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 Climate impact of volcanic eruptions: the sensitivity to eruption season and latitude in MPI-ESM ensemble experiments

2021 ◽  
Author(s):  
Zhihong Zhuo ◽  
Ingo Kirchner ◽  
Stephan Pfahl ◽  
Ulrich Cubasch
Keyword(s):  
Southern Hemisphere ◽  
South Asian ◽  
Volcanic Eruptions ◽  
Climate Impacts ◽  
South Asian Summer Monsoon ◽  
The South ◽  
Radiative Effects ◽  
Near Surface ◽  
Volcanic Aerosols ◽  
The Impact

Abstract. Explosive volcanic eruptions influence near-surface temperature and precipitation especially in the monsoon regions, but the impact varies with different eruption seasons and latitudes. To study this variability, two groups of ensemble simulations are performed with volcanic eruptions in June and December at 0° representing an equatorial eruption (EQ) and at 30° N and 30° S representing northern and southern hemisphere eruptions (NH and SH). Results show significant cooling especially in areas with enhanced volcanic aerosol content. Stronger cooling emerges in the northern (southern) hemisphere after the NH (SH) eruption compared to the EQ eruption. Stronger precipitation variations occur in the tropics than in the high latitudes. Summer and winter eruptions lead to similar climate impacts. The NH and the SH eruptions have reversed climate impacts, especially in the South Asian monsoon regions. After the NH (SH) eruption, direct radiative effects of volcanic aerosols induce changes in the interhemispheric and land-sea thermal contrasts, which move the intertropical convergence zone southward (northward) and weaken (strengthen) the South Asian summer monsoon. This reduces (increases) the moisture transport from the ocean to India, and reduces (enhances) cloud formation. The subsequent radiative feedbacks due to regional cloud cover lead to warming (cooling) in India. This emphasis the sensitivity of regional climate impacts of volcanic eruptions to eruption latitude, which relates to the dynamical response of the climate system to radiative effects of volcanic aerosols and the subsequent regional physical feedbacks.

scholarly journals Projected Significant Increase in the Number of Extreme Extratropical Cyclones in the Southern Hemisphere

2017 ◽  
Vol 30 (13) ◽  
pp. 4915-4935 ◽  
Author(s):  
Edmund K. M. Chang
Keyword(s):  
Sea Level ◽  
Southern Hemisphere ◽  
Cmip5 Models ◽  
General Interest ◽  
Extratropical Cyclones ◽  
The South ◽  
Sea Level Pressure ◽  
Near Surface ◽  
Level Pressure ◽  
South Indian

Extratropical cyclones are responsible for much of the extreme weather in the midlatitudes; thus, how these cyclones may change under increasing greenhouse gas forcing is of much general interest. Previous studies have suggested a poleward shift in the location of these cyclones, but how the intensity may change remains uncertain, especially in terms of maximum wind speed. In this study, projected changes in extreme cyclones in the Southern Hemisphere, based on 26 models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5), are presented. Multiple definitions of extreme cyclones have been examined, including intensity exceeding constant thresholds of sea level pressure perturbations, 850-hPa vorticity, and 850-hPa winds, as well as variable thresholds corresponding to a top-5 or top-1 cyclone per winter month in these three parameters and the near-surface winds. Results presented show that CMIP5 models project a significant increase in the frequency of extreme cyclones in all four seasons regardless of the definition, with over 88% of the models projecting an increase. Spatial patterns of increase are also consistent, with the largest increase projected between 45° and 60°S, extending from the South Atlantic across the south Indian Ocean into the Pacific. The projected increases in cyclone statistics are consistent with those in Eulerian statistics, such as sea level pressure (SLP) variance. However, while the projected increase in SLP variance can be linked to increase in the mean available potential energy (MAPE), the increases in cyclone statistics are not well correlated with those in MAPE.

Midlatitude Cloud Radiative Effect Sensitivity to Cloud Controlling Factors in Observations and Models: Relationship with Southern Hemisphere Jet Shifts and Climate Sensitivity

2021 ◽  
pp. 1-59
Author(s):  
Kevin M. Grise ◽  
Mitchell K. Kelleher
Keyword(s):  
Surface Temperature ◽  
Southern Hemisphere ◽  
Climate Sensitivity ◽  
Vertical Velocity ◽  
Large Scale ◽  
Climate Models ◽  
Controlling Factors ◽  
Cmip5 Models ◽  
Near Surface ◽  
Temperature Advection

AbstractAn effective method to understand cloud processes and to assess the fidelity with which they are represented in climate models is the cloud controlling factor framework, in which cloud properties are linked with variations in large-scale dynamical and thermodynamical variables. This study examines how midlatitude cloud radiative effects (CRE) over oceans co-vary with four cloud controlling factors: mid-tropospheric vertical velocity, estimated inversion strength (EIS), near-surface temperature advection, and sea surface temperature (SST), and assesses their representation in CMIP6 models with respect to observations and CMIP5 models.CMIP5 and CMIP6 models overestimate the sensitivity of midlatitude CRE to perturbations in vertical velocity, and underestimate the sensitivity of midlatitude shortwave CRE to perturbations in EIS and temperature advection. The largest improvement in CMIP6 models is a reduced sensitivity of CRE to vertical velocity perturbations. As in CMIP5 models, many CMIP6 models simulate a shortwave cloud radiative warming effect associated with a poleward shift in the Southern Hemisphere (SH) midlatitude jet stream, an effect not present in observations. This bias arises because most models’ shortwave CRE are too sensitive to vertical velocity perturbations and not sensitive enough to EIS perturbations, and because most models overestimate the SST anomalies associated with SH jet shifts. The presence of this bias directly impacts the transient surface temperature response to increasing greenhouse gases over the Southern Ocean, but not the global-mean surface temperature. Instead, the models’ climate sensitivity is correlated with their shortwave CRE sensitivity to surface temperature advection perturbations near 40°S, with models with more realistic values of temperature advection sensitivity generally having higher climate sensitivity.

scholarly journals Fine-Resolved, Near-Coastal Spatiotemporal Variation of Temperature in Response to Insolation

2013 ◽  
Vol 52 (5) ◽  
pp. 1208-1220 ◽  
Author(s):  
Nikki Vercauteren ◽  
Georgia Destouni ◽  
Carl Johan Dahlberg ◽  
Kristoffer Hylander
Keyword(s):  
Model Development ◽  
Temperature Response ◽  
Lag Time ◽  
Spatiotemporal Variation ◽  
Eastern Coast ◽  
Atmospheric Conditions ◽  
Near Surface ◽  
Average Temperature ◽  
Monthly Average ◽  
Diurnal Temperature Variation

AbstractThis study uses GIS-based modeling of incoming solar radiation to quantify fine-resolved spatiotemporal responses of monthly average temperature, and diurnal temperature variation, at different times and locations within a field study area located on the eastern coast of Sweden. Near-surface temperatures are measured by a network of temperature sensors during the spring and summer of 2011 and then used as the basis for model development and testing. The modeling of finescale spatiotemporal variation considers topography, distance from the sea, and observed variations in atmospheric conditions, accounting for site latitude, elevation, surface orientation, daily and seasonal shifts in sun angle, and effects of shadows from surrounding topography. The authors find a lag time between insolation and subsequent temperature response that follows an exponential decay from coastal to inland locations. They further develop a linear regression model that accounts for this lag time in quantifying fine-resolved spatiotemporal temperature evolution. This model applies in the considered growing season for spatial distribution across the studied near-coastal landscape.

scholarly journals Climate impact of volcanic eruptions: the sensitivity to eruption season and latitude in MPI-ESM ensemble experiments

2021 ◽  
Vol 21 (17) ◽  
pp. 13425-13442
Author(s):  
Zhihong Zhuo ◽  
Ingo Kirchner ◽  
Stephan Pfahl ◽  
Ulrich Cubasch
Keyword(s):  
Southern Hemisphere ◽  
Regional Climate ◽  
Volcanic Eruptions ◽  
Climate Impact ◽  
Climate Impacts ◽  
Cloud Formation ◽  
Radiative Effects ◽  
Near Surface ◽  
Volcanic Aerosols ◽  
The Impact

Abstract. Explosive volcanic eruptions influence near-surface temperature and precipitation especially in the monsoon regions, but the impact varies with different eruption seasons and latitudes. To study this variability, two groups of ensemble simulations are performed with volcanic eruptions in June and December at 0∘ representing an equatorial eruption (EQ) and at 30∘ N and 30∘ S representing Northern and Southern Hemisphere eruptions (NH and SH). Results show significant cooling especially in areas with enhanced volcanic aerosol content. Compared to the EQ eruption, stronger cooling emerges in the Northern Hemisphere after the NH eruption and in the Southern Hemisphere after the SH eruption. Stronger precipitation variations occur in the tropics than in the high latitudes. Summer and winter eruptions lead to similar hydrological impacts. The NH and the SH eruptions have reversed climate impacts, especially in the regions of the South Asian summer monsoon (SASM). After the NH eruption, direct radiative effects of volcanic aerosols induce changes in the interhemispheric and land–sea thermal contrasts, which move the intertropical convergence zone (ITCZ) southward and weaken the SASM. This reduces the moisture transport from the ocean and reduces cloud formation and precipitation in India. The subsequent radiative feedbacks due to regional cloud cover lead to warming in India. After the SH eruption, vice versa, a northward movement of the ITCZ and strengthening of the SASM, along with enhanced cloud formation, lead to enhanced precipitation and cooling in India. This emphasizes the sensitivity of regional climate impacts of volcanic eruptions to eruption latitude, which relates to the dynamical response of the climate system to radiative effects of volcanic aerosols and the subsequent regional physical feedbacks. Our results indicate the importance of considering dynamical and physical feedbacks to understand the mechanism behind regional climate responses to volcanic eruptions and may also shed light on the climate impact and potential mechanisms of stratospheric aerosol engineering.

scholarly journals Uncertainty and detectability of climate surface response to large volcanic eruptions

2016 ◽  
Author(s):  
Fabian Wunderlich ◽  
Daniel M. Mitchell
Keyword(s):  
El Niño ◽  
El Nino ◽  
Temperature Response ◽  
Coupled Model ◽  
Volcanic Eruptions ◽  
Shortwave Radiation ◽  
Cmip5 Models ◽  
Surface Cooling ◽  
Positive Tendency ◽  
Large Volcanic Eruptions

Abstract. In light of the range in presently available observational, reanalysis and model data, we revisit the surface climate response to large tropical volcanic eruptions from the end of the 19th century until present. We focus on the dynamical driven response of the North Atlantic Oscillation (NAO) and the radiative driven tropical temperature response. Using ten different reanalysis products and the Hadley Centre Sea Level Pressure observational dataset (HadSLP2) we confirm a positive tendency in the phase of the NAO during boreal winters following large volcanic eruptions, although conclude that it is not as clear cut as the current literature suggests. Especially during poorly observed periods where higher uncertainties produce a less robust signal. The phase of the NAO leads to a dynamically driven warm anomaly over Northern Europe. At the same time, there is a general cooling of the tropical surface temperatures due to the reduced incoming shortwave radiation. The magnitude of this cooling is uncertain and is hard to isolate using observational data alone (mainly due to the presence of El Niño). Therefore we use regression-based detection and attribution techniques to investigate the volcanic temperature signal with eight Coupled Model Inter-comparison Project phase 5 (CMIP5) models. In all models the volcanic signal can be detected but a general overestimation of the surface cooling is found. The enhanced surface cooling in models is likely driven, in part, by an over absorption of SW radiation in the lower stratosphere, but aliasing with El Niño events is also an issue and further process based studies are necessary to confirm these.

scholarly journals Autumn Precipitation Trends over Southern Hemisphere Midlatitudes as Simulated by CMIP5 Models

2013 ◽  
Vol 26 (21) ◽  
pp. 8341-8356 ◽  
Author(s):  
Ariaan Purich ◽  
Tim Cowan ◽  
Seung-Ki Min ◽  
Wenju Cai
Keyword(s):  
Southern Hemisphere ◽  
Southern Africa ◽  
Climate Models ◽  
Global Climate Models ◽  
Cmip5 Models ◽  
Southern Chile ◽  
Southeastern Australia ◽  
Dry Zone ◽  
Austral Autumn ◽  
Precipitation Trends

Abstract In recent decades, Southern Hemisphere midlatitude regions such as southern Africa, southeastern Australia, and southern Chile have experienced a reduction in austral autumn precipitation; the cause of which is poorly understood. This study focuses on the ability of global climate models that form part of the Coupled Model Intercomparison Project phase 5 to simulate these trends, their relationship with extratropical and subtropical processes, and implications for future precipitation changes. Models underestimate both the historical autumn poleward expansion of the subtropical dry zone and the positive southern annular mode (SAM) trend. The multimodel ensemble (MME) is also unable to capture the spatial pattern of observed precipitation trends across semiarid midlatitude regions. However, in temperate regions that are located farther poleward such as southern Chile, the MME simulates observed precipitation declines. The MME shows a strong consensus in twenty-first-century declines in autumn precipitation across southern Chile in both the medium–low and high representative concentration pathway (RCP) scenarios and across southern Africa in the high RCP scenario, but little change across southeastern Australia. Projecting a strong positive SAM trend and continued subtropical dry-zone expansion, the models converge on large SAM and dry-zone-expansion-induced precipitation declines across southern midlatitudes. In these regions, the strength of future precipitation trends is proportional to the strength of modeled trends in these phenomena, suggesting that unabated greenhouse gas–induced climate change will have a large impact on austral autumn precipitation in such midlatitude regions.

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