Air carrier landing BOS was issued a go around along with other aircraft reportedly because of a ATC ground alert system; i.e. ASDE-X/AMASS; reporter adding weather/runway conditions received were not accurate.

Narrative

On approach to Runway 33L; got sent around by Tower below 400 FT in IMC. Three other aircraft sent around behind us and one in front of us on second approach. Ground Radar showed a target on our runway; another aircraft was cleared for takeoff while we were on approach to go around. I do not know how close we came to the other aircraft on takeoff on intersecting Runways 33L/27. Tower indicated that the problem was due to the Ground Radar System that keeps having issued and painting false targets on the runway. Sending aircraft around in the kind of weather we had for a problem system is unacceptable from a safety stand point. BOS needs to put out accurate weather on the ATIS and include the BRA and MIJ numbers on both the departure and arrival runways. We were told the runway was bare and wet less than 5 minutes before we landed; we broke out less than 400 FT to a completely snow covered runway and field. We slid a bit during the roll out. Pilots need to have the exact information at the time of landing; to break out and see snow everywhere when we were told it was bare and wet and BRAG! This happens at BOS a lot! Please fix this.