Aerosol impacts on drizzle properties in warm clouds from ARM Mobile Facility maritime and continental deployments. Issue 7 (9th April 2014)

• Record Type: Journal Article
• Authors: Mann, Julian A. L.; Christine Chiu, J.; Hogan, Robin J.; O'Connor, Ewan J.; L'Ecuyer, Tristan S.; Stein, Thorwald H. M.; Jefferson, Anne
• Is Part Of: Journal of geophysical research. Volume 119:Issue 7(2014:Jul.)
• Page Start: 4136
• Page End: 4148
• Publication Date: 2014-04-09
• Subjects: Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2013JD021339
• Languages: English
• ISSNs: 2169-897X

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>We have extensively evaluated the response of cloud base drizzle rate (<italic>R</italic><sub>cb</sub>; mm d<sup>−1</sup>) in warm clouds to liquid water path (LWP; g m<sup>−2</sup>) and to cloud condensation nuclei (CCN) number concentration (<italic>N</italic><sub>CCN</sub>; cm<sup>−3</sup>), an aerosol proxy. This evaluation is based on a 19 month long data set of Doppler radar, lidar, microwave radiometers, and aerosol observing systems from the Atmospheric Radiation Measurement (ARM) Mobile Facility deployments at the Azores and in Germany. Assuming 0.55% supersaturation to calculate <italic>N</italic><sub>CCN</sub>, we found a power law <alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg5gfrrk9n" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" overflow="scroll" altimg="urn:x-wiley:2169897X:media:jgrd51297:jgrd51297-math-0001" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi mathvariant="italic">R</mml:mi><mml:mi mathvariant="normal">cb</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mfenced open="(" close=")"><mml:mrow><mml:mn>0.0015</mml:mn><mml:mo>±</mml:mo><mml:mn>0.0009</mml:mn></mml:mrow></mml:mfenced><mml:mo>⋅</mml:mo><mml:msup><mml:mi mathvariant="normal">LWP</mml:mi><mml:mfenced open="(" close=")"><mml:mrow><mml:mn>1.68</mml:mn><mml:mo>±</mml:mo><mml:mn>0.05</mml:mn></mml:mrow></mml:mfenced></mml:msup><mml:msubsup><mml:mi mathvariant="italic">N</mml:mi><mml:mi mathvariant="normal">CCN</mml:mi><mml:mrow><mml:mo>−</mml:mo><mml:mfenced open="(" close=")"><mml:mrow><mml:mn>0.66</mml:mn><mml:mo>±</mml:mo><mml:mn>0.08</mml:mn></mml:mrow></mml:mfenced></mml:mrow></mml:msubsup></mml:mrow></mml:math></alternatives>, indicating that <italic>R</italic><sub>cb</sub> decreases by a factor of 2–3 as <italic>N</italic><sub>CCN</sub> increases from 200 to 1000 cm<sup>−3</sup> for fixed LWP. Additionally, the precipitation susceptibility to <italic>N</italic><sub>CCN</sub> ranges between 0.5 and 0.9, in agreement with values from simulations and aircraft measurements. Surprisingly, the susceptibility of the probability of precipitation from our analysis is much higher than that from CloudSat estimates but agrees well with simulations from a multiscale high‐resolution aerosol‐climate model. Although scale issues are not completely resolved in the intercomparisons, our results are encouraging, suggesting that it is possible for multiscale models to accurately simulate the response of LWP to aerosol perturbations.</p> </abstract>