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

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 (T wave ) RHI - AURA Microwave Limb Sounder (MLS) OLR - Climate Diagnostics Center T wave – HIRDLS and COSMIC (gps) temperature analyses Focus is on the Tropics

Example : Vertical and Seasonal Variations

Example: HIRDLS and CALIPSO Cloud Fields

HIRDLS Cloud Frequency MLS RHI January 2006, 100 hPa

Cloud Frequency Extinction HIRDLS Cirrus Observations at 82 hPa These patterns are very similar to the RHI patterns

Cloud Frequency Extinction MLS RHI and HIRDLS Cirrus at 82 hPa RHI > 100 %

Correlation of RHI and Extinction (β) at 100 hPa

CDC OLR (Proxy of Deep Convection) Deep convection is present when OLR < 170 W / m 2 (green colored regions) Longitudes near 100 are over Indonesia

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

Lidar Observations of Cirrus and Temperature Waves Green: ΔT between -1 and -4 K Boehm and Verlinde, GRL, v27, p3209, 2000

Equatorial Wave Temperatures HIRDLS analyses courtesy of Joan Alexander, and COSMIC analyses courtesy of Bill Randel and Fei Wu

COSMIC Temperature Waves and HIRDLS Extinction

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 < 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