In November 2016, AGU released a new AGUJournal.cls LaTeX template that replaces the fifteen-year old
The syntax is much condensed and improved, and only requires a single command to select your journal. I mention this because I still see submissions using the 2001 version agutex.cls, and the new version has much improved PDF generation and formatting for reviewers and the editor.
Prereqs for new AGU template
sudo apt install texlive-fonts-extra
This fixes error
File ‘newtxtext.sty’ not found