The Dvorak technique (developed in 1974 by Vernon Dvorak) is a widely used system to subjectively estimate tropical cyclone intensity based solely on visible and infrared satellite images. Several agencies issue Dvorak numbers for cyclones of sufficient intensity. These include the National Hurricane Center's Tropical Analysis and Forecast Branch (TAFB), the NOAA/NESDIS Satellite Analysis Branch (SAB), the Joint Typhoon Warning Center at the Naval Pacific Meteorology and Oceanography Center in Pearl Harbor, Hawaii, and the Air Force Weather Agency (AFWA).