 |
| Titel |
Cloud properties in the present-day tropical climate |
| VerfasserIn |
C. Lacagnina, F. Selten |
| Konferenz |
EGU General Assembly 2012
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250059658
|
|
|
|
|
|
| Zusammenfassung |
| We estimate the dependence of the tropical cloud radiative forcing (CRF) and cloud amount
upon mid-tropospheric pressure velocity (Ï500) and sea surface temperature (SST) and
emphasize the deficiencies by using these two proxies separately as tools to sort cloud
regimes. For this reason a bivariate approach has been used to systematically investigate
marine cloud properties at different spatial and time scales in the present-day (1985 to 2001)
tropical climate. During the 1997-1998 El Niño, the greatest regional change in CRF and
cloud cover on average coincides with the greatest local change in circulation and SST. In
addition, we find the stratiform low-clouds tend to reduce their cooling effect at the
rate of approximately 1 W-m2 per percent of less cloudiness in the subsidence
cold pools of the Pacific ocean. However, not all the temporal fluctuations in cloud
properties are associated with Ï500 and SST changes. An extension of the Bony
et al. method is proposed using different environmental factors instead of Ï500
as a proxy. Taking advantage of this diagnostic technique, various cloud-related
variables have been explored with the aim of understanding and assessing the relative
contribution of the regional meteorological conditions responsible for the interannual
and seasonal variations. In this analysis framework, we quantify the contribution
of El Niño-Southern Oscillation (ENSO) to the observed anomalies of tropical
cloudiness and radiative balance at the top of the atmosphere, at the interannual time
scale. |
|
|
|
|
|
|