President Carter and Sen. Edward M. Kennedy exchanged friendly remarks today, a week after their untraditional joint appearance at the closing session of the Democratic National Convention raised doubts about how strongly Kennedy would support Carter's campaign.

Traditions were respected today. Kennedy was a gracious loser and Carter a magnanimous winner who paid tribute to the man who tried unsuccessfully to take the Democratic nomination from him.

"It's a pleasure to welcome Jimmy Carter to Boston, Mass., as the president of the United Stated and as the nominee of the Democratic Party," Kennedy said in greeting Carter in a chilly wind at Logan Airport. p

At the convention finale, Kennedy seemed to dodge Carter for the joint photo symbolizing party unity that the Carter forces badly wanted.

Today, Kennedy and Carter shook hands and smiled for the cameras. The senator followed the president down a receiving line of Massachusetts Democrats, helping to make introductions.

Kennedy delayed his departure for Detroit to greet Carter here and renewed his pledge to aid the president's campaign.

He paid tribute to Carter's ability to come from behind to victory.

"During the early days of summer Mr. Carter was behind Mr. Reagan in the polls, but there is no authority like myself in the country that can say with greater authority than I can . . . when the time comes to a vote, Mr. Carter is successful, and I am confident that he will be successful in November," Kennedy said.

"I'm determined that he'll be relected as the president of the United States."

Carter glossed over the convention scene, saying: "I'm grateful to be on the platform with [Kennedy] twice in less than a week.

"Both times he's been very generous and the expression of support that he's given me is very gratifying."

Carter said one of the major factors that made him confident he would defeat GOP nominee Ronald Reagan "is the assurance that Sen. Kennedy and all those Americans that supported him . . . will be on my side."