Transcript Does Asian dust play a role of CCN?

Does Asian dust play a role as CCN?
Gill-Ran Jeong, Lance Giles, Matthew Widlansky
O3, SO2, NO2, HNO3
Group proposal
Aerosol, Cloud, and Climate ( EAS 8802)
April 24 th, 2006
1. Motivation: Introduction of a problem
The microphysical and chemical properties of aged mineral dust as a candidate of CCN
 sulfate coating in the dust fine mode can become a CCN
Controlling factors to CCN
1.Size
2.Composition
(Hygroscopic property)
Japan spring 2004 (Matsumoto et al., GRL 2006)
ACE-Asia spring 2001 (Clarke et al., JGR 2004)
1: dust-laden cloud
2: dust-free cloud
3:smoke in dust
Tailland, spring 1998 (Rosenfeld et al., PNAS 2001)
1. Motivation: Importance of complexity
The limitation of current understanding
• Lack of long term dust record downwind of Asian outflow.
• Ability to discriminate clouds from dust in current satellite images.
• Measurements of CCN during dust and non-dust periods.
1. Why do we need to do another field experiment in East Asia region?
• New A-train land-ocean satellite coverage (launched yesterday)
i) Overcoming of cloud contamination in dust detection
ii) Three dimensional measurement of cloud structure
• In addition, aircraft and ground-base measurement
• The temporal and spatial resolution of instrumental measurement and are they
consistent?
2. What do we want to see?
During dust and non-dust period:
i) Vertical profiles of the CCN, clouds, water vapor
ii) Time required for a dust CCN to grow into cloud droplets.
iii) Size resolved chemical composition
2. Objectives and goals
1. Analyze the previous data on dust, clouds, and precipitation
in order to find any relation between dust. clouds and precipitation.
2. Investigate satellite observations pertaining to dust, clouds and precipitation
with the same temporal and spatial resolution.
(Cloudsat, MODIS and CALIPSO)
3. Investigate data from airborne and ground-base measurements of dust size
distribution, chemical composition, and pH of precipitation.
4. Compare individual instrumental measurements to map 3-D dust and
precipitable water distributions.
Goals
1. Find what roles Asian dust play as CCN?
2. Investigate effects of mineral dust on the aerosol-cloud-climate system.
3. Strategy
Space
Time
120ºE ~ 150ºE, 20ºN ~ 40ºN
Spring, 2007 (March, April)
Preliminary study
Data analysis
Visibility, cloud and precipitation from
surface meteorological data,
A suit of
Measurement
ISCCP, GPCP
Cloud and
Precipitation
CCN
Dust
(satellite)
Validation of
observation
Expected results
Time series
3-D Cloud, CCN distribution
3-D Dust distribution
Proof of
dust-induced
CCN
Contribution to
understanding
Climate system
Time series Dust size radius
Fraction of chemical composition
Dust – Cloud – Climate
Dust
(ground-base)
4. Experimental instruments
Measured Quantity
Instrument
Past long-term dust concentration
monthly mean precipitation
3-hour average cloud
Surface observation of visibility
GPCP
ISCCP
Cloud profile
Liquid and ice contents
Rain drop and precipitation
CloudSat
Aerosol profile
Cloud profile
Optical depth of thin cirrus cloud
CALIPSO(CALIOP)
Aerosol optical depth
Particle size
MODIS
TOA radiation budget
CERES
Dust size distribution
OPC
IMPACTOR
electron and optical microscopy
Dust chemical compositions
Aerosol mass spectrometer
4. Experimental Instruments
MODIS
- Variable resolutions range:
• 250m (bands 1-2)
• 500m (bands 3-7)
• 1000m (bands 8-36)
- Swath width of 2330km
- Cloud and Aerosol products
by MODIS:
• Cloud and aerosol optical
depths
• Particle size information
• Cloud-top height
• Cloud emissivity
Sample of Aerosol Optical Depth Measurements:
CloudSat
CALIPSO
- 94-GHz nadir-looking
radar measures backscatter
- Active lidar instrument
(CALIOP) with passive
infrared (IIR) and visible
imagers (WFC) to probe
the vertical structure and
properties of thin clouds
- Measure profiles of cloud
optical properties
- Measure cloud liquid and
ice water content
- Profile the vertical
structure of clouds
• (500m vertical resolution)
- Will distinguish between
cloud condensate (cloud
particles) and precipitation
- Polarization-sensitive
lidar
- Measures the 1064nm
backscatter intensity and
the polarized 532nm
backscattered signal
5. A contribution to understanding aerosol-cloud-climate
Asian dust may suppress or enhance precipitation
outflow of Asian dust region.
Asian dust
positive or negative (?)
Cloud and precipitation
negative
Hydrological cycle in Asian region (negative or positive feedback)
Dust properties
Direct impact
Radiative
radiative forcing at TOA
radiative forcing at the sfc
heating/cooling
actinic flux
Chemical
heterogeneous chemistry
on dust surface
Indirect impact
photolysis
5. A contribution to understanding aerosol-cloud-climate
Asian dust may suppress or enhance precipitation
outflow of Asian dust region.
Asian dust
positive or negative (?)
Cloud and precipitation
negative
Hydrological cycle in Asian region (negative or positive feedback)
Dust properties
Direct impact
Indirect impact
Radiative
radiative forcing at TOA
radiative forcing at the sfc
heating/cooling
actinic flux
cloud properties
heterogeneous chemistry
on dust surface
photolysis
Chemical
Hygroscopic
CCN
5. A contribution to understanding aerosol-cloud-climate