Portland police chief Frank Clark announced his resignation Friday in an email sent to members of the police department.Clark said he has accepted a job as a global corporate security director.In the email, Clark said he wasn’t actively seeking a new job when the new opportunity presented itself.“After 33 years in the public sector and knowing the solid team that exists here at 109, it seems like a good time to try something both new and different,” Clark said in the email.In his resignation letter to Portland City Manager Jon Jennings, Clark said his last day would be Nov. 1. “I’d like to thank chief Clark for his dedicated service to our community,” said City Manager Jon Jennings in a statement. “Chief Clark has led the police department with the utmost professionalism and his long career of public service has served Portland and South Portland extremely well.” Jennings said assistant chief Heath Jennings will serve as acting police chief as of Nov. 2.Clark became Portland police chief two years ago. He previously served more than 30 years with the South Portland Police Department.