Aadi Amavasai – the new moon day in the Tamil month Adi or Aadi – is dedicated to ancestors. Amavasai is also an important day for Lord Muruga devotees. The important ritual involves taking bath in the holy rivers. Special poojas and abhishekams are conducted in all the Hindu temples on the occasion.
Lord Muruga devotees believe that all sins will be cleansed by bathing in the Shanmuga River in Palani on the Aadi Amavasai day. Many devotees also tonsure (shaving the head) on the day.The main rites and rituals on the day are dedicated to forefathers and many people observe 'upvaas' or fast. Thousands of people take a holy dip in the various rivers, seas and ponds. Agni Theertham in Rameswaram, Thriveni Sangamam in Kannyakumari and various holy ghats on the Cauvery River banks are favored by many devotees for the holy dip.
In neighbouring Kerala.... it is observed as KARKATA VAVU ==> homage to the souls of dead and relatives and ancestors. In Kerala, ‘
In Karnataka, the same day is observed as BHEEMANA AMAVASYA and married women perform special pujas for the longivity of the male members of the family. It is also known as ASHADA AMAVASYA in Karnataka.
In the same name, this Amavasya is called in Andhra, Maharashtra and Gujarat. As per Hindi Calendar, it is known as Hariyali Shravan Amavasya.
http://www.srijagadguru.org/vishesh9.htm ::::::::===> for mantram and procedure in Tamil.
http://www.kandamangalam.com/new/Karma/AmmavasaiTharppanam/tabid/144/Default.aspx ::::::::===> for amavasya tharpanam audio file in mp3 format.