Coupling between the aerosols and hydrologic cycles

1. Coupling between the aerosols and hydrologic cycles Xiaoyan Jiang Climatology course, 387H Dec 5, 2006

2. Outlines • Aerosols formation • Why we care about the aerosols and hydrologic cycle? • The coupling between the ecosystems and the hydrologic cycle via aerosol processing • What do we need to know? • What tool we can use? • What data we can use to evaluate the model results? • Future Challenges

3. Aerosols in the atmosphere

4. Aerosols formation Secondary and Primary aerosols OXIDATION Fossil Fuel Biomass Burning NATURAL SOURCES ANTHROPOGENIC SOURCES

5. Why we care about the aerosols and hydrologic cycle? • The interaction between the aerosol and meteorological variables. • 1.Direct effects---reducing the amount of solar radiation that reaches the surface • 2.Indirect effects ---Changing the properties of clouds • Aerosols and their relationships with clouds and rainfall are one of the weakest aspects of current meteorological and climate modeling • The role of aerosols in the hydrologic cycle is unknown

6. The coupling between the ecosystems and the hydrologic cycle via aerosol processing Modified from Barth, et al. BAMS, 2005

7. What do we need to know? • Emissions • Anthropogenic and natural aerosols • Microphysics and chemistry (dependent on aerosol type) • Transformation (removal efficiency of various aerosols) • Transport away from source regions (horizontally, vertically) • Effect of relative humidity (especially on cloud-scales) • Precipitation events (intensity and frequency) • Clouds

8. Changes of surface solar radiation induced byurban aerosols for 1 September 2001 based on simulationsfrom a radiative transfer model developed by Chou andSuarez [1999]. Here ‘‘diruv’’ and ‘‘difuv’’ represent direct and diffuse UV radiation, ‘‘dirpar’’ and ‘‘difpar’’ represent direct and diffuse photosynthetically active radiation, and ‘‘dirir’’ and ‘‘difir’’ represent direct and diffuse nearinfrared radiation. The ‘‘total’’ represents the total solar radiation, and the values are shown on the right-hand axis in Wm2.

9. The effect of aerosols in the formation of clouds

10. What tool we can use? • A new fully coupled meteorology- chemistry-aerosol model is being developed ----WRF-chem • It is a version of WRF that simulates trace gases and particulates with meteorological fields. • It allows two-way nesting to simulate the air quality and meteorological fields.

11. Aerosol treatments in WRF-chem • Size distribution and composition: • sectional size distribution; moving-center or two-moment approach for the dynamic equations for mass and number; each size bin is internally mixed • composition: SO4 , NO3 , NH4 , CL, CO3 , NA, CA, other inorganics, OC, EC modal approach MOSAIC - sectional approach Coarse Mode Accumulation Mode Aiken Mode mass mass 0.01 0.1 1 10 100 0.01 0.1 1 10 100 particle diameter (mm) particle diameter (mm) • MOSAIC has 3 unique components (Zaveri et al. 2005a,b,c): • MTEM - Multi-component Taylor Expansion Model: mixing rule for activity coefficients of electrolytes in multi-component aqueous solutions • MESA - Multi-component Equilibrium Solver for Aerosols: thermodynamic equilibrium solver for solid, liquid, or mixed phase aerosols • ASTEEM - Adaptive Step Time-split Explicit Euler Method: dynamic integration of the coupled gas-aerosol partitioning differential equations • numerically efficient (reduces the # of levels of iterations and # of iterations) without sacrificing accuracy; • have been compared with other techniques (Fast,2006)

12. Some results using the fully coupled meteorology-chemistry-aerosol model

13. What data we can use to evaluate the model results?

14. Future Challenges • Coupled model development • Satellite and ground-based Measurements • Physical understanding for the direct and indirect of aerosols in the atmosphere • The cloud microphysics • The role of secondary organic aerosols in hydrologic cycle due to the importance of water and energy cycle. • Data assimilation of air quality datasets in a coupled model • Model evaluation and uncertainty assessment • The feedback mechanisms

15. Thank You !