Impact on Modeled Cloud Characteristics Due to Simplified Treatment of Uniform Cloud Condensation Nuclei During NEAQS 2004
Subgrid-scale cloud condensation nuclei (CCN) heterogeneity is not represented in global climate models (GCM) and potentially contributes systematic errors to simulated cloud effects. High-resolution mesoscale model simulations were performed to investigate the impact of assuming a uniform CCN distribution on cloud properties and surface radiation over a region the size of a GCM grid column. Results indicate that a prescribed CCN distribution allowing for vertical and temporal fluctuations does substantially better in simulating cloud properties and radiative effects than does a prescribed uniform and constant CCN distribution. Spatially and temporally averaged net effects on downwelling shortwave radiation are between -3 and -11 W m-2 for the fluctuating and uniform distributions, respectively, versus a control simulation with fully interactive aerosols. Both prescribed CCN distributions produce optically thicker clouds more often than the control, with the mean cloud optical depth increasing by over 25% when using the uniform and constant CCN distribution.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 919978
- Report Number(s):
- PNNL-SA-54354; GPRLAJ; KP1205030; TRN: US200822%%651
- Journal Information:
- Geophysical Research Letters, 34(19):L19809, Vol. 34, Issue 19; ISSN 0094-8276
- Country of Publication:
- United States
- Language:
- English
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