celsius degrees celsius cm_s-1 centrimeter per second degrees_true degrees clockwise from true north knots knots m meter mS_cm-1 milliSiemens per centimeter m_s-1 meters per second mb 1 mb = 0.001 bar = 100 Pa = 1 000 dyn/cm^2 mg_L-1 milligrams per liter millibar millibar millimeter millimeter millimoles_per_m^2 millimoles per meter squared mph miles per hour nautical_miles equal to 1.151 statue miles ntu nephelometric turbidity units percent percentage ppt parts per thousand psu practical salinity units s seconds ug_L-1 micrograms per liter units a dimensionless unit