scholarly journals Amplified tropical Pacific rainfall variability related to background SST warming

2020 ◽  
Vol 54 (3-4) ◽  
pp. 2387-2402 ◽  
Author(s):  
Ning Sun ◽  
Tianjun Zhou ◽  
Xiaolong Chen ◽  
Hirokazu Endo ◽  
Akio Kitoh ◽  
...  
Keyword(s):  
Rainfall Variability ◽  
Tropical Pacific ◽  
Sst Warming

Tropical Atmospheric Variability Forced by Oceanic Internal Variability

2007 ◽  
Vol 20 (4) ◽  
pp. 765-771 ◽  
Author(s):  
Markus Jochum ◽  
Clara Deser ◽  
Adam Phillips
Keyword(s):  
General Circulation ◽  
Climate Models ◽  
Rainfall Variability ◽  
Circulation Model ◽  
Internal Variability ◽  
Tropical Pacific ◽  
Atmospheric Variability ◽  
Instability Waves ◽  
Tropical Instability Waves ◽  
The Tropical Pacific

Abstract Atmospheric general circulation model experiments are conducted to quantify the contribution of internal oceanic variability in the form of tropical instability waves (TIWs) to interannual wind and rainfall variability in the tropical Pacific. It is found that in the tropical Pacific, along the equator, and near 25°N and 25°S, TIWs force a significant increase in wind and rainfall variability from interseasonal to interannual time scales. Because of the stochastic nature of TIWs, this means that climate models that do not take them into account will underestimate the strength and number of extreme events and may overestimate forecast capability.

scholarly journals Intensification of El Niño Rainfall Variability Over the Tropical Pacific in the Slow Oceanic Response to Global Warming

2019 ◽  
Vol 46 (4) ◽  
pp. 2253-2260 ◽  
Author(s):  
Xiao‐Tong Zheng ◽  
Chang Hui ◽  
Shang‐Ping Xie ◽  
Wenju Cai ◽  
Shang‐Min Long
Keyword(s):  
Global Warming ◽  
El Niño ◽  
El Nino ◽  
Rainfall Variability ◽  
Tropical Pacific ◽  
Oceanic Response ◽  
The Tropical Pacific

The Role of Regional SST Warming Variations in the Drying of Meso-America in Future Climate Projections*

2011 ◽  
Vol 24 (7) ◽  
pp. 2003-2016 ◽  
Author(s):  
Sara A. Rauscher ◽  
Fred Kucharski ◽  
David B. Enfield
Keyword(s):  
North Atlantic ◽  
Coupled Model ◽  
Tropical Pacific ◽  
Future Climate ◽  
Ensemble Average ◽  
Subtropical High ◽  
Future Climate Change ◽  
Eastern Tropical Pacific ◽  
Enso Events ◽  
Sst Warming

Abstract This paper addresses several hypotheses designed to explain why AOGCM simulations of future climate in the third phase of the Coupled Model Intercomparison Project (CMIP3) feature an intensified reduction of precipitation over the Meso-America (MA) region. While the drying is consistent with an amplification of the subtropical high pressure cells and an equatorward contraction of convective regions due to the “upped ante” for convection in a warmer atmosphere, the physical mechanisms behind the intensity and robustness of the MA drying signal have not been fully explored. Regional variations in sea surface temperature (SST) warming may play a role. First, SSTs over the tropical North Atlantic (TNA) do not warm as much as the surrounding ocean. The troposphere senses a TNA that is cooler than the tropical Pacific, potentially exciting a Gill-type response, increasing the strength of the North Atlantic subtropical high. Second, the warm ENSO-like state simulated in the eastern tropical Pacific could decrease precipitation over MA, as warm ENSO events are associated with drying over MA. The authors use the International Centre for Theoretical Physics (ICTP) AGCM to investigate the effects of these regional SST warming variations on the projected drying over MA. First, the change of SSTs [Special Report on Emissions Scenarios (SRES) A1B’s Twentieth-Century Climate in Coupled Model (A1B-20C)] in the ensemble average of the CMIP3 models is applied to determine if the ICTP AGCM can replicate the future drying. Then the effects of 1) removing the reduced warming over the TNA, 2) removing the warm ENSO-event-like pattern in the eastern tropical Pacific, and 3) applying uniform SST warming throughout the tropics are tested. The ICTP AGCM can reproduce the general pattern and amount of precipitation over MA. Simulations in which the CMIP3 A1B-20C ensemble-average SSTs are added to climatological SSTs show drying of more than 20% over the MA region, similar to the CMIP3 ensemble average. Replacing the relatively cooler SSTs over the TNA excites a Gill response consistent with an off-equatorial heating anomaly, showing that the TNA relative cooling is responsible for about 16% (31%) of the drying in late spring (early summer). The warm ENSO-like SST pattern over the eastern Pacific also affects precipitation over the MA region, with changes of 19% and 31% in March–June (MMJ) and June–August (JJA), respectively. This work highlights the importance of understanding even robust signals in the CMIP3 future scenario simulations, and should aid in the design and analysis of future climate change studies over the region.

scholarly journals Cloud–Radiation Feedback as a Leading Source of Uncertainty in the Tropical Pacific SST Warming Pattern in CMIP5 Models

2016 ◽  
Vol 29 (10) ◽  
pp. 3867-3881 ◽  
Author(s):  
Jun Ying ◽  
Ping Huang
Keyword(s):  
Heat Budget ◽  
Tropical Pacific ◽  
Eastern Pacific ◽  
Shortwave Radiation ◽  
Cmip5 Models ◽  
Central Pacific ◽  
Surface Warming ◽  
Sst Warming ◽  
Radiation Feedback ◽  
The Tropical Pacific

Abstract The role of the intermodel spread of cloud–radiation feedback in the uncertainty in the tropical Pacific SST warming (TPSW) pattern under global warming is investigated based on the historical and RCP8.5 runs from 32 models participating in CMIP5. The large intermodel discrepancies in cloud–radiation feedback contribute 24% of the intermodel uncertainty in the TPSW pattern over the central Pacific. The mechanism by which the cloud–radiation feedback influences the TPSW pattern is revealed based on an analysis of the surface heat budget. A relatively weak negative cloud–radiation feedback over the central Pacific cannot suppress the surface warming as greatly as in the multimodel ensemble and thus induces a warm SST deviation over the central Pacific, producing a low-level convergence that suppresses (enhances) the evaporative cooling and zonal cold advection in the western (eastern) Pacific. With these processes, the original positive SST deviation over the central Pacific will move westward to the western and central Pacific, with a negative SST deviation in the eastern Pacific. Compared with the observed cloud–radiation feedback from six sets of reanalysis and satellite-observed data, the negative cloud–radiation feedback in the models is underestimated in general. It implies that the TPSW pattern should be closer to an El Niño–like pattern based on the concept of observational constraint. However, the observed cloud–radiation feedback from the various datasets also demonstrates large discrepancies in magnitude. Therefore, the authors suggest that more effort should be made to improve the precision of shortwave radiation observations and the description of cloud–radiation feedback in models for a more reliable projection of the TPSW pattern in future.

scholarly journals On the Influence of Enso And IOD on Rainfall Variability Over The Musi Basin, South Sumatra

2018 ◽  
Vol 3 (4) ◽  
pp. 157
Author(s):  
Wijaya Mardiansyah ◽  
Dedi Setiabudidaya ◽  
M. Yusup Nur Khakim ◽  
Indra Yustian ◽  
Zulkifli Dahlan ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Rainy Season ◽  
El Nino ◽  
Monsoon Season ◽  
Rainfall Variability ◽  
Tropical Indian Ocean ◽  
Tropical Pacific ◽  
Indonesian Seas ◽  
Sst Anomalies

The southern Sumatera region experiences one rainy season and one dry season in a year associated with seasonal change in monsoonal winds. The peak of rainy season is occurring in November-December-January during the northwest monsoon season, while the dry season comes in June-July-August during the southeast monsoon season. This study is designed to evaluate possible influence of the coupled ocean-atmospheric modes in the tropical Indo-Pacific region, namely the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on the rainfall variability over the catchment area of the Music Basin, South Sumatera. The ENSO and IOD occurrences were reflected by the variability of sea surface temperature (SST) in the tropical Pacific and Indian Ocean, respectively. During El Niño and/or positive IOD episode, negative SST anomalies cover the eastern tropical Indian Ocean and western tropical Pacific including the Indonesian seas, leading to suppress convective activities that result in reduce precipitation over the maritime continent. The situation is reversed during La Niña and/or negative IOD event. The results revealed that the high topography area (e.g. Bukit Barisan) was shown to be instrumental to the pattern of rainfall variability. During the 2010 negative IOD co-occurring with La Niña event, the rainfall was significantly increase over the region. This excess rainfall was associated with warm SST anomaly over the eastern tropical Indian Ocean and the Indonesian seas. On the other hand, extreme drought event tends to occur during the 2015 positive IOD simultaneously with the occurrence of the El Niño events Investigation on the SST patterns revealed that cold SST anomalies covered the Indonesian seas during the peak phase of the 2015 positive IOD and El Niño event.

An Estimate of the Relative Contributions of Sea Surface Temperature Variations in Various Regions to Stratospheric Change

2020 ◽  
Vol 33 (12) ◽  
pp. 4993-5011 ◽  
Author(s):  
Fei Xie ◽  
Jiankai Zhang ◽  
Zhe Huang ◽  
Jinpeng Lu ◽  
Ruiqiang Ding ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Lower Stratosphere ◽  
Tropical Pacific ◽  
North Indian Ocean ◽  
Sea Surface ◽  
High Latitudes ◽  
Stratospheric Temperature ◽  
Sst Warming ◽  
The Tropical Pacific

AbstractThis study investigates the effects of global and regional sea surface temperature (SST) warming from the Industrial Revolution to the present on the stratosphere using a climate model, and estimates the relative contributions of SST warming in different regions. The observed global SST warming is found to cause colder and stronger stratospheric zonal circulations in the high latitudes of both hemispheres, and a colder lower stratosphere in the tropics and ozone depletion. This occurs because the warming in the tropical Atlantic and in the north Indian Ocean and North Pacific strongly cool the stratosphere in the southern and northern high latitudes, respectively. The cooling in the lower stratosphere at lower and midlatitudes is mainly caused by SST warming in the tropical Pacific and north Indian Ocean. The changes in stratospheric temperature are related to changes in circulation and ozone. In addition, we investigate the effects on the stratosphere of ideal 1-K uniform warming of SST in different oceans and compare these effects with those caused by the realistic SST warming. The observed global SST warming and 1-K uniform global SST warming have opposite effects on the high-latitude stratosphere in both hemispheres: 1-K uniform global SST warming results in warmer and weaker stratospheric zonal circulations and a corresponding increase in ozone. This is because the 1-K uniform increase in SST in the tropical Pacific causes extremely strong warming and weakening stratospheric zonal circulations. The contribution of a 1-K uniform increase of SST in the tropical Pacific to stratospheric temperature, circulation, and ozone anomalies overwhelms that of a 1-K uniform increase of SST in other regions.

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