Coupling between the aerosols and hydrologic cycles

Xiaoyan JiangXiaoyan JiangClimatology course, 387HClimatology course, 387H

Dec 5, 2006Dec 5, 2006

OutlinesOutlines

Aerosols formationAerosols formation

Why we care about the aerosols and Why we care about the aerosols and hydrologic cycle?hydrologic cycle?

The coupling between the ecosystems and the The coupling between the ecosystems and the hydrologic cycle via aerosol processinghydrologic cycle via aerosol processing

What do we need to know?What do we need to know?

What tool we can use?What tool we can use?

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

Future ChallengesFuture Challenges

Aerosols in the atmosphereAerosols in the atmosphere

Aerosols formationAerosols formation

ANTHROPOGENIC SOURCESNATURAL SOURCES

Fossil Fuel Biomass Burning

OXIDATION

Secondary and Primary aerosols

Why we care about the aerosols and Why we care about the aerosols and hydrologic cycle?hydrologic cycle?

The interaction between the aerosol and The interaction between the aerosol and meteorological variables.meteorological variables.1.Direct effects---reducing the amount of solar 1.Direct effects---reducing the amount of solar radiation that reaches the surface radiation that reaches the surface 2.Indirect effects ---Changing the properties of 2.Indirect effects ---Changing the properties of cloudscloudsAerosols and their relationships with clouds and rainfall are one of the weakest aspects of current meteorological and climate modelingThe role of aerosols in the hydrologic cycle is The role of aerosols in the hydrologic cycle is unknownunknown

The coupling between the ecosystems and The coupling between the ecosystems and the hydrologic cycle via aerosol processingthe hydrologic cycle via aerosol processing

Modified from Barth, et al. BAMS, 2005

What do we need to know?What do we need to know?

Emissions Emissions Anthropogenic and natural aerosolsAnthropogenic and natural aerosols Microphysics and chemistry (dependent on aerosol Microphysics and chemistry (dependent on aerosol type)type)Transformation (removal efficiency of various aerosols)Transformation (removal efficiency of various aerosols)Transport away from source regions (horizontally, Transport away from source regions (horizontally, vertically)vertically) Effect of relative humidity (especially on cloud-scales)Effect of relative humidity (especially on cloud-scales)Precipitation events (intensity and frequency)Precipitation events (intensity and frequency)CloudsClouds

Changes of surface solar radiation induced byurban aerosols for 1 September 2001 based on simulations

from 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.

The effect of aerosols in the formation of cloudsThe effect of aerosols in the formation of clouds

What tool we can use?What tool we can use?

A new fully coupled meteorology- chemistry-A new fully coupled meteorology- chemistry-aerosol model is being developedaerosol model is being developed

----WRF-chem----WRF-chem

It is a version of WRF that simulates trace It is a version of WRF that simulates trace gases and particulates with meteorological gases and particulates with meteorological fields. fields.

It allows two-way nesting to simulate the air It allows two-way nesting to simulate the air quality and meteorological fields.quality and meteorological fields.

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

Aerosol treatments in WRF-chemAerosol treatments in WRF-chem

particle diameter (m)0.01 0.1 1 10 100 0.01 0.1 1 10 100

particle diameter (m)

mas

s

mas

s

modal approach MOSAIC - sectional approach

Accumulation Mode

CoarseModeAiken

Mode

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)

Some results using the fully coupled Some results using the fully coupled meteorology-chemistry-aerosol modelmeteorology-chemistry-aerosol model

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

Future ChallengesFuture Challenges

Coupled model developmentCoupled model developmentSatellite and ground-based MeasurementsSatellite and ground-based MeasurementsPhysical understanding for the direct and indirect of Physical understanding for the direct and indirect of aerosols in the atmosphereaerosols in the atmosphereThe cloud microphysics The cloud microphysics The role of secondary organic aerosols in The role of secondary organic aerosols in hydrologic cycle due to the importance of water and hydrologic cycle due to the importance of water and energy cycle.energy cycle.Data assimilation of air quality datasets in a Data assimilation of air quality datasets in a coupled modelcoupled modelModel evaluation and uncertainty assessmentModel evaluation and uncertainty assessmentThe feedback mechanismsThe feedback mechanisms

Thank You !Thank You !