Indian monsoon

भाषा हे कोणत्याही समाजातील संवादाचे अत्यंत महत्त्वाचे साधन आहे. संवादासाठी भाषेचा वापर करण्याबरोबरच शिक्षणासाठीही भाषेचा उपयोग केला जातो. खरेतर, भाषेशिवाय शिक्षण पूर्ण होऊ शकत नाही. तसेच, ग्रंथालयाशिवाय शिक्षणाच्या प्रक्रियेची आपण कल्पनाही करू शकत नाही. समाजातील भाषेचे जतन आणि विकास करण्यात ग्रंथालयाची भूमिका महत्त्वाची आहे. या संशोधनाचा उद्देश भाषेच्या प्रचार आणि प्रसाराबरोबरच तिचे संवर्धन व जतन ग्रंथालयाच्या माध्यमातून कसे केले जाते, हे तपासणे हा आहे. या संदर्भात ग्रंथालयाच्या महत्त्वपूर्ण भूमिकेवर या संशोधनात अधिक भर देण्यात आला आहे.

The monsoon is a crucial season for farmers, as southwest monsoon irrigates a large portion of the agricultural land in India. In recent decades, the monsoon has shown variability in timing, amount, and distribution of rainfall. In order to determine the sowing date, crop pattern, plan for protective irrigation, and conduct intercultural operations, it is also crucial to be aware of the onset and withdrawal of the rainy season. The analysis of weekly rainfall data reveals significant variation in the timing and duration of the monsoon across different locations. Lonavala experiences the earliest monsoon onset in week 23 (04 Jun-10 Jun), while Kasbe Digraj sees the latest onset in week 29 (16 Jul-22 Jul). Most locations, such as Gadhinglaj, Igatpuri, and Karad, experience the monsoon beginning around week 24 (11 Jun-17 Jun), with later starts in regions like Savali Vihir. Monsoon withdrawal also varies, with Savali Vihir seeing the earliest withdrawal in week 40, and Pune and Vadgaon Maval experiencing the latest in week 44. The length of the rainy season ranges from 12 weeks in Savali Vihir to 20 weeks in Mahabaleshwar, with other locations falling in between. This variability underscores the influence of local conditions on monsoon patterns and highlights the need for tailored agricultural strategies to optimize crop management and adapt to local climatic conditions. Understanding these variations is crucial for effective planning of planting schedules and irrigation practices. Hence, the present study entitled, "Onset and withdrawal of monsoon in different research stations under MPKV Rahuri jurisdiction, (Maharashtra, India)" conducted.

It is a review of a Book by Dr. Chhaya Goswami: E-Journal or an E-Book in honour of Dr. Mohsina Mukadam to commemorate her 34 years of service in Ramnarain Ruia College, 202 Published in the E-Journal or an E-Book in honour of Dr. Mohsina Mukadam to commemorate her 34 years of service in Ramnarain Ruia College, 2021

The history of the Somali upwelling during the last 18.5 ka has been reconstructed using biogenic silica fluxes estimated from a sediment core retrieved from the western Arabian Sea. The reconstructed record demonstrates periodic weakening and strengthening of the Somali upwelling during the past 18.5 ka. Variations in biogenic silica fluxes suggest weak upwelling during the last glacial period (18.5-15 ka BP). Strengthened upwelling during the Bølling-Allerød period (15-10 13 ka BP) points to post-glacial onset of the southwest monsoon. The Younger Dryas (13-11 ka BP) is again marked by reduced upwelling strength. Intensification of the Somali upwelling at the beginning of the Holocene and a decline at 8 ka BP are observed. Increases in upwelling strength recorded since 8 ka BP suggest strengthening of the southwest monsoon during the latter part of the Holocene. Linking these upwelling variations with southwest monsoon precipitation, a major shift in the relationship between the strength of the Somali upwelling and southwest monsoon rainfall from positive to negative has 15 occurred during the pre-Holocene to the Holocene. The observed shift is attributed to the variation in the southwest monsoon strength due to the latitudinal shift of the Intertropical Convergence Zone (ITCZ) associated with changes in moisture sources. 1 Introduction The greater part of the world's population inhabits the tropical region, where climate is mainly controlled by monsoon rainfall. Understanding the causes of past changes thus plays a critical role in deciphering past, present and future monsoon variability. 20 The economy of India, which is a tropical country that contains a significant part of the world's population, is dependent to a large extent on the southwest monsoon (SWM) rainfall; hence, slight changes in SWM rainfall can lead to immense societal impacts. Several attempts have been made to identify the factors responsible for SWM rainfall variations. SWM rainfall variability is correlated with several global phenomena, such as ENSO (

Somali upwelling history has been reconstructed for the last 18.5 ka BP based on biogenic silica fluxes estimated from a sediment core retrieved from the western Arabian Sea. Surface winds along the east African coast during the southwest monsoon (SWM) cause the Somali upwelling; thus, the intensity of this upwelling has been related to the variability of the SWM. Biogenic silica flux variation suggests periodic weakening and strengthening of the Somali upwelling. Weakened upwelling during the 18.5-15 ka BP period and strengthened upwelling during the Bølling-Allerød (15-12.9 ka BP) suggest the onset of the SWM. The Younger Dryas (12.9-11.7 ka BP) is marked by reduced upwelling strength, with an intensification of the Somali upwelling observed at the beginning of the Holocene and a further decline at 8 ka BP. The increase in the upwelling strength recorded since 8 ka BP suggests SWM strengthening during the latter part of the Holocene. A comparison of upwelling variations with the SWM precipitation record demonstrates a reversal in the relationship between the strength of the Somali upwelling and SWM rainfall at the beginning of the Holocene. This observed shift has been attributed to the variation in the SWM strength due to the latitudinal shift of the intertropical convergence zone (ITCZ) associated with changes in moisture sources.

It is recommended that Ms. Pragya Chalise has completed her dissertation work entitled "Biodiversity of butterflies in Badikhel VDC, Lalitpur" as a partial fulfillment of M.Sc. in Zoology under my supervision. I recommend that the dissertation be accepted for the partial fulfillment of the requirements of Degree of Masters of Science in Zoology (Entomology).

High‐resolution faunal and isotopic analyses of foraminifera were performed on core MD96‐2073 (10°94′N, 52°62′E, 3142 m depth), located close to Socotra Island in the upwelling area of the Somali Basin (NW Indian Ocean). This work focuses on Marine Isotopic Stage 6.5 in order to reconstruct paleo‐upwelling changes and their links with the Arabian Sea summer monsoon and the migration of the Intertropical Convergence Zone (ITCZ). Correspondence and cluster analyses of planktonic foraminiferal abundances, partly controlled by temperature and water mass productivity, together with an upwelling intensification index, show the occurrence of a strong upwelling between 176 and 165 ka. This upwelling intensification responds to a northward migration of the ITCZ. An isotopic depletion in the planktonic foraminifera δ18O records occurring between 180 and 167 ka is interpreted as proof of a large salinity decrease in the surface waters, probably linked to a strong input of fresh rainfall waters...

New bulk sediment Sr and Nd isotope data, coupled with U-Pb dating of detrital zircon grains from sediment cored by the International Ocean Discovery Program in the Arabian Sea, allow the reconstruction of erosion in the Indus catchment since ∼ 17 Ma. Increasing ε Nd values from 17 to 9.5 Ma imply relatively more erosion from the Karakoram and Kohistan, likely linked to slip on the Karakoram Fault and compression in the southern and eastern Karakoram. After a period of relative stability from 9.5 to 5.7 Ma, there is a long-term decrease in ε Nd values that corresponds with increasing relative abundance of > 300 Ma zircon grains that are most common in Himalayan bedrocks. The continuous presence of abundant Himalayan zircons precludes large-scale drainage capture as the cause of decreasing ε Nd values in the submarine fan. Although the initial increase in Lesser Himalaya-derived 1500-2300 Ma zircons after 8.3 Ma is consistent with earlier records from the foreland basin, the much greater rise after 1.9 Ma has not previously been recognized and suggests that widespread unroofing of the Crystalline Lesser Himalaya and to a lesser extent Nanga Parbat did not occur until after 1.9 Ma. Because regional erosion increased in the Pleistocene compared to the Pliocene, the relative increase in erosion from the Lesser Himalaya does not reflect slowing erosion in the Karakoram and Greater Himalaya. No simple links can be made between erosion and the development of the South Asian Monsoon, implying a largely tectonic control on Lesser Himalayan unroofing.

The monsoon plays an important role in determining the cropping pattern of any region. The onset and withdrawal data was obtained from the analysis of weekly rainfall data for all tehsils in Ahmednagar district. This analysis indicated that the tehsils of Jamkhed, Newasa, Pathardi, Rahata, and Shevgaon have a mean week of onset of monsoon at 26 MW (Meteorological Week), while for all other tehsils, the mean week of onset was 27 MW.

The mean week of withdrawal of the monsoon was observed to be 41 MW for tehsils like Kopergaon, Newasa, Rahata, Shevgaon, and Rahuri. For tehsils such as Akole, Jamkhed, Karjat, Pathardi, and Rahuri, the mean week of withdrawal was 42 MW, whereas 43 MW was observed to be the mean week of withdrawal for Ahmednagar, Parner, Sangamner, and Shrigonda. Hence, the given research work studies the onset and withdrawal of the monsoon in Ahmednagar district of Maharashtra.

The physicochemical characters and diatoms of two coastal lakes i.e. the Khajuri Lake and the Babule Lake from the Palghar District Maharashtra were studied to ascertain the relationship between water quality and diatom diversity. The prevalent diatom assemblage from the Khajuri Lake indicates fresh to brackish, alkaliphilous water with mild pollution and mesotrophic to eutrophic status. Similarly, dominant diatom assemblage from the Babule Lake indicates alkalibiontic, eutrophic water with the impact of anthropogenic pollution. The pH values clearly indicate alkaline nature of both the lakes, but very high values of pH were noted for the Khajuri Lake (9.6). Thus, these pH values clearly point moderate to high alkaline nature of water. However, higher values of the pH for the Khajuri Lake suggest increased decomposition of organic matter in addition to elevated photosynthetic activities. The conductivity of these lakes varies from minimum at the Khajuri Lake (255μs/cm) to a maximum at the Babule Lake (620μs/cm). The highest conductivity in the Babule Lake may be due to release of ions from the decomposed organic matter during summer. The total dissolved solids (TDS) content was higher in the Babule Lake (326 mg/l), followed by the Khajuri Lake (125 mg/l), respectively. The low-medium levels of TDS in these lakes may be due to the presence of low to moderate content of potassium, chloride and sodium. The higher values of the total hardness in both these lakes may be due to the usages of excessive fertilizers from the adjoining agriculture fields. The Calcium hardness of both the lake may be categorized as rich lakes. The phosphorous and total nitrogen content suggest fair to poor, eutrophic to hyper-eutrophic water quality for both the lakes.

Interdisciplinary approaches to the Indian Ocean are fairly new, and ecological topics in cultural studies more generally are also rare. This paper, then, is an attempt to begin discussion on these two fronts, hoping that further research will be able to document it in more detail. We cast our argument as being both about Indian Ocean stories and a story in itself, and cast it in three parts: the pre-colonial Indian Ocean, the colonial one, and the postcolonial or contemporary situation.

Analysis of the weather and ocean conditions during recent pirate attacks in the Indian Ocean region suggests that the transition of the summer monsoon limits maritime piracy. A comparison of all known pirate attacks in the region in 2010–11 with surface observations from Socotra and the Somali jet index during the same period indicates that pirates attacking from skiffs are thwarted when winds blow in excess of 9 m s−1. The wind speeds and sea states encountered by pirates during individual attacks were reconstructed using satellite altimetry data for 2010–11. Mean daily wind speeds of up to 20 m s−1 during the two boreal summers resulted in consistently rough seas across the Arabian Sea and Indian Ocean. Surface wind speeds during pirate attacks were generally low (less than 8 m s−1), and once wind speeds exceeded 9 m s−1 no successful attacks occurred. The majority (94%) of pirate attacks took place in waves of sea state 4 or less (wave heights below 2.5 m), with pirates rarely a...

Climate model faces considerable difficulties in simulating the rainfall characteristics of southwest summer monsoon. In this study, the dynamical downscaling of European Centre for Medium-Range Weather Forecast's (ECMWF's) ERA-Interim (EIN15) has been utilized for the simulation of Indian summer monsoon (ISM) through the Regional Climate Model version 4.3 (RegCM-4.3) over the South Asia CoOrdinated Regional Climate Downscaling EXperiment (CORDEX) domain. The complexities of model simulation over a particular terrain are generally influenced by factors such as complex topography, coastal boundary, and lack of unbiased initial and lateral boundary conditions. In order to overcome some of these limitations, the RegCM-4.3 is employed for simulating the rainfall characteristics over the complex topographical conditions. For reliable rainfall simulation, implementations of numerous lower boundary conditions are forced in the RegCM-4.3 with specific horizontal grid resolution of 50 km over South Asia CORDEX domain. The analysis is considered for 30 years of climatological simulation of rainfall, outgoing longwave radiation (OLR), mean sea level pressure (MSLP), and wind with different vertical levels over the specified region. The dependency of model simulation with the forcing of EIN15 initial and lateral boundary conditions is used to understand the impact of simulated rainfall characteristics during different phases of summer monsoon. The results obtained from this study are used to evaluate the activity of initial conditions of zonal wind circulation speed, which causes an increase in the uncertainty of regional model output over the region under investigation. Further, the results showed that the EIN15 zonal wind circulation lacks sufficient speed over the specified region in a particular time, which was carried forward by the RegCM output and leads to a disrupted regional simulation in the climate model. Keywords ECMWF. Regional climate model. Dynamical downscaling. Summer monsoon. Boundary condition. CORDEX Key Points 1. Assessment of sensitivity of RegCM's Mix99 (Grell-> Land & Emanuel-> Ocean) Convective Parameterization Scheme (CPS) in simulating Intraseasonal variability of Indian summer monsoon (ISM). 2. Evaluation of mixed CPS and its dependencies on boundary conditions. 3. Low efficiency of in situ lateral boundary conditions over the particular region causes a disturbed rainfall characteristic in RegCM simulation. 4. Low efficiency in EIN15 zonal wind circulation over Indian region during the phases of monsoon.

The aim of the present study is to find out the possible linkage between the North Atlantic Oscillation (NAO), a major ocean-atmosphere coupled phenomena believed to be responsible for the variability of Indian Summer Monsoon Rainfall (ISMR) and its relation with Quasi-Biennial Oscillation (QBO) using 60 years (1953-2012) period. Spring North Atlantic Oscillation Index (NAOI) has been found to be inversely correlated with the ISMR, which has been highly enhanced during the east years when the NAOI data have been stratified according to the phases of QBO. The effect of NAOI on the ISMR is shown to be strengthening significant in the later years of the study as compared to that of the initial years of the study. This interesting result provides an input to use it as a predictor of the ISMR.

31 32 This study investigates a new possible process linking the quasi-stationary Rossby 33 wave propagation (SWP) over Eurasia along the Asian jet and the Pacific-Japan (PJ) 34 pattern through the Rossby wave breaking (RWB) near the jet exit region during boreal 35 summer using a reanalysis dataset. To assess the statistical significance of the process, 36 we conduct a lag composite analysis of the past 44 RWB events east of Japan. The 37 result of the lag composite analysis shows that the SWP along the Asian jet induces the 38 RWB accompanied by an amplified anomalous anticyclone east of Japan. The 39 associated “inverse-S” shaped overturning of the upper-level potential vorticity (PV) 40 distribution causes the southwestward intrusion of the high PV toward the subtropical 41 western North Pacific (WNP). The Q-vector diagnosis and vorticity budget analysis 42 indicate that the upper-level positive vorticity advection associated with the RWB is an 43 important factor dynamically in...

ABSTRACTMarine high-productivity zones along the continents are of great economic importance, and they account for most organic carbon burial. The carbon cycle in many coastal zones is infl u-enced by the sediments and dissolved nutrients introduced by rivers. However, there is little direct evidence for a regional marine response to changes in river dynamics. Here we present a suite of high-resolution records of organic and inorganic paleoceanographic proxies, which together demonstrate that past changes in Indus River discharge have strongly affected pro-ductivity patterns in the coastal northeastern Arabian Sea. Anthropogenic activity, including the building of dams and irrigation facilities during the past century, has drastically decreased the discharge rate of the Indus River. Between A.D. 1890 and 1998, the period over which this reduction occurred, primary productivity off the Pakistan coast seems to have decreased by more than one-third. Over the same period, the regional ox...

The Red River Delta (RRD), one of the two largest deltas in Vietnam, has been severely affected by natural hazards induced by global climate change. Understanding the Holocene paleoshoreline is crucial in developing adaptive planning in response to future shoreline changes based on past natural shoreline changes. This study presents new data pertaining to pollen, grain size, lithological characteristics, and 14 C dating of six cores from the RRD. The purpose of this study was to determine the paleoenvironments and paleoshorelines of the RRD in the Holocene to provide information useful for modeling future changes, e.g., for calibration sea level in paleobathymetry and sea level change models; for making the necessary ecological and cultural adaption to survive. We identified 4 units and 10 sedimentary facies indicating periods of sedimentary evolution since late Pleistocene. The main indicators for paleoshoreline interpretation are true mangrove and backmangrove pollen. The inferred paleoshoreline changes and five paleogeographic maps for 10.5, 9.2, 7.8, 6.5, and 3.7 cal. kyr BP were constructed based on paleoshoreline indicators, and paleoenvironmental reconstructions from the dataset of our whole RRD study area.

The Dansgaard-Oeschger oscillations and Heinrich events described in North Atlantic sediments and Greenland ice are expressed in the climate of the tropics, for example, as documented in Arabian Sea sediments. Given the strength of this teleconnection, we seek to reconstruct its range of environmental impacts. We present geochemical and sedimentological data from core SO130-289KL from the Indus submarine slope spanning the last~80 kyr. Elemental and grain size analyses consistently indicate that interstadials are characterized by an increased contribution of fluvial suspension from the Indus River. In contrast, stadials are characterized by an increased contribution of aeolian dust from the Arabian Peninsula. Decadal-scale shifts at climate transitions, such as onsets of interstadials, were coeval with changes in productivity-related proxies. Heinrich events stand out as especially dry and dusty events, indicating a dramatically weakened Indian summer monsoon, potentially increased winter monsoon circulation, and increased aridity on the Arabian Peninsula. This finding is consistent with other paleoclimate evidence for continental aridity in the northern tropics during these events. Our results strengthen the evidence that circum-North Atlantic temperature variations translate to hydrological shifts in the tropics, with major impacts on regional environmental conditions such as rainfall, river discharge, aeolian dust transport, and ocean margin anoxia. Sedimentary archives in the northeastern Arabian Sea have been described as sensitive recorders of Indian monsoonal climate on annual to millennial time scales [Schulz et al., 1998; von Rad et al., 1999; Lückge et al., 2002]. During the past years a controversial discussion evolved whether the mainly productivity-related proxies in the Arabian Sea reflect dominantly changes in the Indo-Asian monsoonal intensity or rather changes in the AMOC [

The South Asian Monson (SAM) is one of the most intense climatic elements yet its initiation and variations are not well established. Dating the deposits of SAM wind-driven currents in IODP cores from the Maldives yields an age of 12. 9 Ma indicating an abrupt SAM onset, over a short period of 300 kyrs. This coincided with the Indian Ocean Oxygen Minimum Zone expansion as revealed by geochemical tracers and the onset of upwelling reflected by the sediment's content of particulate organic matter. A weaker 'proto-monsoon' existed between 12.9 and 25 Ma, as mirrored by the sedimentary signature of dust influx. Abrupt SAM initiation favors a strong influence of climate in addition to the tectonic control, and we propose that the post Miocene Climate Optimum cooling, together with increased continentalization and establishment of the bipolar ocean circulation, i.e. the beginning of the modern world, shifted the monsoon over a threshold towards the modern system.

Changes in monsoon precipitation governed agricultural practices and production, health risks, competition and conflict level of preindustrial human societies in South Asia. To understand monsoon shifts and their implication to the South Asian societies, we produced a sub-decadal scale multiproxy record of monsoon variability from the Rewalsar lake, India encompassing the past ~3200 years. Our multi-proxy data from this lake indicate a long, strong Indian monsoon interval during ~1200 BCE to 450 AD with intermittent short-lived dry phases, the latter half is coinciding with the Roman Warm Period. A moderately wet summer monsoon characterizes the Medieval Climate Anomaly during ~950-1300 AD. The Rewalsar lake experienced hypertrophic conditions across the transition from the Medieval Climate Anomaly to the Little Ice Age (~1250 to 1400 AD) marked by severe depletion in δ 15 N ratio (0 to − 5‰). The monsoon was weak during the Little Ice Age cold interval and has intensified during the past four centuries in the study region. We find an evidence of the coincidence between increased summer precipitation and economic boom in South Asia with flourishing dynasties during the last three millennia.

Located at the crossroads between Africa and Eurasia, Arabia occupies a pivotal position for human migration and dispersal during the Late Pleistocene. Deducing the timing of humid and arid phases is critical to understanding when the Rub' al-Khali desert acted as a barrier to human movement and settlement. Recent geological mapping in the northern part of the Rub' al-Khali has enabled the Quaternary history of the region to be put into a regional stratigraphical framework. In addition to the active dunes, two significant palaeodune sequences have been identified. Dating of key sections has enabled a chronology of dune accretion and stabilisation to be determined. In addition, previously published optically stimulated luminescence (OSL) dates have been put in their proper stratigraphical context, from which a record of Late Pleistocene dune activity can be constructed. The results indicate the record of dune activity in the northern Rub' al-Khali is preservation limited and is synchronous with humid events driven by the incursion of the Indian Ocean monsoon.

Climatic changes in Arabia are of critical importance to our understanding of both monsoon variability and the dispersal of anatomically modern humans (AMH) out of Africa. The timing of dispersal is associated with the occurrence of pluvial periods during Marine Isotope Stage (MIS) 5 (ca. 130e74 ka), after which arid conditions between ca. 74 and 10.5 ka are thought to have restricted further migration and range expansion within the Arabian interior. Whilst a number of records indicate that this phase of aridity was punctuated by an increase in monsoon strength during MIS 3, uncertainties regarding the precision of terrestrial records and suitability of marine archives as records of precipitation, mean that the occurrence of this pluvial remains debated. Here we present evidence from a series of relict lake deposits within southeastern Arabia, which formed at the onset of MIS 3 (ca. 61e58 ka). At this time, the incursion of monsoon rainfall into the Arabian interior activated a network of channels associated with an alluvial fan system along the western flanks of the Hajar Mountains, leading to lake formation. Multiproxy evidence indicates that precipitation increases intermittently recharged fluvial systems within the region, leading to lake expansion in distal fan zones. Conversely, decreased precipitation led to reduced channel flow, lake contraction and a shift to saline conditions. These findings are in contrast to the many other palaeoclimatic records from Arabia, which suggest that during MIS 3, the latitudinal position of the monsoon was substantially further south and did not penetrate the peninsula. Additionally, the occurrence of increased rainfall at this time challenges the notion that the climate of Arabia following MIS 5 was too harsh to permit the further range expansion of indigenous communities.

We present a multiproxy record of grain size and stable carbon isotope from the Lilaur lake, Ganga Basin, India to understand the history of lake formation linked to changes in Indian monsoon precipitation during ~13714 to 3073 calibrated year before Present (cal yr BP). A comparison is made between Lilaur lake proxy record with those from other parts of South Asia as well as North Atlantic to understand extent and causes of monsoon variability and its influence on the fauna and flora of the region. Chronology of lake core was constrained using AMS 14 C and optically stimulated luminescence (OSL) dates. This study suggests a transition from river to lake during ~5800 to 5189 cal yr BP which is supported by reduced precipitation with weakening of the Indian summer monsoon (ISM). This river to lake transition culminated in a severe arid phase during 4250 to 4050 cal yr BP (4.2 ka event), corresponding to enhanced El Niño activity, southward shift of the Inter-Tropical Convergence Zone, and aridification of India when the ISM was weak.

Total forty-four surficial samples were collected at six locations (J1 to J6) from the Jhurio and Jumara Formations exposed at the Jhurio (Jhura) Dome, Kachchh district of Gujarat. Thirteen major species were considered for the Principal Component Analysis (PCA) out of forty-five identified foraminiferal species. PCA (both factor and cluster analyses) helped us to retain four foraminiferal groups (Sl, Et, Rr, En). The established ecological preferences of each species are used to reconstruct palaeodepositional environment. The basal golden oolitic
limestone sequence (locations J5 and J6) is dominated by foraminiferal group Et (Epistomina turgidula, Epistomina nuda), suggesting oxygen-depleted, outer shelf environment depositional environment and Bathonian age for the Jhurio Formation. Foraminiferal group En (Epistomina nuda, Verneuilinoides tryphera, Spirillina polygyrata, Tandonina paula) dominates in the Jumara Formation sediments suggesting low-oxygenated, outer shelf depositional environment similar to the Jhurio Formation. However, intervals with foraminiferal groups
Rr (Epistomina nuda, Verneuilinoides tryphera, Spirillina polygyrata, Tandonina paula), and Sl (Saracenaria latifrons) indicate relatively shallower depositional depth (inner shelf) in an oxygen-depleted environment. The established foraminiferal assemblage contains some moderately short-ranging species either restricted to
Bathonian or frequently reported from Bathonian to Oxfordian strata indicating Bathonian to Oxfordian age of the Jumara Formation exposed at Jhurio Dome. The foraminiferal group distribution pattern also shows
variations in depositional depths (outer shelf to inner shelf and vice versa) during the middle Jurassic indicating sea-level fluctuation.

Changes in monsoon precipitation governed agricultural practices and production, health risks, competition and conflict level of preindustrial human societies in South Asia. To understand monsoon shifts and their implication to the South Asian societies, we produced a sub-decadal scale multiproxy record of monsoon variability from the Rewalsar lake, India encompassing the past ~3200 years. Our multi-proxy data from this lake indicate a long, strong Indian monsoon interval during ~1200 BCE to 450 AD with intermittent short-lived dry phases, the latter half is coinciding with the Roman Warm Period. A moderately wet summer monsoon characterizes the Medieval Climate Anomaly during ~950-1300 AD. The Rewalsar lake experienced hypertrophic conditions across the transition from the Medieval Climate Anomaly to the Little Ice Age (~1250 to 1400 AD) marked by severe depletion in δ 15 N ratio (0 to − 5‰). The monsoon was weak during the Little Ice Age cold interval and has intensified during the past four centuries in the study region. We find an evidence of the coincidence between increased summer precipitation and economic boom in South Asia with flourishing dynasties during the last three millennia.

The palaeoceanographic changes in the Bay of Bengal are driven by monsoonal variability. The present study was pursued on benthic foraminifera obtained from the NGHP Hole 3B (15°53.8919′ N, 81°53.9678′ E, water depth 1076m), Bay of Bengal to understand Holocene palaeoceonographic turnovers. A total of 21 species from 30 samples have been considered for multivariate analysis. Four biofacies are identified based on Q-mode cluster and R-mode factor analyses. Biofacies Be-Up (Bulimina exilis and Uvigerina peregrina), Ck-Ba (Cibicides kullenbergi, Bulimina alazanensis, Bulimina striata, Vulvulina pennatula and Chilostomella oolina) and Oc-Ou (Osangularia culter, Oridorsalis umbonatus, Chilostomella oolina and Bolivina alata) dominate during 8226 to 6248, 4815 to 2462 and 1896 to 1262 calibrated years before the present, respectively indicating intervals of high productivity with better aerated bottom water. The other biofacies Hb-Gp (Hyalinea balthica, Globobulimina pupoides, Pullenia subcarinata, Bulimina marginata, Bulimina striata, Bolivinita quadrilatera and Rotaliatinopsis semiinvoluta) dominates from 6070 to 5007 and 2300 to 1896 cal yrs BP indicating presence of cold and oxygen deficient environment. Better aerated condition was developed as a result of intense SW monsoon which was responsible for huge precipitation, supply of more freshwater and nutrients. Besides, during the climatic cold, weak SW monsoon may play an important role for development of oxygen deficient environment. A weak SW monsoon during cold climate causes less input of fresh water in the Bay of Bengal. However, upwelling driven by the intense NE monsoon may be another potential cause for such oxygen deficiency.

A robust response of South Asian summer monsoon precipitation to increasing greenhouse gas concentration during the twenty-first century is identified in 23 models from phase 5 of the Coupled Model Intercomparison Project. The pattern of this response is dominated by two dipole structures, one oriented eastwest across the Maritime Continent and another oriented north-south across the equatorial Indian Ocean, and is characterized by enhanced rainfall in South Asia and diminished rainfall over the Maritime Continent. The response is robust in the sense that the same pattern has a trend that is within one standard deviation of the trend of other models. Another robust feature is that the variability of precipitation about this trend decreases in all models, and hence becomes more detectable with time. The response is negligible compared to internal variability during the twentieth century but emerges clearly by the middle of the twenty-first century. Although the pattern as a whole is robust, the response over small land areas such as India has more uncertainty, with some models disagreeing even with the sign of the response.

Although there is increasing evidence for wet, monsoonal conditions in Southeast Asia during the late Eocene, it has not been clear when this environment became established. Cenozoic sedimentary sequences constrained by radiometrically dated igneous rocks from the Jianchuan Basin in the southeast flank of Tibetan Plateau now provide a section whose facies and climatic proxies determine this evolution. Semi-arid conditions had dominated the region since Paleocene controlled by the northern sub-tropical high pressure system, culminating in mid Eocene when desert dunes developed. From 36 Ma, the basin began to accumulate swamp sediments with coals, together with synchronous braided river deposits and diversified pollen assemblages, indicating significant increase in precipitation. This remarkable transition from dry to wet conditions precedes the Eocene/Oligocene boundary at 34 Ma, thus excluding general global cooling as the prime driver. We propose that uplift of Tibetan Plateau migh...

Campinas, SP v.14 n.4 p. 411-414 out./dez. 2018 2. Material and Methods The didactic collection of microfossils was developed during an extension project of the Terrae Did atic a Flávia a. Pedrosa, enelise K. Piovesan, robbyson M. Melo, Clarissa r. GoMes; CeCília l. barros Sedimentary and environmental GeoloGy laboratory (laGeSe),

The Indian summer monsoon (ISM) precipitation pattern over Indian subcontinent is looked through various high resolution speleothem oxygen (δ 18 O) isotope records from Mid to Late Holocene. The six cave locations distributed from central to northern India describing regional climatic conditions due to stalagmite deposition are considered. The stalagmite deposition reflects precipitation patterns by temporal variations of δ 18 O values. Oxygen isotope values reflect cumulative precipitation that is basically interpreted by averaged latitudinal site of inter tropical convergence zone (ITCZ). Under the Paleoclimate Modelling Intercomparison Project Phase III (PMIP3) simulation, Commonwealth Scientific and Industrial Research Organisation Mk3L version 1.0-Part 2 (CSIRO-Mk3L-1-2) model output shows ITCZ movement from Bay of Bengal (BoB) to Arabian Sea (AS) during Mid to Late Holocene which resulted due to solar insolation changes. It reflects precipitation shift from BoB to AS as well as to core monsoon zone (CMZ) to the western Himalayas. The past millennium epoch, which consists little ice age (LIA) and middle warm period (MWP), shows large variations in 850 hPa geopotential height leading to high anomalous precipitation variability all over India during ISM. The high fluctuation in δ 18 O values during Mid Holocene over northern India led to drought conditions due to which Indus valley civilization vanished. The present study shows that the Himalayas received higher precipitation during late Holocene. That is basically governed by western disturbances (WD) as well as ISM. Present study summarizes that the mean annual precipitation cycle for entire epoch was roughly similar, but spatial distribution of precipitation during various epoch was quite divergent from Mid to Late Holocene. The onset of ISM was also similar but, withdrawal was comparatively unalike. Wherever, peaks of seasonal precipitation were alike over Indian subcontinent region, spatial distribution of precipitation were unlike.

Campinas, SP v.14 n.4 p. 411-414 out./dez. 2018 2. Material and Methods The didactic collection of microfossils was developed during an extension project of the Terrae Did atic a Flávia a. Pedrosa, enelise K. Piovesan, robbyson M. Melo, Clarissa r. GoMes; CeCília l. barros Sedimentary and environmental GeoloGy laboratory (laGeSe),

Asian tectonism and exhumation are critical components to develop modern icehouse climate. In this study, stratigraphic sections of eight wells in the Mannar and Cauvery basins were considered. The author demonstrated that this local system records a wealth of information to understated regional and global paleoclimatic trends over the Cenozoic era. The lithostratigraphic framework has been generally characterized by deposition of carbonate-rich sediments since the Middle Cenozoic. Geological provenance of carbonate sediments had probably related to local sources from Sri Lankan and Indian land masses. The main controlling factor of carbonate burial is rather questionable. However, this carbonate burial has indicated the possible link to the Middle to Late Cenozoic global climatic transition. This major climatic shift was characterized by long-term reduction of atmospheric carbon dioxide concentration over the Cenozoic era. Consequently, this geological trend (carbonate burial) has a straightforward teleconnection to the global cooling towards the glaciated earth followed by the development of polar ice sheets that persist today.

Characteristics of the Indian and Australian summer monsoon systems, their seasonality and interactions are examined in a variety of observational datasets and in the Coupled Model Intercomparison Project Phase 3 and 5 (CMIP3 and CMIP5) climate models. In particular, it is examined whether preferred monsoon transitions between the two regions and from one year to another, that form parts of the Tropospheric Biennial Oscillation, can lead to improved predictive skill. An overall improvement in simulation of seasonality for both monsoons is seen in CMIP5 over CMIP3, with most CMIP5 models correctly simulating very low rainfall rates outside of the monsoon season. The predictability resulting from each transition is quantified using a Monte Carlo technique. The transition from strong/weak Indian monsoon to strong/weak Australian monsoon shows ∼15% enhanced predictability in the observations, in estimating whether the following monsoon will be stronger/weaker than the climatology. Most ...

Ter res trial ver sus ma rine ar chives: biostratigraphical cor re la tion of the Mid dle Pleis to cene lac ustrine re cords from cen tral Eu rope and their equiv a lents in the deep-sea cores from the Por tu guese mar gin. Geo log i cal Quarterly, 62 (1): 69-80,

New bulk sediment Sr and Nd isotope data, coupled with U-Pb dating of detrital zircon grains from sediment cored by the International Ocean Discovery Program in the Arabian Sea, allow the reconstruction of erosion in the Indus catchment since ∼ 17 Ma. Increasing ε Nd values from 17 to 9.5 Ma imply relatively more erosion from the Karakoram and Kohistan, likely linked to slip on the Karakoram Fault and compression in the southern and eastern Karakoram. After a period of relative stability from 9.5 to 5.7 Ma, there is a long-term decrease in ε Nd values that corresponds with increasing relative abundance of > 300 Ma zircon grains that are most common in Himalayan bedrocks. The continuous presence of abundant Himalayan zircons precludes large-scale drainage capture as the cause of decreasing ε Nd values in the submarine fan. Although the initial increase in Lesser Himalaya-derived 1500-2300 Ma zircons after 8.3 Ma is consistent with earlier records from the foreland basin, the much greater rise after 1.9 Ma has not previously been recognized and suggests that widespread unroofing of the Crystalline Lesser Himalaya and to a lesser extent Nanga Parbat did not occur until after 1.9 Ma. Because regional erosion increased in the Pleistocene compared to the Pliocene, the relative increase in erosion from the Lesser Himalaya does not reflect slowing erosion in the Karakoram and Greater Himalaya. No simple links can be made between erosion and the development of the South Asian Monsoon, implying a largely tectonic control on Lesser Himalayan unroofing.

An array of sediment surface samples collected from the coastal lake Eilandvlei and its bar-built estuary, on the southern Cape coast, South Africa were analysed for their micro-and meio-organism diversity to understand the complexity in their distribution in relation to their habitat and in response to physicochemical parameters. The variation in the diatom community proved to be a useful proxy in tracking the movement of various source waters, namely riverine inputs and marine throughflow. Particularly, the transport and deposition of freshwater diatom species are shown to represent the inflow of riverine waters into the lake, revealing internal current flow and a dispersal pattern of inputs. A comprehensive documentation of ostracods and foraminifera was undertaken for the system. Habitatspecific factors, such as pH, macrophyte extent and water depth, are the primary determinant for these species distribution. The combination of these organisms provides information on the provenance of the organisms and assists in distinguishing allochthonous versus autochthonous assemblages. This study shows that biological assemblages are useful indicators of system functionality, even in the most complex environments, when recorded environmental data is absent.

Recent studies using coupled atmosphere–ocean models have shown that the tropical Atlantic has a significant impact on the Indian monsoon. In this article, the observational basis for this teleconnection is examined and the physical mechanism responsible for bridging sea‐surface temperatures (SSTs) in the Atlantic and precipitation over India is investigated with idealized atmospheric general circulation model (AGCM) experiments in which constant SST anomalies are prescribed and ‘switched on’ in the tropical Atlantic region. A simple Gill–Matsuno‐type quadrupole response is proposed to explain the teleconnection between the tropical Atlantic and the Indian basin, with an enforcement of the eastward response likely due to nonlinear interactions with the mean monsoon circulation. The simplicity of this mechanism suggests the reproducibility of this result with a broad range of AGCMs. Copyright © 2009 Royal Meteorological Society

Ø The Existence of the ATAL was recognized through CALIOP lidar observa7ons Ø Buildup of enhanced aerosol associated with Asian Summer Monsoon an7cyclone, extending from the E. Med Sea to W. China Ø Extends from top of convec7ve ou]low over much of SE Asia South Atlan7c Anomaly

Many facets of the early biosphere preserved in the Proterozoic and Early Cambrian successions, recorded during 2011-2015, are reviewed. Recent advancements made in the Precambrian palaeobiology and newer steps recognized in the organismal evolution in the global perspective visa -vis significance of Indian records are discussed. The palaeobiological evidence reported from India are chronicled and grouped under seven categories: MISS (Microbially Induced Sedimentary Structure) & stromatolites, acritarchs, OWM (Organic Walled Microfossils), carbonaceous remains, trace-fossils & Ediacaran fossils, stable isotope studies and organic geochemistry. Present article is a continuum of Sharma et al. (2012), provides the status of Precambrian palaeobiological studies in the country, enumerates the importance of Indian records, and enlist unsolved problems and future research directions.

This study examines climatological potential vorticity streamer (PVS) activity associated with Rossby wave breaking (RWB), which can impact TC activity in the subtropical North Atlantic (NATL) basin via moisture and wind anomalies. PVSs are identified along the 2-PVU (1 PVU 5 10 26 K kg 21 m 2 s 21) contour on the 350-K isentropic surface, using a unique identification technique that combines previous methods. In total, 21 149 individual PVS instances are identified from the ERA-Interim (ERAI) climatology during June-November over 1979-2015 with a peak in July-August. The total number of PVSs identified in this study is more than previous PVS climatologies for this region, since the new technique identifies a wider range of cases. Variations in PVS size and intensity prompt the development of a new PVS activity index (PVSI), which provides an integrated measure of PVS activity that can improve comparisons with TC activity. For instance, PVSI has a stronger negative correlation with seasonal TC activity (r 5 20.55) relative to PVS frequency, size, or intensity alone. PVSI in June-July is also positively correlated with PVSI in August-November (r 5 0.67), suggesting predictive capability. Compared to the ERAI and Japan Meteorological Agency 55-Year Reanalysis (JRA-55) climatology, there are more PVSs in the Climate Forecast System Reanalysis (CFSR) but these have weaker average intensity overall. While no long-term trend in PVSI is observed in the ERAI or JRA-55 climatologies, a negative trend is observed in CFSR, which could be related to differences in near tropopause static stability early in the climatological period (1979-86) between the CFSR and ERAI datasets.

The Song Hong-Yinggehai (SH-Y) and Qiongdongnan (Qi) basins together form one of the largest Cenozoic sedimentary basins in SE Asia. Here we present new records based on the analysis of seismic data, which we compare to geochemical data derived from cores from Ocean Drilling Program (ODP) Site 1148 in order to derive proxies for continental weathering and thus constrain summer monsoon intensity.The SH-Y Basin started opening during the Late Paleocene–Eocene. Two inversion phases are recognized to have occurred at c. 34 Ma and c. 15 Ma. The Qi Basin developed on the northern, rifted margin of South China Sea, within which a large canyon developed in a NE–SW direction.Geochemical and mineralogical data show that chemical weathering has gradually decreased in SE Asia after c. 25 Ma, whereas physical erosion became stronger, especially after c. 12 Ma. Summer monsoon intensification drove periods of faster erosion after 3–4 Ma and from 10–15 Ma, although the initial pulse of eroded sedim...

Climate models often exhibit spurious long-term changes independent of either internal variability or changes to external forcing. Such changes, referred to as model ''drift,'' may distort the estimate of forced change in transient climate simulations. The importance of drift is examined in comparison to historical trends over recent decades in the Coupled Model Intercomparison Project (CMIP). Comparison based on a selection of metrics suggests a significant overall reduction in the magnitude of drift from phase 3 of CMIP (CMIP3) to phase 5 of CMIP (CMIP5). The direction of both ocean and atmospheric drift is systematically biased in some models introducing statistically significant drift in globally averaged metrics. Nevertheless, for most models globally averaged drift remains weak compared to the associated forced trends and is often smaller than the difference between trends derived from different ensemble members or the error introduced by the aliasing of natural variability. An exception to this is metrics that include the deep ocean (e.g., steric sea level) where drift can dominate in forced simulations. In such circumstances drift must be corrected for using information from concurrent control experiments. Many CMIP5 models now include ocean biogeochemistry. Like physical models, biogeochemical models generally undergo long spinup integrations to minimize drift. Nevertheless, based on a limited subset of models, it is found that drift is an important consideration and must be accounted for. For properties or regions where drift is important, the drift correction method must be carefully considered. The use of a drift estimate based on the full control time series is recommended to minimize the contamination of the drift estimate by internal variability.

Three pairs of small, fourth-to sixth-order catchments (approximately 5-80 km 2), draining the margin of the Darjeeling Himalayas into the piedmont, were selected for a comparison of the land-use impact on the morphology and sedimentology of their stream channels. Each pair experienced similar annual rainfall and comprised similar metamorphic bedrock, steep topography, and brown soils; the members of each pair contrast with respect to their land-use structure as they comprise large forest cover (forest > 90%) and a significant contribution of agricultural land with tea plantations (forest < 63%), respectively. A set of rainfall, cross-sectional, and sediment data were collected for the characterization of the stream channels. The obtained results revealed that, under extreme rainfall and high denudation rates as well as frequent flash floods, the geomorphic response to land-use changes involving agricultural expansion at the expense of forest cover was less pronounced in the mountain channels than in the piedmont. Significant differences between the studied pairs of mountain streams draining forested and agricultural catchments were observed only at bankfull width and baseflow depth in fourth-order streams and baseflow depth in fifth-order streams. Local environmental factors such as bedrock channel boundaries, steep topography, high material supply to river networks, and selective sediment mobilization during extreme rainfall and floods override the effects of land use and exert dominant control over stream channels in mountain catchments. However, the effects of agricultural activity in mountains are propagated downstream. In the agricultural catchment in the piedmont, a local rapid decrease in river slope and an increase in water infiltration into alluvia facilitates the deposition of eroded material. In addition, the stream in the agricultural catchment exhibited a rise in the riverbed with the expansion of a braided channel over a dozen kilometers below the Himalayan front in the piedmont, while the streams in the forested catchment revealed a distinct tendency towards incision. The present-day channel morphologies and sediment patterns observed in forested catchments are most likely similar to those that existed in the studied rivers prior to the development of tea plantations and settlements in the mid-19th century. 1. Introduction Catchments and stream channels at the margins of mountain ranges serve as sources of, and transfer routes for, water and sediment to the piedmont (

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