"Ideally we would have liked his appointment to be longer," Clark said. "However we are excited by the coaching group we have appointed for 2017 and are confident we will find a quality replacement for Tony in the time frame we have available."
Brown said he was excited and humbled at the opportunity to take the top job for the 2017 season.
"I wasn't sure the timing was right for me, but having spoken to people inside and outside the organisation, I know now that this is too good an opportunity to pass up," Brown said. "Knowing that I will have Stormy (McLeod) and Hammer (Hammett) with me was an important part of the decision and I'm excited at the prospect of working with them next year."
McLeod, an assistant since 2013, has extended a contract due to end at the end of this season and will remain with the southern side until 2019.
"Obviously whenever you finish a contract you have to weigh up all your options and it certainly wasn't an easy decision, but I get a lot of satisfaction from working with the current group of players and coaches," McLeod said.
Hammett, meanwhile, brings a wealth of experience to the assistant coach role. In 2013 and 2014 he was the head coach of the Hurricanes before taking up a similar role with Cardiff Blues the following season. The former hooker then became the first head coach of the Japanese expansion club the Sunwolves this year, but was lured back to New Zealand by the success of Joseph's team.
"All I really want to do is make a contribution to the group from what I have learned over the last few years as a head coach, assist Brownie and Stormy as much as I can, and build on the good work that has already being done," he said. "The opportunity to work with the Highlanders is very motivating for me and I am looking forward to it."