noise figure plot

[snarkysparky]

I am interested in making an amplifier with 2SC3324 transistor.  My source impedance is 2k ohm. 
Having trouble understanding the noise figure plot for the 1db contour at 2k ohm.

Can the amplifier have a 1db noise figure for all the collector currents in my added red circle.
What is the meaning of the upper curves.

Thanks

[EmmanuelFaure]

It's a contour plot, within the region inside the 1dB contour, the noise figure is below 1dB.