scholarly journals On the Scale Interactions that Dominate the Maintenance of a Persistent Heavy Rainfall Event: A Piecewise Energy Analysis

2018 ◽  
Vol 75 (3) ◽  
pp. 907-925 ◽  
Author(s):  
Shen-Ming Fu ◽  
Rui-Xin Liu ◽  
Jian-Hua Sun
Keyword(s):  
Heavy Rainfall ◽  
Lower Troposphere ◽  
Heavy Rainfall Event ◽  
Scale Interactions ◽  
Leading Role ◽  
Multiscale Systems ◽  
Persistent Heavy Rainfall ◽  
Eddy Flow ◽  
Heavy Rainfall Events ◽  
Separation Results

Abstract Persistent heavy rainfall events (PHREs) are the product of the combined effects of multiscale systems. A PHRE that occurred during the 2016 mei-yu season was selected to further the understanding of the scale interactions accounting for the persistence of this type of event. The scale interactions were analyzed quantitatively using a piecewise energy budget based on temporal scale separation. Results show that the strongest interactions between the precipitation-related eddy flow and its background circulation (BC) occur in the mid- to lower troposphere, where a significant downscale kinetic energy (KE) cascade alone dominates eddy flow persistence. An obvious upscale KE cascade (i.e., a feedback effect) appears in the mid- to upper troposphere but has a negligible effect on the BC. Overall, within the precipitation region, the downscale KE cascade is primarily dependent on BC signals with shorter periods, whereas the upscale KE cascade is more dependent on BC signals with longer periods. Thus, the BC has asymmetric effects on the KE cascades. The most significant BC signal as determined via wavelet analysis [i.e., quasi-biweekly (10–18 days) oscillations in this event] does not play the leading role in the downscale KE cascade. Instead, the quasi-weekly oscillations provide the maximum amount of energy for eddy flow maintenance. Semi-idealized simulations of various BC signals show similar results: precipitation and the intensities of lower-level shear lines and transversal troughs (both of which are closely related to the precipitation-related eddy flow) are more sensitive to the quasi-weekly oscillation than to the quasi-biweekly oscillation.

scholarly journals Evolution of physicochemical species concentration in streams based on heavy rainfall event data obtained for high-frequency monitoring

RBRH ◽  
2016 ◽  
Vol 21 (4) ◽  
pp. 653-665
Author(s):  
Rubia Girardi ◽  
Adilson Pinheiro ◽  
Edson Torres ◽  
Vander Kaufmann ◽  
Luis Hamilton Pospissil Garbossa
Keyword(s):  
Water Quality ◽  
Water Level ◽  
Atlantic Forest ◽  
High Frequency ◽  
Heavy Rainfall ◽  
Rainfall Event ◽  
Heavy Rainfall Event ◽  
Rainfall Events ◽  
Frequency Monitoring ◽  
Heavy Rainfall Events

ABSTRACT Studies carried out over short time intervals assist in understanding the biogeochemical processes occurring relatively fast in natural waters. High frequency monitoring shows a greater variability in the water quality during and immediately after heavy rainfall events. This paper presents an assessment of the surface water quality parameters in the Atlantic Forest biome, caused by heavy rainfall events. The work was developed in two fluviometric sections of the Concordia River watershed, located in the state of Santa Catarina, southern Brazil. The spatial distribution of land use shows the predominance of Atlantic Forest in fluviometric section 1 (FS1) and pasture, forestry, agriculture, and Atlantic Forest in fluviometric section 2 (FS2). In each selected heavy rainfall event, the evolution rainfall height, the water level, and physicochemical parameters of water were analyzed. In all events, the water quality changed due to the heavy rainfall. After the events, an increase in water level and turbidity in both fluviometric sections were detected. In addition, the ammonium ion concentration increased in the river, and the pH value and nitrate concentration decreased. The electrical conductivity presented different behavior in each section. The dissolved oxygen concentration increased in 19 of 27 events. The principal component (PC1) correlated with the turbidity in FS1, and it correlated with level, turbidity, and pH in FS2.

Collaborative Effects of Cold Surge and Tropical Depression–Type Disturbance on Heavy Rainfall in Central Vietnam

2008 ◽  
Vol 136 (9) ◽  
pp. 3275-3287 ◽  
Author(s):  
Satoru Yokoi ◽  
Jun Matsumoto
Keyword(s):  
Heavy Rainfall ◽  
Large Scale ◽  
Lower Troposphere ◽  
Heavy Rainfall Event ◽  
Wind Anomaly ◽  
Southerly Wind ◽  
Cold Surge ◽  
Tropical Depression ◽  
Orographic Rainfall ◽  
Central Vietnam

Abstract This paper reveals synoptic-scale atmospheric conditions over the South China Sea (SCS) that cause heavy rainfall in central Vietnam through case study and composite analyses. The heavy rainfall event discussed in this study occurred on 2–3 November 1999. Precipitation in Hue city (central Vietnam) was more than 1800 mm for these 2 days. Two atmospheric disturbances played key roles in this heavy rainfall. First, a cold surge (CS) northerly wind anomaly in the lower troposphere, originating in northern China near 40°N, propagated southward to reach the northern SCS and then lingered there for a couple of days, resulting in stronger-than-usual northeasterly winds continuously blowing into the Indochina Peninsula against the Annam Range. Second, a southerly wind anomaly over the central SCS, associated with a tropical depression–type disturbance (TDD) in southern Vietnam, seemed to prevent the CS from propagating farther southward. Over the northern SCS, the southerly wind anomaly formed a strong low-level convergence in conjunction with the CS northeasterly wind anomaly, and supplied warm and humid tropical air. These conditions induced by the CS and TDD are favorable for the occurrence of the heavy orographic rainfall in central Vietnam. The TDD can be regarded as a result of a Rossby wave response to a large-scale convective anomaly over the Maritime Continent associated with equatorial intraseasonal variability. Using a 24-yr (1979–2002) reanalysis and surface precipitation datasets, the authors confirm that the coexistence of the CS and TDD is important for the occurrence of heavy precipitation in central Vietnam. In addition, it is observed that CSs without a TDD do not lead to much precipitation.

scholarly journals Investigation of scale interaction between rainfall and ecosystem carbon exchange ofWestern Himalayan Pine dominated vegetation

2018 ◽  
Author(s):  
Sandipan Mukherjee ◽  
K Chandra Sekar ◽  
Priyanka Lohani ◽  
Kireet Kumar ◽  
Prabir Patra ◽  
...  
Keyword(s):  
Confidence Level ◽  
Heavy Rainfall ◽  
Meteorological Parameters ◽  
Western Himalaya ◽  
Pinus Roxburghii ◽  
Rainfall Events ◽  
Scale Interactions ◽  
Daily Average ◽  
Wavelet Coherence Analysis ◽  
Heavy Rainfall Events

Abstract. Forests of the Western Himalaya, India, are impacted by the summer monsoon and winter seasonal rainfall events and associated changes in the meteorology. Here, we assess the scale interactions between observed forest ecosystem fluxes and meteorological parameters, particularly rainfall seasonality and extremes. The scale interactions were investigated using daily observed fluxes and meteorological parameters of 1080 days of 2014–2016 from a Pinus roxburghii dominated forest and using wavelet spectral analysis method. The mixed forest of this study was a sink of CO2 having the average NEE −3.21 gC m−2 day−1 for the period of observations. Result of the wavelet coherence analysis from observed data indicated a statistically significant correlation (> 0.7 at 95 % confidence level) between daily average NEE and daily total rainfall having band periods of 70–120 days, 35–64 days and 60–90 days of monsoon periods of 2014–16, respectively, where rainfall leading to NEE. Impact of heavy rainfall events of monsoon periods over NEE of the forest patch was found to have average band periods of 4 days; whereas, the winter time heavy rainfall events were having average band periods of 15 days with very high local correlation (> 0.7 at 95 % confidence level) inferring that ecosystem exchange rate was mirroring rainfall events. Although CASA-GFDE3 model simulated daily NEE values of 2014–15 were found have a low fraction of explained variance (= 0.08) with respect to observations, modeled NEE-rainfall relationship of 2014 was found to corroborate well with the observed pattern; however for 2015, the phase relationship between modeled NEE and rainfall around band period of 100 days was opposite to the flux tower observations. Subsequently, heavy rainfall events and daily average air temperatures were also found to be coherent during monsoon period having wavelet coherences > 0.8 indicating a cause and effect relationship between both parameters, and rainfall events were mirroring temperature variations. Therefore, it is anticipated that the Pinus roxburghii dominated forest productivity of Western Himalaya, India, are expected to increase even with the increment of heavy rainfall events in the near 20 future.

Redistribution of landslide debris through episodic heavy rainfall events as revealed by multi-period Lidar DEMs

2020 ◽  
Author(s):  
Yu-Chang Chan ◽  
Yu-Chung Hsieh ◽  
Kou-Jen Chang
Keyword(s):  
Heavy Rainfall ◽  
Drainage Basin ◽  
Airborne Lidar ◽  
Heavy Rainfall Event ◽  
Rainfall Events ◽  
Digital Elevation ◽  
Debris Removal ◽  
Elevation Changes ◽  
Heavy Rainfall Events ◽  
Landslide Debris

<p>Landslides are commonly triggered by heavy rainfall events, but how the loose landslide debris is redistributed through time and how fast the landslide scars are healed by vegetation are not well and precisely documented. Due to recent advances in airborne Lidar-derived digital elevation models, we are able to obtain precise DEMs at different time periods and analyze the redistribution of landslide debris that was once difficult to measure because of relatively minor elevation changes. Three periods of Lidar-derived DEMs were used to analyze a drainage basin that was affected by a heavy rainfall event and generated several landslide deposits and scars within the drainage basin in Taiwan. We selected a single drainage basin to better constrain the source of landslide debris for subsequent observations of landslide debris removal. How the landslide debris is transported and redistributed remains an important topic for understanding debris removal and evaluating post-landslide hazards in downstream areas. The multi-period high-resolution Lidar DEMs give the necessary accuracy to calculate small but significant volume changes that were not easily detectable from previous measuring techniques. Our results show that the landslide debris redistributed most effectively during later large rainfall events, and the landslide materials are minimally redistributed during small rainfall events. Areas without existing landslides were also insignificantly affected in terms of volume change even during large rainfall events. The standard deviation of elevations in the drainage basin is used to show how the topography was changed due to heavy rainfall events within the drainage basin. The concept of surface roughness may be useful to characterize the dissipation of landslide debris because the roughness values become lower during the debris redistribution process. The redistribution of landslide debris over the observed years suggests that the dissipation of landslide debris is mainly affected by by episodic heavy rainfall events and the landslide scars recover relatively quickly for smaller affected landslide regions.</p>

Heavy Rainfall Events over Central Oahu under Weak Wind Conditions during Seasonal Transitions

2020 ◽  
Vol 148 (10) ◽  
pp. 4117-4141
Author(s):  
Feng Hsiao ◽  
Yi-Leng Chen ◽  
David Eugene Hitzl
Keyword(s):  
Mixed Layer ◽  
Land Surface ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Subsequent Development ◽  
Precipitable Water ◽  
Trade Wind ◽  
Heavy Rainfall Event ◽  
Rainfall Events ◽  
Heavy Rainfall Events

AbstractShort-lived afternoon heavy rainfall events may form over central Oahu during seasonal transition periods (June and October) under favorable large-scale settings. These include a deep moist layer with relatively high precipitable water (>40 mm), blocking pattern in midlatitudes with a northeast–southwest moist tongue from low latitudes ahead of an upper-level trough, absence of a trade wind inversion, and weak (<3 m s−1) low-level winds. Our high-resolution (1.5 km) model results show that immediately before the storm initiation, daytime land surface heating deepens the mixed layer over central Oahu and the top of the mixed layer reaches the lifting condensation level. Meanwhile, the development of onshore/sea-breeze flows, driven by land–sea thermal contrast, brings in moist maritime air over the island interior. Finally, convergence of onshore flows over central Oahu provides the localized lifting required for the release of instability. Based on synoptic and observational analyses, nowcasting with a lead time of 2–3 h ahead of this type of event is possible. In the absence of orographic effects after removing model topography, processes that lead to heavy rainfall are largely unchanged, and subsequent development of heavy showers over central Oahu are still simulated. However, when surface heat and moisture fluxes are turned off, convective cells are not simulated in the area. These results indicate that daytime heating is crucial for the development of this type of heavy rainfall event under favorable large-scale settings.

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