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Estuaries are known to be strong source for atmospheric CO2, however, little information is available from Indian estuaries. In order to quantify CO2 emissions from the Indian estuaries, samples were collected at 27 estuaries all along the Indian coast during discharge (wet) period. The emissions of CO2 to the atmosphere from Indian estuaries were 4–5 times higher during wet than dry period. The pCO2 ranged between ∼300 and 18492 μatm which are within the range of world estuaries. The mean pCO2 and particulate organic carbon (POC) showed positive relation with rate of discharge suggesting availability of high quantities of organic matter that led to enhanced microbial decomposition. The annual CO2 fluxes from the Indian estuaries, together with dry period data available in the literature, amounts to 1.92 TgC which is >10 times less than that from the European estuaries. The low CO2 fluxes from the Indian estuaries are attributed to low flushing rates and less human settlements along the banks of the Indian estuaries. Key Points Indian estuaries emits ~2TgC annually to atmosphere An order of magnitude high fluxes during discharge period Intensive microbial decomposition of organic matter is the major source

Estuaries have been under sampled to establish them as sources or sinks of the atmospheric carbon dioxide. Such poor coverage is well known for tropical, particularly monsoon driven, estuaries. In an attempt to study the variability in CO2 in a tropical monsoon estuary we made systematic time‐series observations in the Gautami Godavari estuarine system in the east coast of India. Our 18 month‐long extensive monitoring in the tropical Godavari estuarine system revealed pH >7.8 during dry period that decreased by 1.5 ± 0.01 during peak discharge period. The decrease in pH was associated with high nutrients and bacterial activities suggesting significant organic carbon decomposition. High bacterial respiration (20.6 ± 7.2 μMC l−1 d−1) in the estuary resulted in very high pCO2 of ∼30,000 μatm during peak discharge period, which otherwise were <500 μatm during dry period. Such high pCO2 levels were unknown to occur in any aquatic region. Several major and minor estuaries flow into the northern Indian Ocean from the Indian subcontinent and the monsoon associated processes make these systems chimney for emitting CO2 to atmosphere unrealized hitherto. Key Points Tropical estuaries are significant source of CO2 Monsoonal river discharges bring acidic waters to estuary High temporal variability in pCO2 levels in the estuary

Time-series observations were conducted off Visakhapatnam, central west coast of Bay of Bengal, from October 2007 to April 2009 to examine the influence of physical and atmospheric processes on water column nutrients biogeochemistry. The thermal structure displayed inversions of 0.5 to 1.0° C during winter and were weaker in summer. The water column was vertically stratified during the entire study period and was stronger during October–November 2007 and August–December 2008 compared to other study periods. High concentrations of chlorophyll-a and nutrients were associated with the extreme atmospheric events. The strong relationship of nutrients with salinity indicates that physical processes, such as circulation, mixing and river discharge, have a significant control on phytoplankton blooms in the coastal Bay of Bengal. Phosphate seems to be a controlling nutrient during winter whereas availability of light and suspended matter limits production in summer. Formation of low oxygen conditions were observed in the bottom waters due to enhanced primary production by extreme atmospheric events; however, re-oxygenation of bottom waters through sinking of oxygen-rich surface waters by a warm core (anticyclonic) eddy led to its near recovery. This study reveals that atmospheric and physical processes have significant impacts on the water column biogeochemistry in the coastal Bay of Bengal.

In order to examine the influence of forcing (river flow and tides) and anthropogenic activities (dredging and dam regulation) on stratification, a study was conducted over a period of 19 months (June 2008–December 2009) in the Gautami–Godavari estuary (G–GE) during spring and neap tide periods covering entire spectrum of discharge over a distance of 36 km from the mouth. The bathymetry of the estuary was recently changed due to dredging of ∼20 km of the estuary from the mouth for transportation of barges. This significantly changed the mean depth and salinity of the estuary from its earlier state. The variations in the distribution of salinity in the Godavari estuary are driven by river discharge during wet period (June–November) and tides during dry period (December–May). The weak stratification was observed during high discharge (July–August) and no discharge (January–June) periods associated with dominant fresh water and marine water respectively. The strong stratification was developed associated with decrease in discharge during moderate discharge period (October–December). Relatively stronger stratification was noticed during neap than spring tides. The 15 psu isohaline was observed to have migrated ∼2–3 km more towards upper estuary during spring than neap tide suggesting more salt enters during former than latter period. Total salt content was inversely correlated with river discharge and higher salt of about 400×10 6 m 3 psu was observed during spring than neap tide. Flushing times varied between less than a day and more than a month during peak and no discharge periods respectively with lower times during spring than neap tide. The flushing times are controlled by river discharge during high discharge period, tides during dry period and both (river discharge and tides) under moderate discharge period. This study suggests that modification of discharge, either natural due to weak monsoon, or artificial such as dam constructions and re-routing the river flow, may have significant impact on the stratification and biogeochemistry of the Godavari estuary.

The results of untiring efforts by the research community over the past few decades have led to the successful development and processing of a number of advanced titanium alloys with widely varying properties that can cater to niche applications. Advanced titanium alloys on one hand challenge structural steels with their higher specific strength coupled with their low temperature capability down to 4 K and pose serious threat on the other hand to superalloys for long-term applications up to 773 K. An improved understanding of the processing-microstructure-mechanical property correlation led to the realization of large scale as well as performance critical titanium alloy products in space arena. Recent advances in additive manufacturing, wherein the desired components are directly 3D printed from pre-alloyed powders/wires have given a definite advantage for cost-prohibitive titanium alloys. This review article discusses challenges in the processing, mechanical properties and microstructure evolution of various grades of titanium alloys. It also provides useful information for researchers working on titanium alloys with a glimpse in to the recent advances in Ti alloys and transformation of scientific knowledge to technological advancements in products for space applications. Graphic Abstract

The first-branch northward-propagating intraseasonal oscillation (FNISO) over the tropical Indian Ocean (IO) often triggers the onset of the Asian summer monsoon. In this study we investigate the structures and mechanisms associated with FNISO through the diagnosis of ERA-Interim reanalysis data for the period of 1990–2009. A composite analysis is conducted to reveal the structure and evolution characteristics of the FNISO and associated background circulation changes. It is found that the FNISO convection originates from the southwestern IO and propagates eastward. After reaching the eastern IO, the major convective branch moves northward toward the northern Bay of Bengal (BoB). Two possible mechanisms may contribute to the northward propagation of the FNISO. One is the meridional asymmetry of the background convective instability. A greater background convective instability over the northern BoB may destabilize Rossby waves and cause convection to shift northward. The other is the meridional phase leading of perturbation humidity in the planetary boundary layer (PBL). Maximum PBL moisture appears to the north of the convection center, which promotes a convectively unstable stratification ahead of the convection and leads to the northward propagation of the FNISO. A PBL moisture budget analysis reveals that anomalous zonal advection is a dominant process in contributing to the moisture asymmetry.

Knowing where, when, and how much rice is planted and harvested is crucial information for understanding the effects of policy, trade, and global and technological change on food security. We developed RiceAtlas, a spatial database on the seasonal distribution of the world’s rice production. It consists of data on rice planting and harvesting dates by growing season and estimates of monthly production for all rice-producing countries. Sources used for planting and harvesting dates include global and regional databases, national publications, online reports, and expert knowledge. Monthly production data were estimated based on annual or seasonal production statistics, and planting and harvesting dates. RiceAtlas has 2,725 spatial units. Compared with available global crop calendars, RiceAtlas is nearly ten times more spatially detailed and has nearly seven times more spatial units, with at least two seasons of calendar data, making RiceAtlas the most comprehensive and detailed spatial database on rice calendar and production. Design Type(s) data integration objective • database creation objective • observation design Measurement Type(s) agricultural calendar • agricultural production Technology Type(s) digital curation Factor Type(s) geographic location Sample Characteristic(s) Afghanistan • Algeria • Angola • Australia • Azerbaijan • Bangladesh • Belize • Benin • Bhutan • Bolivia • Brazil • Brunei Darussalam • Bulgaria • Burkina Faso • Burundi • Cambodia • Cameroon • Central African Republic • Chad • Chile • China • Colombia • Comoros • Costa Rica • Cote d'Ivoire • Cuba • Democratic Republic of the Congo • Dominican Republic • Ecuador • Egypt • El Salvador • Ethiopia • Fiji • France • Gabon • Gambia • Ghana • Greece • Guatemala • Guinea • Guinea-Bissau • Guyana • Guyane • Haiti • Honduras • Hungary • India • Indonesia • Iran • Iraq • Italy • Jamaica • Japan • Kazakhstan • Kenya • Kyrgyzstan • Laos • Lebanon • Liberia • Madagascar • Malawi • Malaysia • Mali • Mauritania • Mexico • Morocco • Mozambique • Myanmar • Nepal • Nicaragua • Niger • Nigeria • North Korea • Pakistan • Panama • Papua New Guinea • Paraguay • Peru • Philippines • Portugal • Republic of Congo • Republic of South Africa • Reunion Island • Romania • Russia • Rwanda • Saint Lucia • Saudi Arabia • Senegal • Sierra Leone • Solomon Islands • Somalia • South Korea • Spain • Sri Lanka • Sudan • Suriname • Swaziland • Taiwan Province • Tajikistan • Tanzania • Thailand • The Philippines • Timor-Leste • Togo • Trinidad and Tobago • Turkey • Turkmenistan • Uganda • Ukraine • United States of America • Uruguay • Uzbekistan • Venezuela • Viet Nam • Zambia • Zimbabwe • rice field Machine-accessible metadata file describing the reported data (ISA-Tab format)