scholarly journals Recently Strengthened Influence of ENSO on the Wintertime East Asian Surface Air Temperature

Atmosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 720 ◽  
Author(s):  
Hainan Gong ◽  
Lin Wang ◽  
Wen Chen
Keyword(s):  
East Asia ◽  
Air Temperature ◽  
Significant Influence ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Kuroshio Extension ◽  
East Asian ◽  
Surface Air Temperature ◽  
The Kuroshio

Previous studies have indicated that El Niño–Southern Oscillation (ENSO) exerts a significant influence on the East Asian winter climate. This study reveals an interdecadal strengthening of the connection between ENSO and the East Asian surface air temperature (EAT) connection around the late 1990s and investigates the reason for this change. Before the late 1990s, the influence of ENSO on the EAT was weak, and the ENSO-related southerly wind anomalies were confined to the south of 30° N of East Asia. After the late 1990s, by contrast, ENSO’s influence became stronger and capable of extending northward to 50° N of East Asia. The decadal strengthening of the link between ENSO and EAT is primarily modulated by the magnitudes of the ENSO-related Kuroshio anticyclone. The intensity of the Kuroshio anticyclone contributes more than 50% of the variance of the oscillational ENSO–EAT variability. Further investigation indicates that the recovered magnitude of the Kuroshio anticyclone after the late 1990s has been closely tied to the eastward shrinking of the Aleutian Low (AL) pattern, which has weakened the link of atmospheric circulation between the AL and Kuroshio Extension region. Therefore, the offset effect of the AL-induced negative (positive) sea level pressure (SLP) anomalies on the El Niño (La Niña)-induced positive (negative) SLP anomalies over the Kuroshio Extension has also been weakened, which has facilitated the recovery of the significant influence of ENSO on the EAT.

scholarly journals Interannual Variability of Summer Surface Air Temperature over Central India: Implications for Monsoon Onset

2019 ◽  
Vol 32 (6) ◽  
pp. 1693-1706 ◽  
Author(s):  
Zhen-Qiang Zhou ◽  
Renhe Zhang ◽  
Shang-Ping Xie
Keyword(s):  
Indian Ocean ◽  
Air Temperature ◽  
Summer Monsoon ◽  
El Niño ◽  
El Nino ◽  
Surface Air Temperature ◽  
Central India ◽  
Monsoon Onset ◽  
Summer Monsoon Onset ◽  
Sst Anomalies

Abstract Year-to-year variability of surface air temperature (SAT) over central India is most pronounced in June. Climatologically over central India, SAT peaks in May, and the transition from the hot premonsoon to the cooler monsoon period takes place around 9 June, associated with the northeastward propagation of intraseasonal convective anomalies from the western equatorial Indian Ocean. Positive (negative) SAT anomalies during June correspond to a delayed (early) Indian summer monsoon onset and tend to occur during post–El Niño summers. On the interannual time scale, positive SAT anomalies of June over central India are associated with positive SST anomalies over both the equatorial eastern–central Pacific and Indian Oceans, representing El Niño effects in developing and decay years, respectively. Although El Niño peaks in winter, the correlations between winter El Niño and Indian SAT peak in the subsequent June, representing a post–El Niño summer capacitor effect associated with positive SST anomalies over the north Indian Ocean. These results have important implications for the prediction of Indian summer climate including both SAT and summer monsoon onset over central India.

scholarly journals Tropical Temperature and Precipitation Responses to Large Volcanic Eruptions: Observations and AMIP5 Simulations

2016 ◽  
Vol 29 (4) ◽  
pp. 1325-1338 ◽  
Author(s):  
A. Meyer ◽  
D. Folini ◽  
U. Lohmann ◽  
T. Peter
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Surface Air Temperature ◽  
Volcanic Eruptions ◽  
Phase Correlation ◽  
Temperature And Precipitation ◽  
Precipitation Decrease ◽  
El Chichón ◽  
El Chichon

Abstract Tropical land mean surface air temperature and precipitation responses to the eruptions of El Chichón in 1982 and Pinatubo in 1991, as simulated by the atmosphere-only GCMs (AMIP) in phase 5 of the Coupled Model Intercomparison Project (CMIP5), are examined and compared to three observational datasets. The El Niño–Southern Oscillation (ENSO) signal was statistically separated from the volcanic signal in all time series. Focusing on the ENSO signal, it was found that the 17 investigated AMIP models successfully simulate the observed 4-month delay in the temperature responses to the ENSO phase but simulate somewhat too-fast precipitation responses during the El Niño onset stage. The observed correlation between temperature and ENSO phase (correlation coefficient of 0.75) is generally captured well by the models (simulated correlation of 0.71 and ensemble means of 0.61–0.83). For precipitation, mean correlations with the ENSO phase are −0.59 for observations and −0.53 for the models, with individual ensemble members having correlations as low as −0.26. Observed, ENSO-removed tropical land temperature and precipitation decrease by about 0.35 K and 0.25 mm day−1 after the Pinatubo eruption, while no significant decrease in either variable was observed after El Chichón. The AMIP models generally capture this behavior despite a tendency to overestimate the precipitation response to El Chichón. Scatter is substantial, both across models and across ensemble members of individual models. Natural variability thus may still play a prominent role despite the strong volcanic forcing.

scholarly journals Climatic Risk Zoning for Potential Occurrence of Cacao Moniliasis Disease in Northeastern Brazil Under The Influence of ENSO Phases

2021 ◽  
Author(s):  
Ícaro Monteiro Galvão ◽  
Gislaine Silva Pereira ◽  
Paulo Sentelhas
Keyword(s):  
Relative Humidity ◽  
Latin American ◽  
Air Temperature ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
The State ◽  
Northeastern Brazil ◽  
Cocoa Production ◽  
Enso Phases

Abstract Air temperature and relative humidity are the main drivers of many fungal diseases, such as moniliasis (Moniliophthora roreri), which affects cocoa production worldwide. This disease occurs in some Latin American countries; however, it has not yet occurred in Brazil. Moniliasis could cause serious damage to the Brazilian cocoa production if present in the country. Therefore, to know the risks of moniliasis to cocoa production in the largest Brazilian producing region, in the state of Bahia, this study investigated the climatic favorability for the occurrence of this disease in this state, by defining and mapping the climatic risks and by assessing the influence of El Niño Southern Oscillation (ENSO) phases on it. Daily air temperature and relative humidity data from 28 weather stations of the national weather network in the state of Bahia, between 1988 and 2018, were employed to determine the risk index for cocoa moniliasis occurrence (RICM), based on the number of days favorable to the disease, which was categorized in five levels of favorability, ranging from “unfavorable” to “very favorable”. Seasonal and annual RICM maps were generated by a multiple linear regression procedure, considering raster layers of latitude, longitude, and altitude. The maps showed a high spatial and temporal RICM variability in the state of Bahia, with the highest risk for moniliasis occurrence in the eastern part of the state, where most producing areas are located. The ENSO phase showed to influence cocoa moniliasis occurrence, with the years with a transition between El Niño and Neutral phases being the most critical for this disease in majority of assessed locations. These results show that cocoa producers in the state of Bahia, Brazil, should be concerned with moniliasis occurrence as a potential disease for their crops, mainly in the traditional producing regions and when ENOS is in a transition from El Niño to Neutral.

scholarly journals Quantifying the contribution of anthropogenic influence to the East Asian winter monsoon in 1960–2012

2019 ◽  
Author(s):  
Xin Hao ◽  
Shengping He ◽  
Huijun Wang ◽  
Tingting Han
Keyword(s):  
East Asia ◽  
Air Temperature ◽  
General Circulation ◽  
East Asian Winter Monsoon ◽  
East Asian ◽  
Surface Air Temperature ◽  
Winter Monsoon ◽  
Anthropogenic Influence ◽  
Anthropogenic Forcing ◽  
Asian Winter Monsoon

Abstract. The East Asian winter monsoon (EAWM) can be greatly influenced by many factors that can be classified as anthropogenic forcing and natural forcing. Here we explore the contribution of anthropogenic influence to the change in the EAWM over the past decades. Under all forcings observed during 1960–2013 (All-Hist run), the atmospheric general circulation model is able to reproduce the climatology and variability of the EAWM-related surface air temperature and 500 hPa geopotential height, and shows a statistically significant decreasing EAWM intensity with a trend coefficient of ∼−0.04 yr−1 which is close to the observed trend. By contrast, the simulation, which is driven by the same forcing as All-Hist run but with the anthropogenic contribution to them removed, shows no decreasing trend in the EAWM intensity. By comparing the simulations under two different forcing scenarios, we further reveal that the responses of the EAWM to the anthropogenic forcing include a rise of 0.6 ° in surface air temperature over the East Asia as well as weakening of the East Asia trough, which may result from the poleward expansion and intensification of the East Asian jet forced by the change of temperature gradient in the troposphere. Additionally, compared with the simulation without anthropogenic forcing, the frequency of strong (weak) EAWM occurrence is reduced (increased) by 45 % (from 0 to 10/7). These results indicate that the weakening of the EAWM during 1960–2013 may be mainly attributed to the anthropogenic influence.

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