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?