LOGICAL FUNCTION UA_SDID  ( field )
C************************************************************************
C* UA_SDID								*
C*									*
C* This function determines whether the input field (i.e. group)	*
C* contains a sounding system and sea-surface temperature data		*
C* indicator.								*
C*									*
C* UA_SDID  ( FIELD )							*
C*									*
C* Input parameters:							*
C*	FIELD		CHAR*		Field				*
C*									*
C**									*
C* Log:									*
C* J. Ator/NCEP		10/99						*
C************************************************************************
	INCLUDE		'GEMPRM.PRM'
	INCLUDE		'uacmn.cmn'
C*
	CHARACTER*(*)	field
C------------------------------------------------------------------------
	IF  ( field (1:5) .eq. '31313' )  THEN
	    UA_SDID = .true.
	ELSE
	    UA_SDID = .false.
	END IF
C*
	RETURN
	END