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Abstract Tropical average shortwave cloud radiative effect (SWCRE) anomalies observed by CERES/EBAF v4 are explained by observed average sea surface temperature () and the difference between the warmest 30% where deep convection occurs and). Observed tropospheric temperatures show variations in boundary layer capping strength over time consistent with the evolution of SST#. The CERES/EBAF v4 data confirm that associated cloud fraction changes over the colder waters dominate SWCRE. This observational evidence for the “pattern effect” noted in General Circulation Model simulations suggests that SST#captures much of this effect. The observed sensitivities (dSWCRE/dW·m−2·K−1, dSWCRE/dSST#≈−4.8W·m−2·K−1) largely reflect El Niño–Southern Oscillation. As El Niño develops,increases and SST#decreases (both increasing SWCRE). Only after the El Niño peak, SST#increases and SWCRE decreases. SST#is also relevant for the tropical temperature trend profile controversy and the discrepancy between observed and modeled equatorial Pacific SST trends. Causality and implications for future climates are discussed.
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Changes in Tropical Precipitation Intensity With El Niño Warming
Abstract Mesoscale convection generates the majority of extreme precipitation in tropical regions. Changes to these precipitation intensities,P, with long‐term modes of climate variability have been hard to assess because they are not well represented in current climate models. Here we stratify a satellite climatology of convective systems by El Niño phase and cloud top temperature. We find that gains (losses) in high precipitation intensity ( 10 mm hr−1) are largest for the deepest (least deep) systems during El Niño relative to La Niña. The surface temperature and wind changes that define El Niño manifest as surface flux changes but are not sufficient to explain thesetrends. We explore also the dynamical component of precipitation generation with a vertical momentum budget. Midtropospheric drying in the vicinity of the deepest systems boosts instability and ascent rates during El Niño, while the strengthened large‐scale ascent minimizes the drag force on their updrafts.
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- Award ID(s):
- 1649770
- PAR ID:
- 10386837
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 47
- Issue:
- 14
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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