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Retrieving Liquid Water Contents of Boundary-layer Clouds Using Dual-frequency Cloud Radars

Retrieving Liquid Water Contents of Boundary-layer Clouds Using Dual-frequency Cloud Radars. Courtney Laughlin 1 , Dong Huang 2 , Eugene Clothiaux 1 , Johannes Verlinde 1 , Kultegin Aydin 1 1 The Pennsylvania State University 2 Brookhaven National Laboratory. Objectives.

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Retrieving Liquid Water Contents of Boundary-layer Clouds Using Dual-frequency Cloud Radars

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  1. Retrieving Liquid Water Contents of Boundary-layer Clouds Using Dual-frequency Cloud Radars Courtney Laughlin1, Dong Huang2, Eugene Clothiaux1, Johannes Verlinde1, Kultegin Aydin1 1The Pennsylvania State University 2Brookhaven National Laboratory

  2. 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

  3. Brief History of Dual-frequency Retrieval • Atlas 1954 • Sekelsky 2000 • Hogan et al. 2005 • Huang et al. 2009

  4. Instruments Liquid water cloud

  5. Instruments Liquid water cloud

  6. Instruments Liquid water cloud

  7. 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

  8. 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

  9. November 26, 2012 14:00 – 15:00 UTC

  10. November 26, 2012 14:00 – 15:00 UTC

  11. November 26, 2012 14:00 – 15:00 UTC

  12. November 26, 2012 14:00 – 15:00 UTC

  13. July 08, 2013 16:00-17:00 UTC

  14. July 08, 2013 16:00-17:00 UTC

  15. July 08, 2013 16:00-17:00 UTC

  16. Results

  17. Results Mean = -0.0065(-0.0015) MAGIC Standard Dev. = 0.14(0.10) Mean = 0.09(0.09) NSA Standard Dev. = 0.09(0.09) Mean = 0.54 (0.052) TCAP Standard Dev. = 0.12(0.12) Mean = -0.17(-0.037) SGP Standard Dev. = 0.64(0.23)

  18. Also… • Assess satellite retrievals of cloud properties in the vicinity of the MAGIC ship tracks

  19. Coincident MWACR and KAZR Data

  20. What about the next MAGIC period? There were 3! • July 07, 2013 ~ 21 UTC • August 18, 2013 ~ 21 UTC • August 19, 2013 ~ 21 UTC

  21. What about the next MAGIC period? • July 07, 2013 Leg 14A – Just left Los Angeles • August 18, 2013 No MWACR Data  • August 19, 2013

  22. Coincident MWACR and KAZR Data

  23. A Closer Look..

  24. Ceilometer Data

  25. 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

  26. 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

  27. Acknowledgements • Eugene Clothiaux • Dong Huang • Johannes Verlinde • Ernie Lewis • Maria Caddedu • Karen Johnson • Kultegin Aydin • Seiji Kato

  28. Thank You!Questions?Comments?

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