text:  The initial development of this technique occurred in 1969 by Vernon Dvorak , using satellite pictures of tropical cyclones within the northwest Pacific ocean . The system as it was initially conceived involved pattern matching of cloud features with a development and decay model . As the technique matured through the 1970s and 1980s , measurement of cloud features became dominant in defining tropical cyclone intensity and central pressure of the tropical cyclone 's low @-@ pressure area . Use of infrared satellite imagery led to a more objective assessment of the strength of tropical cyclones with eyes , using the cloud top temperatures within the eyewall and contrasting them with the warm temperatures within the eye itself . <unk> on short term intensity change are used less frequently than they were back in the 1970s and 1980s . The central pressures assigned to tropical cyclones have required modification , as the original estimates were 5 @-@ 10 hPa ( 0 @.@ 15 @-@ 0 @.@ 29 inHg ) too low in the Atlantic and up to 20 hPa ( 0 @.@ 59 inHg ) too high in the northwest Pacific . This led to the development of a separate wind @-@ pressure relationship for the northwest Pacific , devised by Atkinson and Holliday in 1975 , then modified in 1977 . 
  