  Here, we explore the different characteristics of a possible coupling between
tropospheric and ionospheric activities during the impact of tropical cyclones
(TC) like Amphan and Nisarga in the Indian subcontinent. We have analyzed the
effect of TCs Amphan and Nisarga on the low latitude ionosphere using the
measurements from several IGS stations around India and a GPS+ NavIC station in
Indore, India. For the first time, this study assesses the impact of tropical
cyclones on the equatorial ionosphere using both GPS and NavIC. After the
landfall of TC Amphan, the VTEC analysis shows a significant drop from nominal
values in both NavIC as well in GPS by $5.1$ TECU and $3.6$ TECU, respectively.
In contrast to TC Amphan, Nisarga showed a rise in VTEC which ranged from $0.9$
TECU in GPS to $1.7$ - $5$ TECU in NavIC satellites except for PRN6. The paper
examines Outgoing Longwave Radiation as a proxy to the convective activity
which may be responsible for the ionospheric variation through the generation
of gravity waves. In addition, the horizontal neutral wind observations at the
location of TC landfall confirm the presence of ionospheric disturbances. VTEC
perturbation analysis using a band-pass filter reveals a variation in
differential TEC values between $\pm0.4$ and $\pm0.8$ based on the IGS station
measurements. This indicates that the gravity wave is one of the responsible
mechanisms for the lower-upper atmospheric coupling during both cyclones.
