Influence Of Monsoon Research Articles

A dataset of water transparency of Sanya River based on Sentinel-2 data during 2019–2021

As one of the most important water quality parameters on the radar screen of environmental protection sectors, water transparency reveals the turbidity degree of water and plays an important role in the primary productivity of water body and water ecosystem. As an independent island water system, Hainan Province has abundant surface inland water resources and plentiful river runoff. However, due to the influence of dry and wet monsoons and topography, the aquatic systems are characterized by uneven spatial and temporal distribution, and there are few studies on the water quality of inland water bodies on Hainan Island. In this study, we took Sanya River in Sanya, Hainan Province as the study area, and used the QAAv6-based semi-analytic model to retrieve the water transparency of Sanya River in time series from 2019 to 2021 based on the GEE cloud computing platform and the massive Sentinel-2 surface reflectance data stored in Google Cloud. With regard to the extraction of dynamic water area from Sanya River, we adopted the algorithm combining the normalized water body index NDWI with OTUS automatic threshold segmentation to extract the small river water. The data are stored in GeoTiff raster format, and the pixel transparency value and coordinate information are stored at the same time for easy reading and analysis by relevant GIS software. The inversion of long time series transparency based on the GEE cloud database is highly efficient. The dataset can serve as valuable scientific evidence for the water quality monitoring, water pollution control, and aquatic ecological protection of Sanya River.

A multi-strategy-mode waterlogging-prediction framework for urban flood depth

Abstract. Flooding is one of the most disruptive natural disasters, causing substantial loss of life and property damage. Coastal cities in Asia face floods almost every year due to monsoon influences. Early notification of flooding events enables governments to implement focused preventive actions. Specifically, short-term forecasts can buy time for evacuation and emergency rescue, giving flood victims timely relief. This paper proposes a novel multi-strategy-mode waterlogging-prediction (MSMWP) framework for forecasting waterlogging depth based on time series prediction and a machine learning regression method. The framework integrates historical rainfall and waterlogging depth to predict near-future waterlogging in time under future meteorological circumstances. An expanded rainfall model is proposed to consider the positive correlation of future rainfall with waterlogging. By selecting a suitable prediction strategy, adjusting the optimal model parameters, and then comparing the different algorithms, the optimal configuration of prediction is selected. In the actual-value testing, the selected model has high computational efficiency, and the accuracy of predicting the waterlogging depth after 30 min can reach 86.1 %, which is superior to many data-driven prediction models for waterlogging depth. The framework is useful for accurately predicting the depth of a target point promptly. The prompt dissemination of early warning information is crucial to preventing casualties and property damage.

Coupling of the ecosystems in North China with the East Asian summer monsoon rainfall during the Holocene

The influence of Holocene East Asian Summer Monsoon (EASM) rainfall on ecosystems over northern China remains controversial: delay or synchronization. Here we present Holocene quantitatively reconstructed temperature and salinity records based on alkenone proxies in the Dali Lake from northern China. Our data indicate that the Dali Lake was significantly diluted to a freshwater lake (0.8 ± 0.4 g/L) during ∼11.4–3.8 cal ka BP, relative to the modern brackish state. From the early Holocene (before 8.0 cal ka BP) to the middle Holocene (8.0–5.0 cal ka BP), the average salinity value of Dali Lake decreased by ∼0.3 g/L (ca. 30%), but our reconstructed temperature record shows an increase of ∼2.1 °C. In the context of climate warming, the evaporation was enhanced, and thus the decline in salinity is attributed to the increased precipitation, indicating a mid-Holocene EASM rainfall maximum. After comparing our reconstruction with vegetation data, we proposed that the stable and abundant EASM rainfall promoted the forest expansion and vegetation recovery over northern China during the mid-Holocene, suggesting the coupling of ecosystems and EASM rainfall in North China.

Bacterial dynamics along the west coast of India during the non-monsoon and monsoon season

The West Coast of India (WCI) is influenced largely by semi-annual changes in the wind pattern and monsoonal currents. This is reported to cause upwelling which increases the phytoplankton growth in this region during the summer monsoon and it is recorded to be one of the world's highest primary productivity. Increase in the phytoplankton productivity is known to influence the microbial activity which is one of the key biogeochemical processes of the marine ecosystem as it plays an important role in the biotransformation of organic matter. However, the changes in the bacterial community structure and their heterotrophic enzyme activity with increasing primary production are not clearly understood from this region. Hence in this study, the bacterial dynamics along the WCI at Goa, Mangalore and Trivandrum, were investigated from the continental shelf, slope and off-shore region during the non-monsoon and monsoon season. Seasonal changes in the bacterial parameters such as abundance, viable counts and radioactivity based in-situ primary and bacterial productivity were estimated, along with the physicochemical characteristics. Statistical analysis shows a significant (p < 0.05) correlation between primary and bacterial productivity. Significant seasonal variations could also be established for the physicochemical parameters such as dissolved oxygen, nitrate, nitrite and phosphate, fluorescence values representing the chlorophyll concentration, bacterial abundance, viable counts and productivity. Taxonomic diversity studies on the cultivable bacterial morphotypes have shown that Proteobacteria, Firmicutes and Actinobacteria were the major phyla found during both the non-monsoon and monsoon season and Bacteroidetes, was represented only in the non-monsoon season. The bacterial community structure at phylum, genus and operational taxonomic unit levels also changed with higher diversity in the monsoon season. However, the hydrolytic enzyme activity of the bacterial morphotypes was comparatively lower during the monsoon season probably due to the active primary production. Though this study has improved our understanding of the monsoonal influence on the bacterial dynamics along the WCI, further studies based on metagenomic and transcriptome analysis are required to get a better understanding of the role played by the bacterial community from this region.

Organizational Modes of Spring and Summer Convective Storms and Associated Severe Weather over Southern China during 2015–19

Abstract This study investigates the organizational modes of convective storms and associated severe weather in spring and summer (March–August) of 2015–19 over southern China. These storms are classified into three major organizational structures (cellular, linear, and nonlinear), including 10 dominant morphologies. In general, cellular systems are most frequent, followed by linear systems. Convective storms are common in spring, increasing markedly from April to June, and peak in June. Convective storm cases are usually longer lived in spring, while shorter lived in summer. They also present pronounced diurnal variations, with a primary peak in the afternoon and several secondary peaks during the night to the morning. Approximately 79.7% of initial convection clearly exhibits a dominant eastward movement, with a faster moving speed in spring. Convective storms frequently evolve among organizational modes during their life spans. Linear systems produce the most severe weather observations, in which convective lines with trailing stratiform rain are most prolific. Bow echoes are most efficient in producing severe weather events among all systems, despite their rare occurrences. In spring, lines with parallel stratiform rain are abundant producers of severe wind events, ranking the second highest probability. In summer, embedded lines produce the second largest proportion of intense rainfall events, whereas lines with leading stratiform rain are most efficient in generating extremely intense rainfall and thus pose a distinct flooding threat. Broken lines produce the largest proportion of severe weather events among cellular storms. In contrast, nonlinear systems possess the weakest capability to produce severe weather events. Significance Statement Under the influence of the East Asian summer monsoon, severe weather events produced by convective storms occur frequently in China, leading to serious natural disasters. Numerous studies have demonstrated that the morphologies of convective storms are helpful to improve our understanding and prediction of convective storms. However, fewer attempts have been made to examine the convective morphologies over southern China. We aim to reveal the general features of convective organizational modes (e.g., frequencies, durations, variations, etc.) and determine which particular types of severe weather are more or less likely to be associated with particular convective morphologies. These results are of benefit to local forecasters for better anticipating the storm types and issuing warnings for related hazardous weather.

A distinctive Eocene Asian monsoon and modern biodiversity resulted from the rise of eastern Tibet

The uplift of eastern Tibet, Asian monsoon development and the evolution of globally significant Asian biodiversity are all linked, but in obscure ways. Sedimentology, geochronology, clumped isotope thermometry, and fossil leaf-derived numerical climate data from the Relu Basin, eastern Tibet, show at ∼50–45 Ma the basin was a hot (mean annual air temperature, MAAT, ∼27 °C) dry desert at a low-elevation of 0.6 ± 0.6 km. Rapid basin rise to 2.0 ± 0.9 km at 45–42 Ma and to 2.9 ± 0.9 km at 42–40 Ma, with MAATs of ∼20 and ∼16 °C, respectively, accompanied seasonally varying increased annual precipitation to > 1500 mm. From ∼39 to 34 Ma, the basin attained 3.5 ± 1.0 km, near its present-day elevation (∼3.7 km), and MAAT cooled to ∼6 °C. Numerically-modelled Asian monsoon strength increased significantly when this Eocene uplift of eastern Tibet was incorporated. The simulation/proxy congruence points to a distinctive Eocene Asian monsoon, quite unlike that seen today, in that it featured bimodal precipitation and a winter-wet regime, and this enhanced biodiversity modernisation across eastern Asia. The Paleogene biodiversity of Asia evolved under a continually modifying monsoon influence, with the modern Asian monsoon system being unique to the present and a product of a long gradual development in the context of an ever-changing Earth system.

Complex network reveals the spatiotemporal pattern of summer extreme precipitation in Eastern China

In this study, complex networks were constructed based on the synchronization of summer extreme precipitation events (SEPEs) in eastern China. Then, a detailed analysis of spatiotemporal patterns of SEPEs and the relationship between SEPEs in eastern China with the eastern Asian monsoon was presented. The results showed that (1) the event synchronization is low in the coastal region but high in the inland region; (2) the intensity of the monsoon varies at different phases of summer and the area and intensity of the monsoon's influence on the summer extreme rainfall events were different. In conclusion, this study provides valuable insights to reveal the influence of monsoon strength on SEPEs in different regions of China.

Effect of Radio Frequency Interference-Contaminated AMSR2 Signal Restoration on Soil Moisture Retrieval

Soil moisture is a key variable of the climate system. Microwave remote sensing has become an essential means of obtaining soil moisture because of the unique advantages of its all-day and all-weather observation capability. Theoretically, low-frequency C-band observations are highly suitable for soil moisture retrieval because of their high sensitivity to soil moisture at vegetation roots. However, the quality of C-band observations suffers from radio frequency interference (RFI) over the United States. This paper used the iterative principal component analysis (PCA) method to repair RFI-contaminated second-generation Advanced Microwave Scanning Radiometer (AMSR-2) C-band observations, and the results of soil moisture retrieval based on restored data were evaluated. It was found that RFI could lead to nonconvergence in the retrieval of a large amount of data, and the application of repaired data in retrieval could result in the recovery of more than 80% of nonconvergent data, especially in spring and autumn. The retrieval results based on restored data attained a satisfactory correlation with ERA5 reanalysis data and European Space Agency Climate Change Initiative (ESA-CCI) soil moisture data and suitably agreed with precipitation observation data. Soil moisture generally exhibited a gradual increase from west to north and east. This feature was weakened due to the influence of monsoons in the east in summer. The western side of the Cascade Mountains is the wettest area of the United States, with soil moisture exceeding 0.4 m3 m−3. The driest region of the United States is located between the Rockies and Cordillera Mountains, and the soil moisture value is lower than 0.1 m3 m−3.

Influences of tropical monsoon and El Niño Southern Oscillations on surface chlorophyll-a variability in the Gulf of Thailand

This study investigated the seasonal variability of surface chlorophyll-a (chl-a) and the influence of the El Niño Southern Oscillation (ENSO) related to environmental parameters in the Gulf of Thailand (GoT). Monthly chl-a data from MODIS from 2002 to 2020 as well as sea surface temperature (SST), wind, precipitation, and river discharge were used in this analysis. Results from seasonal climatology and Empirical Orthogonal Function (EOF) described high chl-a concentration areas along the western to the southern coasts and near Ca Mau Cape during the northeast monsoon (NEM), and the upper GoT (UGoT), eastern coast, and the GoT mouth during the southwest monsoon (SWM), while low chl-a took place during the non-monsoon (NON). The GoT was divided into six areas based on the EOFs of chl-a, and then the correlation between chl-a variability and environmental parameters was also examined. The results suggested that chl-a in coastal and offshore areas were controlled by different mechanisms. Chl-a in coastal areas responded to precipitation and river discharge as well as the shoreward wind; meanwhile, chl-a in offshore areas correlated with SST and wind magnitude indicating the importance of water mixing and upwelling. The fluctuation of chl-a in each season related to ENSO was captured by EOF based on the seasonal anomaly. The influence of ENSO was strong during NEM and NON but minimal during SWM. El Niño/La Niña generally caused low/high precipitation and high/low SST. Moreover, El Niño/La Niña caused anomalously weak/strong wind during NEM contrary to during NON. Anomalous high/low chl-a were observed in shallow regions during El Niño/La Niña corresponding to strong/weak wind in NON. Abnormal wind under ENSO also created the shifting in the high chl-a area near Ca Mau Cape. These results have improved our understanding of monsoons and ENSO variabilities as the crucial drivers of changes in the tropical marine ecosystem in both seasonal and interannual time scales.

Characterizing the Distribution Pattern and a Physically Based Susceptibility Assessment of Shallow Landslides Triggered by the 2019 Heavy Rainfall Event in Longchuan County, Guangdong Province, China

Rainfall-induced landslides pose a significant threat to the lives and property of residents in the southeast mountainous and hilly area; hence, characterizing the distribution pattern and effective susceptibility mapping for rainfall-induced landslides are regarded as important and necessary measures to remediate the damage and loss resulting from landslides. From 10 June 2019 to 13 June 2019, continuous heavy rainfall occurred in Longchuan County, Guangdong Province; this event triggered extensive landslide disasters in the villages of Longchuan County. Based on high-resolution satellite images, a landslide inventory of the affected area was compiled, comprising a total of 667 rainfall-induced landslides over an area of 108 km2. These landslides consisted of a large number of shallow landslides with a few flowslides, rockfalls, and debris flows, and the majority of them occurred in Mibei and Yanhua villages. The inventory was used to analyze the distribution pattern of the landslides and their relationship with topographical, geological, and hydrological factors. The results showed that landslide abundance was closely related to slope angle, TWI, and road density. The landslide area density (LAD) increased with the increase in the above three influencing factors and was described by an exponential or linear relationship. In addition, southeast and south aspect hillslopes were more prone to collapse than the northwest­–north aspect ones because of the influence of the summer southeast monsoon. A new open-source tool named MAT.TRIGRS(V1.0) was adopted to establish the landslide susceptibility map in landslide abundance areas and to back-analyze the response of the rainfall process to the change in landslide stability. The prediction results were roughly consistent with the actual landslide distribution, and most areas with high susceptibility were located on both sides of the river valley; that is, the areas with relatively steep slopes. The slope stability changes in different periods revealed that the onset of heavy rain on 10 June 2019 was the main triggering factor of these group‑occurring landslides, and the subsequent rainfall with low intensity had little impact on slope stability.

Future projections of extreme temperature events in Southwest China using nine models in CMIP6

Southwest China, which is close to the Qinghai-Tibet Plateau, presents complex topography. As a result of the combined influence of the South Asian monsoon, East Asian monsoon, and plateau monsoon, climate in this region is unique. Since Southwest China is one of the areas where extreme weather events occur more frequently, this region is sensitive and vulnerable to climate change. In the present research, daily temperature from 1969 to 2020 recorded at 93 weather stations in Southwest China, and data from nine models for the period 1995 to 2040 were used in CMIP6 (Coupled Model Intercomparison Project Phase 6) to calculate 17 ETIs (Extreme Temperature Indices). Furthermore, we analyzed and compared the annual change rate, temporal and spatial change trend, and mean change of extreme temperature events in Southwest China and four subzones during historical period and under SSP2-4.5 scenario for the next 20 years. The results showed: 1) The 8 ECTIs (Extreme Cold Temperature Indices) and the 8 EWTIs (Extreme Warm Temperature Indices) in 1969–2020 were corroborated. These results indicated a warming trend. Also, DTR (Diurnal temperature range) showed a decreasing trend, and different degrees of warming were observed in the four subzones. 2) From 2021 to 2040 and under the SSP2-4.5 scenario, the annual rates of change for 17 ETIs in Southwest China showed that extreme cold events will continue to decrease. On the other hand, extreme warm events will continue to increase. 3) Under the SSP2-4.5 scenario in the next 20 years, CSDI (cold spell duration indicator) will decrease, while WSDI (warm spell duration indicator), TMINmean (average daily minimum temperature), and TMAXmean (average daily maximum temperature) will increase. Moreover, the decrease in amplitude of CSDI was smaller than the increase in amplitude of WSDI. Also, the increase in amplitude of TMINmean was slightly smaller than that of TMAXmean. The projected WSDI, TMINmean, and TMAXmean obtained with the preferred three models and MEM-9 (nine-Model Ensemble Mean) showed an overall growing trend with respect to space; however, the increased range fluctuated in different regions. 4) In 2021–2040, mean values of 4 ETIs in different subzones indicated that the lowest TMINmean and TMAXmean were observed in the ZP (Zoigê Plateau), the highest in the YGP (Yunnan-Guizhou Plateau), and intermediate higher in the SB (Sichuan Basin). Compared with the 4 ETI mean values corresponding to 1969–2020, the persistence and average state of extreme cold and warm events in different subzones showed that future change trends depend on altitude.

Fruits of Firmiana and Craigia (Malvaceae) from the Eocene of the Central Tibetan Plateau with emphasis on biogeographic history

AbstractThe fossil record evidences an old origin and diversification of Malvaceae in the Northern Hemisphere. The central Tibetan Plateau was at a low elevation with a monsoon influence during the Eocene, allowing the development of a subtropical flora containing Malvaceae. The taxonomic study of fossils from the Eocene of what is now the Tibetan Plateau is still ongoing. Malvaceae fossils from the Eocene Jianglang flora, are attributed to sub‐families Tilioideae and Sterculioideae, and are compared with modern species. A new specimen of Firmiana is described based on a fruit valve with a pinnate venation, the secondary veins starting at the ventral suture and reaching the midvein, and the seeds attached at the proximal part of the ventral suture. This specimen represents the earliest known occurrence of the genus. A new occurrence of Craigia is also reported based on detached membranous valves of a fruit capsule with a prominent fusiform locular area and radiating venation. Based on the fossil record of Firmiana and its modern distribution, we infer that the genus may have originated in East Asia and subsequently diversified in South China and Southeast Asia. The new occurrence of Craigia indicates that the genus was distributed in humid areas in South, Southwest and North China during the Eocene. Both fossil records evidence the important role that the Tibetan region played in the diversification of plants in East and Southeast Asia.

​Impact of Media, Market and Monsoon on Agriculture Sector: A Review

Agriculture is the prime importance to human beings. Without agricultural produce, no one can imagine surviving. The influence of monsoon and market on the farm, farmer and farming sector is increasing day by day due to global warming and political interference to some extent. Considering these facts the present review report is focused on the study of the impacts of various aspects of media, market and monsoon on agriculture. This study reports that the media in spite of being the fourth pillar of democracy is not able to play its role properly either intentionally or unintentionally. Media is not giving much importance to covering the farmer’s demands, difficulties, the monsoon forecast and the interference of the middleman/ or Dalal (i.e. intermediaries) in the market. Consequently, the condition of farmers has reached a critical situation and the cases of farmer’s suicide have been increased abruptly in the current decade. This article is, thus, tried to report the farmer’s pain and punctuations in their life and also reported how media and the market, like a monsoon, are exacerbating their wound in place healing. This article also discusses how media can take part in agricultural development to some extent.

Spatio-Temporal Variation of Precipitation in the Qinling Mountains from 1970 to 2100 Based on CMIP6 Data

Estimating future precipitation changes in the Qinling Mountains has significance, for understanding how to reveal the basic characteristics of the atmospheric water cycle in mountainous areas under the action of monsoons and the temporal- and spatial-variation mechanism of water resources in the ‘central water tower’, under the background of climate change. Based on four scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) of the CMIP6 model, the Taylor diagram method was used to select the best regional simulation model, according to historical observation data (1970–2014). On this basis, the precipitation change and circulation background of the Qinling Mountains over the next 86 years (2015–2100) were analyzed. The results show that the simulation effect of the optimal mode is better than that of the single mode. Under the four scenarios, the variation trends of the annual precipitation in the Qinling Mountains from 2015 to 2100 were 4.4 mm/10a, 18.5 mm/10a, 18.1 mm/10a, and 19.1 mm/10a, respectively. By the middle of this century (2041–2060), compared with the reference period of 1995–2014, the average annual precipitation in the Qinling Mountains under the four scenarios will increase by 64.1 mm, 7 mm, 28.8 mm, and −51 mm, respectively. By the end of this century (2081–2100), the average annual precipitation under the four scenarios will increase by 29.5 mm, 77.2 mm, 82.9 mm, and 21.2 mm, respectively. The abnormal increase (decrease) of water vapor, transported northward from the western Pacific and the Bay of Bengal, is the main reason for the abnormal increase (decrease) of precipitation in the flood season in the Qinling Mountains. With the increase in emission scenarios, the influence of the South Asian summer monsoon on precipitation in the Qinling Mountains becomes more significant.

Characterization and Health Risk Assessment of Heavy Metals in PM2.5 in Xiamen Port

PM2.5 samples at Haitian and Songyu container terminals in Xiamen Port were collected in summer and autumn/winter in 2020 and analyzed for 20 elements to investigate their temporal-spatial distribution features, sources, and health risk. The results showed that the levels of PM2.5 were relatively low and did not show significant spatial and diurnal differences. Ca and Si were the main crustal elements, and Zn and Mn were the main heavy metals in PM2.5. Compared with GB 3095-2012 guidelines, Cr(Ⅵ) was in the range of 27.4-28.6 times above the standard. Under the influence of monsoon and port throughput, the concentrations of some elements in summer were higher than those in autumn/winter. Significant diurnal variations were observed for Cu, Zn, SO2, and NO2 but not for V and Ni. Industrial sources were identified as the primary contributor (55.2%-59.4%), followed by traffic (28.7%-31.3%), ship emissions (7.1%-7.7%), and sea salt plus construction dust (4.8%-5.8%). The results of health risk assessment showed that heavy metals in PM2.5in Xiamen Port had potential carcinogenic risk (ECR>1(10-5) to people living near the port, and Cr(Ⅵ), V, and As together accounted for 97.3%-97.5% of the total risks; however, the non-carcinogenic risk was negligible (HI<1), and the major contributors were V, Mn, Ni, and As (89.6%-91.2%). The relative contributions of each contributor to ECR was in the order of traffic (47.2%-49.4%)>industrial (23.8%-24.2%)>ship emissions (16.9%-20.8%)>sea salt plus construction dust (5.7%-12.1%), and the relative contribution to HI was in the order of traffic (38.7%-42.3%)>industrial (24.5%-28.2%)>ship emissions (24.1%-27.2%)>sea salt plus construction dust (5.4%-9.6%).

Importance of the seasonal temperature and precipitation variation on glacial evolutions during the LGM at monsoonal Himalaya based on Cogarbu valley

Glacier models have played a more and more important role in reconstructing the paleoglacier and paleoclimate, but the detailed analysis based on high spatial and temporal resolution simulations is rare. In this study, we deeply analyzed the paleoglacial evolution on seasonal scale and its relationship with the large-scale circulation shifts during the Last Glacial Maximum (LGM) in Cogarbu valley, a typical monsoon influence region, using the Open Global Glacier Model driven by 12 Global Circulation Models and their average. The paleoglacier reconstructed under the mean climate is closer to the observations, with the glacier length, area, and volume of 19.8 km, 35.7 km2, and 6.6 km3, respectively. The reconstructed equilibrium-line altitude is ~5253 m, about 662 m lower than modern. The temperature has a 4.6 °C decreasing with a 16.3% reduction of precipitation. The seasonal temperature decreases about −4.0, −4.6, −4.2, and − 5.5 °C in spring, summer, autumn, and winter, respectively. Detailed analysis on atmospheric circulation shifts indicates that the high correlation of temperature change between TP and North Atlantic Ocean might be caused by their similar response to the global climate change results from the reduction of insolation rather than baroclinic waves. In summer, southward-shifted and narrowed the Intertropical Convergence Zone weakened the Indian Summer Monsoon, decreasing the summer precipitation of −22.4% compared to modern. In winter, the enhancement of the South Branch of Westerlies increased the winter precipitation of 10.0%. Despite more winter precipitation refueled the glacial accumulation, the decreasing of the summer temperature has dominant influence on the annual net surface mass balance via reducing the summer ablation during the LGM.

An Intertropical Convergence Zone shift controlled the terrestrial material supply on the Ninetyeast Ridge

Abstract. Among various climate drivers, direct evidence for the Intertropical Convergence Zone (ITCZ) control of sediment supply on the millennial scale is lacking, and the changes in ITCZ migration demonstrated in paleoclimate records need to be better investigated. Here, we use clay minerals and Sr–Nd isotopes obtained from a gravity core on the Ninetyeast Ridge to track the corresponding source variations and analyze the relationship between terrestrial material supply and climatic changes. On the glacial–interglacial scale, chemical weathering weakened during the North Atlantic cold-climate periods and falling sea level hindered the transport of smectite into the study area due to the exposure of Andaman and Nicobar Islands. However, the influence of the South Asian monsoon on the sediment supply was not obvious on the millennial scale. We suggest that the north–south migration of the ITCZ controlled the rainfall in Myanmar and further directly determined the supply of clay minerals on the millennium scale because the transport of smectite was highly connected with the ITCZ location; thus, the regional shift of the ITCZ induced an abnormal increase in the smectite percentage during the late Last Glacial Maximum (LGM) in our records. The smectite percentage in the studied core is similar to distinct ITCZ records but different in some periods, revealing that regional changes in the ITCZ were significantly obvious, the ITCZ is not a simple north–south displacement, and closer connections occurred between the Northern–Southern Hemisphere in the eastern Indian Ocean during the late LGM.

Environmental reconstruction potentials of Loess-Paleosol-Sequences in Kashmir through high-resolution proxy data

Loess Paleosol Sequences (LPS) are valuable archives of climatic and environmental change in terrestrial systems and contribute to local and global dust systems. Due to their widespread occurrence across continents, LPS are well suited to study the interface of climate subsystems, on different time scales. Yet, high-resolution investigations of LPS have been mainly performed in Europe, East Asia and North America. In contrast, other loess-covered areas are less intensively studied, and low sampling resolution often limits the assessment of the full potential of these paleo-environmental archives. This is particularly true for LPS in the Kashmir region, where competing monsoonal- and continental climate subsystems in Southern Asia interact. In this study, we test the potential of the Wanihama LPS in the northern fringe of the Kashmir Valley to reflect climatic- and paleo-environmental variability between- and within stratigraphic units. For this, we present the stratigraphic log of the section and contribute a high-resolution (2 cm interval) dataset comprising rock-magnetic parameters, grain size- and colorimetric data for the Wanihama LPS in Kashmir. Overall, our multi-proxy-study supports the stratigraphy to different degrees. Classic climate-driven magnetic enhancement in paleosols is evident, despite possible waterlogging effects through monsoonal influences. Our results highlight the potential of LPS in Kashmir and illustrate the need for reliably dated logs with proxy data in a high resolution, to i) validate the LPS in the context of paleo-environmental and climatic studies, and to ii) establish a correlative framework for LPS across Kashmir and beyond. Once high-resolution proxy data are available for long and continuous LPS in Kashmir, we will be able to gain a better understanding of interactions between climate sub-systems in the context of oscillating supra-regional climate systems in Southern Asia.

Immigration Pathways of White-Backed Planthopper in the Confluence Area of the Two Monsoon Systems.

The white-backed planthopper, WBPH, Sogatella furcifera (Horváth) is a plant pest that migrates long-distances. The migration pathway of WBPH in eastern China coincides with the north-south round trip of the East Asian monsoon. However, in Yunnan China, which is affected by two monsoon systems, the migration pathway is unclear. Light-trap data and analysis of female ovarian development showed that the peak period of immigration of WBPH into western Yunnan was earlier than in eastern Yunnan. Using meteorological reanalysis data and flight parameters of WBPH, trajectory modeling showed that there are two immigration pathways to Yunnan. One is from Myanmar to western Yunnan, and the other is from Vietnam and Laos to eastern Yunnan. The reason for the differences in source areas and immigration pathways between eastern and western Yunnan is that the west wind prevails in western Yunnan and is controlled by South Asian monsoon, while southwesterly winds prevail in eastern Yunnan due to the combined influence of South Asian monsoon and East Asian monsoon. The results indicate that WBPH invades Yunnan via two pathways under a two-monsoon system. These data will allow earlier prediction and population management of WBPH.

Species richness is a strong driver of forest biomass along broad bioclimatic gradients in the Himalayas

AbstractForest biomass is an important component of terrestrial carbon pools. However, how climate, biodiversity, and structural attributes co‐determine spatiotemporal variation in forest biomass remains not well known. We aimed to shed light on these drivers of forest biomass by measuring diversity and structural attributes of tree species in 400‐m2 plots located every 100 m along a 4200‐m elevational gradient in the eastern Himalayas. We applied structural equation models to test how climate, species richness, structural attributes, and their interactions influence forest biomass. Importantly, species richness was a stronger driver of biomass than environmental and structural attributes such as annual air temperature or stem density. Integrating the availability of energy and the demand for water, potential evapotranspiration was more strongly correlated with biomass than water availability, likely due to the strong influence of the Indian summer monsoon. Thus, interactions between climate and tree community composition ultimately control how much carbon is stored in woody biomass across bioclimatic gradients. This fundamental understanding will support predictive efforts of the forest carbon sink in this hydroclimatically important region and help preserving regional forests as a potent natural solution for climate change mitigation.