Buoyed by a strong performance in the second half of last year, Southern California radio revenues jumped 7.5% in 1993 to a record $ 600 million.The growth was spurred by an 8.6% surge in the third and fourth quarters, with revenue in December soaring 13.1% for the strongest monthly gain in several years. The vibrant year-end performance helped offset a somewhat sluggish 5.8% gain in the first half of the year. Although Southern California still lagged behind the national growth average of 9.3% during the year, industry watchers were encouraged by the final local tally. “It was a very good year for Southern California radio,” says George Nadel Rivin, an analyst for the accounting firm Miller Kaplan Arase & Co. “The industry rebounded from a couple of pretty black years.” Of the markets tracked by Miller Kaplan in Southern California, revenues rose 7% to $ 534 million from $ 500 million in 1992. But those figures don’t take into account Spanish-language stations in the Los Angeles market — the L.A. market accounts for about 80% of Southern California radio revenues — or Southland markets that are too small to measure. With Spanish-language KLAX-FM dominating the ratings charts over the past year, and others in the category also turning in decent performances, Rivin estimates that total revenue for the region rose to $ 600 million from $ 558 million in ’92. Although a final revenue analysis for ’93 has not been completed, the Southern California Broadcasters Assn. notes there were substantial increases in ad spending among the automobile, beverage, department and discount store, financial services, supermarket and transportation industries. Rivin attributes the radio gains to a desire among businesses to reduce their advertising expenditures. “People are turning more toward radio because of the lower production costs,” he says. “Nationwide, radio growth doubled that of TV.” In the L.A. market alone, revenue jumped 6.2% to a record $ 412.3 million. Sales to local advertisers for the year amounted to $ 298.9 million, an increase of 5% over the previous year but still $ 4.2 million short of local revenues registered in 1990. Stations compensated for the shortfall by racking up $ 113.5 million in sales to national sponsors, which topped the prior year’s national sales by 9.3% and set a new high. For the region as a whole, national sales were up 11% while local rose 6%. In December, however, national sales in the Southland skyrocketed 23.2% while local advertising jumped a rosy 9.5%. Miller Kaplan, which works with the SCBA, estimates the final L.A. tally will rise to about $ 448 million once 21 non-reporting stations are added into the mix.