“known as the secular...”做后置定语修饰“a pattern ”,但是“a pattern ”在

“known as the secular...”做后置定语修饰“a pattern ”,但是“a pattern ”在整个句子中做什么成分?
But as diet and health improved, children and adolescents have, on average, increased in height by about an inch and a half every 20 years, a pattern known as the secular trend in height.