# Presentation: 777918

## Column Water Vapor And

- AERONET Size distributions (fine mode only; Fig. 1) for Amazonian forest sites were partitioned into two ranges of column water vapor CWV). We found an increase of volume median radius of the fine mode (VMRf) as a function of AOD that was enhanced for the almucantars acquired during conditions of greater column water vapor, suggesting a mildly hygrophilic aerosol.
- The sensitivity of VMRf to CWV was observed to be dependent on the amount of aerosol (smoke) present.  In Fig. 2, VMRf was plotted vs. CWV for moderate to high AOD440nm (0.25 to 1.5; N=825) and for very high AOD (> 1.5; N=192). The significance of the correlation and the regression slopes were notably greater for the highest AOD conditions, perhaps due to higher AOD being correlated with more aged smoke which has evolved under stagnation conditions or during prolonged transport where the aerosol would have longer exposure to the ambient water vapor.

- Aerosol Particle Growth

- Fig. 1

- Fig. 2

## Name: Joel Schafer1, Tom Eck1, Brent Holben1, Paulo Artaxo2 and Alejandro Fonseca Duarte3  

**Name: **Joel Schafer1, Tom Eck1, Brent Holben1, Paulo Artaxo2 and Alejandro Fonseca Duarte3
- (1) NASA/GSFC (2) Univ. of São Paulo (3) Univ. of Acre
**E-mail:**Joel.Schafer@nasa.gov
**Phone: **301-614-6668
**References:**
- J.S. Schafer, Eck T.F., Holben B.N., Artaxo P.,Duarte A.F., Characterization of the optical properties of atmospheric aerosols in Amazônia from long-term AERONET monitoring [1993-95;1999-2006], J. Geophys. Res., 2007JD009319, *in Press*.
- Holben, B.N. et al., AERONET - A federated instrument network and data archive for aerosol characterization, Remote Sensing of Environment, 66, 1-16,  1998.
- Sinyuk, A., O. Dubovik, B. Holben, T.F. Eck, F-M Breon, J. Martonchik, R. Kahn, D. J. Diner, E. F. Vermote, J-C Roger, T. Lapyonok, and I. Slutsker, 2007, Simultaneous retrieval of aerosol and surface properties from a combination of AERONET and satellite, Remote Sensing of Environment, 107, doi:10.1016/j.rse.2006.07.022.
**Data Sources:  **A new climatology of atmospheric aerosols (primarily pyrogenic and biogenic) is presented for the Brazilian tropics based upon a high-quality data set of spectral aerosol optical depth and directional sky radiance measurements from AERONET CIMEL sun-sky radiometers at more than 15 sites distributed across the Amazon basin and adjacent Cerrado region.
- Seasonal time series of aerosol optical depth (AOD), Ångström exponent, and columnar-averaged microphysical properties of the aerosol derived from sky radiance inversion techniques (single-scattering albedo, volume size distribution, fine mode fraction of AOD, etc.) are described and contrasted for the defined regions.  During the wet season, occurrences of mineral dust penetrating deep into the interior were observed.
**Technical Description of Figures:**
***Figure 1: ***Averaged volume size distributions (fine mode only) grouped by aerosol optical depth for the composite Amazonian southern forest sites partitioned into two ranges of column water vapor.
***Figure 2: ***Volume median radius of the fine mode (VMRf) as a function of column water vapor for two aerosol optical depth (440nm) bins.
**Scientific significance: **This network is the only long-term project (with a record including observations from more than 11 years at some locations) ever to have provided ground-based remotely-sensed column aerosol properties for this critical region.