A near earth orbit satellite of earth experiences very small air resistance. It’s period of revolution decreases by $1.08 sec/day$.

$\mathrm{T}=2\pi \sqrt{\frac{\mathrm{GM}}{{\mathrm{R}}^3}}$

${\mathrm{T}}^2=\frac{4{\pi }^2\mathrm{GM}}{{\mathrm{R}}^3}\Rightarrow \frac{2\mathrm{\Delta T}}{\mathrm{T}}=-\frac{3\mathrm{\Delta R}}{\mathrm{R}}$

$\Rightarrow \frac{2\times 1.08}{86,400}=\frac{-3\times \mathrm{\Delta R}}{6400\mathrm{km}}\Rightarrow \mathrm{\Delta R}=\frac{160}{3}\mathrm{m}$

Its angular  momentum decreases because its radius decreases due to air resistance. This is because due to air resistance its energy decreases.