An evaluation of East Asian summer monsoon forecast with the North American Multimodel Ensemble hindcast data

Abstract Future changes in the East Asian summer monsoon (EASM) are estimated from historical and Representative Concentration Pathway 6.0 (RCP6) experiments of the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The historical runs show that, like the CMIP3 models, the CMIP5 models produce slightly smaller precipitation. A moisture budget analysis illustrates that this precipitation deficit is due to an underestimation in evaporation and ensuing moisture flux convergence. Of the two components of the moisture flux convergence (i.e., moisture convergence and horizontal moist advection), moisture convergence associated with mass convergence is underestimated to a greater degree. Precipitation is anticipated to increase by 10%–15% toward the end of the twenty-first century over the major monsoonal front region. A statistically significant increase is predicted to occur mostly over the Baiu region and to the north and northeast of the Korean Peninsula. This increase is attributed to an increase in evaporation and moist flux convergence (with enhanced moisture convergence contributing the most) induced by the northwestward strengthening of the North Pacific subtropical high (NPSH), a characteristic feature of the future EASM that occurred in CMIP5 simulations. Along the northern and northwestern flank of the strengthened NPSH, intensified southerly or southwesterly winds lead to the increase in moist convergence, enhancing precipitation over these areas. However, future precipitation over the East China Sea is projected to decrease. In the EASM domain, a local mechanism prevails, with increased moisture and moisture convergence leading to a greater increase in moist static energy in the lower troposphere than in the upper troposphere, reducing tropospheric stability.

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Climatic Effects of China Large-Scale Urbanization on East Asian Summer Monsoon under Different Phases of Pacific Decadal Oscillation

Atmosphere ◽

10.3390/atmos10020090 ◽

2019 ◽

Vol 10 (2) ◽

pp. 90

Author(s):

Yongxiao Liang ◽

Pengfeng Xiao

Keyword(s):

Summer Monsoon ◽

Pacific Decadal Oscillation ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Eastern China ◽

Vertical Motion ◽

Positive Phase ◽

The North ◽

Asian Summer

The effects of urbanization over eastern China on the East Asian summer monsoon (EASM) under different sea surface temperature background are compared using a Community Atmosphere Model (CAM5.1). Experiments of urbanization investigated by comparing two climate simulations with and without urban land cover under both positive and negative phases of Pacific Decadal Oscillation (PDO) show the spatial distribution of precipitation with ‘southern flood and northern drought’ and weakening status of EASM. The climate effect of urbanization in eastern China is significantly different from north to south. Anomalous vertical ascending motion due to the role of urbanization in the south of 30° N have induced an increase in convective available potential energy (CAPE) and precipitation increase over southern China. At the same time, the downward vertical motion occurs in the north of 30° N which cause warming over northern China. Due to the anti-cyclonic anomalies in the upper and lower layers of the north, the monsoon circulation is weakened which can reduce the precipitation. However, urbanization impact under various phases of PDO show different effect. In the 1956–1970 urbanization experiments of negative PDO phase, the downward vertical motion and anti-cyclonic anomalies in the north of 30° N are also weaker than that of positive phase of PDO in 1982–1996. In terms of this situation, the urbanization experiments of negative phase of PDO reveal that the range of the warming area over the north of 40° N is small, and the warming intensity is weak, but the precipitation change is more obvious compared with the background of positive phase of PDO.

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Projections of East Asian summer monsoon change at global warming of 1.5 and 2 °C

Earth System Dynamics ◽

10.5194/esd-9-427-2018 ◽

2018 ◽

Vol 9 (2) ◽

pp. 427-439 ◽

Cited By ~ 8

Author(s):

Jiawei Liu ◽

Haiming Xu ◽

Jiechun Deng

Keyword(s):

East Asia ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Precipitation Change ◽

High Latitudes ◽

Multimodel Ensemble ◽

Epr Method ◽

Asian Summer

Abstract. Much research is needed regarding the two long-term warming targets of the 2015 Paris Agreement, i.e., 1.5 and 2 ∘C above pre-industrial levels, especially from a regional perspective. The East Asian summer monsoon (EASM) intensity change and associated precipitation change under both warming targets are explored in this study. The multimodel ensemble mean projections by 19 CMIP5 models show small increases in EASM intensity and general increases in summer precipitation at 1.5 and 2 ∘C warming, but with large multimodel standard deviations. Thus, a novel multimodel ensemble pattern regression (EPR) method is applied to give more reliable projections based on the concept of emergent constraints, which is effective at tightening the range of multimodel diversity and harmonize the changes of different variables over the EASM region. Future changes projected by using the EPR method suggest decreased precipitation over the Meiyu belt and increased precipitation over the high latitudes of East Asia and Central China, together with a considerable weakening of EASM intensity. Furthermore, reduced precipitation appears over 30–40∘ N of East Asia in June and over the Meiyu belt in July, with enhanced precipitation at their north and south sides. These changes in early summer are attributed to a southeastward retreat of the western North Pacific subtropical high (WNPSH) and a southward shift of the East Asian subtropical jet (EASJ), which weaken the moisture transport via southerly wind at low levels and alter vertical motions over the EASM region. In August, precipitation would increase over the high latitudes of East Asia with more moisture from the wetter area over the ocean in the east and decrease over Japan with westward extension of WNPSH. These monthly precipitation changes would finally contribute to a tripolar pattern of EASM precipitation change at 1.5 and 2 ∘C warming. Corrected EASM intensity exhibits a slight difference between 1.5 and 2 ∘C, but a pronounced moisture increase during extra 0.5 ∘C leads to enhanced EASM precipitation over large areas in East Asia at 2 ∘C warming.

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Improving the Prediction of the East Asian Summer Monsoon: New Approaches

Weather and Forecasting ◽

10.1175/waf-d-11-00092.1 ◽

2012 ◽

Vol 27 (4) ◽

pp. 1017-1030 ◽

Cited By ~ 48

Author(s):

Ke Fan ◽

Ying Liu ◽

HuoPo Chen

Keyword(s):

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Southern Oscillation ◽

Asian Summer Monsoon ◽

East Asian ◽

Statistical Prediction ◽

Multimodel Ensemble ◽

Prediction Ability ◽

Asian Summer ◽

Prediction Approach

Abstract East Asian summer monsoon (EASM) prediction is difficult because of the summer monsoon’s weak and unstable linkage with El Niño–Southern Oscillation (ENSO) interdecadal variability and its complicated association with high-latitude processes. Two statistical prediction schemes were developed to include the interannual increment approach to improve the seasonal prediction of the EASM’s strength. The schemes were applied to three models [i.e., the Centre National de Recherches Météorologiques (CNRM), the Met Office (UKMO), and the European Centre for Medium-Range Weather Forecasts (ECMWF)] and the Multimodel Ensemble (MME) from the Development of a European Multimodel Ensemble System for Seasonal-to-Interannual Prediction (DEMETER) results for 1961–2001. The inability of the three dynamical models to reproduce the weakened East Asian monsoon at the end of the 1970s leads to low prediction ability for the interannual variability of the EASM. Therefore, the interannual increment prediction approach was applied to overcome this issue. Scheme I contained the EASM in the form of year-to-year increments as a predictor that is derived from the direct outputs of the models. Scheme II contained two predictors: both the EASM and also the western North Pacific circulation in the form of year-to-year increments. Both the cross-validation test and the independent hindcast experiments showed that the two prediction schemes have a much better prediction ability for the EASM than does the original scheme. This study provides an efficient approach for predicting the EASM.

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Improvement of Multimodel Ensemble Seasonal Prediction Skills over East Asian Summer Monsoon Region Using a Climate Filter Concept

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-12-0123.1 ◽

2013 ◽

Vol 52 (5) ◽

pp. 1127-1138 ◽

Cited By ~ 12

Author(s):

Doo Young Lee ◽

Joong-Bae Ahn ◽

Karumuri Ashok

Keyword(s):

Summer Monsoon ◽

North Atlantic ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Seasonal Prediction ◽

Multimodel Ensemble ◽

Suitable Climate ◽

Asian Summer ◽

Summer Monsoon Region

AbstractThe authors propose the use of a “climate filter” concept to enhance prediction skill of a multimodel ensemble (MME) suite for the East Asian summer monsoon (EASM) precipitation and temperature at 850 hPa. The method envisages grading models on the basis of the degree of reproducibility of the association of EASM variability with a few relevant climate drivers with the respective model hindcasts for the period 1981–2003. The analysis identifies the previous winter Niño-3.4 and spring North Atlantic Oscillation indices as the most suitable climate drivers in designing a climate filter for evaluating models that replicate the observed teleconnections to EASM well. The results show that the hindcast skills of a new MME with the better-performing models are significantly higher than those from the nonperforming models or from an all-inclusive operational MME.

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Influence of the Summer NAO on the Spring-NAO-Based Predictability of the East Asian Summer Monsoon

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-15-0199.1 ◽

2016 ◽

Vol 55 (7) ◽

pp. 1459-1476 ◽

Cited By ~ 20

Author(s):

Fei Zheng ◽

Jianping Li ◽

Yanjie Li ◽

Sen Zhao ◽

Difei Deng

Keyword(s):

Summer Monsoon ◽

North Atlantic ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Dominant Mode ◽

The North ◽

Secondary Role ◽

Asian Summer ◽

The North Atlantic

AbstractThe dominant mode of atmospheric circulation over the North Atlantic region is the North Atlantic Oscillation (NAO). The boreal spring NAO may imprint its signal on contemporaneous sea surface temperature (SST), leading to a North Atlantic SST tripolar pattern (NAST). This pattern persists into the following summer and modulates the East Asian summer monsoon (EASM). Previous studies have shown that the summer NAST is caused mainly by the preceding spring NAO, whereas the contemporaneous summer NAO plays a secondary role. The results of this study illustrate that, even if the summer NAO plays a secondary role, it may also perturb summer SST anomalies caused by the spring NAO. There are two types of perturbation caused by the summer NAO. If the spring and summer NAO patterns have the same (opposite) polarities, the summer NAST tends to be enhanced (reduced) by the summer NAO, and the correlation between the spring NAO and EASM is usually stronger (weaker). In the former (latter) case, the spring-NAO-based prediction of the EASM tends to have better (limited) skill. These results indicate that it is important to consider the evolution of the NAO when forecasting the EASM, particular when there is a clear reversal in the polarity of the NAO, because it may impair the spring-NAO-based EASM prediction.

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Tropospheric ozone variability during the East Asian summer monsoon as observed by satellite (IASI), aircraft (MOZAIC) and ground stations

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-10489-2016 ◽

2016 ◽

Vol 16 (16) ◽

pp. 10489-10500 ◽

Cited By ~ 17

Author(s):

Sarah Safieddine ◽

Anne Boynard ◽

Nan Hao ◽

Fuxiang Huang ◽

Lili Wang ◽

...

Keyword(s):

Summer Monsoon ◽

Tropospheric Ozone ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

The Other ◽

The North ◽

Asian Summer ◽

Tropospheric O3 ◽

Aircraft Data

Abstract. Satellite measurements from the thermal Infrared Atmospheric Sounding Interferometer (IASI), aircraft data from the MOZAIC/IAGOS project, as well as observations from ground-based stations, are used to assess the tropospheric ozone (O3) variability during the East Asian Summer Monsoon (EASM). Six years 2008–2013 of IASI data analysis reveals the ability of the instrument to detect the onset and the progression of the monsoon seen by a decrease in the tropospheric 0–6 km O3 column due to the EASM, and to reproduce this decrease from one year to the other. The year-to-year variability is found to be mainly dependent on meteorology. Focusing on the period of May-August 2011, taken as an example year, IASI data show clear inverse relationship between tropospheric 0–6 km O3 on one hand and meteorological parameters such as cloud cover, relative humidity and wind speed, on the other hand. Aircraft data from the MOZAIC/IAGOS project for the EASM of 2008–2013 are used to validate the IASI data and to assess the effect of the monsoon on the vertical distribution of the tropospheric O3 at different locations. Results show good agreement with a correlation coefficient of 0.73 (12 %) between the 0–6 km O3 column derived from IASI and aircraft data. IASI captures very well the inter-annual variation of tropospheric O3 observed by the aircraft data over the studied domain. Analysis of vertical profiles of the aircraft data shows a decrease in the tropospheric O3 that is more important in the free troposphere than in the boundary layer and at 10–20° N than elsewhere. Ground station data at different locations in India and China show a spatiotemporal dependence on meteorology during the monsoon, with a decrease up to 22 ppbv in Hyderabad, and up to 5 ppbv in the North China Plain.

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Projections of East Asian summer monsoon change at global warming of 1.5 °C and 2 °C

10.5194/esd-2018-2 ◽

2018 ◽

Cited By ~ 1

Author(s):

Jiawei Liu ◽

Haiming Xu ◽

Jiechun Deng

Keyword(s):

East Asia ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

High Latitudes ◽

Multimodel Ensemble ◽

Epr Method ◽

Asian Summer ◽

Precipitation Changes

Abstract. Much research is needed regarding two long-term warming targets of the 2015 Paris Agreement, i.e., 1.5 °C and 2 °C above pre-industrial levels, especially from a regional perspective. The East Asian summer monsoon (EASM) intensity and associated precipitation changes under both warming targets are explored in this study. Multimodel ensemble mean projections by 19 CMIP5 models show small increases in EASM intensity and general increases in summer precipitation at 1.5° and 2 °C warming, but with large multimodel standard deviations. Thus, a novel multimodel ensemble pattern regression (EPR) method is applied to give more reliable projections based on the concept of emergent constraints, which is effective to tighten the range of multimodel diversity and harmonize the changes of different variables over the EASM region. Future changes projected by using the EPR method suggest decreased precipitation over the Meiyu belt and increased precipitation over the high latitudes of East Asia and central China, together with a considerable weakening of EASM intensity. Furthermore, suppressed precipitation would appear over 30°–40° N of East Asia in June and over the Meiyu belt in July, with enhanced precipitation at their north and south sides. These changes in early summer are attributed to a southeastward retreat of western North Pacific high (WNPSH) and a southward shift of East Asian subtropical jet (EASJ), which weaken the moisture transport via southerly wind at low level and alter vertical motions over the EASM region. In August, precipitation would increase over the high latitudes of East Asia with more moisture from the wetter area over the ocean in the east and decrease over Japan with westward extension of WNPSH. These monthly precipitation changes would finally contribute to a tripolar pattern of EASM precipitation change at 1.5° and 2 °C warming. Corrected EASM intensity exhibits a slight difference between 1.5 °C and 2 °C, but a pronounced moisture increase during extra 0.5 °C leads to enhanced EASM precipitation over large areas in East Asia at 2 °C warming.

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Recent Intensification of the Western Pacific Subtropical High Associated with the East Asian Summer Monsoon

Journal of Climate ◽

10.1175/jcli-d-14-00569.1 ◽

2015 ◽

Vol 28 (7) ◽

pp. 2873-2883 ◽

Cited By ~ 30

Author(s):

Shinji Matsumura ◽

Shiori Sugimoto ◽

Tomonori Sato

Keyword(s):

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Western Pacific Subtropical High ◽

Western Pacific ◽

Subtropical High ◽

The Past ◽

The North ◽

Asian Summer

Abstract The summer western Pacific subtropical high (WPSH) has intensified during the past three decades. However, the underlying mechanism is not yet well understood. Here, it is shown that baiu rainband activity in midsummer, which is part of the East Asian summer monsoon, plays an important role in recent intensification in the WPSH along the baiu rainband. In contrast with the WPSH, the summer Okhotsk high, which is located to the north of the baiu rainband, has weakened during the past three decades. The north–south contrasting changes between the two highs reflect a response to northward-moved and enhanced baiu heating, which intensifies the upper-tropospheric ridge, resulting in the baroclinic intensification of the WPSH. Regional climate model experiments also support the observational analysis. Therefore, baiu convective activity in midsummer can act as a major driver for the WPSH intensification. The results here suggest that the mechanism intensifying the summer North Pacific subtropical high clearly differs between the western and eastern Pacific.

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