This web page's content and links are no longer actively maintained. It is available for reference purposes only. NASA Official: Luke Oman

Confirming the Problem with CFC's

CFC's in the Stratosphere

CLAES made the first global measurements of CFC's (chlorofluorocarbons) in the stratosphere. CFC's enter the stratosphere through upwelling in the tropics. The CFC's decrease with height as they are broken down by UV radiation. CFC's are the major source of stratospheric chlorine. Red indicates large amounts of CFC-12.

CFC amounts measured by CLAES

CFC By-Products in the Stratosphere

HALOE made the first global measurements of stratospheric hydrogen fluoride (HF). HF is a stable by-product of CFC destruction. HALOE observations of HF confirm the breakdown of CFC's. HF values are high where CFC values are low. Yellow indicates large amounts and purple indicates small amounts of HF.

CFC's measured by HALOE

Growth of CFC By-Products in the Stratosphere

HCI is a by-product of the destruction of CFC's by UV radiation in the stratosphere. HALOE measurements of HCI in the upper stratosphere (50 km) show that HCI amounts increased steadily until mid-1997. The time delay between ground-based changes in CFC trends and the HALOE HCI trends corresponds to the time it takes troposheric gases to reach the upper stratosphere.

CFC Trends in the Troposphere

Ground-level CFC concentrations increased steadily until the late 1980's. After that time, CFC growth rate slowed as international agreements to eliminate CFC production began to take effect.

CFC's Diagram

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Last modified: March 08, 2017