Southern African Temperature Responses to Major Volcanic Eruptions since 1883: simulated by CMIP5 Models

2021 ◽  
Author(s):  
P. J. Harvey ◽  
S. W. Grab
Keyword(s):  
Volcanic Eruptions ◽  
Cmip5 Models ◽  
Temperature Responses

Southern Hemisphere Continental Temperature Responses to Major Volcanic Eruptions Since 1883 in CMIP5 Models

2021 ◽  
Author(s):  
Pamela J Harvey ◽  
Stefan W Grab
Keyword(s):  
Southern Hemisphere ◽  
Temperature Response ◽  
Volcanic Eruptions ◽  
Lag Time ◽  
Cmip5 Models ◽  
Seasonal Temperature ◽  
Near Surface ◽  
Santa Maria ◽  
Temperature Responses ◽  
Austral Autumn

Abstract Although global and Northern Hemisphere (NH) temperature responses to volcanic forcing have been extensively investigated, knowledge of such responses over Southern Hemisphere (SH) continental regions is still limited. Here we use an ensemble of CMIP5 models to explore SH temperature responses to four major volcanic eruptions: Krakatau (1883), Santa Maria (1902), Agung (1963) and Pinatubo (1991). Focus is on near-surface temperature responses over southern continental landmasses including southern South America (SSA), southern Africa (SAF) and Australia and their seasonal differences. Findings indicate that for all continents, temperature responses were strongest and lasted longest following the Krakatau eruption. Responses in Australia had the shortest lag time, strongest maximum seasonal response, as well as the most significant monthly anomalies. In contrast, SSA records the longest lag time, weakest maximum seasonal temperature response, and lowest number of monthly negative anomalies following these eruptions. In most cases, the strongest single-season response occurred in austral autumn or winter, and the weakest in summer or spring. We tentatively propose that cooler temperature responses are likely caused, at least in part, by the intensification of the westerlies and associated mid-latitude cyclones and anti-cyclones.

scholarly journals Reconciling the disagreement between observed and simulated temperature responses to deforestation

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Liang Chen ◽  
Paul A. Dirmeyer
Keyword(s):  
Land Use ◽  
Radiation Effects ◽  
Climate Models ◽  
Climate Model ◽  
Land Use Changes ◽  
Cmip5 Models ◽  
Analysis Methodology ◽  
Atmospheric Feedbacks ◽  
Changes Over Time ◽  
Temperature Responses

AbstractLand use changes have great potential to influence temperature extremes. However, contradictory summer daytime temperature responses to deforestation are reported between observations and climate models. Here we present a pertinent comparison between multiple satellite-based datasets and climate model deforestation experiments. Observationally-based methods rely on a space-for-time assumption, which compares neighboring locations with contrasting land covers as a proxy for land use changes over time without considering possible atmospheric feedbacks. Offline land simulations or subgrid-level analyses agree with observed warming effects only when the space-for-time assumption is replicated. However, deforestation-related cloud and radiation effects manifest in coupled climate simulations and observations at larger scales, which show that a reduction of hot extremes with deforestation – as simulated in a number of CMIP5 models – is possible. Our study provides a design and analysis methodology for land use change studies and highlights the importance of including land-atmosphere coupling, which can alter deforestation-induced temperature changes.

scholarly journals Boreal Winter Surface Air Temperature Responses to Large Tropical Volcanic Eruptions in CMIP5 Models

2020 ◽  
Vol 33 (6) ◽  
pp. 2407-2426 ◽  
Author(s):  
Chen Xing ◽  
Fei Liu ◽  
Bin Wang ◽  
Deliang Chen ◽  
Jian Liu ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Surface Air Temperature ◽  
Polar Vortex ◽  
Volcanic Eruptions ◽  
Cmip5 Models ◽  
Boreal Winter ◽  
Model Intercomparison ◽  
Global Cooling ◽  
Intercomparison Project

AbstractWe analyzed global surface air temperature (SAT) responses to five major tropical volcanic eruptions from 1870 to 2005 using outputs from 97 historical and 58 Atmospheric Model Intercomparison Project (AMIP) runs that participated in phase 5 of the Coupled Model Intercomparison Project (CMIP5). In observations, there was a 3-yr global cooling trend after the eruption due to reduced shortwave radiation, and a 0.1-K average global-mean SAT recovery, consisting of El Niño–like tropical warming and Eurasian warming, occurred in the first posteruption boreal winter. This global cooling pause was simulated by the multimodel ensemble (MME) mean of the AMIP runs, but not the MME of the historical runs due to the absence of El Niño–like warming. In the historical runs, simulation of El Niño–like warming was influenced by the initial ocean condition (IOC). An El Niño–like response was simulated when the IOC was not in an El Niño state, but the warming was much weaker compared to observations. The Eurasian warming response, despite being reproduced by the MME mean of both AMIP and historical runs, was not as strong as in observations. This is because the simulated positive polar vortex response, an important stratospheric forcing for Eurasian warming, was very weak, which suggests that the CMIP5 models, and even the Climate Forecast System model, underestimate volcanic effects on the stratosphere. Most of the coupled models failed to replicate both the El Niño and the enhanced polar vortex responses, indicating an urgent need for improving air–sea interaction and stratospheric processes in these models.

Volcanic-induced global monsoon drying modulated by diverse El Niño responses

2021 ◽  
Author(s):  
Seungmok Paik ◽  
Seung-Ki Min ◽  
Carley E. Iles ◽  
Erich M. Fischer ◽  
Andrew P. Schurer
Keyword(s):  
Coupled Model ◽  
Volcanic Eruptions ◽  
Western Pacific ◽  
Cmip5 Models ◽  
Water Volume ◽  
Global Monsoon ◽  
Model Simulations ◽  
Two Factors ◽  
Warm Water Volume ◽  
Global Precipitation

<p>This study identifies a crucial cause of the large uncertainty in global precipitation response after volcanic eruptions. We find an important contribution of diverse El Niño responses to the inter-simulation spread in the global monsoon drying responses to tropical eruptions. Most Coupled Model Intercomparison Project Phase 5 (CMIP5) models simulate El Niño–like equatorial eastern Pacific warming at the year after eruptions but with different amplitudes, which drive a large spread of summer monsoon weakening and corresponding precipitation reduction. Two factors are further identified for the diverse El Niño responses among CMIP5 model simulations. First, difference in imposed volcanic forcings induces systematic differences in the Maritime Continent precipitation drying and subsequent westerly winds over equatorial western Pacific, accounting for a large portion (29%) of inter-simulation spread in El Niño intensities following eruptions. In addition, the internally generated warm water volume over the equatorial western Pacific in the pre-eruption month also contributes to the diverse El Niño development, explaining about 14% of the total inter-simulation variance through the recharge oscillator mechanism. Our findings based on CMIP5 multi-model simulations confirm that reliable estimates of the volcanic forcing magnitude as well as the pre-eruption oceanic condition are required to obtain more reliable simulations or predictions of the hydrological responses to tropical eruptions.</p>

Global surface-temperature responses to major volcanic eruptions

Nature ◽  
1987 ◽  
Vol 330 (6146) ◽  
pp. 365-367 ◽  
Author(s):  
C. B. Sear ◽  
P. M. Kelly ◽  
P. D. Jones ◽  
C. M. Goodess
Keyword(s):  
Surface Temperature ◽  
Volcanic Eruptions ◽  
Global Surface Temperature ◽  
Temperature Responses ◽  
Global Surface
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