Author Details

Water vapour transport over the Indian Ocean has been computed for the 30-year period (1979-2009). The monthly evolution of meridional moisture fluxes across different sections is presented. March and April clearly indicate the north to south flow of moisture across the equatorial region. During May there is intensification in the northward cross-equatorial moisture transport, which may act as a precursor of the rainy season. During the monsoon season maximum transport occurs in June with values of 1.24 ×10¹¹ and 5.58 ×10¹² tonnes/day for moisture and air flux across the equator respectively, which occurs in the lower atmospheric level between 1000 and 650 hPa. Our finding clearly shows that during the monsoon season across the equatorial cross-section major transport occurs between 42°E and 60°E. Analysis of moisture transport over two regions, i.e. (i) 6°S-6°N and 42- 60°E and (ii) 1.5°S-1.5°N and 42-60°E for two good (1988, 2008) and two bad (1987, 2009) monsoon years shows that during 1987, which was a drought year, the amount of moisture crossing the equator was less by about one order of magnitude compared to 1988. While during 2008, which was a normal/good monsoon year, the amount of moisture transported was almost three times compared to 2009. This clearly indicates that the moisture transport in May can be used as a predictor of monsoon performance.

Keywords

Air flux, Cross-Equatorial flow, Moisture Transport, Monsoon Season.

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Lunar Near Surface Plasma Environment from Chandrayaan-2 Lander Platform:RAMBHA-LP payload

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Authors

G. Manju ¹, Tarun K. Pant ¹, P. Sreelatha ¹, Santhosh J. Nalluveettil ¹, P. Pradeep Kumar ¹, Nirbhay Kumar Upadhyay ¹, Md. Mosarraf Hossain ¹, Neha Naik ¹, Vipin Kumar Yadav ¹, Rosmy John ¹, R. Sajeev ¹, Jothi Ramalingam ¹, Philip George ¹, Amarnath Nandi ¹, N. Mridula ¹, Aswathy R. P. Janmejay Jaiswal Rana ¹, Snehil Srivastava ¹, Satheesh Thampi ¹

Affiliations
1 Vikram Sarabhai Space Centre, ISRO, Thiruvananthapuram 695 022, IN

Source

Current Science, Vol 118, No 3 (2020), Pagination: 383-391

Abstract

The near surface lunar plasma environment is modulated by important components like the photoelectron sheath, solar wind, lunar surface potential, etc. In situ measurements of lunar near surface plasma are not available as of now. Previous lunar missions which explored the near surface environment have arrived at estimates of lunar photo electron densities mainly from lunar sample returns. The Chandrayaan-2 lunar mission affords a unique opportunity to explore the near surface lunar plasma environment from the lunar lander platform. A Langmuir probe is developed indigenously for probing the tenuous lunar near surface plasma environment from the top deck of the lunar lander. The probe is designed to cater to a wide dynamic range of 10/cc to 10,000/cc. The probe behaviour is characterized in the ambient room conditions using a current source. The sensitivity of the probe to incoming ionized species is also characterized in a vacuum chamber. The Langmuir probe response is characterized such that the input current to the probe is correctly deciphered during the mission duration. The calibration of the present Langmuir probe is carried out using a standard calibrated Langmuir probe. The details of the theoretical simulations of the expected currents, the characterization and calibration activities are presented and discussed.

Keywords

Debye Length, Electron Density, Electron Temperature, Langmuir Probe.

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