scholarly journals Recent decadal enhancement of Meiyu–Baiu heavy rainfall over East Asia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hiroshi G. Takahashi ◽  
Hatsuki Fujinami
Keyword(s):  
East Asia ◽  
Heavy Rainfall ◽  
Wave Train ◽  
Eastern China ◽  
Heavy Precipitation ◽  
Radar Data ◽  
Northwest Pacific ◽  
Satellite Radar ◽  
Baiu Front

AbstractEast of Eurasia, moist air is transported poleward, forming the Meiyu–Baiu front over East Asia in late June and early July. Recently, unusually heavy rainfall may have increased, causing catastrophic flooding in East Asia. Here, unique 23-year precipitation satellite radar data confirm recent enhancement in Meiyu–Baiu heavy rainfall from eastern China to southwestern Japan, which is also evident from independent conventional observations. Decadal changes in rainfall have been physically consistent with enhanced transport of water vapour due to the intensified Pacific subtropical high associated with weakened tropical cyclone activity over the Northwest Pacific. Furthermore, the upper-tropospheric trough, associated with wave train along the subtropical jet, influenced Meiyu–Baiu precipitation over East Asia. Long-term and continuous satellite radar observations reveal that the frequency of heavy precipitation along the Meiyu–Baiu front has increased in the last 22 years. In particular, heavy precipitation (10 mm/h) increased by 24% between 1998–2008 and 2009–2019, and the abruptly-changed level likely induced recent meteorological disasters across East Asia. This trend may also explain the severity of the 2020 Meiyu–Baiu season. Over the last decade, this front has likely transitioned to a new climate state, which requires adaptation of disaster prevention approaches.

ESTIMATION OF THE ICE-FREE PERIOD LENGTH FOR THE RUSSIAN ARCTIC SEAS BASED ON SATELLITE DATA FOR 2018-2020

2021 ◽  
pp. 48-56
Author(s):  
V. G. SMIRNOV ◽  
◽  
I. A. BYCHKOVA ◽  
N. YU. ZAKHVATKINA ◽  
S. V. MIKHAL’TSEVA ◽  
...  
Keyword(s):  
Neural Network ◽  
Satellite Data ◽  
Radar Data ◽  
Russian Arctic ◽  
Arctic Seas ◽  
Neural Network Method ◽  
Northern Sea Route ◽  
Network Method ◽  
Satellite Radar

The paper describes the experience of using routine satellite radar data to estimate the length of the ice-free period in the Northern Sea Route using a neural network method for the ice cover classification. An earlier onset of melt and a later freezing of ice in the Russian Arctic seas as compared to long-term dates is confirmed.

Analysis of the Evolution of a Meiyu Frontal Rainstorm Based on Doppler Radar Data Assimilation

2020 ◽  
Author(s):  
Hongli Li ◽  
Yang Hu ◽  
Zhimin Zhou
Keyword(s):  
Heavy Rainfall ◽  
Doppler Radar ◽  
Heavy Precipitation ◽  
Radar Data ◽  
Economic Losses ◽  
Mature Stage ◽  
Convective System ◽  
Low Level ◽  
Sufficient Energy ◽  
Study Results

<p>During the Meiyu period, floods are prone to occur in the middle and lower reaches of the Yangtze River due to the highly concentrated and heavy rainfall, which caused huge life and economic losses. Based on numerical simulation by assimilating Doppler radar, radiosonde, and surface meteorological observations, the evolution mechanism for the initiation, development and decaying of a Meiyu frontal rainstorm that occurred from 4th to 5th July 2014 is analyzed in this study. Results show that the numerical experiment can well reproduce the temporal variability of heavy precipitation and successfully simulate accumulative precipitation and its evolution over the key rainstorm area. The simulated “rainbelt training” is consistent with observed “echo training” on both spatial structure and temporal evolution. The convective cells in the mesoscale convective belt propagated from southwest to northeast across the key rainstorm area, leading to large accumulative precipitation and rainstorm in this area. There existed convective instability in lower levels above the key rainstorm area, while strong ascending motion developed during period of heavy rainfall. Combined with abundant water vapor supply, the above condition was favorable for the formation and development of heavy rainfall. The Low level jet (LLJ) provided sufficient energy for the rainstorm system, and the low-level convergence intensified, which was an important reason for the maintenance of precipitation system and its eventual intensification to rainstorm. At its mature stage, the rainstorm system demonstrated vertically tilted structure with strong ascending motion in the key rainstorm area, which was favorable for the occurrence of heavy rainfall. In the decaying stage, unstable energy decreased, and the rainstorm no longer had sufficient energy to sustain. The rapid weakening of LLJ resulted in smaller energy supply to the convective system, and the stratification tended to be stable in the middle and lower levels. The ascending motion weakened correspondingly, which made it hard for the convective system to maintain.</p>

Subseasonal Dynamical Prediction of East Asian Cold Surges

2017 ◽  
Vol 32 (4) ◽  
pp. 1675-1694 ◽  
Author(s):  
Qiaoping Li ◽  
Song Yang ◽  
Tongwen Wu ◽  
Xiangwen Liu
Keyword(s):  
Geopotential Height ◽  
Lead Time ◽  
Large Scale ◽  
Wave Train ◽  
East Asian ◽  
Eastern China ◽  
Northwest Pacific ◽  
Cold Surge ◽  
Circulation Patterns ◽  
Cold Surges

Abstract Predictability of East Asian cold surges is studied using daily data from the hindcasts of 45-day integrations by the NCEP Climate Forecast System version 2 (CFSv2). Prediction skills of the CFSv2 in forecasting cold surges, their annual variation, and their physical links to large-scale atmospheric circulation patterns are examined. Results show that the climatological characteristics of the East Asian winter monsoon can be reasonably reproduced by the CFSv2. The model can well capture the frequency, intensity, and location of cold surges at a lead time of about two weeks. Obviously, fewer-than-observed cold surge days are found in the predictions when the lead time is above 14 days. The spatiotemporal evolutions of high-, mid-, and low-level circulation patterns during cold surge occurrences are all accurately indicated in the CFSv2 prediction. Except for precipitation, the other variables associated with cold surges, such as geopotential height, wind, sea level pressure, and surface air temperature, exhibit higher skills. The lead time of skillful prediction of precipitation is limited to around 1 week, with systematic wet biases over the South China Sea, the Philippine Islands, and the northwest Pacific, but dry biases over India, the Indo-China Peninsula, and most high-latitude regions. Wave train–like patterns of geopotential height and wind differ distinguishably when cold surges occur in northern and southern regions (using 35°N as the dividing line), and the CFSv2 gives a consistent prediction to these anomalous patterns. A weaker-than-observed Siberian high and weaker northerly winds over eastern China are found in the predictions especially at longer lead times.

The Effect of Midlatitude Transient Eddies on Monsoonal Southerlies over Eastern China

2015 ◽  
Vol 28 (21) ◽  
pp. 8450-8465 ◽  
Author(s):  
Hyo-Seok Park ◽  
Benjamin R. Lintner ◽  
William R. Boos ◽  
Kyong-Hwan Seo
Keyword(s):  
East Asian Monsoon ◽  
Wave Train ◽  
Eastern China ◽  
Potential Temperature ◽  
Heavy Precipitation ◽  
Static Stability ◽  
Monsoon Circulation ◽  
The North ◽  
Subtropical Highs ◽  
Wind Events

Abstract The strengthening of monsoonal southerlies over East Asia is associated with the westward intensification of the North Pacific subtropical high. Previous work has shown that the seasonal-mean position and strength of subtropical highs are affected by tropical and subtropical diabatic heating. Here it is shown that the synoptic-time-scale strengthening of southerlies over eastern China is dynamically tied to extratropical eddy activity. Composite analysis based on strong southerly wind events highlights an antecedent baroclinic wave train propagating southeastward into eastern China from extratropical central Asia. This wave train generates quasigeostrophic ascent over eastern China that is associated with heavy precipitation. The anomalously cold upper-tropospheric conditions associated with the wave train decrease static stability throughout the lower and middle troposphere in eastern China, while low-level moistening enhances equivalent potential temperature. It is proposed that the resulting reductions in dry and moist static stability intensify the eddy-induced precipitating ascent. These results illustrate how East Asian monsoon circulation and precipitation can be enhanced by the interaction of midlatitude baroclinic waves with the moist subtropical monsoon region.

scholarly journals Spatiotemporal patterns of synchronous heavy rainfall events in East Asia during the Baiu season

2020 ◽  
Author(s):  
Frederik Wolf ◽  
Ugur Ozturk ◽  
Kevin Cheung ◽  
Reik V. Donner
Keyword(s):  
East Asia ◽  
Heavy Rainfall ◽  
Spatial Organization ◽  
Asian Summer Monsoon ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Heavy Precipitation ◽  
Extreme Weather Events ◽  
Window Approach ◽  
High Level

Abstract. Investigating the synchrony and interdependency of heavy rainfall occurrences is crucial to understand the underlying physical mechanisms and reduce physical and economic damages by improved forecasting strategies. In this context, studies utilizing functional network representations have recently contributed to significant advances in the understanding and prediction of extreme weather events. To thoroughly expand on previous works employing the latter framework to the East Asian Summer Monsoon (EASM) system, we focus here on changes in the spatial organization of synchronous heavy precipitation events across the monsoon season (April to August) by studying the temporal evolution of corresponding network characteristics in terms of a sliding window approach. Specifically, we utilize functional climate networks together with event coincidence analysis for identifying and characterizing synchronous activity from daily rainfall estimates between 1998 and 2018. Our results demonstrate that the formation of the Baiu front as a main feature of the EASM is reflected by a double-band structure of synchronous heavy rainfall with two centers north and south of the front. Although the two separated bands are strongly related to either low- or high-level winds which are commonly assumed to be independent, we provide evidence that it is rather their mutual interconnectivity that changes during the different phases of the EASM season in a characteristic way. Our findings shed some new light on the interplay between tropical and extratropical factors controlling the EASM intraseasonal evolution, which could potentially help to improve future forecasts of the Baiu onset in different regions of East Asia.

scholarly journals Spatiotemporal patterns of synchronous heavy rainfall events in East Asia during the Baiu season

2021 ◽  
Vol 12 (1) ◽  
pp. 295-312
Author(s):  
Frederik Wolf ◽  
Ugur Ozturk ◽  
Kevin Cheung ◽  
Reik V. Donner
Keyword(s):  
East Asia ◽  
Heavy Rainfall ◽  
Spatial Organization ◽  
Asian Summer Monsoon ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Heavy Precipitation ◽  
Extreme Weather Events ◽  
Window Approach ◽  
High Level

Abstract. Investigating the synchrony and interdependency of heavy rainfall occurrences is crucial to understand the underlying physical mechanisms and reduce physical and economic damages by improved forecasting strategies. In this context, studies utilizing functional network representations have recently contributed to significant advances in the understanding and prediction of extreme weather events. To thoroughly expand on previous works employing the latter framework to the East Asian summer monsoon (EASM) system, we focus here on changes in the spatial organization of synchronous heavy precipitation events across the monsoon season (April to August) by studying the temporal evolution of corresponding network characteristics in terms of a sliding window approach. Specifically, we utilize functional climate networks together with event coincidence analysis for identifying and characterizing synchronous activity from daily rainfall estimates between 1998 and 2018. Our results demonstrate that the formation of the Baiu front as a main feature of the EASM is reflected by a double-band structure of synchronous heavy rainfall with two centers north and south of the front. Although the two separated bands are strongly related to either low- or high-level winds, which are commonly assumed to be independent, we provide evidence that it is rather their mutual interconnectivity that changes during the different phases of the EASM season in a characteristic way. Our findings shed some new light on the interplay between tropical and extratropical factors controlling the EASM intraseasonal evolution, which could potentially help to improve future forecasts of the Baiu onset in different regions of East Asia.

Event synchrony based complex network analysis of heavy precipitation in different monsoon regions revealing dynamical patterns of extreme event formation and propagation

2021 ◽  
Author(s):  
Reik Donner ◽  
Frederik Wolf
Keyword(s):  
Network Analysis ◽  
East Asia ◽  
Summer Monsoon ◽  
Heavy Rainfall ◽  
Spatial Organization ◽  
Extreme Event ◽  
Heavy Precipitation ◽  
Relevant Information ◽  
Extreme Weather Events ◽  
South American

<p>Investigating the synchrony and interdependency of heavy rainfall occurrences across and between different tropical regions offers a new perspective on the underlying physical mechanisms. In this context, studies utilizing functional network representations have recently contributed to significant advances in the understanding and prediction of extreme weather events. Here, we systematically contrast previous results on spatiotemporal extreme precipitation patterns in three key monsoon regions (India, South America and East Asia) based on the concept of event synchronization (ES) with corresponding patterns obtained using the closely related event coincidence analysis (ECA) approach. Our findings demonstrate that an additional window size parameter of ECA not involved in ES allows for a more detailed analysis of the formation and propagation processes associated with heavy precipitation events. While the resulting network connectivity patterns based on both approaches closely resemble each other for the case of the South American monsoon system and the Indian summer monsoon, there exist subtle differences that carry climatologically relevant information. We further exploit the advanced potentials provided by ECA for studying in greater detail the spatial organization of East Asian summer monsoon (EASM) related heavy precipitation across the relevant season in a time-dependent fashion. Our results show that the formation of the Baiu front as a main feature of the EASM is accompanied by a double-band of synchronous heavy rainfall with two spatially dislocated centers north and south of the front. Although these bands are closely related to low- and high-level winds which are commonly assumed to be independent of each other, it is rather their mutual interconnectivity that changes during the different phases of the EASM season in a characteristic way. The thus obtained insights could provide relevant information for improving existing forecasting strategies for monsoon onset and strength.</p><p> </p><p>References:</p><p>Odenweller, R.V. Donner: Disentangling synchrony from serial dependency in paired-event time series. Physical Review E, 101(5), 052213 (2020)</p><p>Wolf, J. Bauer, N. Boers, R.V. Donner: Event synchrony measures for functional climate network analysis: A case study on South American rainfall dynamics. Chaos, 30(3), 033102 (2020)</p><p>Wolf, U. Öztürk, K. Cheung, R.V. Donner: Spatiotemporal patterns of synchronous heavy rainfall events in East Asia during the Baiu season. Earth System Dynamics Discussions. doi:10.5194/esd-2020-69 (2020)</p><p>Wolf, R.V. Donner: Spatial organization of connectivity in functional climate networks describing event synchrony of heavy precipitation. European Physical Journal Special Topics (in review)</p>

Physical and synoptic predictors and their optimal values leading to the formation of heavy rainfall

2021 ◽  
pp. 24-43
Author(s):  
A.A. Alekseeva ◽  
◽  
B.E. Peskov ◽  
Keyword(s):  
Lead Time ◽  
Heavy Rainfall ◽  
Heavy Precipitation ◽  
Radar Data ◽  
Weather Forecasters ◽  
Optimal Values ◽  
Convective Phenomenon

The physical and synoptic predictors are presented, which allow refining the automated forecasts of heavy precipitation implemented in the Hydrometeorological Center of Russia on the recommendation of the Roshydromet Central Methodological Forecasting Commission, as well as hydrodynamic forecasts of precipitation and forecasts of weather forecasters. The physical substantiation of the considered predictors is given. Their optimal values for the formation of heavy precipitation are determined. The parameters of convection and the intensity of the convective phenomenon diagnosed on the basis of radar data further expand the possibilities of refining forecasts of heavy and very heavy precipitation and, if necessary, allow issuing a storm warning with a sufficient lead time or refining a storm warning. Keywords: heavy precipitation, physical and synoptic predictors, diagnosed convection parameters, DMRL-C data

scholarly journals Combined Study of a Significant Mine Collapse Based on Seismological and Geodetic Data—29 January 2019, Rudna Mine, Poland

2020 ◽  
Vol 12 (10) ◽  
pp. 1570
Author(s):  
Maya Ilieva ◽  
Łukasz Rudziński ◽  
Kamila Pawłuszek-Filipiak ◽  
Grzegorz Lizurek ◽  
Iwona Kudłacik ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Radar Data ◽  
Satellite System ◽  
High Frequency Oscillations ◽  
System Data ◽  
Satellite Radar ◽  
Global Navigation Satellite ◽  
Mine Collapse ◽  
Mine Roof

On 29 January 2019, the collapse of a mine roof resulted in a significant surface deformation and generated a tremor with a magnitude of 4.6 in Rudna Mine, Poland. This study combines the seismological and geodetic monitoring of the event. Data from local and regional seismological networks were used to estimate the mechanism of the source and the ground motion caused by the earthquake. Global Navigation Satellite System data, collected at 10 Hz, and processed as a long-term time-series of daily coordinates solutions and short-term high frequency oscillations, are in good agreement with the seismological outputs, having detected several more tremors. The range and dynamics of the deformed surface area were monitored using satellite radar techniques for slow and fast motion detection. The radar data revealed that a 2-km2 area was affected in the six days after the collapse and that there was an increase in the post-event rate of subsidence.

scholarly journals Dipole Structure of Interannual Variations in Summertime Tropical Cyclone Activity over East Asia

2005 ◽  
Vol 18 (24) ◽  
pp. 5344-5356 ◽  
Author(s):  
Joo-Hong Kim ◽  
Chang-Hoi Ho ◽  
Chung-Hsiung Sui ◽  
Seon Ki Park
Keyword(s):  
Tropical Cyclone ◽  
East Asia ◽  
Function Analysis ◽  
Wave Train ◽  
Jet Stream ◽  
Atmospheric Flows ◽  
Dipole Structure ◽  
Dipole Pattern ◽  
Rossby Wave Train

Abstract The present study examines variations in summertime (July–September) tropical cyclone (TC) activity over East Asia during the period 1951–2003. To represent TC activity, a total of 853 TC best tracks for the period were converted to TC passage frequencies (TPFs) within 5° × 5° latitude–longitude grids; TPFs are defined as the percentage values obtained by dividing the number of TC appearances in each grid box by the total number of TCs each year. Empirical orthogonal function analysis of the TPF showed three leading modes: two tropical modes that represent the long-term trend and the relationship with ENSO and one midlatitude mode that oscillates between south of Korea and southeast of Japan with an interannual time scale. The latter proved to be the most remarkable climatic fluctuation of summertime TC activity in the midlatitudes and is referred to as the East Asian dipole pattern (EADP) in this paper. Anomalous atmospheric flows directly connected to the EADP are an enhanced anticyclonic (cyclonic) circulation centering around Japan when the TPF is high south of Korea (southeast of Japan), thereby showing an equivalent barotropic structure in the entire troposphere. This regional circulation anomaly varies in conjunction with the zonally oriented quasi-stationary Rossby wave train in the upper troposphere. This wave train is meridionally trapped in the vicinity of the summer-mean jet stream; therefore, the mean jet stream alters its internal meandering structure according to the phase of the wave train.

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