HR: 0830h
AN: A31E-0090    [PDF]
TI: The ENSO Signal on Tropospheric and Stratospheric MSU Temperatures
AU: * Calvo, N
EM: nataliac@fis.ucm.es
AF: Facultad CC.Fisicas (UCM).Dpto.Fisica de la Tierra II, Avda/Complutense sn, Madrid, 28040 Spain
AU: Garcia-Herrera, R
EM: rgarcia@6000aire.fis.ucm.es
AF: Facultad CC.Fisicas (UCM).Dpto.Fisica de la Tierra II, Avda/Complutense sn, Madrid, 28040 Spain
AU: Garcia, R R
EM: rgarcia@ucar.edu
AF: ACD NCAR, Table Mesa Drive, Boulder, CO 80305 United States
AU: Hernandez, E
EM: emiliano@6000aire.fis.ucm.es
AF: Facultad CC.Fisicas (UCM).Dpto.Fisica de la Tierra II, Avda/Complutense sn, Madrid, 28040 Spain
AU: Gimeno, L
EM: l.gimeno@uvigo.es
AF: Facultad de Ciencias de Orense.Dpto.Fisica Aplicada.Universidad de Vigo, Campus As Lagoas, Orense, 32004 Spain
AB: The ENSO signal on tropospheric and stratospheric temperatures has been investigated using Microwave Sounding Unit (MSU) data for the period 1979-2000.Monthly mean T2lt and T4 MSU temperatures have been analysed in terms of emphirical orthogonal functions in the Tropics. This study has been extended to extratropical regions by multiple regression of the data onto the principal components of the tropical EOFs. In order to produce a clearer description of ENSO, EOF analysis have been carried out separately to the zonal mean temperature field and to the deviations from the zonal mean both in troposphere and lower stratosphere.\\ In the tropical troposphere, ENSO is the main source of variability, it accounts for 68% of the variance and it is related to three different EOFs. The first one accounts for almost 50% of the tropical variability. It is a zonal mean pattern and lags the Ni¤o3.4 index by 3 or 4 months. The remaining ENSO variability, is explained by two independent wavelike signals. The former, in phase with Ni¤o3.4, seems to be the atmospheric response to the warming of the Eastern Pacific SSTs. The second one leads N3.4 by 10,12 months and shows the atmospheric tropical disturbances near the date line. It might be considered as a precursor of ENSO.\\ In the lower stratosphere, 89% of the variance is explained by two zonal mean patterns not related to ENSO. The first one explains 77% of the variance and it is strongly influenced by the volcanic eruptions of El Chinch¢n and Mt. Pinatubo. The second one is closely related to the behaviour of the QBO. ENSO accounts for 6% of the tropical variability and it is a wave phenomeno in the lower stratosphere. There is no indication of any ENSO related zonal mean response, but there are two ENSO related eddy EOFs almost perfectly correlated with the eddy tropospheric EOFs. They reflect the vertical structure of internal equatorial waves in the tropics and quasi-geostrophic wavetrains in extratropical latitudes.
DE: 1620 Climate dynamics (3309)
DE: 3309 Climatology (1620)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting