair of aerosol, i.e, one from 5 predefined fine mode models and one from 4 coarse mode model is chosen to give best fit to the observed TOA reflectance at channels used for ocean aerosol retrievals.

Disclaimer: The views, opinions, and findings contained in this work are those of the authors and should not be interpreted as an official NOAA or US Government position, policy, or decision.

Status of GOES-R Advanced Baseline Imager (ABI) Suspended Matter/Aerosol Optical Depth (SM/AOD) Algorithm and Product Validation

The Aerosol Team (NOAA/NESDIS/STAR)

Global Aerosol optical depth for 07/ 01/2009, Terra

ABI

MODIS

ABI-MODIS

Global GOES-WEST CONUS

Figure 8. scatter plots of ABI AOD v.s. AERONET AOD in spring, summer, Autumn, and Winter for GOES-EAST coverage

Table 2. Statistics of ABI AOD v.s. AERONET AOD for different geographical coverage and season. L – Land; W – Water

GLOBAL GOES-EAST GOES-WEST CONUS

spring summer autumn winter all spring summer autumn winter all spring summer autumn winter all spring summer autumn winter all

Accuracy

(slope)

L0.045

(0.89)

0.051

(0.93)

0.015

(0.88)

-0.018

(0.80)

0.032

(0.87)

0.048

(0.81)

0.056

(0.93)

0.022

(0.94)

-0.015

(0.74)

0.038

(0.86)

0.050

(0.78)

0.062

(0.90)

0.025

(0.89)

-0.016

(0.74)

0.041

(0.82)

0.055

(0.75)

0.053

(0.86)

0.025

(0.81)

0.039

(0.77)

w0.014

(0.88)

0.007

(0.88)

0.007

(0.84)

0.005

(0.85)

0.011

(0.88)

0.017

(0.92)

0.006

(0.86)

0.008

(0.83)

0.005

(0.84)

0.011

(0.88)

0.019

(0.97)

0.013

(0.93)

0.006

(0.84)

0.005

(0.84)0.012

0.014

(0.97)

0.001

(0.93)

0.003

(0.81)

0.007

(0.91)

Precision

L 0.149 0.142 0.111 0.080 0.134 0.147 0.145 0.107 0.073 0.135 0.154 0.154 0.105 0.072 0.140 0.162 0.147 0.111 0.143

W 0.098 0.083 0.068 0.040 0.086 0.076 0.083 0.063 0.040 0.070 0.080 0.083 0.061 0.040 0.071 0.078 0.072 0.064 0.066

spring summer autumn winter

LAND

LAND

Figure 2 .Global distribution of ABI AOD, MODIS AOD and the difference

between them on a daily base.

Figure 3. Dynamic monitoring of algorithm performance by monitoring the time series of ensemble statistic parameters, such as global mean AOD, bias between ABI AOD and MODIS AOD and it’s standard deviation

Figure 1. Flowchart of GOES-R ABI SM/AOD retrieval algorithm

OCEAN

OCEAN

a. Aerosol Optical Depth (AOD)

Figure 7. scatter plot of ABI AOD v.s. AERONET AOD for different geographic coverage, such as global, GOES-EAST, GOES-WEST and CONUS

global GOES-E GOES-W conusLAND

OCEAN

As figure 3 shows , the difference between ABI AOD and MODIS AOD has not only large magnitude but also has clear seasonal pattern.

The difference between ABI ocean algorithm and MODIS collection-5 ocean algorithm are: 1. MODIS used fixed wind speed (6m/s) and wind direction (westerly wind). ABI

algorithm used wind speed and direction from NCEP reanalysis data 2. ABI used actual NCEP surface pressure to correct for rayleigh scattering 3. MODIS used all 7 bands, but ABI used only 4 bands, the missing bands are 0.47, 0.55

and 1.24 um)

030 060 098 129 159 189 219 249 279 309 339-0.040

-0.035

-0.030

-0.025

-0.020

-0.015

-0.010

-0.005

0.000

0.005030 060 098 129 159 189 219 249 279 309 342

-0.040

-0.035

-0.030

-0.025

-0.020

-0.015

-0.010

-0.005

0.000

0.005

030 060 098 129 159 189 219 249 279 309 339-0.040

-0.035

-0.030

-0.025

-0.020

-0.015

-0.010

-0.005

0.000

0.005030 060 098 129 159 189 219 249 279

-0.040

-0.035

-0.030

-0.025

-0.020

-0.015

-0.010

-0.005

0.000

0.005

AB

I-M

OD

IS

day of the year 2002

fixed wind speed and direction

NCEP wind speed and direction

fixed windspeed, direction and surface pressure

same number of channles as MODIS were used

AOD (MODIS-C5) AOD (ABI-NCEP) wind speed (m/s) AOD(ABI-fixed wind speed

And direction)

RGB image for MODIS (Aqua) on 03/01/2005, 17:45 UTCFigure 9. daily global mean of difference of ABI aod with MODIS aod for year of 2002.

LAND/OCEAN

OCEAN

LAND/OCEAN

LAND/OCEAN

LAND

275213.313.0-13.616

Dust/Smoke281312.311.8-12.815

Dust/Smoke289311.210.8-11.614

296610.3510.1-10.613

210419.619.42-9.812

211768.58.3-8.711

213627.347.24-7.4410

214396.956.75-7.159

216166.195.77-6.68

Dust/Smoke225643.903.80-4.007

Smoke244442.252.225 - 2.2756

162111.611.58-1.645

Dust272571.3781.371-1.3864

Smoke1115610.8650.846-0.8853

Dust/Smoke0.5156250.640.59-0.692

Dust/Smoke1212770.470.45-0.491

Sample Use

SM/AOD SMOKE/DUST

Nominal sub-satellite

IGFOV(km)

Nominal CentralWavenumber

(cm-1)

Nominal CentralWavelength

(μm)

NominalWavelength

Range(μm)

Future GOESImager

(ABI)Band

LAND/OCEAN

OCEAN

LAND/OCEAN

LAND/OCEAN

LAND

275213.313.0-13.616

Dust/Smoke281312.311.8-12.815

Dust/Smoke289311.210.8-11.614

296610.3510.1-10.613

210419.619.42-9.812

211768.58.3-8.711

213627.347.24-7.4410

214396.956.75-7.159

216166.195.77-6.68

Dust/Smoke225643.903.80-4.007

Smoke244442.252.225 - 2.2756

162111.611.58-1.645

Dust272571.3781.371-1.3864

Smoke1115610.8650.846-0.8853

Dust/Smoke0.5156250.640.59-0.692

Dust/Smoke1212770.470.45-0.491

Sample Use

SM/AOD SMOKE/DUST

Nominal sub-satellite

IGFOV(km)

Nominal CentralWavenumber

(cm-1)

Nominal CentralWavelength

(μm)

NominalWavelength

Range(μm)

Future GOESImager

(ABI)Band

Start retrieval over land

Loop over aerosol models in LUT

Loop over AOD550 in LUT

Retrieve surface reflectance at 2.25 µm using current AOD550, aerosol model

and 2.25-μm ABI observation.

Check if all (0.47-, 0.64- and 2.25-µm) surface reflectances are

physical?

Yes

Calculate TOA reflectance at 0.47µm with current AOD550, aerosol model

and retrieved 0.47-μm surface reflectance

No

Does thecalculated reflectance

from the current and previous retrievals bracket the

observation at 0.47µm?

Calculate AOD550 and 0.47-, 0.64- and 2.25-µm surface reflectances by

linear interpolation

Yes

Calculate AOD550 and surface reflectance by extrapolation

No

Has a valid AOD550 been retrieved?

No

Yes

Find minimum residual

Calculate the residual of TOA reflectance at 0.64-µm channel

Calculate 0.47- and 0.64-µm surface reflectances from 2.25-µm surface

reflectance using “dark-dense vegetation” relationships

0.470, 0.64- and 2.25-μm ABI reflectances

Select AOD and aerosol model

corresponding to minimum residual

End retrieval over land

OCEAN

OCEANLAND

5. Accuracy and precision of ABI AOD product

• AOD measurement range is -1.0 ~ 5.0 (from year 2000 for Terra (2002 for Aqua) to year 2009)

• Algorithm allows linear extrapolation at the lower end of look-up table for negative AOD retrieval.

• MODIS 10 by 10 gas absorption corrected clear-sky radiance was used as proxy

Accuracy Precision RMSE Correlation MinErr MaxErr

ABI 0.0279 0.1370 0.1398 83.29% -2.1794 1.9816

MODIS 0.0266 0.1243 0.1271 87.21% -1.8892 3.3308

Accuracy Precision RMSE Correlation MinErr MaxErr

ABI 0.0078 0.0906 0.0909 86.96% -1.0138 2.5461

MODIS 0.0172 0.1002 0.1017 84.83% -0.9756 2.6681

ρc

Fast GOES–R ABI SIMULATOR

viewing geometry GOES-R

aerosol optical depth

MOD04

water vapor, O3

MOD07

look-up tables (no gases, black surface)

TOA reflectance Band 1 to 6

viewing geometry MOD03

surface reflectance MOD09A1

gas absorption

aerosol type MOD04

parameterization of

gas absorption

Rayleigh correction

Surface contribution coupling

surface BRDF

MOD43B1

surface elevation

MOD03

ocean BRDF LUTs

wind-speed

fine mode

weight (η)

ρ=η *ρf+(1-η)* ρc

ρf

land

7. Fast GOESR-ABI clear-sky radiance simulator and application

Comparison of input to simulation with those retrieved from the simulated radiance with the ABI algorithm . a and b are for an granule over ocean, respectively for AOD and fine-mode weight (FW) in

percentage. C and d are for two granules over land

RangeLand Ocean

AOD Accuracy Precision AOD Accuracy Precision

Low <0.04 0.06 0.13<0.4 0.02 0.15

Medium 0.04 - 0.8 0.04 0.25

High > 0.8 0.12 0.35 >0.4 0.10 0.23

GOESR-ABI AOD SPEC:

Retrieval AOT over water

Loop through all finel mode aerosol models

Interpolate aerosol lookup table to the current geometry

Calculate aerosol independent optical parameters

Calculate surface reflectance parameters

Search for the optimal solution of fine mode weight (retrieve corresponding AOT550 and

residual) which gives the minimum residual for the

current combination of fine and coarse mode aerosol.

Initialize minimum residual

Update minimum residual and output structure if necessary

Done

Done

Return output

End

Calculate AOT at first 6 ABI bands

Interpolate sunglint lookup table to the current geometry

Loop through all coarse mode aerosol models