Retrieving Liquid Water Contents of Boundary-layer Clouds Using Dual-
frequency Cloud RadarsCourtney Laughlin1, Dong Huang2, Eugene Clothiaux1,
Johannes Verlinde1, Kultegin Aydin1
1The Pennsylvania State University2Brookhaven National Laboratory
Objectives
• Retrieve accurate cloud LWCs of boundary-layer stratus and stratocumulus via an improved dual-frequency attenuation approach
• Analyze and quantify possible sources of error and assess any means to correct for them
Brief History of Dual-frequency Retrieval
• Atlas 1954
• Sekelsky 2000
• Hogan et al. 2005
• Huang et al. 2009
Liquid water cloud
Instruments
Liquid water cloud
Instruments
Liquid water cloud
Instruments
Possible Retrieval Sources of Error• Precision of reflectivity measurements• Overlap of sample volumes– Radar separation– Radar pointing differences– Radar range gate offsets
• Accuracy of radiosonde measurements• Temperature dependent absorption
coefficients of oxygen, water vapor, and liquid water
• Cloud drop size assumption
Possible Assessment Sources of Error
• Precision of LWP measurements• Beam-filling effects• Accuracy of radiosonde measurements• Temperature dependent absorption
coefficients of oxygen, water vapor, and liquid water
November 26, 2012 14:00 – 15:00 UTC
November 26, 2012 14:00 – 15:00 UTC
November 26, 2012 14:00 – 15:00 UTC
November 26, 2012 14:00 – 15:00 UTC
July 08, 2013 16:00-17:00 UTC
July 08, 2013 16:00-17:00 UTC
July 08, 2013 16:00-17:00 UTC
Results
ResultsMean = -0.0065(-0.0015) MAGICStandard Dev. = 0.14(0.10)
Mean = 0.09(0.09) NSAStandard Dev. = 0.09(0.09)
Mean = 0.54 (0.052) TCAPStandard Dev. = 0.12(0.12)
Mean = -0.17(-0.037) SGPStandard Dev. = 0.64(0.23)
Also…
•Assess satellite retrievals of cloud properties in the vicinity of the MAGIC ship tracks
Coincident MWACR and KAZR Data
What about the next MAGIC period?
• July 07, 2013 ~ 21 UTC
• August 18, 2013 ~ 21 UTC
• August 19, 2013 ~ 21 UTC
There were 3!
What about the next MAGIC period?
• July 07, 2013 Leg 14A – Just left Los Angeles
No MWACR Data
Coincident MWACR and KAZR Data
A Closer Look..
Ceilometer Data
Conclusions• Multiple errors arise using this dual-frequency
retrieval approach • More work and analysis will be done to fully
understand reasons for these errors to correct for them
• Once accurate LWC measurements are achieved and corresponding retrieved LWPs are comparable to radiometer LWPs, we will extend approach to retrieve LWCs from all directions
Future Work
• Evaluate retrieval response to beam offsets from KAZR
• Study beamwidth differences between MWR3C and radars in more detail - especially in broken cloud periods
• Start analysis on the coincident time with CALIPSO/CloudSat soon
Acknowledgements
• Eugene Clothiaux • Dong Huang• Johannes Verlinde• Ernie Lewis• Maria Caddedu• Karen Johnson• Kultegin Aydin• Seiji Kato
Thank You!
Questions?Comments?