Lidar Measurements During INTEX-B

Thomas J. DuckDepartment of Physics and Atmospheric ScienceDalhousie University

Atmospheric-Optics Laboratoryhttp://aolab.phys.dal.ca/

At Pemberton Helicopters

Helping Hands

Operations at Twilight

INTEX-B Measurements Summary

11 May 2006, 01-11 UTC 14 May 2006, 01-09 UTC 15 May 2006, 02-16 UTC 16 May 2006, 0400-0435 UTC 16 May 2006, 0640-1830 UTC 17 May 2006, 03-10 UTC 17 May 2006, 1700-1930 UTC

Lidar Backscatter Ratio (R)

Ratio of total to molecular signal Clear air: R=1 Typical aerosol pollution: 2<R<5 Clouds R>10

Can be formed using either: molecular channel of lidar radiosonde density profile

AEROSOLS

CLOUDS

AEROSOLS

THIN COULDSAND AEROSOLS?

AEROSOLS

SIGNALINDUCEDNOISE?

AEROSOLS

CLOUDS

NOTE SHORT TIME INTERVAL

HIGH ALTITUDEAEROSOLS

HIGH ALTITUDEAEROSOLS(AGAIN!)

AEROSOLS

THINCLOUDS

AEROSOLS

CLOUDS

Data Issues

Products: aerosol/molecular backscatter ratio

can convert to backscattering cross-section aerosol extinction

aerosols are too optically thin for this can estimate given assumption of lidar ratio

Signal-induced noise need to apply correction to get lower

altitudes

Some Context: Alaskan Smoke over NS during ICARTT

11/12 July 2004

FLEXPART Column Retroplume

(for measurement on next day)

FLEXPART Footprint

Lidar/Model Comparisons

Next Steps

Refine/improve data products FLEXPART footprint determination

in collaboration with Andreas Stohl may provide useful input to GEOS-Chem work

Use AMS info for lidar ratio estimate (?) Comparisons with sondes, Met charts

reasons for constant descent? water vapour impact?

The End

Thomas J. Duck <tom.duck@dal.ca>Atmospheric-Optics Laboratoryhttp://aolab.phys.dal.ca/