scholarly journals Combined Effects of Synoptic-Scale Teleconnection Patterns on Summer Precipitation in Southern China

Atmosphere ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 154 ◽  
Author(s):  
Chao Wang ◽  
Lijuan Wang
Keyword(s):  
Southern China ◽  
Summer Precipitation ◽  
Combined Effects ◽  
Synoptic Scale ◽  
Teleconnection Patterns

Combined Effects of Synoptic-Scale Teleconnection Patterns on Summer Precipitation in Southern China

2020 ◽  
Author(s):  
Chao Wang
Keyword(s):  
East Asia ◽  
Extreme Precipitation ◽  
Southern China ◽  
Summer Precipitation ◽  
Western Pacific Subtropical High ◽  
Asia Pacific ◽  
Combined Effects ◽  
Teleconnection Patterns ◽  
South Asia High ◽  
Westerly Jet

<p>Using ERA-Interim daily reanalysis and precipitation data, the combined effects of East Asia-Pacific (EAP) and Silk Road (SR) teleconnection patterns on summer precipitation in southern China were investigated on synoptic to sub-monthly timescales. Combined EAP and SR patterns lead to more persistent and extreme precipitation in the Yangtze River Valley (YRV) and exhibit an obvious zonal advance between the South Asia High (SAH) and Western Pacific Subtropical High (WPSH) prior to its onset. During typical combined events, an overlap between the SAH and WPSH remains in a favorable position for Persistent Extreme Precipitation (PEP). Furthermore, SR-induced acceleration of the westerly jet stream and extra positive vorticity advection provide persistent upper-level divergence for YRV precipitation. An anomalous EAP-related cyclone/anticyclone pair over East Asia induces enhanced low-level southwesterlies to the northern anticyclone flank and northerlies from the mid-latitudes, advecting anomalously abundant moisture toward the YRV, resulting in clear moisture convergence. Moreover, the strong ascent of warmer/moister air along a quasi-stationary front may be crucial for PEP. During decay, the SAH and WPSH diverge from each other and retreat to their normal positions, and the strong ascent of warmer/moister air rapidly weakens to dissipation, terminating PEP in the YRV.</p>

scholarly journals A Synoptic Scale Perspective on Greenland Ice Core δ18O Variability and Related Teleconnection Patterns

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 294
Author(s):  
Norel Rimbu ◽  
Monica Ionita ◽  
Gerrit Lohmann
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Synoptic Scale ◽  
Local Climate ◽  
Rossby Wave Breaking ◽  
Weather Patterns ◽  
Teleconnection Patterns ◽  
Climate Anomalies ◽  
The North ◽  
Oxygen Isotope Ratios

The variability of stable oxygen isotope ratios (δ18O) from Greenland ice cores is commonly linked to changes in local climate and associated teleconnection patterns. In this respect, in this study we investigate ice core δ18O variability from a synoptic scale perspective to assess the potential of such records as proxies for extreme climate variability and associated weather patterns. We show that positive (negative) δ18O anomalies in three southern and central Greenland ice cores are associated with relatively high (low) Rossby Wave Breaking (RWB) activity in the North Atlantic region. Both cyclonic and anticyclonic RWB patterns associated with high δ18O show filaments of strong moisture transport from the Atlantic Ocean towards Greenland. During such events, warm and wet conditions are recorded over southern, western and central part of Greenland. In the same time the cyclonic and anticyclonic RWB patterns show enhanced southward advection of cold polar air masses on their eastern side, leading to extreme cold conditions over Europe. The association between high δ18O winters in Greenland ice cores and extremely cold winters over Europe is partly explained by the modulation of the RWB frequency by the tropical Atlantic sea surface temperature forcing, as shown in recent modeling studies. We argue that δ18O from Greenland ice cores can be used as a proxy for RWB activity in the Atlantic European region and associated extreme weather and climate anomalies.

Case Dependence of Multiscale Interactions between Multisource Perturbations for Convection-Permitting Ensemble Forecasting during SCMREX

2021 ◽  
Author(s):  
Xubin Zhang
Keyword(s):  
Perturbation Methods ◽  
Monsoon Rainfall ◽  
Southern China ◽  
Ensemble Forecasting ◽  
Ensemble Prediction ◽  
Synoptic Scale ◽  
Ensemble Prediction System ◽  
Control Member ◽  
Probabilistic Forecasts ◽  
Perturbation Energy

AbstractThis study examines the case dependence of the multiscale characteristics of initial condition (IC) and model physics (MO) perturbations and their interactions in a convection-permitting ensemble prediction system (CPEPS), focusing on the 12-h forecasts of precipitation perturbation energy. The case dependence of forecast performances of various ensemble configurations is also examined to gain guidance for CPEPS design. Heavy-rainfall cases over Southern China during the Southern China Monsoon Rainfall Experiment (SCMREX) in May 2014 were discriminated between the strongly and weakly forced events in terms of synoptic-scale forcing, each of which included 10 cases. In the cases with weaker forcing, MO perturbations showed larger influences while the enhancements of convective activities relative to the control member due to IC perturbations were less evident, leading to smaller dispersion reduction due to adding MO perturbations to IC perturbations. Such dispersion reduction was more sensitive to IC and MO perturbation methods in the weakly and strongly forced cases, respectively. The dispersion reduction improved the probabilistic forecasts of precipitation, with more evident improvements in the cases with weaker forcing. To improve the benefits of dispersion reduction in forecasts, it is instructive to elaborately consider the case dependence of dispersion reduction, especially the various sensitivities of dispersion reduction to different-source perturbation methods in various cases, in CPEPS design.

scholarly journals Relative impact of insolation and Warm Pool surface temperature on the East Asia Summer Monsoon during the MIS-13 interglacial

2014 ◽  
Vol 10 (2) ◽  
pp. 1025-1051 ◽  
Author(s):  
Q. Z. Yin ◽  
U. K. Singh ◽  
A. Berger ◽  
Z. T. Guo ◽  
M. Crucifix
Keyword(s):  
Surface Temperature ◽  
Summer Monsoon ◽  
Climate Modeling ◽  
Southern China ◽  
Asian Summer Monsoon ◽  
Summer Precipitation ◽  
Northern China ◽  
Warm Pool ◽  
Pool Surface ◽  
The Impact

Abstract. During Marine Isotope Stage (MIS) 13, an interglacial about 500 000 years ago, the East Asian summer monsoon (EASM) was suggested exceptionally strong by different proxies in China. However, MIS-13 is a weak interglacial in marine oxygen isotope records and has relatively low CO2 and CH4 concentrations compared to other interglacials of the last 800 000 years. In the mean time, the sea surface temperature (SST) reconstructions show that the Western Pacific Warm Pool was relatively warm during MIS-13. Based on climate modeling experiments, this study aims at investigating whether this Warm Pool warming could explain the exceptionally strong EASM occurring during the relatively cool interglacial MIS-13. The individual contributions of insolation and of the Warm Pool SST as well as their synergism are quantified through experiments with the Hadley Centre atmosphere model, HadAM3 and using the factor separation technique. The SST over the Warm Pool region has been increased based on geological reconstructions. Our results show that the pure impact of a strong summer insolation contributes to strengthen significantly the summer precipitation in northern China but only little in southern China. The pure impact of enhanced Warm Pool SST reduces, slightly, the summer precipitation in both northern and southern China. However, the synergism between insolation and enhanced Warm Pool SST contributes to a large increase of summer precipitation in southern China but to a decrease in northern China. Therefore, the ultimate role of enhanced Warm Pool SST reinforces the impact of insolation in southern China but reduces its impact in northern China. We conclude that enhanced SST over the Warm Pool region does help to explain the strong MIS-13 EASM precipitation in southern China as recorded in proxy data, but other explanation is needed for explaining the exceptionally strong EASM in northern China.

scholarly journals Source apportionment of atmospheric water over East Asia – a source tracer study in CAM5.1

2017 ◽  
Vol 10 (2) ◽  
pp. 673-688 ◽  
Author(s):  
Chen Pan ◽  
Bin Zhu ◽  
Jinhui Gao ◽  
Hanqing Kang
Keyword(s):  
East Asia ◽  
Source Apportionment ◽  
Water Vapour ◽  
Southern China ◽  
Source Region ◽  
Summer Precipitation ◽  
Small Contribution ◽  
Atmospheric Water ◽  
Transport Pathway ◽  
Moisture Source

Abstract. The atmospheric water tracer (AWT) method is implemented in the Community Atmosphere Model version 5.1 (CAM5.1) to quantitatively identify the contributions of various source regions to precipitation and water vapour over East Asia. Compared to other source apportionment methods, the AWT method was developed based on detailed physical parameterisations, and can therefore trace the behaviour of atmospheric water substances directly and exactly. According to the simulation, the northern Indian Ocean (NIO) is the dominant oceanic moisture source region for precipitation over the Yangtze River valley (YRV) and southern China (SCN) in summer, while the north-western Pacific (NWP) dominates during other seasons. Evaporation over the South China Sea (SCS) is responsible for only 2.7–3.7 % of summer precipitation over the YRV and SCN. In addition, the Indo-China Peninsula is an important terrestrial moisture source region (annual contribution of  ∼  10 %). The overall relative contribution of each source region to the water vapour amount is similar to the corresponding contribution to precipitation over the YRV and SCN. A case study for the SCS shows that only a small part ( ≤  5.5 %) of water vapour originates from local evaporation, whereas much more water vapour is supplied by the NWP and NIO. In addition, because evaporation from the SCS represents only a small contribution to the water vapour over the YRV and SCN in summer, the SCS mainly acts as a water vapour transport pathway where moisture from the NIO and NWP meet.

scholarly journals Physiological and Nutritional Responses of ‘HB’ Pummelo [Citrus grandis (L.) Osbeck ‘Hirado Buntan’] to the Combined Effects of Low pH Levels and Boron Deficiency

HortScience ◽  
2020 ◽  
Vol 55 (4) ◽  
pp. 449-456
Author(s):  
Gaofeng Zhou ◽  
Bixian Li ◽  
Jianmei Chen ◽  
Fengxian Yao ◽  
Guan Guan ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Southern China ◽  
Leaf Gas Exchange ◽  
Mineral Nutrients ◽  
Low Ph ◽  
Stress Factors ◽  
Mineral Nutrient ◽  
Nutrient Concentrations ◽  
Boron Deficiency ◽  
Combined Effects

Soil acidification and boron (B) starvation are two dominant abiotic stress factors impacting citrus production in the red soil region of southern China. To evaluate the combined effects of low pH and B deficiency on plant growth, gas exchange parameters, and the concentrations of B and other mineral nutrients, ‘HB’ pummelo seedlings were treated under B deficiency (0 μM H3BO3) or adequate B (23 μM H3BO3) conditions at various low pH levels (4.0, 5.0, and 6.0). The seedlings were grown with modified half-strength Hoagland’s solution under greenhouse conditions for 12 weeks. Plant biomass, leaf area, seedling height, and root traits were remarkably inhibited by low pH and B deficiency stresses, and these parameters were extremely reduced with the decrease in pH levels. After 12 weeks of treatment, typical stress symptoms associated with B deficiency in citrus leaf were observed, with more severe symptoms observed at pH 4.0 and 5.0 than at pH 6.0. Leaf gas exchange parameter measurements showed that leaf photosynthesis was significantly inhibited under both low pH and B-deficient conditions. Notably, the lower the pH level, the greater the inhibition under both normal and deficient B conditions. Further investigations of the mineral nutrient concentrations showed that under both low pH and B deficiency, the concentrations of B and other mineral nutrients were influenced remarkably, particularly at pH 4.0 and 5.0. The physiological and nutritional results of the ‘HB’ pummelo seedlings indicated that low pH can exacerbate the effects of B deficiency to a certain extent.

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