Summer Precipitation In China Research Articles

Unstable interdecadal relationship between the Pacific Decadal Oscillation and eastern China summer precipitation in simulated warm interglacial epochs and twenty-first century

The modern connection between the Pacific Decadal Oscillation (PDO) and eastern China summer precipitation (ECSP) at the decadal scale has been extensively studied. However, whether this correlation is stable during the warmer backgrounds in the past and future remains unclear. Clarifying this issue may yield meaningful insights into past PDO reconstruction and decadal climate projection in eastern China (EC). Based on the FGOALS-f3-L, which performs best in reproducing the observed PDO pattern and the decadal PDO–ECSP relationship among 10 models under the framework of the coupled Model Intercomparison Project phase 6 (CMIP6), we find an unstable relationship between the PDO and ECSP at the decadal scale during the last Interglacial (LIG), mid-Holocene, and the twenty-first century under the Shared Socioeconomic Pathway (SSP) SSP5–8.5 scenario. The PDO-related ECSP roughly shows a west–east dipole pattern with excessive precipitation in the east during the LIG, whereas the mid-Holocene witnesses a generally decreased ECSP, except for South and Northeast China. Under the SSP5–8.5 scenario, the PDO-related decadal ECSP exhibits excessive precipitation in the west but a deficit in the east, especially in South and Northeast China. This instability is ascribed to changes in the vertical motions and moisture divergence associated with various configurations of large-scale atmospheric circulations from the lower to upper troposphere. Furthermore, these diverse atmospheric circulation patterns relate to the variations in the convective heating over the western North Pacific and the propagation of extratropical Rossby waves, which are connected with the different PDO patterns and the mean state differences in the westerly jet stream locations during the past and future warm periods

Ensemble tree model prediction of summer precipitation in north china based on predictor selection strategy

Ensemble tree model prediction of summer precipitation in north china based on predictor selection strategy

Contrasted changes of sea-surface salinity in the southern and northern Okinawa Trough since the mid-Holocene

A reconstruction of sea-surface salinity (SSS) in the southern Okinawa Trough (OT) since 6800 cal. yr BP has been presented in this study. We found that the SSS record increased gradually from the middle to late Holocene, indicating reduced summer precipitation in Taiwan. Our results also suggest regional patterns of SSS with SSS increasing in the southern OT and decreasing in the northern OT since the mid-Holocene. Observational data indicate that the SSS in the southern and northern OT are strongly affected by fluvial discharge from Taiwan and the Changjiang River, linked to summer precipitation in South and Central Eastern China, respectively. The contrasting changes in SSS from the OT since the mid-Holocene suggest different spatial patterns of precipitation, with decreasing summer precipitation in South China and increasing summer precipitation in central-eastern China due to the weakened East Asian Summer Monsoon (EASM) and solar insolation. The delayed seasonal transitions of the EASM, with a longer Meiyu stage and a shorter midsummer stage from the mid-Holocene to late Holocene, are consistent with the delayed northward migration of the westerlies in the late Holocene.

The Impacts of Regime Shift in Summer Arctic Oscillation on Precipitation in East Asia

Using multiple observational and reanalysis data, this paper investigates the impact of the interdecadal shift in summer Arctic Oscillation (AO) on precipitation in East Asia, by removing ENSO influences. The results indicate that the lower-layer activity center of summer AO in Atlantic shifted eastward after the mid-1980s. This regime shift of summer AO has a significant impact on precipitation in East Asia. Before the mid-1980s, the key regions in which precipitation was affected by AO in East Asia were northern East Asia and Northeastern China and adjacent regions. After the mid-1980s, the key regions in which precipitation was affected by AO in East Asia were central Inner Mongolia and Southern China. The mechanism of precipitation changes can be attributed to changes in atmospheric circulation and water vapor transport related to AO changes. After the mid-1980s, the influence of AO on geopotential height over northern East Asia weakened; meanwhile, the impact of AO on geopotential height over China increased. Consistent with the changes in atmospheric circulation, water vapor transport in East Asia also underwent interdecadal changes before and after the mid-1980s. The differences in atmospheric circulation and water vapor transport in East Asia can be traced back to the North Atlantic. Before the mid-1980s, wave activity flux related to summer AO tended to propagate in high latitudes and subtropics; after the mid-1980s, the wave activity flux changed in its subtropical path and propagated eastward from the North Atlantic through the Middle East to China, significantly affecting the summer precipitation in China.

Hydroclimatic changes in eastern China during the Holocene based on pollen data and climate modeling

The Asian monsoon system represents one of the world's most dynamic interactions of the cryosphere-continent-ocean-atmosphere system. Understanding and responding to changes in monsoonal precipitation is a major component of environmental management in this region, given its profound influence on socioeconomic activity in monsoonal Asia. In particular, characterizing the spatiotemporal variability of the East Asian summer monsoon (EASM) is critical for comprehensively understanding its dynamics and future impacts. Although substantial progress has been made in reconstructing past changes in the EASM, the spatial pattern of EASM intensity in China on the orbital-scale remains controversial. This is mainly because of uncertainties in the climatic interpretation of EASM-related proxies. Here, we present a quantitative seasonal precipitation reconstruction for monsoonal China during the Holocene, using the Modern Analog Technique (MAT) based on pollen data. The results show that during the Holocene both the annual and summer precipitation in monsoonal China increased gradually and reached a peak during the early mid-Holocene, with respective values that were ∼ 170 mm and 60 mm higher than today, followed by a decrease in the late Holocene. On the regional scale, the temporal pattern of monsoon rainfall was discrepant: a decrease from the early through late Holocene in northern China, and an increase from the early through late Holocene in southern China.To investigate the possible forcing mechanisms of these phenomena, we used the full TraCE-21 k simulation and single-forcing transient simulations to analyze spatial and temporal rainfall patterns. The results suggest that the north-south pattern is the product of orbital forcing. Intensified summer insolation during the early Holocene enhanced the land-sea thermal contrast, which strengthened the EASM along with the northward extension of the west Pacific subtropical high. Both factors caused the increased withdrawal of oceanic water vapor and the northward advance of the EASM rain belt, delivering more rainfall to northern China and less rainfall to southern China, and vice versa. Overall, our results indicate that insolation variations were the dominant factor determining the spatial pattern of EASM precipitation during the Holocene. Our findings are relevant to the calibration of palaeoclimate models and they contribute to an improved understanding of the Asian monsoon sub-systems.

Modulation of the intraseasonal variability in early summer precipitation in eastern China by the Quasi-Biennial Oscillation and the Madden–Julian Oscillation

Abstract. Using the reanalysis and multiple observations, the possible impact of the Madden–Julian Oscillation (MJO) on early summer (June–July) rainfall in eastern China and its modulation by the Quasi-Biennial Oscillation (QBO) are examined. The composite results show that the suppressed (enhanced) convection anomalies for MJO phases 8–1 (4–5) are more concentrated over the maritime continent and the western Pacific during easterly QBO (EQBO). As a consequence, more significant wet (dry) anomalies develop in South (eastern) China during MJO phases 8–1 (4–5) configured with easterly (westerly) QBO. The enhancement and expansion of the anomalous tropical convection band do not necessarily correspond to enhancement of the extratropical circulation response to MJO phases 8–1 (4–5) configured with westerly (easterly) QBO. The anomalous high (low) over the maritime continent and western Pacific associated with MJO phases 8–1 (4–5) is intensified (deepened) during easterly (westerly) QBO, leading to large southwesterly (northeasterly) anomalies in South China and the coasts, carrying abundant (sparse) moisture. Two anomalous meridional circulation cells are observed for MJO phases 8–1 in the East Asia sector, with downwelling anomalies around 5–20∘ N, upwelling anomalies around 20–30∘ N, and another downwelling branch northward of 30∘ N, which are enhanced during easterly QBO. The anomalous meridional circulation cells are reversed for MJO phases 4–5, which are stronger during westerly QBO with the anomalous downwelling and dry anomalies covering eastern China. The combined impact of MJO phases 8–1 and easterly QBO on the early summer rainfall is noticeable in 1996, 2016, and 2020. The enormous rainfall amount appeared along the Yangtze River in 1996, 2016, and 2020 due to the extended period of MJO phases 8–1 under the background of the easterly QBO.

Lagrangian Simulations of Moisture Sources for Northeast China Precipitation during 1979–2018

Abstract In this study, the Flexible Particle Dispersion Model (FLEXPART) is applied to analyze the moisture sources of Northeast China precipitation from March 1979 to February 2018. The results show that there is mainly one particle aggregation channel in winter, namely the eastern Europe–Siberia–Lake Baikal–Northeast Asia channel (the western channel). In comparison with winter, there are two extra channels in summer, namely the Indochina Peninsula–South China Sea–East China channel (the southern channel) and the Philippine Sea–Ryukyu Islands channel (the southeastern channel). From the long-term mean, the Siberia–Mongolia–Xinjiang region (SMX) is the most dominant moisture source of Northeast China precipitation in all seasons. As for the moisture contribution rate of each source region to Northeast China precipitation, there is a seesaw interannual relationship between SMX and other source regions. The moisture from Central and East China is critical to the interdecadal shift of Northeast China summer precipitation. This interdecadal shift is related to the moisture transport from low latitudes to Northeast China, which is modulated by the positive phase of the Pacific decadal oscillation and the negative phase of the Atlantic multidecadal oscillation.

Spatio-Temporal Variation Characteristics of Summer Precipitation in China and Its Response to ENSO

Spatio-Temporal Variation Characteristics of Summer Precipitation in China and Its Response to ENSO

Multidecadal Oceanic Modulation of Summer Precipitation in North China in 1200-Year Global Climate Simulations

Abstract The multidecadal decrease of precipitation in North China since the 1960s has caused a significant impact on the ecological environment and social development. It has become a key concern for meteorologists and national decision-makers to understand what is driving this. To better understand the oceanic impact on the interdecadal variation of summer precipitation in North China, we analyze two 1200-yr global climate simulations from state-of-the-art coupled models with an explainable convolutional neural network (CNN). The accuracy of the CNN model in correctly diagnosing the increased and decreased summer precipitation anomaly in North China reaches 98% and 96.6% in two CMIP6 models, respectively. We find that a sea surface temperature anomaly (SSTA) in the northern Pacific, associated with the Pacific decadal oscillation (PDO), and an SSTA in the northern Atlantic, associated with the Atlantic multidecadal oscillation (AMO), play essential roles in the interdecadal variation of summer precipitation in North China. The modulations of the PDO and AMO on summer precipitation in North China are consistent with the results derived from limited observations and simulations, which means these mechanisms are robust. In particular, when the PDO is in a negative phase and the AMO is in a positive phase, the positive anomaly of precipitation and the associated circulation anomalies are intensified. This study also confirms that with the explainable deep learning method, a convolutional neural network can be used to identify multidecadal variability in North China summer precipitation, although limited datasets such as observational records make it more challenging to apply deep learning methods.

Combined Impacts of the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation on Summer Precipitation in Eastern China During the Medieval Climate Anomaly and Little Ice Age

AbstractWe investigate the joint effects of the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) on eastern China summer precipitation (ECSP) during two typical periods in the last millennium [i.e., the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA)] using simulations from five selected climate models. The multimodel mean indicates that the ECSP anomalies under the four combined AMO and PDO phases differ between the MCA and the LIA. During the MCA, the meridional wave train induced by the PDO‐related convective heating over the northwestern Pacific is dominant and the zonal wave train related to the AMO is secondary. Independent of the AMO phase, deficient precipitation appears over South China in both PDO+ phases and vice versa. Meanwhile, most areas north of the Yangtze River valley feature positive anomalies in the PDO+/AMO+ phase but deficits in the PDO+/AMO− phase. In comparison, the Huanghe‐Huaihe River valley and southern Northeast China receive excessive and deficient precipitation in the PDO−/AMO+ and PDO−/AMO− phases, respectively. During the LIA, the zonal wave train induced by the AMO locates more southeastward than that during the MCA and has an overwhelming impact on the ECSP. Specifically, regardless of the PDO phase, excessive ECSP exists over Northeast China and South China in both AMO+ phases and vice versa. Moreover, precipitation between the two regions is excessive when the PDO is in phase with the AMO but deficient when they are out of phase.

A Statistical Prediction Model for Summer Precipitation in China Based on TSD Method and EOF Modes’ Time Coefficients

It is a challenge to improve the skill of seasonal precipitation prediction, because there are many factors affecting summer precipitation in China, which are found on different time scales and have complex interactions with each other. For these reasons, we establish a prediction model with the time-scale decomposition (TSD) method to investigate whether the TSD has an improving effect on the prediction skill of summer precipitation in China. Using this statistical model, the predictors and predictands will be separated into interannual and interdecadal time scales, after which Empirical Orthogonal Function (EOF) decomposition is performed on these two components, and their time coefficients are predicted, respectively. The hindcast cross-validation results show that the model without TSD has prediction skills only in some regions of East China and South China. Compared with the model without TSD, surprisingly, the model with TSD can significantly improve the prediction performance in more regions in China, such as Xinjiang Province and Northeast China. The anomaly correlation coefficients (ACC) between hindcast precipitation with TSD and observation are higher in most years than that without TSD. The results of the independent sample test show that the forecast model with TSD has a stable and gratifying prediction skill, and the averaged ACC is increased by more than 0.1.

Prediction of Summer Precipitation in North China: Role of the Evolution of Sea Surface Temperature Anomalies from Boreal Winter to Spring

Abstract Prediction of summer precipitation in north China (NCP) has long been a challenge partly because its low correlation with previous sea surface temperature (SST) anomalies (SSTA) limits the application of SST in NCP prediction. This study aims to extract optimal predictors of NCP from the SST field using an objective method—empirically optimal screening (EOS). It finds that the optimal precursory signal of NCP lies in the change of SSTA from winter to spring rather than the SSTA itself. This study identifies two optimal precursory signs predicting a positive (negative) NCP anomaly: the anomalous SST cooling (warming) from winter to spring in the coastal area of Somalia and Peru. Interestingly, these two presummer conditions have considerable independence, but they lead to a similar summer development of La Niña (El Niño). In summer, the tropical precipitation anomaly pattern associated with La Niña (El Niño) development excites a meridional wave train over the western Pacific and the circumglobal teleconnection in the Northern Hemisphere. Both of the anomalous wave trains show abnormal high (low) pressure over northeast Asia, which induces the south (north) wind anomalies over north China and produces abundant (deficient) precipitation there. These results highlight the importance of the SST evolution from winter to spring, break through the limitation of SST application in NCP prediction, and thus bring a prospect of improving NCP forecast skills. Significance Statement Sea surface temperature (SST) anomalies are most used as predictors in climate prediction. However, the forecast of summer precipitation in north China is limited by its low correlation with prior SST anomalies. In this paper, we find that the optimal precursory signal of north China precipitation (NCP) is not the SST anomaly itself, but the changes of SST anomalies from winter to spring in the coastal area of Somalia and Peru. These two precursory signals are almost independent yet indicate similar summer situations leading to NCP anomaly. These results highlight the importance of the dynamic evolution of sea surface temperature in improving the forecast skill of NCP.

Enhanced Seasonal Predictability of Spring Soil Moisture over the Indo-China Peninsula for Eastern China Summer Precipitation under Non-ENSO Conditions

Enhanced Seasonal Predictability of Spring Soil Moisture over the Indo-China Peninsula for Eastern China Summer Precipitation under Non-ENSO Conditions

Lagged Linkage between the Kara–Barents Sea Ice and Early Summer Rainfall in Eastern China in Chinese CMIP6 Models

The lagged relationship between Kara–Barents sea ice and summer precipitation in eastern China is evaluated for Chinese models participating in phase 6 of the Coupled Model Intercomparison Project (CMIP6). A previous study revealed a dipole rainfall structure in eastern China related to winter Arctic sea ice variability. Almost all Chinese CMIP6 models reproduce the variability and climatology of the sea ice in most of the Arctic well except the transition regions with evident biases. Further, all Chinese CMIP6 models successfully simulate the decreasing trend for the Kara–Barents sea ice. The dipole centers located in the Yangtze–Huai River Valley (YHRV) and South China (SC) related to Kara–Barents sea ice variability are simulated with different degrees of success. The anomalous dipole rainfall structure related to the winter Kara–Barents sea ice variability can roughly be reproduced by two models, while other models reproduce a shifted rainfall anomaly pattern or with the sign reversed. The possible delayed influence of sea ice forcing on early summer precipitation in China is established via three possible processes: the long memory of ice, the long-lasting stratospheric anomalies triggered by winter sea ice forcing, and the downward impact of the stratosphere as the mediator. Most Chinese models can simulate the negative Northern Hemisphere Annular Mode (NAM) phase in early winter but fail to reproduce the reversal of the stratospheric anomalies to a positive NAM pattern in spring and early summer. Most models underestimate the downward impact from the stratosphere to the troposphere. This implies that the stratospheric pathway is essential to mediate the winter sea ice forcing and rainfall in early summer over China for CMIP6 models.

Decadal variation of the relationship between the previous autumn IOD and the South China Sea summer monsoon

Using reanalysis data from the ECMWF and Hadley Centre of the UK Meteorological Office, the present study analyzes the relationship between Indian Ocean Dipole (IOD) in the previous autumn (September–November) and South China Sea Summer (June–August) Monsoon (SCSSM) from 1951 to 2021. It is found that the relationship between the two indices was significantly enhanced from the late 1970s to the beginning of the 21st century, with a significant resonance cycle of 2–4a. The previous autumn IOD forced the Gill pattern in the upper troposphere by changing the Sea Surface Temperature Anomaly (SSTA) of the following summer in the Tropical Indian Ocean (TIO), resulting in the anticyclonic circulation anomaly in the Philippine Sea. It eventually alters the southwest monsoon near the South China Sea and the Philippine Sea. However, for a decade or more, as the Pacific Decadal Oscillation (PDO) phase turns from warm to cold and the relationship between El Niño–Southern Oscillation (ENSO) and IOD weakens, the impact of the previous autumn IOD on Indian Ocean SSTA in the summer of the following year weakens, resulting in a decrease in the correlation between the previous autumn IOD and SCSSM. The impact of the previous autumn’s Indian Ocean SSTA on the following year’s SCSSM is more considered in terms of the eastern Bay of Bengal and the Somali Sea basin. In addition, during the warm phase of PDO, the IOD of the previous autumn can cause abnormal summer precipitation in South China by strengthening or weakening the Western Pacific Subtropical High (WPSH) of the following summer, but there is no significant effect in the cold phase of PDO.

Interannual Variability of Extreme Precipitation during the Boreal Summer over Northwest China

Herein, we investigated the characteristics and mechanisms of interannual variability of extreme summer precipitation in northwest China (NWC). The four high-resolution precipitation predicting products under assessment indicated that both the accumulation of summer daily precipitation ≥95th percentile, and the summer maxima of daily precipitation generally decreased in a southeast—northwest direction, while relatively high values were observed in the Tienshan and Qilian Mountain areas. In turn, the Tropical Rainfall Measuring Mission (TRMM) satellite dataset underestimated extreme precipitation in mountainous areas, while Asian precipitation highly—resolved observational data integration towards evaluation (APHRODITE) and Climate Prediction Center (CPC) captured the characteristics of extreme precipitation in NWC. AMIP-type simulations of the interannual variability of extreme summer precipitation in NWC were quite unsuccessful. However, all of them can capture the increasing trends. Therefore, we further found that the interannual increase in extreme precipitation in NWC is strongly correlated with the weakened South Asian high, strengthened Western Pacific Subtropical high, the enhanced westerly jet, and the mid- to high-latitude Rossby wave trains, whose formation and sustenance can be traced back to sea surface temperature-anomalies in the western Pacific in May, June, and July. An increased sea surface temperature promotes convection and induces diabatic heating, which stimulates anticyclonic anomalies that disturb the enhanced westerly jet, resulting in a barotropic Rossby wave train via the Gill-type response. Additionally, it guides more water vapor convergence to NWC and enhances upward motion via anticyclonic anomalies over western Europe and Eastern Asia, and cyclonic anomalies over Central Asia.

Stage-dependent influence of PDO on interdecadal summer precipitation anomalies in eastern China

Pacific decadal oscillation (PDO) has been regarded as one of the most important interdecadal factors to the interdecadal summer precipitation in eastern China, which, however, cannot keep a consistent pattern during the same positive or negative PDO phase. Because sea surface temperature (SST) anomalies vary along with PDO evolvement, the PDO impacts are investigated in terms of developing and decaying stages of its positive and negative phases, respectively. It is found that the SST cooling in mid-latitude North Pacific and SST warming in off-equator central-eastern Pacific are generally intensified from the developing stage to the decaying stage for positive PDO phase, and vice versa. Particularly, during the decaying stage of positive (negative) PDO phase, the enhanced SST warming (cooling) in northeastern tropical Pacific triggers a stronger (weaker) large-scale Walker circulation and suppresses (enhances) the convective activities in western tropical Pacific, which favors a meridional wave train like East Asia–Pacific (EAP) teleconnection over East Asia. Meanwhile, the westward extended SST cooling (warming) in mid-latitude North Pacific together with the SST warming (cooling) to its south significantly increases (decreases) the meridional SST gradient and low-level atmospheric baroclinicity, conductive to the strengthened (weakened) and southward (northward) shifted East Asian subtropical westerly jet as well as an equivalent barotropic “cold trough” in western North Pacific. Because of such tropical and extratropical dynamical processes, a meridional tripole pattern of precipitation anomalies occurs in eastern China which dominates the PDO impact in the same phase and distinctly different from the dipole pattern during the developing stage.

Decade-to-decade variations in summer precipitation patterns in eastern China since the 1960s: roles of water vapor transport and sea surface temperature

Based on the observational precipitation data and multiple reanalysis datasets, this study analyzes the decade-to-decade spatiotemporal evolution of anomalous summer precipitation in eastern China (SPEC) for 1961-2019 and explores the roles of water vapor transport and global sea surface temperatures (SSTs). Results show that SPEC patterns in the last 60 yr were mainly classified into 3 categories: dipole (the 1960s and 1970s), tripole (the 1990s) and quadrupole (the 1980s and 2000s), with marked decade-to-decade variations. In the 2010s, the precipitation pattern exhibited a more complex nature. Obvious differences can be detected in the water vapor channels (WVCs) associated with the 3 SPEC patterns. Specifically, the dipole pattern of the SPEC was mainly related to the Pacific Ocean WVC (POW) and the westerly WVC (WW). The tripole pattern was mainly associated with the Tibetan Plateau Southern Side WVC (TPW), the South China Sea WVC, the POW and the WW. The quadrupole pattern was quite clearly correlated with the Indian Ocean WVC, the Bay of Bengal WVC, the TPW, the POW and the WW. Furthermore, the dipole SPEC pattern was correlated with the Pacific decadal oscillation (PDO), the Indian Ocean basin mode (IOBM) and the Atlantic multi-decadal oscillation. The tripole and quadrupole patterns were related to the IOBM and PDO, respectively. The PDO has a marked influence on the interdecadal shifting of the SPEC pattern in the late 1970s, favoring the formation of the quadrupole SPEC pattern. However, the decadal shifting of the SPEC pattern in the early 1990s is mainly influenced by the IOBM, which favored the formation of the tripole precipitation pattern.

A hybrid statistical-dynamical prediction model for summer precipitation in northwestern China based on NCEP CFSv2

As a typical arid/semi-arid area, summer rainfall in northwestern China (NWC) is critical for the ecological environment there. The NWC summer rainfall prediction using statistical and dynamical models shows very poor performance. The dynamical model NCEP CFSv2 shows very low prediction skill in NWC summer precipitation. NWC precipitation index (NWC PI) is defined as the regional mean summer precipitation over NWC. This study first investigates the soil moisture and SST (sea surface temperature) signals in the preceding months, and CFSv2 April predicted summer large-scale circulation anomalies significantly related with NWC PI during 1982–2016 (2011 missing). The April soil moisture in the upstream central Asia, and SST in the preceding winter over tropical Pacific, Atlantic and Indian Ocean are identified as predictor candidates in the observation. Besides, six April predicted large-scale circulation factors in CFSv2 are also hired. The potential model predictors are selected generally based on three criteria: where CFSv2 has significant prediction skill, and NWC PI is significantly correlated with the variable in both the observation and its counterpart in CFSv2 prediction. Hybrid models are then constructed based on different predictor combinations. The leave-one-out cross validation illustrates that the hybrid model using three predictors (April soil moisture in the upstream central Asia, April predicted zonal wind over the Maritime Continent, April predicted SLP over the Mediterranean Sea) presents best performance, with anomalies correlation coefficient–ACC of 0.65, percentage of the same sign–PERC 76.5%, relative error–RE 6.97%, and root mean square error–RMSE 0.344 mm/day for NWC PI. The April soil moisture in the upstream central Asia is linked with the summer water vapor flux over NWC, and April predicted zonal wind over the Maritime Continent is related with the large-scale circulation over NWC, while caution must be taken when April predicted SLP over the Mediterranean Sea is used as predictor of NWC PI.

An interdecadal enhancement of relationship between Northwest and North China summer precipitation since early 2000

An interdecadal enhancement of relationship between Northwest and North China summer precipitation since early 2000