Abstract
Abstract. Precipitation susceptibility to aerosol perturbation plays a key role in understanding aerosol–cloud interactions and constraining aerosol indirect effects. However, large discrepancies exist in the previous satellite estimates of precipitation susceptibility. In this paper, multi-sensor aerosol and cloud products, including those from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, Moderate Resolution Imaging Spectroradiometer (MODIS), and Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) from June 2006 to April 2011 are analyzed to estimate precipitation frequency susceptibility SPOP, precipitation intensity susceptibility SI, and precipitation rate susceptibility SR in warm marine clouds. We find that SPOP strongly depends on atmospheric stability, with larger values under more stable environments. Our results show that precipitation susceptibility for drizzle (with a −15 dBZ rainfall threshold) is significantly different than that for rain (with a 0 dBZ rainfall threshold). Onset of drizzle is not as readily suppressed in warm clouds as rainfall while precipitation intensity susceptibility is generally smaller for rain than for drizzle. We find that SPOP derived with respect to aerosol index (AI) is about one-third of SPOP derived with respect to cloud droplet number concentration (CDNC). Overall, SPOP demonstrates relatively robust features throughout independent liquid water path (LWP) products and diverse rain products. In contrast, the behaviors of SI and SR are subject to LWP or rain products used to derive them. Recommendations are further made for how to better use these metrics to quantify aerosol–cloud–precipitation interactions in observations and models.
Highlights
Aerosol–cloud interactions play an important role in the climate system and affect the global energy budget and hydrological cycle
The monotonic increase of SI_CDNC with increasing liquid water path (LWP) in Terai et al (2015) is mainly because the LWP range in their study is relatively narrow and our results suggest that when the upper bound of LWP is extended to ∼ 800 g m−2, the “descending branch” (S decreases with increasing LWP) noted in Feingold et al (2013) appears, though the exact LWP value where SI_CDNC peaks depends on LWP and rain products used as well as the rainfall threshold choices
We estimate precipitation susceptibility on warm clouds over global oceans based on multi-sensor aerosol and cloud products from the A-Train satellites, including Moderate Resolution Imaging Spectroradiometer (MODIS), AMSR-E, Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), and CPR observations, covering the period June 2006 to April 2011
Summary
Aerosol–cloud interactions play an important role in the climate system and affect the global energy budget and hydrological cycle. Over the past few decades, numerous methodologies have been developed to understand and quantify the impacts of aerosol–cloud interactions on the climate system. A unique method is to use the so-called “susceptibility” to explain and predict how clouds and precipitation would respond if there were some aerosol perturbations. Susceptibility is defined as the derivative of cloud and/or precipitation properties with respect to aerosolrelated properties. Platnick and Twomey (1994) proposed a cloud albedo susceptibility as Sλ = ∂A/∂CDNC, where A is cloud albedo and CDNC is cloud droplet number concentration, to quantify the cloud albedo effect of aerosol
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