Improved ice content, radiation, precipitation and low-level circulation over the tropical pacific from ECMWF ERA-interim to ERA5

Jui Lin F. Li, Kuan Man Xu, Mark Richardson, Jonathan H. Jiang, Graeme Stephens, Wei Liang Lee, Eric Fetzer, Jia Yuh Yu, Yi Hui Wang, F. J. Wang

Research output: Contribution to journalLetterpeer-review

2 Scopus citations

Abstract

This study evaluates changes in simulated Pacific climate between two ECMWF re-analyses; the ERA Interim (ERAI) and the newest ERA5. Changes in the Integrated Forecasting System (IFS) and possibly sea surface temperature result in greatly reduced discrepancies in ERA5’s ice water path (IWP), radiative fluxes and precipitation relative to satellite-based observational products. IWP shows the largest percentage change, increasing by over 300% from ERAI to ERA5, due to inclusion of falling ice (snow) that impacts radiative calculation. ERAI to ERA5 changes in high-cloud fraction are generally anticorrelated as expected with outgoing longwave radiation, with ERA5 having smaller longwave discrepancies versus CERES observations compared with ERAI. Reflected shortwave discrepancies are similarly reduced from ERAI to ERA5, which appears to be due to changes in both cloud fraction and optical depth. Finally, ERA5 also reduces a longstanding precipitation excess relative to the GPCP observational product in the southern trade winds region between the Southern Pacific and intertropical convergence zones. This appears to be related to cooler prescribed sea surface temperatures, thereby reducing local moisture supply via suppressing net latent heat flux and stronger surface trade-winds. Compared with GPCP and CERES, ERA5 shows similar geographic patterns of discrepancies to ERAI in terms of precipitation and top-of-atmosphere radiation, but their magnitudes are greatly reduced in ERA5.

Original languageEnglish
Article number081006
JournalEnvironmental Research Communications
Volume3
Issue number8
DOIs
StatePublished - 2021

Keywords

  • Convective zone (ITCZ)
  • Global climate model
  • Hydrometeor-radiation
  • Large-scale circulation
  • Reanalysis
  • Tropical ocean

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