Thesis and Guide details:
Details of CSIR Fellowship/ Associateship held, if any or from other sources/ agencies.
Significant foreign assignments:
(a) Significant contributions to science and/ or technology development by the nominee
based on the work done in India during most part of last 5 years:
Nominee is first to observe that the tropical mesopause is close to 100 km, which is much
higher than what has been commonly reported (Ratnam et al., JGR, 2010). The implications of this
unusually high altitude of mesopause in terms of altitude of turbopause and consequent effects on the
e-region plasma turbulence have been comprehensively investigated. He is pioneer to show the role of
anthropogenic effects on the mesospheric winds directly from the observational study using long-term
observations (Ratnam et al., GRL, 2008) while providing strong support through modelling (Ratnam et
al., GRL, 2013a, with UCAR collaboration). His work on mesospheric dynamics greatly advanced our
understanding on the long-term trends and coupling processes between lower and upper atmospheric
region over the tropical latitudes. Nominee’s work on Sun-Earth interactions on the middle atmospheric
dynamics is commendable which made him to appoint as a Scientific Discipline Representatives
(SDR) of SCOSTEP from India effective from June 2015 for three years.
The nominee has discovered unusual behavior in the tropical tropopause characteristics i.e.,
increase in the tropopause altitude away from the equator within the tropics, not only during monsoon
and over Indian region (anti-cyclonic zone) but also in other seasons and longitudes, and offered
potential mechanisms to delineate the causes (Ratnam et al., SOLA, 2005). He is first to observe the
limitation in the World Meteorological Organization (WMO) definition for the multiple tropopauses and
offered alternative definition (Mehta et al., 2013, student as lead author).He has effectively utilized
space borne high accuracy observations to quantity the cross tropopause flux during severe cyclones
for the first time over Indian region which could shed light on stratosphere-troposphere exchange
process (Ratnam et al., ACP, 2015). This has led to recognize him to participate in the international
SPARC capacity development activities from Asia from 2015. He is first to detect increase in the
trend in the Tropical Easterly Jet strength from the year 2000 (Ratnam et al., GRL, 2013b), unlike that
reported earlier.Nominee has taken lead role in generating several focused experimental campaigns
like, Tropical Tropopause Dynamics (TTD) campaigns (Ratnam et al., JASTP, 2014) under CAWSES
India Phase-II national programe of ISRO (as coordinator and convener). The research highlights
from these campaigns has generated a special issue in prestigious J. Atmos. Sci. Terr. Phys.
Nominee’s research has uncovered the exact source mechanisms for the generation of gravity
waves over tropical latitudes making use for the first time combined observations from state-of-art
Indian MST radar, radiosonde observations (Ratnam et al., JGR, 2008) and Air glow measurments at
mesospheric altitudes using advanced ray tracing (Pramitha et al., ACP, 2015, student as lead
author) for the first time over Indian region. These results play an important role in gravity wave
parametrization in the general circulation models (GCM) for better forecasting. He has taken lead in
assessing quality of Relative humidity obtained from SAPHIR on-board Megha Tropiques satellite
(Ratnam et al., JGR, 2013). He is actively involved in retrieval, validation and application of Radio
Occultation Sounding of the Atmosphere (ROSA) on-board Megha Tropiquies as a Test and Evaluation
Committee member (Ratnam et al., 2015, Technical report submitted to ISRO).
(b) Impact of the contributions in the field concerned:
Basic (major) and applied (partly).
Places where work of last 5 years has been referred/ cited in Books, Reviews:
Names of the industries in which the technology (ies) has (have) been used :
The achievements already been recognised by Awards by any learned body:
The Awardee a fellow of the Indian National Science Academy/Indian Academy of Sciences/National
Academy of Sciences/Others:
The Awardee delivered invited lecture(s) in India/abroad and/or chaired any scientific
Internatiional Conference Symposium:
List of Awardee's 10 most significant publications.
List of Awardee's 5 most significant publications during the last 5 years
List of Awardee's 5 most significant publications from out of work done in India
during the last five years:
Complete list of publications in standard refereed journals:
Complete list of publications with foreign collaborators (indicating your status
as author):
List of papers published in Conferences /Symposia/ Seminars, etc:
List of the most outstanding Technical Reports/ Review Articles:
Statement regarding collaboration with scientists abroad:
Total number of patents granted in last five years.
Details of Books published: