District of Columbia government officials have revised upward their estimates of unemployment in the city, because of a declining population and area economic trends that show greater recovery from recession in the suburbs.

The actual number of unemployed persons in D.C. at the end of 1977 was 28,400 out of an estimated civilian work force of 328,000, compared with earlier estimates of 23,700 and 337,100. The percentage of joblessness was increased to 8.7 percent from the earlier projection of 7 percent.

For all of 1977, average D.C. unemployment is now estimated to have been 9.7 percent compared with previous estimates of 8 percent and a revised average of 9.1 percent for 1976.

During 1977, monthly unemployment rates ranged from 11 percent in June, when students entered the work force, to a low of 8.7 percent in December. However, the new estimates at unemployment rates are not adjusted for normal seasonal variations in job market opportunities, as are most government jobs figures.

In terms of number of workers, the D.C. labor force also was at a peak last June of 335,000, when 37,000 persons were reported out of work.

According to a D.C. Department of Manpower analysis, three factors led to the upward revisions of the unemployment data:

Earlier monthly estimates used a fixed ratio of areawide employment to determine D.C. resident employment, and "as a result, econimic growth and recovery in the suburbs was erroneously attributed to the city."

Various studies show a continuing decline in the city's population - thereby reducing overall labor force levels and making the number of unemployed persons a higher percentage of the total.

There has been an apparent shift in the composition of the unemployed work force - with more new entrants to the labor force or persons re-entering the work force as compared with experienced persons who have lost jobs. New entrants traditionally have a more difficult task in seeking jobs.

The latter factor is significant because previous estimating procedures relied on historical relationships between total joblessness and the number of unemployed insurance claims filed. But this measure failed to reflect true unemployment given the increased number of new job market entrants, who do not file such claims, the department said.

"It is obvious that this upward revision to the level and rate of unemployment in the city of Washington will come as a disappointment to those looking for signs of local economic recovery," the agency stated. At the same time, there has been continued improvement in the data since mid-summer.

As reported earlier, more than 30,000 new jobs were added to the metropolitan Washington economy last year - the first substantial gain in three years. But most of the increase came in Montgomery County and other suburban jurisdictions. The total increase in the number of area jobs in 1977 barely kept pace with growth of the work force.