Showing papers by "Vikram Sarabhai Space Centre published in 2023"

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Abstract: The light-absorbing Black Carbon (BC) aerosols have very sensitive role in affecting the Earth’s radiation budget and climate. In this study, satellite-based retrieval of BC over India is presented based on observations from the Cloud and Aerosol-Imager-2 (CAI-2) on-board the Greenhouse gases Observing Satellite-2 (GOSAT-2). To evaluate and validate the satellite retrievals, near surface BC mass concentrations measured across a network of aerosol observatories (ARFINET) over India are used and the findings are extended to comprehend the global BC features. As the analysis revealed, this satellite retrieval fairly depicts the regional and seasonal features of BC over the Indian region, which are similar to those recorded by surface observations. The validation and closure studies between the two data sets show RMSE < 1 and absolute difference below 2 µg m-3 for > 60 % of simultaneous observations, possessing fairly good associations in Dec-Jan-Feb (R ~ 0.73) and Mar-Apr-May (R ~ 0.76). Over the hotspot regions of India, the satellite retrievals show soot volume fraction of ~ 5 %, columnar single scattering albedo of ~ 0.8 and BC column optical depth of ~ 0.1; which are comparable to that of other in-situ or satellite measurements. In terms of global spatio-temporal variability, satellite retrieval shows higher BC occurring mostly in areas where biomass burning is intense. Overall, this study highlights the effectiveness of satellite retrieval of BC, which could be effectively used for the regular monitoring of BC load arising out of vehicular/ industrial/ biomass burning activities across the globe.

Adaptive Threshold Peak Detection for Launch Vehicle Simulation Time Series Data Analysis

Abstract: A strategy is devised to detect the peaks in a Launch vehicle simulation time series data. A tool is developed for automated detection of peaks using this strategy. The tool is capable of identifying the peaks based on the parent data characteristics with minimum user interventions. Various algorithms for data transformation have been explored for this purpose. The methodology used here is of the first kind when compared with the available methods in the literature. A piecewise approach for threshold generation using the concepts of Divided Average Method (DAM) and Moving Average Method (MAM) are applied on the transformed data for peak detection. Adaptive threshold setting is introduced for filtering the peaks. The performance of the algorithms was compared using standard measures derived from the Contingency matrix.

PS4-Orbital Platform: An Ideal Suite for Scientific Experiments

Abstract: PS4-Orbital Platform (PS4-OP) refers to a novel idea by ISRO (Indian Space Research Organisation) to use the spent PS4 stage (fourth stage of PSLV) as a three-axis-stabilized platform for small scientific payloads to carry out in-orbit scientific experiments for an extended duration of 4–6 months. The PS4 stage has standard interfaces and packages for power generation, telemetry, tele-command, stabilization, orbit keeping and orbit maneuvering. The scientific community/research organizations can design the scientific payload and utilize the OP interfaces offered by spent PS4 stage for powering, data management and specific experimental requirements. In short, ISRO is extending its expertise in space technology to the scientific community as a platform to design, develop and validate their experiments in an effective manner.

Ozone Changes Due To Sudden Stratospheric Warming‐Induced Variations in the Intensity of Brewer‐Dobson Circulation: A Composite Analysis Using Observations and Chemical‐Transport Model

Abstract: We quantify the changes in the intensity of Brewer-Dobson Circulation (BDC) during sudden stratospheric warming (SSW) and its impact on the tropical stratospheric thermal structure and ozone distribution by composite analysis using observations and a chemical-transport model. An increase in the planetary wave activity and enhancement in BDC intensity before the central date of SSW is noticed. A positive ozone anomaly is observed in the tropical upper stratosphere. The tropical lower stratosphere shows a cooling (1–2 K) and negative ozone anomaly (∼0.1 ppmv) after ∼10 days from the central date. The polar stratosphere experiences a positive ozone anomaly, whereas the upper stratosphere shows ozone depletion due to the downwelling of NOx-rich mesospheric air. The cold-point tropopause temperature shows a cooling of ∼0.5 K for major warming which in turn dries the lower stratosphere.

Modelling of 12-DoF Parachute - Riser - Payload System Dynamics using Kane’s method

Abstract: Abstract Dynamic behaviour of parachutes is highly complex and characterised by non-linear, time dependant Fluid Structure Interaction, which is computationally intensive and hence not a viable option for incorporating into trajectory simulations. The paper describes modelling of ”Computationally efficient, High Fidelity Multi-Body” Parachute - Elastic Riser - Payload system, capable of simulating trajectory from parachute deployment to parachute separation. The differential equations of motion, including the kinematical and kinetic relationships are derived using the matrix form of Kane’s method, which avoids the typical complexity involved in symbolic derivations, available in published literature.The developed model is validated with published literature results formulated using Newton Euler method and simulation results demonstrating the typical characteristic motion of the system during descend are presented.

Challenges in the Dynamic Condensation and Internal Response Prediction of Small Satellites

Abstract: Emerging small satellite market faces many challenges mainly to protect their payload during the launch. Satellite team has to share their finite element model to the launch vehicle team for the various analysis like launch vehicle dynamic characteristics, Coupled Load Analysis (CLA), dynamic envelop studies, etc. FE model contains sensitive details about the satellite, and dynamic condensation of the satellite is the only way to protect satellite details. This also helps in reducing the number of degrees of freedom of the satellite finite element model. Craig-Bampton technique is the most popular method to reduce the satellite into a mass and stiffness matrix with the required number of modes. Satellite team needs a physical node at critical locations to study the responses, and these nodes need to be retained while reduction. This paper examines the Craig-Bampton reduction method and discusses how to compute the response at various locations of the satellite. A frequency response analysis with reduced model and full model is also compared in this paper.

Reply on RC1

Abstract: The light-absorbing Black Carbon (BC) aerosols have very sensitive role in affecting the Earth’s radiation budget and climate. In this study, satellite-based retrieval of BC over India is presented based on observations from the Cloud and Aerosol-Imager-2 (CAI-2) on-board the Greenhouse gases Observing Satellite-2 (GOSAT-2). To evaluate and validate the satellite retrievals, near surface BC mass concentrations measured across a network of aerosol observatories (ARFINET) over India are used and the findings are extended to comprehend the global BC features. As the analysis revealed, this satellite retrieval fairly depicts the regional and seasonal features of BC over the Indian region, which are similar to those recorded by surface observations. The validation and closure studies between the two data sets show RMSE < 1 and absolute difference below 2 µg m-3 for > 60 % of simultaneous observations, possessing fairly good associations in Dec-Jan-Feb (R ~ 0.73) and Mar-Apr-May (R ~ 0.76). Over the hotspot regions of India, the satellite retrievals show soot volume fraction of ~ 5 %, columnar single scattering albedo of ~ 0.8 and BC column optical depth of ~ 0.1; which are comparable to that of other in-situ or satellite measurements. In terms of global spatio-temporal variability, satellite retrieval shows higher BC occurring mostly in areas where biomass burning is intense. Overall, this study highlights the effectiveness of satellite retrieval of BC, which could be effectively used for the regular monitoring of BC load arising out of vehicular/ industrial/ biomass burning activities across the globe.

Structural Analyses for a Typical Small Satellite

Abstract: Miniaturisation of electronics, newer materials especially composites and advanced manufacturing techniques including 3D printing has encouraged the development of small satellites. This enabled many commercial companies to venture in to this area since the development can be made possible with small budget. The market size of small satellite is expected to flourish in the next few years. Small satellites are used mainly in the areas of Earth observation services, monitoring of agricultural fields, detection of climatic changes, disaster mitigation, meteorology, etc. In the current day scenario of launch vehicle industry, every mission of a launch vehicle is unique since they are used for putting satellites of different mass, size, shape, purpose and to various orbits. Satellites are exposed to dynamic/fluctuating excitations due to different dynamic environment from lift off to the completion of its intended mission. The dynamic environment of the satellite will be different for different launch vehicle configuration and its mounting scheme. This paper addresses quasi-static and dynamic analyses carried out for a typical small satellite using indigenously developed finite element software FEASTSMT by Vikram Sarabhai Space Centre (VSSC). This study helps in assessing the structural adequacy of small satellite as well as the acceleration level experienced by different components and packages. This will help the satellite team to modify the structure, change the mounting location or by adopting new mounting schemes of components/packages in order to optimise the design well before realising the hardware.

A Lagrangian Study of Tidal Advection of Mesospheric Water Vapor

Abstract: Previous studies have demonstrated that the diurnal variability of mesospheric water vapor involves a non-linear interplay between dynamics, photochemistry, and catalytic processes. The inherent difficulty in measurement of winds and water vapor in this region makes the study of mesospheric water vapor complex. Here we study the sources of diurnal variability of mesospheric water vapor with the help of the specified dynamics configuration of the Whole Atmosphere Community Climate Model (WACCM) with thermosphere-ionosphere eXtension (SD-WACCM-X) for typical equinox conditions during the solar minimum year 2009. Special emphasis is given to the advective transport by the migrating diurnal tide and its impact on the mean water vapor in the mesosphere. To isolate the contribution from advective and non-advective processes, a Lagrangian parcel trajectory model is employed. Using this model, we incorporated the effect of both vertical and horizontal tidal advection on the diurnal variability of mesospheric water vapor. Our results indicate that the vertical tidal advection dominates the transport of water vapor in the upper mesosphere and that there is a significant contribution from horizontal tidal advection below 70 km. Among non-advective processes, chemical loss of water vapor has the largest contribution. The Lagrangian parcel trajectory approach is further extended using the recently released version 2.07 of water vapor observations from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument and dynamical tides from the empirical Climatological Tidal Model for the Thermosphere (CTMT). Differences in SD-WACCM-X and CTMT + SABER results are discussed in light of the veracity of SABER water vapor measurements.

Anthropogenic sulfate-driven secondary organic aerosol formation over the eastern Himalayas through aqueous phase photochemical reactions

Abstract: The ubiquitous presence of organic aerosols (OA) and their dominant role in climate forcing via direct and indirect effects are increasingly recognized. Among the large spectrum of OAs, water-soluble secondary organic aerosols (SOA) have gained considerable scientific interest due to the in-cloud formation process and consequent climate effects. However, a lack of consensus on the molecular fingerprints and formation pathways of SOA limits our ability to assess their climate impact globally.In this study, a detail investigation is made on water-soluble SOA components such as dicarboxylic acids, oxocarboxylic acids and dicarbonyls in springtime (March to May 2019) PM10 samples collected from a remote high-altitude site Lachung (27.4&#730;N and 88.4&#730;E, 2700 m a.s.l.) in the eastern Himalayas. The molecular fingerprints of water-soluble SOA components showed the predominance of oxalic acid (C2) followed by phthalic (Ph) and succinic acid. The diagnostic mass ratio of Ph to azelaic (C9) acid (2.1-7.7) indicated that anthropogenic emissions are the major sources of water-soluble OA at this remote high-altitude site. Moreover, SO42- dominates total water-soluble inorganic constituents and correlates significantly (R2 = 0.66) with the ISORROPIA-II model-derived aerosol liquid water content (LWC), indicating a crucial role of anthropogenic SO42- in controlling LWC of aerosols over the eastern Himalayas. Notably, we found significant positive relationships of C2 acid with both SO42- (R2 = 0.94) and aerosol LWC (R2 = 0.76), suggesting oxalic acid formation in LWC-enriched aerosols largely controlled by anthropogenic SO42- via aqueous phase photochemical processes. The increased formation of oxalic acid and related polar compounds with increasing SO42- is indicative of the fact that the reduction in anthropogenic emissions at the regional scale or source regions could control the water-soluble SOA loading in the atmosphere of the eastern Himalayas.

Source apportionment of fine aerosol at a rural background site in Central Europe based on seasonal distributions of dicarboxylic acids, sugars and related compounds

Abstract: Water-soluble dicarboxylic acids (hereafter diacids) and sugars are an important part of the atmospheric water-soluble organic aerosol. Here, we studied diacids and other compounds in fine aerosol particles (PM1) collected at a rural background site National Atmospheric Observatory Ko&#353;etice (NAOK), Czech Republic, Central Europe. Aerosol samples were collected every second day for 24 h from September 2013 to August 2014 (n=146). Based on receptor modeling (PMF), we identified PM1 organic compounds that are more typical to anthropogenic and to biogenic sources. We have apportioned two anthropogenic sources especially evident during the heating season from mid-October to mid-April: (i) biomass burning (BB) (main contribution of levoglucosan and methylsuccinic, maleic, methylmaleic and azelaic acids) and (ii) fossil fuel combustion (FF) (represented by phthalic, terephthalic and ketomalonic acids). Furthermore, we identified two sources of biogenic aerosols: (iii) summer factor was largely characterized by compounds with three and seven carbons (malonic, 4-ketopimelic, oxoheptanoic, methylmalonic acids) while (iv) spring biogenic factor was characterized mostly by primary sugars, normal chain diacids and their precursors (oxalic, malonic, succinic, glutaric, ketomalonic, 4-oxobutanoic and 5-oxopentanoic acids). Last but not least, we distinguished (v) background factor mainly represented by less oxidized diacids precursors such as glyoxal, methylglyoxal, glyoxylic and pyruvic acids, but also by aromatic diacids, which may originate from traffic emissions; a stable and year-round source.Acknowledgement: This conference contribution was supported by the Ministry of Education, Youth and Sports of the Czech Republic under the project ACTRIS-CZ-LM2018122, by the Czech Science Foundation grant No. 20&#8211;08304J and by the Japan Society for the Promotion of Science (JSPS) through Grant-in-Aid No. 24221001. We appreciate the financial support of JSPS fellowship to P. Vodi&#269;ka (P16760) in Japan.Reference: Vodi&#269;ka, P., Kawamura, K., Deshmukh, D.K., Pokorn&#225;, P., Schwarz, J., &#381;d&#237;mal, V.: Anthropogenic and biogenic tracers of fine aerosol based on seasonal distributions of dicarboxylic acids, sugars and related compounds at a rural background site in Central Europe, Atmos. Environ., submitted, 2023.