The NOAA IR serves as an archival repository of NOAA-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by NOAA or funded partners.
As a repository, the NOAA IR retains documents in their original published format to ensure public access to scientific information.
i
Variations in solar UV spectral irradiance and X-ray flux
-
1982
[PDF-91.42 MB]
Details:
-
Personal Author:
-
Corporate Authors:
-
NOAA Program & Office:
-
Description:Solar variations in the UV spectral irradiance are discussed with emphasis on the wavelengths important for producing or destroying ozone and heating the stratosphere. Short-term variations of days and weeks have now been well observed by the NIMBUS-7 and SME satellites. The size of the short-term variations at wavelengths longer than 160 nm are smaller than the 7% annual variation in incident flux produced by the orbital variations in the Sun-Earth distance. The percentage short-term variations are about twice as strong at the ozone production wavelengths as at the ozone destruction and stratospheric heating wavelengths. The short-term temporal variations are not simple sinusoids of the 27 day solar-rotation rate but include a much larger range of periods and also shifts in phase according to the location and apparent motion of active regions on the sun. Intermediate-term UV variations lasting a few months, associated with major rounds of solar activity, are discussed. They may account for some of the missing energy blocked by sunspots. The very important long-term and solar-cycle variations are the most poorly observed because of problems in satellite instrument degradation in space and difficulties in intercomparing measurements from different experiments. Long-term results are reviewed with emphasis on their limitations and speculation on long-term trends other than the 11 year sunspot cycle. Progress in modeling the solar UV flux temporal variations based on solar spatial data is reviewed with emphasis on the role of modeling in intercomparing isolated measurements and for providing better UV estimates for past times than indices like the 10.7 cm solar radio flux or sunspot number can provide.
-
Keywords:
-
Series:
-
Document Type:
-
License:
-
Rights Information:CC0 Public Domain
-
Compliance:Library
-
Main Document Checksum:
-
Download URL:
-
File Type:
