Northrop Grumman Corp. on Monday announced a trio of contracts whose total value exceeds $620 million.

The U.S. Army is giving the Los Angeles defense contractor an additional $574 million for work on a system that offers soldiers in Iraq and Afghanistan situational awareness, the Los Angeles defense contractor said.

Northrop will provide installation kits and related hardware for the Army’s Force XXI Battle Command Brigade and Below program. This award brings the total value of Northrop’s six-year contract, set to expire in 2011, to $908 million.

Northrop also received a deal from the Navy worth up to $40 million to begin building the last batch of drones. Northrop will deliver three unmanned aerial vehicles, known as MQ-8B Fire Scouts, and corresponding ground control stations and light harpoon grids.

In addition, Northrop Grumman Corp. received a $6 million contract from the Navy to study how the service can replace its aging electronic attack system. The service wants to be able to counter a wide range of electronic weapons, communications and enemy air defenses.

The six-month study is the first step toward developing and producing a jamming system that the Navy will be able to use in several ways. The program eventually could be worth several hundred millions of dollars, Northrop said.

In a separate announcement, Tawazun Holding, an investment company established by the United Arab Emirates’ Offset Program Bureau, said it signed a memorandum of understanding with Northrop to explore the establishment of a collaborative business alliance on various defense programs.

Northrop shares were down 78 cents, or 2 percent, to $44.65 in morning trading on the New York Stock Exchange.