EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Exploring satellite-derived relationships between cloud droplet number concentration and liquid water path using large-domain large-eddy simulation

Sudhakar Dipu1, Matthias Schwarz2,6, Annica M. L Ekman2, Edward Gryspeerdt3, Tom Goren1, Odran Sourdeval4, Johannes Mülmenstädt1,5, and Johannes Quaas1
Sudhakar Dipu et al.
  • 1University of Leipzig, Institute for meteorology, Leipzig, Germany (
  • 2Department of Meteorology and Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
  • 3Imperial College, London, UK
  • 4Laboratoired’Optique Atmosphérique, Université de Lille, France
  • 5Pacific Northwest National Laboratory, Richland, USA
  • 6ZAMG – Zentralanstalt für Meteorologie und Geodynamik, Vienna, Austria

Important aspects of the adjustments to aerosol-cloud interactions can be examined using the relationship between cloud droplet number concentration (Nd) and liquid water path (LWP). Specifically, this relation can constrain the role of aerosols in leading to thicker or thinner clouds in response to adjustment mechanisms. This study investigates the satellite retrieved relationship between Nd and LWP for a selected case of mid-latitude continental clouds using high-resolution Large-eddy simulations (LES) over a large domain in weather prediction mode. Since the satellite retrieval uses the adiabatic assumption to derive the Nd (NAd), we have also considered NAd from the LES model for comparison. The joint histogram analysis shows that the NAd-LWP relationship in the LES model and the satellite is in approximate agreement. In both cases, the peak conditional probability (CP) is confined to lower NAd and LWP, and the corresponding mean LWP shows a weak relation with NAd. In contrast, at higher NAd (> 50 cm−3 ), the CP shows a larger spread; consequently, the mean LWP increases non-monotonically with increasing NAd in both cases. However, the NAd-LWP relation lacks, in particular, the negative sensitivity at higher NAd. This case over continent thus behaves differently compared to previously-published analysis of Oceanic clouds using satellite retrievals. Additionally, our analysis illustrates a regime dependency (marine and continental) in the NAd-LWP relation from the satellite retrievals. When considering the relationship of the simulated cloud-top Nd, rather than NAd, with LWP, the result shows a much more nonlinear (positive and negative) relationship and is inconsistent with the satellite retrievals. However, the difference is much less pronounced when the sensitivity (Nd-LWP) is considered for shallow stratiform (adiabatic) than convective (sub-adiabatic) clouds. Comparing local vs large-scale statistics from satellite data shows that continental clouds exhibit only a weak nonlinear Nd-LWP relationship. Hence a regime-based Nd-LWP analysis is even more relevant when it comes to continental clouds and its comparison to satellite retrievals. 

How to cite: Dipu, S., Schwarz, M., Ekman, A. M. L., Gryspeerdt, E., Goren, T., Sourdeval, O., Mülmenstädt, J., and Quaas, J.: Exploring satellite-derived relationships between cloud droplet number concentration and liquid water path using large-domain large-eddy simulation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8789,, 2022.

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