Corrigendum to “Assessment of precipitation extremes and their association with NDVI, monsoon and oceanic indices over Pakistan” [Atmospheric Research 292 (2023) 106873]
Azfar HussainIshtiaq HussainShaukat AliWaheed UllahFirdos KhanAbolfazl RezaeiSafi UllahHaider AbbasAsima ManzoomJianhua CaoJinxing Zhou
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Abstract We use an unprecedented ensemble of regional climate model (RCM) projections over seven regional CORDEX domains to provide, for the first time, an RCM-based global view of monsoon changes at various levels of increased greenhouse gas (GHG) forcing. All regional simulations are conducted using RegCM4 at a 25 km horizontal grid spacing using lateral and lower boundary forcing from three General Circulation Models (GCMs), which are part of the fifth phase of the Coupled Model Inter-comparison Project (CMIP5). Each simulation covers the period from 1970 through 2100 under two Representative Concentration Pathways (RCP2.6 and RCP8.5). Regional climate simulations exhibit high fidelity in capturing key characteristics of precipitation and atmospheric dynamics across monsoon regions in the historical period. In the future period, regional monsoons exhibit a spatially robust delay in the monsoon onset, an increase in seasonality, and a reduction in the rainy season length at higher levels of radiative forcing. All regions with substantial delays in the monsoon onset exhibit a decrease in pre-monsoon precipitation, indicating a strong connection between pre-monsoon drying and a shift in the monsoon onset. The weakening of latent heat driven atmospheric warming during the pre-monsoon period delays the overturning of atmospheric subsidence in the monsoon regions, which defers their transitioning into deep convective states. Monsoon changes under the RCP2.6 scenario are mostly within the baseline variability.
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ABSTRACT It is known that the El Niño – Southern Oscillation ( ENSO ) episodes have a great influence on South American precipitation and its extreme events during austral autumn (from March until May, MAM ) and winter (from June until August, JJA ) that occur after the ENSO peak (normally this happens on austral summer). Recent papers have studied the two types of ENSO and their influence on atmosphere–ocean system. This study analysed the influence of Central and East equatorial Pacific ENSO on South American seasonal/monthly mean precipitation and its extreme events during MAM and JJA . The composites of precipitation anomalies, during these two types of ENSO , show that there are different, even opposite patterns over South America. In MAM , there is an increased precipitation in southeastern South America and a decrease in the northeast South America during East El Niño ( EEN ) and an increased precipitation in central Brazil during Central El Niño ( CEN ). In JJA , the signs of anomaly precipitation are opposite between CEN (less precipitation) and EEN (more precipitation) over southeastern South America. The extreme precipitation events show patterns consistent with the precipitation anomaly patterns, but, normally, the changes in the frequency of extremes precipitation events affect more extensive areas than the total precipitation. If monthly or seasonal atmospheric anomalies in a certain region during one of the types of ENSO are similar (opposite) to the atmospheric anomalies associated with extreme precipitation events in this region, then there is enhancement (suppression) of the frequency of extreme events in this region during this type of ENSO .
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This paper is the first of a two-part study to investigate the possible relationships between summer and winter monsoons over East Asia during the period 1958 to 1999. It documents the approach employed in the study. Assuming the existence of relationships, the central theme of the study is to answer the questions: Is there evidence for the relationships and, if so, what are the relationships? In particular, the approach used to interpret the available evidence to make inferences about the conditions of the summer monsoon is described. Six winter monsoon categories are defined in terms of the monsoon strength and the conditions of the El Niño–southern oscillation. The conditions of the summer monsoons preceding and following each winter monsoon category are assessed to identify the possible summer-to-winter monsoon and winter-to-summer monsoon relationships respectively. Summer monsoons are classified into unlikely strong (notS) or unlikely weak (notW) according to the bias in the relative occurrence of positive and negative anomalies of several summer monsoon indices. The rainfall condition over China and the characteristics of the subtropical high are also used to provide supplementary evidence for the summer monsoon strength and to describe the accompanying synoptic situations. Copyright © 2005 Royal Meteorological Society.
Subtropical ridge
East Asian Monsoon
Tropical monsoon climate
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Abstract Although the monsoon break is a well-known phenomenon for the South Asian summer monsoon, it has not been well documented for the other monsoons, for instance, the western North Pacific (WNP) summer monsoon. This study identified a distinct monsoon break over the WNP by analyzing the subseasonal evolution of atmospheric convection and precipitation. This WNP monsoon break occurs climatologically in early August (3–8 August), but shows a strong variation, in either intensity or timing, from year to year. For about 30% of years, the rainfall amount reduces by more than 10 mm day −1 over the northeast WNP (10°–20°N, 140°–160°E) in early August, and is even less than that before the monsoon onset. However, for the other 30% of years, the subseasonal evolution of rainfall tends to be out of phase with the climatology, and rainfall reduction appears in mid-August. Furthermore, the 10–25-day oscillations, which originate at the equatorial western Pacific and propagate northwestward, are found to play a crucial role in forming the monsoon break. The 10–25-day oscillations exhibit a strong interannual variation, associated with the WNP monsoon trough during the period from late July to mid-August, and contribute greatly to the year-to-year variation in both the timing and intensity of the monsoon break. Considering the close link in subseasonal evolution between the WNP and East Asian monsoons, the present results indicate the necessity to investigate the possible role of the WNP monsoon break on the weather and climate over East Asia.
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To simulate the onset and intraseasonal variability of summer monsoons, the National Centers for Environmental Prediction Eta Model (80 km, L38) is nested in the Center for Ocean–Land–Atmosphere Studies GCM (R40, L18). The region of the Eta Model is (30°S–50°N and 30°–140°E), which includes the Indian, Chinese, and Southeast Asian monsoons. The summer monsoons of 1987 and 1988 are simulated by integrating the nested model from mid-April to the end of September, prescribing the seasonal variations of SST of the respective years. The summer monsoons of 1987 and 1988 were extreme. In 1987, an El Niño year, the Indian monsoon rainfall was far below normal but over southeast China the rainfall exceeded normal. In contrast, in 1988, a La Niña year, Indian monsoon rainfall was far above normal but the rainfall over southeast China was below normal. The Eta Model was able to simulate the typical observed features of the monsoon onset, that is, an abrupt increase in the precipitation rate as well as in the strength of the circulation. The simulated onset dates for 1987 and 1988 were in good agreement with observations. The Eta Model was also able to simulate the observed circulation features of the break and active periods during these two years. To investigate the contrasting characteristics of the Indian and the Chinese monsoons, for these two years the following hypothesis, largely based on observational evidence, is verified. There are two preferred locations of ITCZ: one over the warm waters of the equatorial Indian Ocean and the other over the heated continent in the vicinity of the seasonal monsoon trough. There is a northward migration of the convective precipitation bands from the equatorial ITCZ to the continental ITCZ with the timescale of a few weeks. There exists an inverse relationship between the strength of the two ITCZs. During an El Niño year, sea level pressure over the Indian subcontinent and over the Maritime Continent increases. Consequently, the ITCZ over the Indian subcontinent and over the Maritime Continent weakens and the ITCZ over the equatorial Indian Ocean, Southeast Asia, and southeast China strengthens. The Eta Model simulated circulations are in support of the hypothesis. The simulations also show that there is a northward migration of convective precipitation bands from the equatorial ITCZ to the continental ITCZ.
Intertropical Convergence Zone
East Asian Monsoon
Atmospheric Circulation
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Previous research has suggested that a general inverse relation exists between winter precipitation in the southwestern United States (US) and summer monsoon precipitation. In addition, it has been suggested that this inverse relation between winter precipitation and the magnitude of the southwestern US monsoon breaks down under certain climatic conditions that override the regional winter/monsoon precipitation relations. Results from this new study indicate that the winter/monsoon precipitation relations do not break down, but rather shift location through time. The strength of winter/monsoon precipitation relations, as indexed by 20-year moving correlations between winter precipitation and monsoon precipitation, decreased in Arizona after about 1970, but increased in New Mexico. The changes in these correlations appear to be related to an eastward shift in the location of monsoon precipitation in the southwestern US. This eastward shift in monsoon precipitation and the changes in correlations with winter precipitation also appear to be related to an eastward shift in July/August atmospheric circulation over the southwestern US that resulted in increased monsoon precipitation in New Mexico. Results also indicate that decreases in sea-surface temperatures (SSTs) in the central North Pacific Ocean also may be associated with the changes in correlations between winter and monsoon precipitation. Copyright © 2006 Royal Meteorological Society.
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Multivariate ENSO index
Walker circulation
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Abstract. The recently proposed global monsoon hypothesis interprets monsoon systems as part of one global-scale atmospheric overturning circulation, implying a connection between the regional monsoon systems and an in-phase behaviour of all northern hemispheric monsoons on annual timescales (Trenberth et al., 2000). Whether this concept can be applied to past climates and variability on longer timescales is still under debate, because the monsoon systems exhibit different regional characteristics such as different seasonality (i.e. onset, peak and withdrawal). To investigate the interconnection of different monsoon systems during the pre-industrial Holocene, five transient global climate model simulations have been analysed with respect to the rainfall trend and variability in different sub-domains of the Afro-Asian monsoon region. Our analysis suggests that on millennial timescales with varying orbital forcing, the monsoons do not behave as a tightly connected global system. According to the models, the Indian and North African monsoons are coupled, showing similar rainfall trend and moderate correlation in centennial rainfall variability in all models. The East Asian monsoon changes independently during the Holocene. The dissimilarities in the seasonality of the monsoon sub-systems lead to a stronger response of the North African and Indian monsoon systems to the Holocene insolation forcing than of the East Asian monsoon and affect the seasonal distribution of Holocene rainfall variations. Within the Indian and North African monsoon domain, precipitation solely changes during the summer months, showing a decreasing Holocene precipitation trend. In the East Asian monsoon region, the precipitation signal is determined by an increasing precipitation trend during spring and a decreasing precipitation change during summer, partly balancing each other. A synthesis of reconstructions and the model results do not reveal an impact of the different seasonality on the timing of the Holocene rainfall optimum in the different sub-monsoon systems. Rather they indicate locally inhomogeneous rainfall changes and show that single palaeo-records should not be used to characterise the rainfall change and monsoon evolution for entire monsoon sub-systems.
East Asian Monsoon
Orbital forcing
Forcing (mathematics)
Tropical monsoon climate
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Precipitation plays vital roles in the global water cycle, knowledge of the spatial and temporal variation of the precipitation is essential to understanding extreme environmental phenomena such as floods, landslides, and drought. In this paper, the integrated characteristics of precipitation during 1980–2016 over Nepal along with the seasonal elevation dependency of precipitation were examined for three different regions over the country using Multi-Source Weighted-Ensemble Precipitation (MSWEP) product. The spatial distribution of mean annual precipitation varies significantly with the highest (lowest) precipitation of ~5500 (~100) mm/year in the Arun valley (Manang and Mustang). The precipitation regime of the country is determined by the contribution of the monthly precipitation amount with distinct spatial gradients between the eastern and the western sides during pre-monsoon, post-monsoon, and winter seasons. On the contrary, the spatial distribution of monsoon precipitation tends to more heterogeneous with visible differences between the lowland, midland, and highlands as similar to the annual one. Further, elevation dependency of seasonal precipitation revealed that the winter and post-monsoon precipitation distribution in western and central are very similar, whereas post-monsoon precipitation was found slightly higher than winter season in the eastern region. The highest precipitation areas in eastern and central region are located between 2000-2500 m, which is between 500 and 1000 m in the western region of the country. Overall, the pre-monsoon, summer monsoon and annual precipitation increases gradually with elevation upto 2500 m and then decreases with increasing elevation, whereas winter and post-monsoon precipitation are almost identical to each elevation interval of 500 m.
Elevation (ballistics)
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