scholarly journals A Case Study of Subtropical Frontogenesis during a Blocking Event

2007 ◽  
Vol 135 (7) ◽  
pp. 2588-2609 ◽  
Author(s):  
George Tai-Jen Chen ◽  
Chung-Chieh Wang ◽  
An-Hsiang Wang
Keyword(s):  
Large Scale ◽  
Frontal Zone ◽  
Southern China ◽  
Sensible Heat Flux ◽  
Northern China ◽  
Sensible Heat ◽  
Surface Data ◽  
Sea Area ◽  
Blocking Event

Abstract During 8–14 June 2000, a 500-hPa blocking event occurred over Mongolia and northern China (near 45°N, 108°E), which was the only case over this region in June since 1981. As the block developed, the initially weak low-level mei-yu front over southern China evolved into a system with strong baroclinity and subsequently moved south. The frontal passage over Taiwan caused temperatures to drop by 10°C, the largest in June over two decades. Using gridded analyses, manually analyzed weather maps, and satellite and surface data, the present study investigates the evolution of this mei-yu front under the influence of the block. The 925-hPa frontogenetical function is computed and effects of different processes are discussed. As the blocking event developed, concurrent ridge–trough amplification in the lower–midtroposphere produced a reversed thermal pattern. The lower-tropospheric high moved southward, and large-scale confluence and deformation were enhanced between the northerly flow and the prefrontal southwesterly flow. The location of the block, to the west-southwest of the Okhotsk Sea area, allowed it to affect the front over southern China and caused it to penetrate inside 20°N, unusual for the month of June. The distribution of the frontogenetical function indicated that the mei-yu frontogenesis and the maintenance of the front were attributed to both deformation and convergence. These two processes together counteracted the strong frontolysis along the frontal zone from diabatic effects, caused by evaporative cooling of frontal precipitation on the warm side and stronger sensible heat transfer (and daytime heating over less cloudy areas) on the cold side of the front. When deformation, convergence, and diabatic effects were all combined, the net total frontogenesis peaked slightly ahead of the frontal zone, thus contributing to the southward propagation of the front in addition to the advection by postfrontal cold air in the present case. When the front moved into the South China Sea, the cross-frontal thermal gradient diminished rapidly, mainly due to the frontolytic effect from sensible heat flux over warm waters.

scholarly journals Contrasting Performance of the Remotely-Derived GPP Products over Different Climate Zones across China

2019 ◽  
Vol 11 (16) ◽  
pp. 1855 ◽  
Author(s):  
Yanan Chen ◽  
Hongfan Gu ◽  
Munan Wang ◽  
Qing Gu ◽  
Zhi Ding ◽  
...  
Keyword(s):  
Large Scale ◽  
Climatic Factors ◽  
Southern China ◽  
Gross Primary Production ◽  
Terrestrial Ecosystems ◽  
Northern China ◽  
Tibet Plateau ◽  
Semiarid Region ◽  
Interannual Variations ◽  
Climate Zones

Precise quantification of terrestrial gross primary production (GPP) has been recognized as one of the most important components in understanding the carbon balance between the biosphere and the atmosphere. In recent years, although many large-scale GPP estimates from satellite data and ecosystem models have been generated, few attempts have been made to compare the different GPP products at national scales, particularly for various climate zones. In this study, two of the most widely-used GPP datasets were systematically compared over the eight climate zones across China’s terrestrial ecosystems from 2001 to 2015, which included the moderate resolution imaging spectroradiometer (MODIS) GPP and the breathing Earth system simulator (BESS) GPP products. Additionally, the coarse (0.05o) GPP estimates from the vegetation photosynthesis model (VPM) at the same time scale were used for auxiliary analysis with the two products. Both MODIS and BESS products exhibited a decreasing trend from the southeast region to the northwest inland. The largest GPP was found in the tropical humid region with 5.49 g C m−2 d−1 and 5.07 g C m−2 d−1 for MODIS and BESS, respectively, while the lowest GPP was distributed in the warm temperate arid region, midtemperate semiarid region and plateau zone. Meanwhile, the work confirmed that all these GPP products showed apparent seasonality with the peaks in the summertime. However, large differences were found in the interannual variations across the three GPP products over different climate regions. Generally, the BESS GPP agreed better than the MODIS GPP when compared to the seasonal and interannual variations of VPM GPP. Furthermore, the spatial correlation analysis between terrestrial GPP and the climatic factors, including temperature and precipitation, indicated that natural rainfall dominated the variability in GPP of Northern China, such as the midtemperate semiarid region, while temperature was a key controlling factor in the Southern China and the Tibet Plateau area.

scholarly journals Coastal Wind and Turbulence Observations during the Morning and Evening Transitions over Tropical Terrain

2017 ◽  
Vol 56 (12) ◽  
pp. 3167-3185 ◽  
Author(s):  
Derek D. Jensen ◽  
Timothy A. Price ◽  
Daniel F. Nadeau ◽  
Jacob Kingston ◽  
Eric R. Pardyjak
Keyword(s):  
Heat Flux ◽  
Large Scale ◽  
Sensible Heat Flux ◽  
Sea Breeze ◽  
Flow Regimes ◽  
Resource Assessment ◽  
Sensible Heat ◽  
Coastal Site ◽  
Synoptic Forcing ◽  
Mean Wind Speed

AbstractData collected during a multiyear, wind-resource assessment over a multi-land-use coastal environment in Belize are used to study the development and decay of wind and turbulence through the morning and evening transitions. Observations were made on three tall masts, forming an inland transect of approximately 5 km. The wind distribution is found to be bimodal and governed by synoptic scales, with onshore and offshore flow regimes. The behavior between the coastal and inland sites is found to be very similar when the flow is directed offshore; for onshore flow, stark differences occur. The mean wind speed at the coastal site is approximately 20% greater than the most inland site and is nearly constant throughout the diurnal cycle. For both flow regimes, the influence of the land–sea breeze circulation is inconsequential relative to the large-scale synoptic forcing. Composite time series are used to study the evolution of sensible heat flux and turbulence kinetic energy (TKE) throughout the morning and evening transitions. The TKE budget reveals that at the coastal site mechanical production of TKE is much more important than buoyant production. This allows for the unexpected case in which TKE increases through the ET despite the decrease of buoyant TKE production. Multiresolution flux decomposition is used to further study this phenomenon as well as the evolution of the sensible heat flux at differing time scales. An idealized schematic is presented to illustrate the timing and structure of the morning and evening transitions for an inland site and a coastal site that are subjected to similar synoptic forcing.

Monitoring the Sensible Heat Flux over Urban Areas using Large Aperture Scintillometry: Case Study of Marseille City During the Escompte Experiment

2005 ◽  
Vol 118 (3) ◽  
pp. 449-476 ◽  
Author(s):  
J. -P. Lagouarde ◽  
M. Irvine ◽  
J. -M. Bonnefond ◽  
C. S. B. Grimmond ◽  
N. Long ◽  
...  
Keyword(s):  
Heat Flux ◽  
Urban Areas ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Large Aperture

scholarly journals Contamination With Fumonisin B and Deoxynivalenol Is a Threat to Egg Safety and Contributes to Gizzard Ulcerations of Newborn Chickens

2021 ◽  
Vol 12 ◽  
Author(s):  
Yihui Wang ◽  
Hongkun Quan ◽  
Xiaohui Li ◽  
Qiang Li ◽  
Md Atiqul Haque ◽  
...  
Keyword(s):  
Large Scale ◽  
Southern China ◽  
Northern China ◽  
Poultry Feed ◽  
Hatching Rate ◽  
Post Inoculation ◽  
Poultry Industry ◽  
Average Residual ◽  
Poultry Diets ◽  
Aflatoxin B

Fumonisin B (FB) and other fumonisins, deoxynivalenol (DON), and zearalenone (ZEN) are mycotoxins (secondary metabolites of fungi) present at high levels of contamination in poultry diets and threatening the sustainability of the poultry industry and egg safety for consumers. However, residual mycotoxins in breeder eggs and their effects on chicken progeny and gizzard ulcerations remain unclear. To unveil mycotoxin contaminations from daily diets to breeder eggs, 293 poultry feed samples were collected from three large-scale poultry provinces across Northern China to Southern China. Average levels of 1,628 ± 4.36 μg/kg of FB1, 593 ± 11.16 μg/kg of DON, 69 ± 9.21 μg/kg of ZEN, 52 ± 7.33 μg/kg of OTA, and 24 ± 5.85 μg/kg of AFB1 were found in feedstuffs and poultry diets using commercial ELISA kits. In terms of residual mycotoxins in breeder eggs, FB1 and DON contaminations dominated residues in egg albumen and yolk samples. Out of 221 breeder eggs, the average residual of FB1 in albumen were 320.6 ± 10.12 μg/kg (Hebei), 420.2 ± 10.98 μg/kg (Guangdong), and 549.4 ± 10.27 (Guangxi). Moreover, higher residual of DONs were determined in Guangdong and Guangxi provinces compared to Hebei province. ZEN, ochratoxins A (OTA), and aflatoxin B1 (AFB1) contamination at low levels were found in the above samples collected from afronmentioned three provinces. Based on residual mycotoxins in breeder eggs, SPF embryonated eggs aged 11 days were inoculated into albumen with different doses of FB1, FB2 or DON, or a combination of FB1 and DON, or a combination of FB1 with FB2 and FB3. A lower hatching rate was observed in the chicken progenies with the combination of 24 μg of FB1 and 0.1 μg of DON compared to other treatments. Moreover, typical gizzard ulcerations with hemorrhagic lungs were observed in the progeny of breeder eggs post-inoculation of 24 μg of FB1 and synergetic inoculation of FB1 and DON. Finally, residual FB mycotoxins were detected in the gizzards and in the lungs of the progenies. Based on the above evidence, feed-borne FB1 and DON are dominant mycotoxins in breeder eggs and threatening food security using breeder eggs as a Trojan horse. More importantly, the residual of FB1 alone and in combination with of DON contamination are associated with low hatching rate and gizzard ulcerations in chicken progenies, hampering sustainable development perspectives of the poultry industry.

scholarly journals Insights from a joint analysis of Indian and Chinese monsoon rainfall data

2011 ◽  
Vol 15 (8) ◽  
pp. 2709-2715 ◽  
Author(s):  
M. Zhou ◽  
F. Tian ◽  
U. Lall ◽  
H. Hu
Keyword(s):  
Large Scale ◽  
Monsoon Rainfall ◽  
Indian Monsoon ◽  
Southern China ◽  
Principal Component ◽  
Northern China ◽  
Rainfall Data ◽  
Joint Analysis ◽  
Climate Indices ◽  
The Common

Abstract. Monsoon rainfall is of great importance for agricultural production in both China and India. Understanding the features of the Indian and Chinese monsoon rainfall and its long term predictability is a challenge for research. In this paper Principal Component Analysis (PCA) method was adopted to analyze Indian monsoon and Chinese monsoon separately as well as jointly during the period 1951 to 2003. The common structure of Indian monsoon and Chinese monsoon rainfall data was explored, and its correlation with large scale climate indices and thus the possibility of prediction were analyzed. The joint PCA results gives a clearer correlation map between Chinese monsoon rainfall and Indian monsoon rainfall. The common rainfall structure presents a significant teleconnection to Sea Surface Temperature anomaly (SSTa), moisture transport and other climate indices. Specifically, our result shows that Northern China would garner less rainfall when whole Indian rainfall is below normal, and with cold SSTa over the Indonesia region more rainfall would be distributed over India and Southern China. The result also shows that SSTa in the previous winter months could be a good indicator for the summer monsoon rainfall in China.

Dynamics of East Asian Spring Rainband and spring-autumn contrast: Environmental forcings of large-scale circulation

2021 ◽  
pp. 1-59
Author(s):  
Shi-Xin Wang ◽  
Hong-Chao Zuo ◽  
Fen Sun ◽  
Li-Yang Wu ◽  
Yixing Yin ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Large Scale ◽  
Southern China ◽  
East Asian ◽  
Baroclinic Instability ◽  
Northern China ◽  
Reanalysis Dataset ◽  
Warm Advection ◽  
Westerly Jet ◽  
External Forcings

AbstractDynamics of the East Asian spring rainband are investigated with reanalysis dataset and station observations. Here, it is revealed that the rainband is anchored by external forcings. Midtropospheric jet core stays quasi-stationary around Japan. It has two branches in its entry region, which originate from the south and north flanks of Tibetan Plateau and then run northeastward and southeastward, respectively. The southern branch advects warm air from the Hengduan-Tibetan plateaus northeastwards, forming rainband over southern China through both causing adiabatic ascent motion and triggering diabatic feedback. The rainband is much stronger in spring than in autumn due to the stronger diabatic heating over Hengduan-Tibetan Plateau, more southward-displaced midtropospheric jet and resultant stronger warm advection over southern China. The northern jet branch forms a zonally-elongated cold advection belt, which reaches the maximum around northern China, and then weakens and extends eastwards towards east of Japan. The westerly jet also steers strong disturbance activities roughly collocated with the cold advection belt via baroclinic instability. The high disturbance activities belt causes large cumulative warm advections (CWA) through drastically increasing extremely warm-advection days in its eastern and south flank, where weak cold advection prevails. CWA is more essential for monthly/seasonally rainfall than conventionally-used time-average temperature advection because it is revealed that strengthened warm advection can increase rainfall through positive diabatic feedback, while cold advection cannot cause negative rainfall. Thus, the rainband is collocated with the large CWA belt instead of the 48 warm advection south of it. This rainband is jointed to the rainband over southern China, forming the long southwest-northeast-oriented East Asian spring rainband. Southeastward-increasing moisture slightly displaces the rainband southeastwards.

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