Changes in spring–summer cirrus cloud amount over Estonia, 1958–2003
✍ Scribed by Kalju Eerme
- Book ID
- 102392570
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 115 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0899-8418
- DOI
- 10.1002/joc.1055
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✦ Synopsis
Abstract
The data of hourly cloud detection during daytime at the Tartu–Tõravere meteorological station for the period 1958–2003 have been treated to find the monthly mean amounts of cirrus clouds (in tenths) for March–September and to study their variance. The highest mean value (4.1 tenths) was found in April and the lowest (three tenths) in July. The results of previous cloud‐type notation frequency‐based studies using no quantitative measure for cirrus cloud amount exhibit a maximum in June. The smoothed March–September cirrus cloud amount for 1958–2003 manifests alternation of relatively high and relatively low amounts with a period of approximately 20 years. The relative contribution of clear skies (cirrus amounts less than one tenth) has decreased, the lowest being during 1991–96. The cirrus cloud amount was weakly correlated with local characteristics of atmospheric moisture, such as precipitation, total cloud amount and low cloud amount. Low average cirrus amounts, however, were often recorded when the spring was dry. High cirrus amounts were observed when spring and most months were wet. Copyright © 2004 Royal Meteorological Society