  We study the vacuum topology of 2+1 flavor QCD above the chiral crossover
transition, at $T \lesssim 1.2~T_c$, on lattices of size $32^3\times 8$. Since
overlap fermions have exact chiral symmetry and an index theorem even on a
finite lattice, we use them to detect the topological content of gauge fields
generated using domain wall fermion discretization for quarks. We further use
different periodicity phases along the temporal direction for the valence
overlap quarks, which allows us to probe different topological structures
present in the gauge field ensembles, through its zero modes. This procedure
provides strong evidences that fermion zero-modes can be quantitatively
understood to arise due to different species of instanton-dyons. We estimate
their relative abundances from the Dirac-eigenvalue density and resolve the so
called "topological clusters" via multi-parameter fits to their density,
providing therefore an understanding of the interactions between
instanton-dyons. The typical separation between dyons we obtain, is $\sim 0.3$
fm. Surprisingly, it emerges out from this study that a semi-classical
description of the fermionic zero modes in the QCD vacuum is quite accurate
just above $T_c$.
