Showing papers by "Vikram Sarabhai Space Centre published in 2022"

Effects of Aerosol–Induced Snow Albedo Feedback on the Seasonal Snowmelt Over the Himalayan Region

Abstract: Aerosol-induced snow darkening and its feedback on seasonal snow cover, snowmelt, and runoff were investigated using the Regional Climate Model (RegCM4.6) coupled with SNow, Ice, and Aerosol Radiation (SNICAR) and aerosol modules over the Himalayas during the melting season (March-September). The snow albedo reduction due to the deposition of absorbing aerosols increases the 2 m air temperature (1.47°C) and thus decreases the snow cover (10.6%) over the Himalayas during spring. This aerosol-induced excess warming accelerates the seasonal snowmelt (1.2 mm day−1), which reduces the number of snow-covered periods by more than 20 days throughout the Himalayas. The accumulated total snowmelt also increased by 41.3% over the Himalayas during the melting season. The early snowmelt and increase in runoff due to aerosol forcing have significant implications on rivers originating from the western Himalayas (Indus Basin). The change in snowmelt distribution and doubling of snowmelt extremes due to aerosol-induced snow darkening could also translate to an increase in flood risks across the Himalayan river basins. Therefore, the present study highlights the importance of aerosol-induced snow albedo forcing and its feedback on snowmelt and runoff over the Himalayan region, which has further implications on water availability over the South Asian region.

Distribution of reactive trace gases over South Asia: Observations and modeling

Abstract: Reactive trace gases (O3, CO, NOx, SO2, VOCs) play vital roles in air pollution and climate change. In this chapter, the distributions of trace gases and governing processes over the South Asian region are discussed. Primary trace gases show enhanced levels over Indo-Gangetic Plain (IGP) particularly during winter, whereas O3 over IGP is highest in spring due to favorable meteorology and regional pollution including biomass burning emissions. Trace gases exhibit lower levels during monsoon mainly due to inflow of marine air, washout effect, and suppressed photochemistry. While the diurnal characteristics of O3 are distinct and depend on local environments (urban, rural, clean), the seasonality is similar over subregions. O3 pollution causes significant crop losses over South Asia, besides impacting human health. Models reproduce the observed variations of trace gases but have a bias in capturing magnitude. More detailed measurements and improvements in models are important future perspectives for the South Asian region.

The Renaissance of High-Capacity Cathode Materials for Lithium Ion Cells

Abstract: Lithium-ion (Li-ion) cell technology is one of the most booming electrochemical energy storage technologies owing to its high volumetric and gravimetric energy densities, long cycle life, high efficiency and low self-discharge. The energy density of Li-ion cells depends to a greater extent on the type of cathode material used. A plethora of cathode materials have been developed and deployed in Li-ion cells viz. LiCoO2, LiNi0.8Co0.15Al0.05O2, LiMn0.33Ni0.33Co0.33O2, LiFePO4, LiMn2O4, etc. The requirements for Li-ion cells with improved energy density for various applications push researchers to develop newer cathode materials with superior specific capacities and high working voltage. This chapter discusses the state-of-the-art research activities related to high capacity cathode materials, including their structural and electrochemical features, challenges and strategies that have been adopted to improve their performance.

Observations of particle number size distributions and new particle formation in six Indian locations

Abstract: Abstract. Atmospheric new particle formation (NPF) is a crucial process driving aerosol number concentrations in the atmosphere; it can significantly impact the evolution of atmospheric aerosol and cloud processes. This study analyses at least 1 year of asynchronous particle number size distributions from six different locations in India. We also analyze the frequency of NPF and its contribution to cloud condensation nuclei (CCN) concentrations. We found that the NPF frequency has a considerable seasonal variability. At the measurement sites analyzed in this study, NPF frequently occurs in March–May (pre-monsoon, about 21 % of the days) and is the least common in October–November (post-monsoon, about 7 % of the days). Considering the NPF events in all locations, the particle formation rate (JSDS) varied by more than 2 orders of magnitude (0.001–0.6 cm−3 s−1) and the growth rate between the smallest detectable size and 25 nm (GRSDS-25 nm) by about 3 orders of magnitude (0.2–17.2 nm h−1). We found that JSDS was higher by nearly 1 order of magnitude during NPF events in urban areas than mountain sites. GRSDS did not show a systematic difference. Our results showed that NPF events could significantly modulate the shape of particle number size distributions and CCN concentrations in India. The contribution of a given NPF event to CCN concentrations was the highest in urban locations (4.3 × 103 cm−3 per event and 1.2 × 103 cm−3 per event for 50 and 100 nm, respectively) as compared to mountain background sites (2.7 × 103 cm−3 per event and 1.0 × 103 cm−3 per event, respectively). We emphasize that the physical and chemical pathways responsible for NPF and factors that control its contribution to CCN production require in situ field observations using recent advances in aerosol and its precursor gaseous measurement techniques.

Characterisation of Multi-sensor 6D Pose Determination System for Underslung Winged Body

Abstract: Micro electro-mechanical system (MEMS) based inertial sensors (accelerometers and gyros) are being widely used in recent times due to low cost and compact size. Navigation unit with MEMS based sensors are employed to measure the body rates and accelerations of a winged body, while being airlifted using an aircraft. The MEMS sensors are aided with global navigation satellite system (GNSS), barometer and magnetometer measurements, while using an extended kalman filter to attain good precision. Prior to the trial, thorough testing and characterisation of the navigation units are done to determine the performance of the navigation unit and repeatability of the results. Electromagnetic interference test ensured the functioning and acquisition of data from the navigation unit in the presence of various frequencies from the aircraft. The body rates and accelerations are measured by mounting the navigation unit on an Angular Motion Simulator (AMS). Deviation of the pose estimation by the MEMS navigation unit with respect to the reference inertial navigation system (INS) is found to be within bounds, justifying the selection of the navigation unit for instrumentation of the winged body. Post test results of the trial validates the pre-flight simulations with an accuracy as predicted from the pre-flight tests.

Deciphering the Role of Aerosol‐Induced Snow Albedo Feedback on Dust Emission Over the Tibetan Plateau

Abstract: The aerosol-induced snow albedo effect (SAE) and its feedback on the dust emission over the Tibetan plateau (TP) are investigated using the regional climate model (RegCM4.6) coupled with SNow, ICe and Aerosol Radiative (SNICAR) model. The deposition of absorbing aerosols (black carbon and dust) decreases the albedo of snow over Himalayan-Tibetan region, which results in significant surface warming of 1-4K. This aerosol-induced surface warming and accelerated snow melting decreased fractional snow cover by 8% and number of snow cover days by 20 days over the region. Compared to the control simulation, this early and more exposure of non-vegetated land resulted in the increase of dust emission flux by 60% over central Tibet and therefore the columnar dust loading by 10 to 40%. This effect alone results in a surface cooling of -4 Wm-2 and also increases the occurrence of dust events by 10-20 %. Therefore, the snow darkening effect due to the deposition of black carbon and dust increases the local emission of dust aerosols, which further increases the aerosol-induced snow melting and thus perturbs the air quality and radiation balance over the high mountains of Asia. This article is protected by copyright. All rights reserved.

Summertime High Abundances of Succinic, Citric, and Glyoxylic Acids in Antarctic Aerosols: Implications to Secondary Organic Aerosol Formation

Abstract: Observations of organic compounds associated with natural sources are scarce in Antarctica, which limits our understanding of their sources and formation processes over the pristine region. Summertime Antarctic PM10 samples collected from Bharati station were studied for a homologous series of dicarboxylic acids (C2-C12), ω-oxoacids (C2-C9), α-dicarbonyls (C2-C3) as well as citric and pyruvic acids by employing a water-extraction followed by dibutyl ester derivatization technique and analyzed using capillary gas chromatography (GC). Results show that succinic (C4) and citric acids are the foremost abundant among the measured organic acids followed by glyoxylic (ωC2), azelaic (C9), and adipic (C6) acids. Such a typical molecular distribution of organic acids suggests the dominance of natural sources over the Antarctic. Two distinct air masses arrived from different altitudes, high and low altitude-troposphere (HTAs and LTAs), showed a significant difference in mass concentrations of organic acids with higher values in LTAs. Total diacids-C accounted for ∼9% of total carbon in HTAs, which is linked to chemical aging during long-range transport. The higher abundance of C4 and citric acids are likely produced through secondary photooxidation of marine-derived organic precursors, such as unsaturated fatty acids, phenolic, and biogenic isoprene compounds enriched in sea-surface microlayer, via sea-to-air emission as confirmed by the significant (p < 0.05) correlations among the organic tracer compounds. Minor concentrations of oxalic and malonic (C2 and C3) acids were attributed to photo iron-complex reactions in the aqueous-phase atmosphere. These findings may help in reducing model uncertainties and present new insights into the secondary formation of organic aerosols in the polar environment.

Perturbation of Wall Boundary Condition to Trigger Vortex Shedding Over a Circular Cylinder

Abstract: A circular cylinder placed in a uniform flow with its axis perpendicular to the flow direction can result in an unsteady flow caused by vortex shedding. Numerical simulations attempting to capture this phenomenon may lack a trigger to cause the appropriate vortex shedding, consequently, asymmetric vortex shedding can be delayed or may not occur. Therefore, an artificial disturbance can be introduced into the flow field to initiate an earlier onset of vortex shedding. Here, the wall boundary condition is used to perturb the local shear layer. It is tested for a circular cylinder at Reynolds numbers of 40, 60 and 150. Application of wall perturbation technique triggers the onset of asymmetrical vortex shedding and in the absence of a perturbation, asymmetrical vortex shedding does not occur. The effect of the patch size and duration of application of initial perturbation on the onset of vortex shedding for Re = 150 is reported.

Automation of Launch Vehicle Telemetry—Requirement Capture to Analysis of Data

Abstract: Telemetry parameters provide an assessment of health of hardware systems and performance of flight software onboard launch vehicles. The uniqueness of Avionics configurations and mission specifications necessitates formulation of specific telemetry frame formats for each project, meeting the communication bandwidth constraints. Analysis of pre-flight test data is crucial in determining the flightworthiness of hardware and software. Post-flight analysis of telemetry data helps in planning future missions. This emphasizes the importance of careful selection of mission-critical parameters for telemetry monitoring. Our aim is end-to-end process automation, encompassing the activities of requirement elicitation from Avionics subsystem designers, telemetry frame format generation, and presentation of data for analysis, catering to multiple stakeholders. The software will reduce the turnaround time and number of errors due to manual operations involved, both during generation of frame formats for digital telemetry and analysis of data. The workflow incorporated in the software framework will enable smooth collaboration between various domain experts remotely located.

Type dependent role of aerosols in reversing the first indirect effect over the north Indian Ocean

Abstract: Present study investigates the role of aerosol types in modulating warm cloud microphysics over the north Indian Ocean using long-term (2006–2016) satellite and re-analysis data. Analysis of well-mixed aerosol and marine warm cloud layers observed from daily co-located Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite over northern Indian Ocean revealed the occurrence of reverse Twomey effect in warm clouds having liquid water path (LWP) less than 75 g m−2. Such clouds are found to occur under a rather stable (Estimated Inversion Strength (EIS) > 2) and dry atmospheric conditions (Free Tropospheric Humidity (FTH) < 40%). Analysis of estimated cloud-top entrainment index (ECTEI) and cloud-top entrainment instability (CTEI) quantitatively suggested that entrainment of dry air can have a significant role in reversing the first indirect effect. Further, investigation on the role of various aerosol types in well mixed clouds revealed that dust aerosols have predominant role in reversing the Twomey effect over the north Indian Ocean.

VIPER:A Plasma Wave Detection Instrument onboard Indian Venus Orbiter Spacecraft

Abstract: Plasma waves are observed in almost all the solar system objects - planets, their satellites, comets, Sun, interplanetary medium, etc. The planetary ionospheres are capable of sustaining plasma waves which are observed there and play an important role in the ionospheric dynamics by propagating energy across different space regions and provide acceleration to particles to attain high energies for transportation. The study of planetary plasma waves also provides information on the solar wind - planet interaction, the energy distribution in the ionospheric plasma of that planet, etc. Venus does not possess a global magnetic field unlike Earth. Thesolar EUV radiation ionizes the neutrals and generates a plasma environment around Venus which can sustain plasma waves. Very few attempts are made to observe all plasma waves that can exist around Venus and that too with instruments having a limited dynamic range such as with PVO (Pioneer Venus Orbiter) and Venus Express. However, there are some other plasma waves which can exist around Venus but are yet to be observed. ISRO is planning to send an orbiter mission to Venus in near future where a suit of instruments named VIPER (Venus Ionospheric Plasma wavE detectoR) is onboard to observe Venusian plasma waves. The plasma wave observations around Venus and VIPER onboard ISRO's Venus Orbiter Spacecraft are discussed in this paper.

Mathematical Modelling and Numerical Simulations of Underslung Dynamics

Abstract: Primary aim of this work is to investigate the slung body dynamics of a winged body suspended from a helicopter. A two body, six degree of freedom (DoF) model is used to capture the system dynamics where linear accelerations of the helicopter are used as an input to the model. The rotational and translational equations of motion of the underslung are represented in generalised coordinates and velocities, obtained from the Newton–Euler equations. The formulated mathematical model is validated against a commercially available software, with the first and second pendulum modes successfully captured. Sensitivity studies of several parameters have been carried out, and based on the study, it is inferred that the lateral plane aerodynamic coefficients play a momentous role in contributing to the stability of the winged body underslung. Further, this model can also be used to study distinct underslung configurations required to safely operate the helicopter-underslung system.

Effect of Synoptic‐Scale Dynamics on the Vertical Distribution of Tropospheric Ozone Over the Arabian Sea and the Indian Ocean During the Boreal Winter of 2018

Abstract: Ozone (O3) and relative humidity profiles obtained from in situ electrochemical concentration cell ozonesonde-radiosonde observations over the Arabian Sea and the Indian Ocean from 16 January to 14 February 2018 during the Integrated Campaign for Aerosols gases and Radiation Budget cruise were analyzed. On the basis of the prevailing synoptic conditions during the cruise period, the cruise track was divided into three legs which were studied separately. The main objective of this study was to investigate the influence of prevailing synoptic scale dynamics and transport on the vertical distribution of ozone in the troposphere, especially in the tropical tropopause layer (TTL) region. Tropospheric ozone exhibits pronounced latitude variations over the Arabian Sea and the Indian Ocean with very high values (∼60–70 ppbv) above the marine boundary layer near the Indian landmass. Distinct ozone-rich plume-like structures are observed in the free troposphere around 1–3 and 4–5 km. At around 1–3 km, the ozone plume was maintained by the continental outflows from the Indian sub-continent. The mid-tropospheric (4–5 km) high ozone-low water vapor layer is hypothesized to be associated with the equatorward return flow of the Hadley circulation. Enhanced (declined) ozone is observed below 12 km altitude in the descending (ascending) branch of Hadley circulation. The ozone distribution in the TTL shows distinct structures associated with the prevailing synoptic dynamics and transport during respective legs. Evidences of stratospheric intrusion and air mass transport from biomass burning locations are seen regarding upper tropospheric ozone enhancements.

Thermo-Mechanical Processing

Abstract: Manufacturing based on thermo-mechanical processing (TMP) is critical to many of the engineered products. In this article, the evolution of TMP processes is discussed from the historical perspective based on early days of processing steels and solid-state joining. Then, TMP is discussed as an industrial system with sub-systems based on material feedstock, the tooling, tool-material interface; deformation zone; forging equipment; product geometry and plant environment. The above sub-systems are discussed with case studies based on microstructures and plastic flow in metals and alloys. In addition, future directions of thermo-mechanical processing are outlined.

Tools for Alloy Design

Abstract: Alloy design is an important step in realizing the optimal microstructure in a manufactured metallic component. Attaining the right microstructure distribution within a component is necessary for ensuring mechanical and functional performances that is expected in service. The inspiration for alloy design by empirical experimental observations has always been part of the human evolution. In the modern times, the alloy design methodologies have evolved into materials as system. This system level concept relies on the linkage between process, structure and properties based on data streams from numerical models and characterization. In this article the role of computational thermodynamic and kinetic models to describe process-structure linkages are discussed with a few case studies with specific application to manufacturing.

Lithium-Ion Pouch Cells: An Overview

Abstract: Among the various configurations available for lithium-ion cells, the pouch type has been grabbing attention because of its high energy density, design flexibility, low cost and lightweight. Such a pouch pack enables further reduction in the size and weight of portable electronic devices where they power and for the same reason the pouch cells are not only suitable for terrestrial applications but also attractive for space applications too. Lithium-ion pouch cells have been successfully used in many applications including space. However, this design has certain limitations. The poor rigidity of the pouch case makes them more susceptible to external mechanical damage and swelling under elevated temperature and overcharging. Therefore, the manufacturers are constantly striving to improve the performance of pouch cells. This chapter provides a brief overview about the different aspects of lithium ion pouch cells and the various strategies introduced in upgrading the performance of this thin design.

Selection of Appropriate Manufacturing Processes

Abstract: This article introduces the definition of metal manufacturing with an overview of the different processes. Then, a case study is presented to illustrate the methodology for selecting appropriate process by asking series of questions based on the Heilmeier Catechism, data from published literature and legacy knowledge. A case study is presented which evaluates two competing welding processes, one based on laser beam welding and another based on friction stir welding, for joining aluminum metal matrix composites. In addition, emerging trends in agile manufacturing methods are outlined that may dictate the future selection of manufacturing processes based on rapidly changing customer needs.

The State‐of‐the‐Art Model Atmosphere From the Surface to 110 km Over the Indian Tropical Region for ISRO Launching Vehicle Applications: Developed From In Situ and Space‐Based Measurements

Abstract: The atmospheric model at any location is an altitude variation of temperature, pressure, and density. Such models are crucial for designing launch vehicles and as well as for scientific research. The models available over the Indian region were developed three decades ago using in situ observations till 1990, and hence a need was felt to revamp and regenerate the model. The focus of the present revised atmosphere is to look into the variability on a monthly and annual scale using long-term data from both in situ and space-based observations. The new model can accommodate and address the appropriate temporal variability and dispersions over time. It will also account for the seasonal and decadal variability and the variations due to climate change. The present reference atmosphere utilizes data from different platforms to provide a robust mean and bounds for the temperature, pressure, and density. The new model is developed using observations from 44 years (1975–2018) of radiosonde (0–25 km), 20 years (1971–1991) of M-100 rocket (26–80 km), and 17 years (2002–2018) of SABER (26–110 km). The reference atmosphere contains monthly and annual means with ±3σ bounds for temperature, pressure, and density. The reference atmosphere can be directly used to design future ISRO launching vehicles.

Light absorption of forest organic aerosol fractions with different polarity

Abstract: &lt;p&gt;Organic aerosol (OA) is a ubiquitous component of atmospheric aerosol and affects radiative forcing not only by scattering but also by absorbing solar radiation. The light absorption property of OA should vary depending on its composition, which is not well understood to date. Humic-like substances (HULIS), a medium polar part of OA, constitute significant part of water-soluble organic matter (WSOM) and have light-absorbing capacity. In addition, recent studies showed that less polar water-insoluble organic matter (WISOM) absorbed light stronger than WSOM. Knowledge on the light absorption property of all the parts of OA in atmospheric aerosols is important to understand their contribution to aerosol light absorption. In this study, the light absorption property of extractable organics with low-to-high polarity in submicron aerosols collected at a forest site was characterized.&lt;/p&gt;&lt;p&gt;PM&lt;sub&gt;0.95&lt;/sub&gt; samples (particles with a diameter smaller than 0.95 mm) were collected on quartz filters in Tomakomai Experimental Forest of Hokkaido University, Japan, from June 2012 to May 2013. Organic aerosol components in the samples were extracted and fractionated by the combination of solvent extraction and solid-phase extraction methods. WSOM and WISOM were extracted sequentially by using multiple solvents. HULIS and highly-polar water-soluble organic matter (HP-WSOM) were fractionated from WSOM by solid-phase extraction. The light absorption by the OA fractions were measured using a UV-visible spectrometer. Further, a high-resolution time-of-flight aerosol mass spectrometer was used to quantify the OA fractions and to analyze the types of generated ions.&lt;/p&gt;&lt;p&gt;The mass absorption efficiency at 365 nm (MAE&lt;sub&gt;365&lt;/sub&gt;) for WISOM was highest among all OA fractions (mean &amp;#177; standard deviation: 0.37 &amp;#177; 0.22 m&lt;sup&gt;2&lt;/sup&gt;g&lt;sup&gt;-1&lt;/sup&gt;), followed by the efficiencies for HULIS (0.14 &amp;#177; 0.09 m&lt;sup&gt;2&lt;/sup&gt;g&lt;sup&gt;-1&lt;/sup&gt;) and HP-WSOM (0.07 &amp;#177; 0.05 m&lt;sup&gt;2&lt;/sup&gt;g&lt;sup&gt;-1&lt;/sup&gt;). HULIS was shown to be whiter (more transparent) than that reported from previous studies. WISOM was the predominant light-absorbing OA fraction among three OA fractions. The absorption of solar radiation by the OA fractions relative to that by elemental carbon (&lt;em&gt;f&lt;/em&gt;) was analyzed, and it showed an increase with the decrease of polarity: on average, the &lt;em&gt;f &lt;/em&gt;values were 12%, 8%, and 2%, for WISOM, HULIS, and HP-WSOM, respectively, for the solar spectrum in a range from 300 to 500 nm. HULIS and WISOM showed noticeable seasonal changes in MAE&lt;sub&gt;365&lt;/sub&gt;, which were higher in winter than in summer. Pearson&amp;#8217;s correlation analyses between MAE&lt;sub&gt;365&lt;/sub&gt; and ion groups of OA fractions indicate that organic compounds with N, O, and S atoms may contribute substantially to the light absorption of OA components.&lt;/p&gt;

Characterization of particle number size distributions and new particle formation in different Indian locations

Abstract: &lt;p&gt;Particle number size distribution has critical importance in characterizing the number, size, surface area, volume, and evolution of aerosols in the atmosphere. Atmospheric new particle formation (NPF) is one the largest source of aerosol numbers to the terrestrial atmosphere and greatly impact the evolution of particle number size distribution. Here, we analyzed at least one year of asynchronous measurements of particle number size distributions from six different locations in India. We found that NPF frequently occurs at all locations in the pre-monsoon season (March through May) and is the least common in the post-monsoon season (October-November).&amp;#160;&amp;#160; Considering all sites (mountain background, mountain semi-rural, coastal semi-urban and urban), the particle formation rate of lowest detectable size (J&lt;sub&gt;LDS&lt;/sub&gt;) varied by more than an order of magnitude (0.01 - 0.6 cm&lt;sup&gt;-3&lt;/sup&gt; s&lt;sup&gt;-1&lt;/sup&gt;) and the growth rate between the lowest detectable size and 25 nm (GR&lt;sub&gt;LDS-25nm&lt;/sub&gt;) by about three orders of magnitude (0.2 - 17.2 nm h&lt;sup&gt;-1&lt;/sup&gt;). The site-specific J&lt;sub&gt;LDS&lt;/sub&gt; and GR&lt;sub&gt;LDS-25nm&lt;/sub&gt; are positively correlated, indicating their co-dependence on gas-phase production rates of low-volatility vapors, driven by the source and atmospheric conditions. Our results also showed that NPF events significantly modulate the shape of particle number size distributions, particularly in the pre-monsoon season. The NPF-associated CCN concentrations were higher in urban locations than the mountain background sites. Although using asynchronous measurements, our results implicate the process-level characterization of particle number size distribution.&lt;/p&gt;