Clines on an Autumn Festival in Israel
Clines, D. J.A. (1974) “The Evidence for an Autumnal New Year in Pre-exilic Israel Reconsidered“, JBL, 93 , pp. 22-40.
A much debated question in the study of the calendar in pre-exilic Israel and Judah concerns the point at which the new year was reckoned to begin. The prevailing scholarly opinion appears to be that expressed in a typical encyclopaedia article: ‘There is abundant indication that a new year in the fall was standard during the monarchical period’. Within this general view there has been room for a number of varying qualifications. Some have believed that at a time before the Judaean exile the Assyrian and Babylonian spring calendar came into use in Judah. Others have thought that it was only in Judah that autumnal reckoning was employed, whereas northern Israel adopted a spring year at the time of the division of the Solomonic Kingdom. Only a handful of scholars have dissented from the prevailing opinion and have maintained that in both Israel and Judah throughout the monarchy the year was reckoned from the spring. It is the purpose of this paper to open up the question again and to test the arguments that have been advanced for the view that during the greater part of the monarchical period the year began in the autumn.
תהלים 
And what was his conclusion?
Clines writes; “The conclusion of this study is that, while there are no data that categorically exclude autumnal reckoning of the calendar year prior to c. 605 bce, there are no data that support it, not even cumulatively. On the other hand, there is one piece of evidence (the reference to Abib in the festival ‘calendars’ ) that may suggest spring new year reckoning, but that admittedly does not amount to a strong argument in favour of such reckoning. What can be claimed, however, is that it can no longer be confidently affirmed that in pre-exilic Israel the calendar year began in the autumn, nor can it be said with confidence that the Babylonian calendar was adopted c. 605 bce, nor can it be assumed that the reckoning of months according to a spring new year can be used as a criterion for dating a document in which it occurs.”
As an aside, I would agree with Mowinckel in general regarding his idea of an enthronement festival (and therefore an Autumn festival) whilst recognising that his argument needs tightening.