# Presentation: 349380

## OMI Near UV Aerosol Product

***Greece Fires, August 27, 2007***

**Aerosol absorption from space using OMI observations**** **

- OMAERUV

*Omar Torres*
*Hampton University*
*(omar.torres@hamptonu.edu)*

## The EOS-Aura Mission

-                                  **Launched on July 15, 2004**
**                           ****Four sensors:**
**                ****MLS (Micro Limb Sounder)**
**                ****TES (Tropospheric Emission Spectrometer)**
**                ****HIRDLS (High Resolution Dynamics Limb Sounder)**
**                ****OMI (Ozone Monitoring Instrument)**

## Aura is one of seven satellites in the A-train

**Aura is one of seven satellites in the A-train**

**Aura-OMI, PARASOL, Calipso, and Aqua-MODIS, retrieve aerosol**
**properties**
**Glory-APS (not shown) will join the A-train in 2008**

## Ozone Monitoring Instrument (OMI)

- 270-500 nm
- 13X24 km footprint
- 2600 km swath width
- Retrieval Products:
- Radicals: Column O3, NO2,BrO,OClO,
- O3 profile
- Tropospheric Ozone
- Tracers: Column SO2
- Cloud top pressure
**Tropospheric Aerosols:**
**-Aerosol Index (AI)**
**-Extinction Optical Depth (AOD)**
**-Absorption Optical Depth (AAOD)**

**Ozone Monitoring Instrument (OMI)**

**Principal Investigator:** P.F. Levelt, Royal Netherlands Meteorological Institute (KNMI*)*
**US Science Team Leader:** P.K. Bhartia, Code 916, NASA-GSFC* *

## OMI Near UV Aerosol Product

- -TOMS heritage
- -Uses as input radiances as two near UV channels: 354 and 388 nm
- -Pixel size: 13x24 km at nadir
- -Retrieved Products: Absorbing Aerosol Index (AAI)
-                                   388 Aerosol Extinction Optical Depth  (AOD)
-                                   388 Aerosol Single Scattering Albedo  (SSA)
- Aerosol Absorption Optical Depth is calculated as
- AAOD = AOD (1.0-SSA)
- AAOD is affected less by sub-pixel cloud contamination than AOD
- and SSA

- Retrieved AAOD on August 27, 2007

## Extinction optical depth τext 

***Assumed aerosol parameters:***
***-Particle size distribution***
***-Real comp. refractive index***
***-Relative spectral dep. of imag. refractive index.***

***Retrieved parameters: ***
***Extinction optical depth ******τ******ext****** ***
***single scattering albedo ******ω******0***
***τ******abs= ******τ******ext*** (1- ***ω******0******)***

***Other input:***
***-Surface Albedo (354, 388 nm)***
***-Aerosol Type***
***-Aerosol Vertical Distribution***

**LUT’s:**

*Retrieval *
*Algorithm*

- Three aerosol types:
- Desert Dust
- Carbonaceous aerosols
- Weakly absorbing
-  Seven aerosol models per type
-  (varying ***ω******0****)*
- Nodal points on:
- Extinction Optical Depth
- Single scattering Albedo
- Aerosol Layer Height

- Aerosol Layer height
- Weakly absorbing (surface)
- Carbonaceous aerosols:
-    3 km  ± 30° of Equator
-    6 km  mid and high latitudes
- -Desert Dust
-    Global monthly Climatology
-    from GOCART calculations.

- Retrieved results reported at 354, **388** and 500 nm
- Two sets of retrieval results are produced:
- 1) For different aerosol layer height assumptions:
-  0, 1.5, 3, 6 and 10 km.
- 2) For recommended aerosol layer height

## Aerosol Products

- -OMTO3 Aerosol Index, uses measurements at 331 and 360 nm
- -OMAERUV Retrieved Products (388 nm):
-   Extinction (AOD) and Absorption (AAOD) Optical Depth

- Single Scattering Albedo (SSA) = (AOD-AAOD)/AOD
- AOD and AAOD are also reported at 354 and 500 nm
- Resolution 13X24 km (Nadir)

- Data Availability:
- L2, Orbital Data (original footprint 13X24 and larger)
- L2G, Level 2 binned data in a 0.25x0.25 degree grid
- L3, averaged gridded product 1X1

## Science Value of OMI Aerosol Products

- Aerosol Absorption Information is a unique OMI aerosol product unavailable from any other sensor

- OMI Aerosol Index

- April 14, 2006

- MODIS RGB

- Detects absorbing aerosols mixed with and above clouds
- and over bright surfaces (ice/snow)

## Science Value of OMI Aerosol Products

- Quantitative Aerosol Information: Extinction and Absorption Optical depth

- March 9, 2007

## OMI – AERONET  Comparison

**OMI – AERONET  Comparison**
**         ****Monthly means****      **

- Non-absorbing Aerosols

- Dust Aerosols

- Data averaging reduces noise considerably

## Summary

- The OMI near UV aerosol products contribute significantly to fill the observational gap on aerosol absorption. Aerosol absorption information is not currently available from any other sensor.
- OMI retrievals of aerosol optical depth over deserts provide daily regional coverage with an accuracy similar to that of MISR measurements.
- Future plans include the combined use of OMI  measurements with those of other A-train sensors.

- Data available at:
**Level 2****: **_[http://disc.gsfc.nasa.gov/Aura/OMI/omaeruv_v003.shtml](http://disc.gsfc.nasa.gov/Aura/OMI/omaeruv_v003.shtml)_
**Level 3:**** **_[http://disc.gsfc.nasa.gov/Aura/OMI/omaeruvd_v003.shtml](http://disc.gsfc.nasa.gov/Aura/OMI/omaeruvd_v003.shtml)_