Export data as .csv or .dat

Hello,

I am working on a 2D transient problem. I have the results and want to post processing them.
I can easily export data in those formats(csv or dat) and open in Matlab or Excel.
I want to select just a part of data. as my domain in big, the exported file size is big(more than 2G).
Is there any way to export just a part of domain and specific time and my variable magnitude (suppose temperature)?
So in the file I need to have the data for x,y,t(time) and my calculated variable(like temperature).

Any idea?
Thank you in advance!