Publication Abstracts

Fahrin et al. 2026, accepted

Fahrin, F., A.O. Gonzalez, G. Cesana, C. DeMott, and R. Neale, 2026: Representation of stratocumulus and shallow cumulus cloud fraction near the southeast Pacific Ocean ITCZ in ERA5 and MERRA-2 Reanalyses. J. Geophys. Res. Atmos., accepted.

Model precipitation biases in the southeast Pacific Ocean intertropical convergence zone (ITCZ) are often tied to the underestimation of stratocumulus (Sc) and shallow cumulus (Cu) clouds. We design a method to distinguish between Sc and Cu cloud fraction (CF) regimes on daily timescales based on cloud top pressure and vertical velocity to investigate the spatial distributions, seasonal evolution, and large-scale atmospheric conditions associated with these CF near the southeast Pacific ITCZ. We compare the Cumulus and Stratocumulus Cloudsat-CALIPSO Dataset (CASCCAD) with the European Center for Medium-range Weather Forecasts ERA5 reanalysis and the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2). In both reanalyses, the spatial patterns, vertical structure, and seasonal cycle of Sc CF are faithful to CASCCAD observations, but the amplitudes are underestimated. Cu CF vertical structure and spatial patterns are well simulated in ERA5, but both reanalyses vastly underestimate Cu CF magnitude. MERRA-2 cannot capture the Cu CF vertical structure and has no Cu low cloud fraction (LCF) near the southern ITCZ in March. An investigation of Sc and Cu days suggests that while both reanalyses have favorable conditions for Sc LCF, however, MERRA-2 has weaker vertical motions and relatively high cloud liquid water content during Cu days. Lastly, there is an increase in Sc and a decrease in Cu LCF in the southern hemisphere when the northern ITCZs are prevalent. The opposite happens during southern ITCZs. Overall, despite similar mean southern ITCZ precipitation, ERA5 provides more realistic Sc and Cu cloud populations than MERRA-2.

Export citation: [ BibTeX ] [ RIS ]

BibTeX Citation

@unpublished{fa07200b,
  author={Fahrin, F. and Gonzalez, A. O. and Cesana, G. and DeMott, C. and Neale, R.},
  title={Representation of stratocumulus and shallow cumulus cloud fraction near the southeast Pacific Ocean ITCZ in ERA5 and MERRA-2 Reanalyses},
  year={2026},
  journal={Journal of Geophysical Research: Atmospheres},
}

[ Close ]

RIS Citation

TY  - INPR
ID  - fa07200b
AU  - Fahrin, F.
AU  - Gonzalez, A. O.
AU  - Cesana, G.
AU  - DeMott, C.
AU  - Neale, R.
PY  - 2026
TI  - Representation of stratocumulus and shallow cumulus cloud fraction near the southeast Pacific Ocean ITCZ in ERA5 and MERRA-2 Reanalyses
JA  - J. Geophys. Res. Atmos.
JO  - Journal of Geophysical Research: Atmospheres
ER  -

[ Close ]

• Return to In-Press / Accepted Publications

• Return to Publications Homepage