Elevated duct data-base improvement

Corrections of radiosonde data, the primary source of ducting information, or the response time of the radiosonde's humidity element are reported. This correction procedure was applied for five years of radiosonde data for Washington, DC and it is found that a 25% increase in the annual occurrence of elevated ducts took place. Two types of ducting information are presented: comparing corrected and uncorrected data from the Washington, DC, source, and comparing the Washington, DC, uncorrected data with data used in another study. Overwater elevated duct occurrence data obtained from refractometer are compared with nearby, nearly simultaneous overland radiosonde data.