dissenting.
I would affirm the superior court’s holding that Mrs. Larson’s discovery that she would require an additional year of study to obtain her doctorate constituted a material and substantial change of circumstances warranting modification of the support provisions of the decree of dissolution. Our prior decisions have established the principle that the superior court is accorded great latitude in determining awards of spousal support. Faro v. Faro, 579 P.2d 1377, 1380 (Alaska 1978); Schoning v. Schoning, 550 P.2d 373, 374 (Alaska 1976). As in other areas of family law where discretionary authority is involved, the trial court’s judgment should not be reversed absent a showing that its ruling constituted an abuse of discretion.1 An abuse of discretion will not be found “unless we are left with the definite and firm conviction on the whole record that the judge made a mistake.... ” Houger v. Houger, 449 P.2d 766, 771 (Alaska 1969).
*631Here the superior court s decision was amply supported by the record and well within the scope of its discretionary authority. The parties contemplated that the spousal support provided under the initial decree would enable Mrs. Larson to obtain an advanced degree. At the time it was framed, they mistakenly assumed that she could complete a doctoral program in art education in four, rather than five years. Thus, the award of spousal support established by the dissolution decree was insufficient to accomplish its intended purpose. The discovery that the expectations underlying the original award were erroneous constituted a change in circumstances justifying the modification under AS 09.55.220.2
My conclusion that the superior court reached a proper result is based in large measure upon our recent decision in Headlough v. Headlough, 639 P.2d 1010 (Alaska 1982). In Headlough, this court held that the discovery that a mistaken assumption regarding the custodial parent’s need for child support was made at the time a divorce decree was entered constituted a change of circumstances warranting modification of the decree. We permitted the superior court to entertain a motion for an increase in support filed seven and one-half months after the divorce decree was entered. The custodial parent testified in part that her expenses had not changed. Nevertheless, in Headlough this court held that the custodial parent’s discovery that the original sum was inadequate to support her children constituted a change of circumstances. We reasoned that:
[t]here was a “change” in the sense that there may have been a mistake in the assumption made when the decree was entered — that the real needs of Kathy for support of the children were something different from that which had been assumed seven months earlier. We agree with the Supreme Court of California in Bratnober v. Bratnober, 48 Cal.2d 259, 309 P.2d 441, 443-44 (1957) where it was held that a failure to realize the reasonable expectations upon which a divorce decree is based may constitute a change in circumstances that will warrant modification of a child support award.
639 P.2d 1010, 1013 (footnote omitted).
In the instant case, Mrs. Larson discovered that as a result of a mistaken assumption underlying her initial request for alimony, her need for support was “something different” than that she had anticipated when the dissolution was finalized. Thus, she was justified under Headlough in seeking a modification.3
In order to obtain relief under AS 09.55.-220, a petitioner must demonstrate that a change in circumstances was material and substantial. Headlough, 639 P.2d at 1013; Curley, 588 P.2d at 291. In my view, the superior court correctly concluded that Mrs. Larson succeeded in making such a showing. The rehabilitative alimony she received under the terms of the initial decree *632proved insufficient to accomplish its intended purpose.4 The disparity between her anticipated and actual needs was significant. The superior court concluded correctly that the financial burden imposed by an additional year of study constituted a material and substantial change in circumstances.5 Thus, I would affirm its modification of the dissolution decree to grant Mrs. Larson the additional support necessary to enable her to complete her doctoral studies.6
. See Headlough v. Headlough, 639 P.2d 1010, 1014 (Alaska 1982); Curley v. Curley, 588 P.2d 289, 291 n. 3 (Alaska 1979).
. Rehabilitative alimony, in contradistinction to permanent alimony, is an award of spousal support of limited duration and for a specified purpose. We approved such arrangements in Bussell v. Bussell, 623 P.2d 1221, 1224 (Alaska 1981).
. Compare Lumsden v. Lumsden, 61 Hawaii 338, 603 P.2d 564 (Hawaii 1979) (per curiam), where the court rejected a similar petition for modification of an award of rehabilitative alimony. The petitioner claimed she needed additional support to obtain a Ph.D. After observing that
“ ‘[T]he amount of alimony is to be determined upon a realistic appraisal of the situation of the parties at tie time of the divorce,’ ”
Id. at 568, quoting Richards v. Richards, 44 Hawaii 491, 355 P.2d 188, 202 (Hawaii 1960) (emphasis by Lumsden court), the court found that the record clearly established that at that time
it was [Mrs. Lumsden’s] intention to seek a master’s degree alone, and that her decision to pursue a doctorate was reached sometime in 1973, 16 months after the initial divorce proceedings had been concluded.
603 P.2d at 568. Finding that she had received sufficient alimony to attain her original goal, the court refused to permit a modification to enable her to achieve an objective formulated several months later. By contrast, Mrs. Larson has consistently sought a Ph.D. She desires a modification of the dissolution decree that will permit her to realize her original goal.
. I disagree with the majority’s conclusion that Civil Rule 60(b), which governs relief from final judgments on grounds of mistake or fraud, applies to petitions for modification of support awards. Specifically, I do not believe that Mrs. Larson should have been required to comply with the provisions of Civil Rule 60(b) in order to obtain relief from the support provisions of an initial decree. AS 09.55.220 furnishes the basis for modifying portions of divorce or dissolution decrees providing for alimony, child custody, child support and spousal maintenance. Since AS 09.55.220, unlike Civil Rule 60(b), does not require that motions for modification of the judgment be filed within one year after the original decree was entered, I would not deny as untimely Mrs. Larson’s application for relief on the ground of mistake.
O’Link v. O’Link, 632 P.2d 225, 228-31 (Alaska 1981), cited by the majority in support of the proposition that Rule 60(b) governs modification of final divorce decrees on grounds of mistake or fraud, involved an application for relief from a property settlement. Since property settlements are not included within the ambit of provisions which may be modified under AS 09.55.220, and thus are indisputably governed by Civil Rule 60(b), O’Link has no bearing upon the issue at hand. Similarly, the other cases cited in the majority opinion at note 3 were decided solely under provisions similar to Rule 60(b). No reference was made in those opinions to statutes similar to AS 09.-55.220. Thus, they do not controvert my position that Rule 60(b) limitations simply do not apply to motions for modification filed under AS 09.55.220.
. AS 09.55.220 (amended 1982) provided in part:
Modification of judgment. Any time after judgment, the court, upon the motion of either party, may set aside, alter, or modify so much of the judgment as may provide for alimony....
AS 09.55.235 provides:
Effect and modiñcation of decree, (a) A decree of dissolution issued under AS 09.55.-231-09.55.237 shall have the same force and effect as a decree granted under AS 09.55.-070-09.55.230.
(b) A decree of dissolution granted under AS 09.55.231-09.55.237 may be modified or enlarged as prescribed by AS 09.55.205-09.55.-220.
In Curley v. Curley, 588 P.2d 289, 291-92 (Alaska 1979), this court said in part that a child support order “may be modified notwithstanding the fact that it was based on a separation agreement or stipulation signed by the parties.”
. I disagree with the majority’s conclusion that Headlough should be limited to child support awards and thus is inapposite in cases involving alimony. AS 09.55.220, the statutory provision giving the courts authority to modify divorce judgments, makes no distinction between child and spousal support decrees. There is no basis for a conclusion that the legislature intended different standards to be applied in modifications of different portions of a judgment. Thus, I believe it is entirely appropriate to apply the reasoning in Headlough in reaching a determination of the merits of the instant appeal.