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Mesoscale convective systems (MCSs) play an important role in modulating the global water cycle and energy balance and frequently generate high-impact weather events. The majority of existing literature studying MCS activity over East Asia is based on specific case studies and more climatological investigations revealing the precipitation characteristics of MCSs over eastern China are keenly needed. In this study, we use an iterative rain cell tracking method to identify and track MCS precipitation during 2008–16 to investigate regional differences and seasonal variations of MCS precipitation characteristics. Our results show that the middle-to-lower reaches of the Yangtze River basin (YRB-ML) receive the largest amount and exhibit the most pronounced seasonal cycle of MCS precipitation in eastern China. MCS precipitation over YRB-ML can exceed 2.6 mm day−1 in June, contributing over 30.0% of April–July total rainfall. Particularly long-lived MCSs occur over the eastern periphery of the Tibetan Plateau (ETP), with 25% of MCSs over the ETP persisting for more than 18 h in spring. In addition, spring MCSs feature larger rainfall areas, longer durations, and faster propagation speeds. Summer MCSs have a higher precipitation intensity and a more pronounced diurnal cycle except for southeastern China, where MCSs have similar precipitation intensity in spring and summer. There is less MCS precipitation in autumn, but an MCS precipitation center over the ETP still persists. MCSs reach peak hourly rainfall intensities during the time of maximum growth (a few hours after genesis), reach their maximum size around 5 h after genesis, and start decaying thereafter.

Observations are required to understand monsoon changes over time. Reanalyses are useful supplements to observations; however, their ability to reveal long-term monsoon changes remains unknown. Here, we evaluate against observations the performance of two reanalysis datasets covering the whole twentieth century, the ECMWF reanalysis of the twentieth century (ERA20C) and the Twentieth Century Reanalysis Project (20CR), in terms of reproducing the climatological averages, the centennial co-variation, and long-term trends of Northern Hemisphere land monsoon rainfall (NHLMR). Their performance is compared with three other widely used reanalyses, the NCEP–NCAR reanalysis (NCEP1), the ECMWF 40-year reanalysis (ERA40), and the Japanese 55-year Reanalysis Project (JRA55), for the period after 1955. Results show that the five reanalysis datasets reasonably reproduce the climatological NHLMR and NHLM domains. The leading co-variation mode of NHLMR, with an overall increasing tendency before 1955 and a decreasing tendency afterwards, is captured by the corresponding principal components of the two long-term datasets, with some spatial biases. For the long-term precipitation trends, both the ERA20C and 20CR reproduce the increasing trend during 1901–1955, except for parts of the North African (NAF) monsoon region. However, neither dataset captures the decreasing trend of NHLMR after 1955 because of limitations in the NAF and North American (NAM) monsoon region. The NCEP1, ERA40, and JRA55 datasets also have shortcomings in the NAM region. An overall decreasing NHLMR is only shown in the NCEP1 dataset. A moisture budget analysis reveals that the long-term trends of NHLMR are dominated by the dynamic component of moisture convergence, suggesting a prominent role for atmospheric circulation changes. The influence of residual terms related to observations assimilated in the reanalyses is also discussed.

During the period from June 30th to July 6th, 2016, a heavy rainfall event affected the middle and lower reaches of the Yangtze River valley in eastern China. The event was characterized by high‐intensity, long‐duration (lasted more than 6 days) precipitation and huge amounts (over 600.0 mm) of rainfall. The rainfall moved eastward from the Sichuan basin to the middle Yangtze River valley during the first 2 days, then Mei‐yu front formed and circulations became more “quasi‐stationary”. During the second‐phase, successive heavy rainfall systems occurred repeatedly over the same areas along the front, leading to widespread and catastrophic flooding. In this study, limited‐area convection‐permitting models (CPMs) covering all of eastern China, and global‐model simulations from the Met Office Unified Model are compared to investigate the added values of CPMs on the veracity of short‐range predictions of the heavy rainfall event. The results show that all the models can successfully simulate the accumulated amount and the evolution of this heavy rainfall event. However, the global model produces too much light rainfall (10.0 mm/day), fails to simulate the small‐scale features of both atmospheric circulations and precipitation, and tends to generate steady heavy rainfall over mountainous region. Afternoon precipitation is also excessively suppressed in global model. By comparison, the CPMs add some value in reproducing the spatial distribution of precipitation, the smaller‐scale disturbances within the rain‐bands, the diurnal cycle of precipitation and also reduce the spurious topographical rainfall, although there is a tendency for heavy rainfall to be too intense in CPMs.

The Yellow River Basin is a major economic development area in China, and the high quality development of the basin still has great room for improvement. The coordinated development of energy, environment, economy and ecology is one of the keys to high quality development of the watershed. Aiming at the problem of energy, environment, economy and ecology restricting and promoting, this paper takes the nine provinces of the Yellow River as the research object, based on data from 2004 to 2017, through establishing the coupling coordination system of ecology, environment, economy and energy, using CRITIC method to study the characteristics of each subsystem of the basin in time and space. The results show that the score of energy, environment, economy and ecology is phased in time, and the level of compound coupling coordination is increasing year by year and the growth rate is obvious. The coupling coordination degree of the Yellow River basin has significant stage and regional characteristics in time and space, the coordination degree of the upper and middle reaches is higher than the coordination degree of the downstream coupling, but the difference between the three is gradually reduced with time.

More than one hundred days were simulated over very large domains with fine (0.156 km to 2.5 km) grid spacing for realistic conditions to test the hypothesis that storm (kilometer) and large-eddy (hectometer) resolving simulations would provide an improved representation of clouds and precipitation in atmospheric simulations. At scales that resolve convective storms (storm-resolving for short), the vertical velocity variance becomes resolved and a better physical basis is achieved for representing clouds and precipitation. Similarly to past studies we found an improved representation of precipitation at kilometer scales, as compared to models with parameterized convection. The main precipitation features (location, diurnal cycle and spatial propagation) are well captured already at kilometer scales, and refining resolution to hectometer scales does not substantially change the simu-lations in these respects. It does, however, lead to a reduction in the precipitation on the time-scales considered – most notably over the ocean in the tropics. Changes in the distribution of precipitation, with less frequent extremes are also found in simulations incorporating hectometer scales. Hectometer scales appear to be more important for the representation of clouds, and make it possible to capture many important aspects of the cloud field, from the vertical distribution of cloud cover, to the distribution of cloud sizes, and to the diel (daily) cycle. Qualitative improvements, particularly in the ability to differentiate cumulus from stratiform clouds, are seen when one reduces the grid spacing from kilometer to hectometer scales. At the hectometer scale new challenges arise, but the similarity of observed and simulated scales, and the more direct connection between the circula-tion and the unconstrained degrees of freedom make these challenges less daunting. This quality, combined with already improved simulation as compared to more parameterized models, underpins our conviction that the use and further development of storm-resolving models offers exciting opportunities for advancing understanding of climate and climate change.

A limited area convection permitting model (CPM) based on the Met Office Unified Model, with a 0.04° (4.4 km) horizontal grid spacing, is used to simulate an entire warm-season of the East Asian monsoon (from April to September 2009). The simulations are compared to rain gauge observations, reanalysis and to a lower resolution regional model with a 0.12° (13.2 km) grid spacing that has a parametrization of subgrid-scale convective clouds and precipitation. The 13.2 km simulation underestimates precipitation intensity, produces rainfall too frequently, and shows evident biases in reproducing the diurnal cycle of precipitation and low-level wind fields. In comparison, the CPM shows significant improvements in the spatial distribution of precipitation intensity, although it overestimates the intensity magnitude and has a wet bias over central eastern China. The diurnal cycle of precipitation over Mei-yu region, southern China and the eastern periphery of the Tibetan Plateau, as well as the diurnal cycle of low-level winds over both the Mei-yu region and southern China are better simulated by the CPM. Over the Mei-yu region, in both simulations and observations, the local atmospheric instability in the afternoon is favorable for upward motion and rainfall. The CPM receives more sensible heat flux from the surface, has a stronger upward motion, and overestimates water vapor convergence based on moisture budget diagnosis. All these processes help explain the excessive late afternoon rainfall over the Mei-yu region in the CPM simulation.

In this study, atmospheric water vapor transport was analyzed to study the changes in spring persistent rainfall (SPR) over southeastern China from 1980 to 2012. The performances of five sets of reanalysis data in reproducing the climatology, the long-term trend and interannual variability of the SPR were synthetically evaluated. To understand the mechanisms dominating SPR variation, the major components of moisture budget, including vertical moisture advection, horizontal moisture advection and evaporation, were examined based on the five reanalysis datasets. The results show that all five reanalysis datasets reproduce the climatology of the SPR reasonably well. Strong westerly wind flow over the southern Tibetan Plateau and southwest wind flow over the western North Pacific are the two main channels remotely supplying water vapor for the SPR. Locally, moisture budget diagnosis shows that the SPR is primarily contributed by the evaporation and vertical moisture advection terms. The SPR shows a decreasing tendency [−0.38 mm day−1 (10 year)−1] during 1980–2012 along with strong interannual variation, which is reasonably captured by all five reanalysis datasets. Vertical moisture advection dominates the SPR variation, and the decreasing trend of the SPR is mainly due to the weakening of ascending motion during this period. In an El Nino decaying spring, the anomalous lower-tropospheric anticyclone over the western North Pacific intensifies vertical upward motion and leads to more precipitation. Both the Japanese 55-year reanalysis (JRA55) and the European Centre for Medium-Range Weather Forecast interim reanalysis (ERAIM) show higher skill in reproducing the climatology and changes of the SPR.

Understanding the energy development ideas of the Yellow River Basin has a very important impact on the high-quality development of the Yellow River Basin. Aiming at the restriction and promotion of energy consumption in the Yellow River Basin to its high-quality development, this article takes the nine provinces of the Yellow River as the research object, builds an evaluation model based on the data of the river basin from 2004 to 2017, and uses the entropy method and elastic coefficient method to study the coupling characteristics of watershed energy consumption for its high-quality development in time and space. The results show that the high-quality development level of the river basin is generally increasing, the consumption level is generally decreasing, and the coupling of energy consumption and high-quality development is optimized year by year. Finally, according to the coupling of energy consumption level and high-quality development level, a development strategy suitable for improvement is proposed.