# Presentation: 270964

## The Effects of Aerosols on California Climate

- Mark Z. Jacobson
- Dept. of Civil & Environmental Engineering
- Stanford University
- Collaborators on MODIS project:
- Yang Zhang (NCSU); Ned Snell (AER)
- MODIS Science Team Meeting
- March 23, 2005

## Scientific Question

- What are the effects in California and the South Coast Air Basin of all anthropogenic particles and their gas precursors on
- 	rainfall
- 	winds
- 	pollution content of rainwater
- 	cloudiness
- 	near-surface air temperatures
- 	vertical temperature profiles
- 	relative humidity
- 	ultraviolet/total solar/thermal-infrared radiation
- and how can MODIS data help evaluate these effects?

## GATOR-GCMOM

- Gas processes
- Emission
- Photchemistry
- Gas-to-particle conversion
- Cloud removal
- Aerosol processes
- Emission
- Nucleation/condensation
- Aerosol, cloud coagulation
- Dissolution/chem./crystallization
- Dry deposition/sedimentation
- Rainout/washout
- Cloud processes (3-D clouds)
- Described next page

- Radiative transfer
- UV/visible/near-IR/thermal-IR
- Scattering/absorption
- Gas	Aerosol	Hydrometeor
- Predicted snow, ice, water albedos
- Meteorological processes
- Velocity, geopotential, pressure
- Water vapor, temperature, density
- Turbulence
- Surface processes
- Temperatures and water content of
- Soil, Water, Snow, Sea ice, Vegetation, Roads, Roofs
- 2-D ocean dynamics
- 3-D ocean diffusion, chemistry
- Ocean-atmosphere exchange

## GATOR-GCMOM

- 3-D size-resolved clouds form from size-resolved aerosols without parameterization or equilibrium assumption.
- Time-dependent, grid-scale clouds form and move in 3-D.
- Activation and growth/evaporation of size-resolved liquid and ice on size-resolved aerosol particles
- Homogeneous/heterogeneous/contact/evaporative freezing
- Size-resolved liquid-liquid, liquid-ice, liquid-graupel, ice-ice, ice-graupel, graupel-graupel coagulation.
- Size-resolved liquid-aerosol, ice-aerosol, graupel-aerosol coagulation and liquid drop breakup
- Size-resolved precipitation (including aerosol inclusions).
- Subcloud size-resolved evaporation/melting
- Lightning calculated from size-resolved bounceoffs
- Gas dissolution/aqueous chemistry
- Treats first and second indirect effects explicitly

## Aerosol-Cloud Interactions

**Aerosol-Cloud Interactions**

## Model Grids Treated for California Case

**Model Grids Treated for California Case**

## Feb/Aug BC Dif. w-w/o AAPPG

**Feb/Aug BC Dif. w-w/o AAPPG**

## Feb/Aug POM Dif. w-w/o AAPPG

**Feb/Aug POM Dif. w-w/o AAPPG**

## Feb/Aug SOM Dif. w-w/o AAPPG

**Feb/Aug SOM Dif. w-w/o AAPPG**

## Feb/Aug S(VI) Dif. w-w/o AAPPG

**Feb/Aug S(VI) Dif. w-w/o AAPPG**

## Feb/Aug NO3- Dif. w-w/o AAPPG

**Feb/Aug NO****3****-**** Dif. w-w/o AAPPG**

## Feb/Aug Aerosol LWC Dif. w-w/o AAPPG

**Feb/Aug Aerosol LWC Dif. w-w/o AAPPG**

## Feb/Aug Total Column Aerosol Mass Dif. w-w/o AAPPG

**Feb/Aug Total Column Aerosol Mass Dif. w-w/o AAPPG**

## Feb/Aug Near-Surface Aerosol Number Dif. w-w/o AAPPG

**Feb/Aug Near-Surface Aerosol Number Dif. w-w/o AAPPG**

## Feb/Aug Aerosol 550 nm Optical Depth Dif. w-w/o AAPPG

**Feb/Aug Aerosol 550 nm Optical Depth Dif. w-w/o AAPPG**

## Feb/Aug Baseline Cloud Opt. Depth

**Feb/Aug Baseline Cloud Opt. Depth**

## Feb/Aug Cloud Optical Depth Dif. w-w/o AAPPG

**Feb/Aug Cloud Optical Depth Dif. w-w/o AAPPG**

## Feb/Aug Near-Surface Cloud Fraction Dif. w-w/o AAPPG

**Feb/Aug Near-Surface Cloud Fraction Dif. w-w/o AAPPG**

## Feb/Aug Cloud LWC Dif. w-w/o AAPPG

**Feb/Aug Cloud LWC Dif. w-w/o AAPPG**

## Feb/Aug Cloud Top Pressure Dif. w-w/o AAPPG

**Feb/Aug Cloud Top Pressure Dif. w-w/o AAPPG**

## Feb/Aug Down-Up Surface Solar Radiation Dif. w-w/o AAPPG

**Feb/Aug Down-Up Surface Solar Radiation Dif. w-w/o AAPPG**

## Feb/Aug Down-Up Surface Thermal-IR Radiation Dif. w-w/o AAPPG

**Feb/Aug Down-Up Surface Thermal-IR Radiation Dif. w-w/o AAPPG**

## Feb/Aug Near-surface Temperature Dif. w-w/o AAPPG

**Feb/Aug Near-surface Temperature Dif. w-w/o AAPPG**

## Modeled vs. Measured Feb. 1999 Precipitation

**Modeled vs. Measured Feb. 1999 Precipitation**

## Feb/Aug Precipitation Dif. w-w/o AAPPG

**Feb/Aug Precipitation Dif. w-w/o AAPPG**

## Feb/Aug BC in Fog and Precip. Dif. w-w/o AAPPG

**Feb/Aug BC in Fog and Precip. Dif. w-w/o AAPPG**

## Feb/Aug Near-Surface Wind Speed Dif. w-w/o AAPPG

**Feb/Aug Near-Surface Wind Speed Dif. w-w/o AAPPG**

## Feb/Aug Near-Surface Water-Vapor Dif. w-w/o AAPPG

**Feb/Aug Near-Surface Water-Vapor Dif. w-w/o AAPPG**

## Paired-in-Time-and-Space Modeled (Red) v. Measured Solar Radiation

## Paired-in-Time-and-Space Modeled (Red) v. Measured T and RH

## Paired-in-Time-and-Space Modeled (Red) v. Measured Wind Speed & Direction

## Summary

- Anthropogenic aerosols and gas precursors in California and the South Coast Air Basin were found to
- 	decrease near-surface wind speeds
- decrease rainfall in the Central Valley, South Coast, and mountains (e.g., Sierras, San Bernardino)
- 	increase the pollution content of rainfall
- 	increase cloud optical depth, fraction, LWC, top height
- 	decrease near-surface air temperatures
- 	stabilize the boundary layer
- 	decrease UV, solar radiation at surface
- 	increase thermal-IR radiation at surface