HIRDLS Oxford Open Science Meeting

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HIRDLS Oxford Open Science Meeting HIRDLS
Observations of Cirrus Near the Tropopause Based
upon Spring 2008 AGU Joint Assembly Ft.
Lauderdale, Florida Steven T. Massie, John
Gille, John Barnett, Joan Alexander, William
Reed, Rashid Khosravi, Cheryl Craig, Bill Randel,
Fei Wu massie_at_ucar.edu
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Outline
Cirrus is produced in-situ by freezing of humid
layers blow-off from deep convection cold
temperature perturbations of dynamical waves The
HIRDLS observations are correlated to RHI
(relative humidity with respect to ice) OLR
(outgoing longwave radiation) Wave temperature
perturbations (Twave) RHI - AURA Microwave
Limb Sounder (MLS) OLR - Climate Diagnostics
Center Twave HIRDLS and COSMIC (gps)
temperature analyses Focus is on the Tropics
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Example Vertical and Seasonal Variations
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Example HIRDLS and CALIPSO Cloud Fields
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January 2006, 100 hPa
HIRDLS Cloud Frequency MLS RHI
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HIRDLS Cirrus Observations at 82 hPa
Cloud Frequency
Extinction
These patterns are very similar to the RHI
patterns
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MLS RHI and HIRDLS Cirrus at 82 hPa
Cloud Frequency
Extinction
RHI gt 100
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Correlation of RHI and Extinction (ß) at 100 hPa
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CDC OLR (Proxy of Deep Convection)
Longitudes near 100 are over Indonesia
Deep convection is present when OLR lt 170 W /
m2 (green colored regions)
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Correlations of RHI and Extinction with OLR
Correlations are not as strong as RHI versus
Extinction Not all Cirrus is directly related to
deep convection
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Lidar Observations of Cirrus and Temperature
Waves
Green ?T between -1 and -4 K Boehm and Verlinde
, GRL, v27, p3209, 2000
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Equatorial Wave Temperatures
HIRDLS analyses courtesy of Joan Alexander, and
COSMIC analyses courtesy of Bill Randel and Fei
Wu
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COSMIC Temperature Waves and HIRDLS Extinction
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Discussion
HIRDLS vertical resolution 1 Km, while MLS
several Km A 1 KM cirrus layer can be
sandwiched by low RHI air above and below the
cloud structure, and clouds can be present for
RHI lt 100 Largest correlations are between RHI
and Extinction A consequence of thermodynamics
! Correlations of OLR and cirrus extinction are
weak Not all cirrus is derived from convective
blow-off Negative temperature perturbations due
to tropical dynamical waves are correlated with
larger cirrus extinction