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Natural variability of monsoon climates - WP 1000
Partners involved: the
Met Office (lead contractor), UREADMY,
CNRM, LMD,
MPI
Summary
PROMISE aims to study the
natural variability of monsoonal systems on seasonal, interannual and
interdecadal timescales, using observations and model results. The analysis
will include application of advanced statistical techniques. In addition,
the interaction between various time and space scales will be investigated.
some key achievements:
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the simulation of the mean and variability of monsoon climates
using an atmosphere only GCM at a range of horizontal and vertical
resolutions with an idealised El Nino/La Nina cycle. This study
showed that the model has limited skill in reproducing observed
interannual variability although reporducibility is quite high.
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comparison of dynamical and statistical models used to predict
monsoon rainfal anomalies over the Central Sahel. The results indicate
that the GCM was less reliable than a simple regression. However,
the GCM showed a better ability to simulate the variability of the
large-scale African monsoon circulation.
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the African monsoon onset has been studied through recurrent abrupt
shift of the ITCZ which has been pointed out in the daily rainfall
dataset for each year between 1968 and 1990. It has been found that
the observed northward shift of the ICTZ is associated with westward
travelling atmospheric circulation pattern in the monsoon layer,
persistent up to 600hPa, at intraseasonal scale.
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sepctral analysis of daily Sahelian rainfall indexes have highlighted
rainfall fluctuations at intra-seasonal time-scale coherent with
an intra-seasonal wind field pattern at 926 and 700hPa
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The interannual variability of sea surface temperature in the tropical
Indian Ocean has been studied to evaluate its relationship with
monsoon systems and ENSO. It has been shown htat the Indian Ocean
SST exhibits a strong ENSO-related interannual variability which
accounts for most of the variance. The recently described dipole
mode was found to exist only during the boreal autumn as a response
to ENSO.
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the impact of improving representation of oboundary layer turbulent
mixin and convective transport was found to result in an improve
simulation of the monsoon and its variability. Furthermore the teleconnection
pattern of AIR with SST is greatly improved. However, the monsoon
climatology was worsened wuggesting that the correct response to
SST forcing is not the sufficient to correctly simulate the monsoon.
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improved simulation of the Somali jet and intensit of West African
rainfall distribution were achieved for a 20 year integration using
a development version of the global climate model with better representaiton
of convection
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the vegetation scheme of the Hadley Centre climate model has been
upgraded and will be used to examine the effect of vegetation seasonality
on the simulation of monsoon climates
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A set of statistical procedures in the PV-wave languate has been
assembled for the analysis of intraseasonal variability in climate
simulations.
Publications on this topic arising from PROMISE
Bader, J., M. Latif, and R. Schnur 2003 The Impact of Decadal-Scale
Indian Ocean SST Anomalies on Tropical and Extra-Tropical Climate in
preparation
Diedhiou, A., S. Janicot, A. Viltard and P. de Felice 2001 Energetics
of easterly wave disturbances over West Africa and the tropical Atlantic
: A climatology from the 1979-95 NCEP/NCAR reanalyses Climate Dynamics
18 487-500
Diedhiou, A., S. Janicot, A. Viltard and P. de Felice 2001 Composite
patterns of easterly disturbances over West Africa and the tropical
Atlantic : A climatology from the 1979-95 NCEP/NCAR reanalyses Climate
Dynamics 18 241-253
Fontaine B., Philippon, N., Trzaska S. and Roucou P. 2002 Spring to
summer changes in the West African monsoon through NCEP/NCAR reanalyses
(1968-1998) Journal of Geophysical Research 107 10.1029-10.1037
Janicot, S. and B. Sultan 2001 Intra-seasonal modulation of convection
in the West African monsoon Geophysical Research Letters 28 523-526
Molteni F 2003 Atmospheric simulations using a GCM with simplified physical
parametrizations. I: model climatology and variability in multi-decadal
experiments Climate Dynamics 20 175-191
Neale, R. B. and Slingo, J.M. 2003 The Maritime Continent and its role
in the global circulation: A GCM study Journal of Climate 16 834 - 848
Poccard, I., S. Janicot and P. Camberlin 2000 Comparison of rainfall
structures between NCEP/NCAR reanalysis and observed data over tropical
Africa Climate Dynamics 16 897-915
Slingo, J. M. 2002 Monsoon Overview. Contribution to 'Encyclopedia of
Atmospheric Sciences', Academic Press, 1356-1370
Sultan, B. and S. Janicot 2003 The West African monsoon dynamics. Part
II: The pre-onset and the onset of the summer monsoon Journal of Climate
in press
Sultan, B., S. Janicot and A. Diedhiou 2003 The West African monsoon
dynamics. Part I: Documentation of intra-seasonal variability in press
Sultan, B. and S. Janicot 2000 Abrupt shift of the ITCZ over West Africa
and intra-seasonal variability Geophysical Research Letters 27 3353-3356
Publications on this topic by PROMISE partners
Sperber, K. R., J. M. Slingo and H. Annamalai: Predictability and the
relationship between subseasonal and interannual variability during
the Asian Summer Monsoon. Q. J. R. Meteorol. Soc., in press.
Annamalai, H., J. M. Slingo, K.R. Sperber and K. Hodges, 1999: The
mean evolution and variability of the Asian Summer Monsoon: Comparison
of ECMWF and NCEP/NCAR Reanalyses. Mon. Weath. Rev., 127, 1157-1186
Ferranti, L., J. M. Slingo, T. N. Palmer and B. J. Hoskins, 1997: Relations
between interannual and intraseasonal monsoon variability as diagnosed
from AMIP integrations. Q. J. R. Meteorol. Soc., 123, 1323-1357.
Stephenson D.B., Douville H. and Kumar, K. (In press) Searching for
a fingerprint of global warming in the Asian summer monsoon
Janicot, S. Spatio-temporal variability of West African rainfall. Part
I : Regionalizations and typings. Journal of Climate, 5, 489-497.
Janicot, S. Spatio-temporal variability of West African rainfall.
Part II : Associated surface and air masses characteristics. Journal
of Climate, 5, 499-511
Fontaine, B. and Janicot, S Wind field coherence and its variations
over West Africa. Journal of Climate, 5, 512-524.
Janicot, S. The West African monsoon of 1987 and 1988 : Pacific or
Atlantic signal ? International Conference on Monsoon Variability and
Prediction, Trieste, Italie, WCRP-84, WMO/TD-No 619, 765-772.
Janicot, S. The recent West African rainfall variability through empirical
and modelling investigations. Global precipitations and climate change,
NATO ASI Series, I, Vol.26, 135-150.
Fontaine, B. Janicot, S. and Moron, VRainfall anomaly patterns and
wind field signals over West Africa in August (1958-1989). Journal of
Climate, 8, 1503-1510. Abstract
Roucoup P. et al Vertical motion changes related to north-east Brazil
rainfall variability : a AGCM simulation. Int. J. Climatology, 16, 879-891.
Fontaine, B. and Janicot, S. Near-global sea surface temperature variability
associated with West African rainfall anomaly types. Journal of Climate,
9, 2935-2940.
Rowell, D.P., 1996: Reply
to comments by Y.C. Sud and W.K.-M. Lau on `Variability of summer rainfall
over tropical north Africa (1906-92): Observations and modelling' by
D.P. Rowell, C.K. Folland, K. Maskell and M.N. Ward (April 4, 1995,
121, 669-704): Further analysis of simulated interdecadal and interannual
variability of summer rainfall over tropical north Africa. Q. J.
R. Meteorol. Soc., 122, 1007-1013
Rowell, D.P., Folland, C.K.,
Maskell, K. and Ward, M.N., 1995: Variability of summer rainfall over
Tropical North Africa (1906-92): Observations and modelling. Q. J.
R. Meteorol. Soc., 121, 669-704
Rowell, D.P., Folland, C.K.,
Maskell, K., Owen, J.A. and Ward, M.N., 1992: Modelling the influence
of global sea surface temperatures on the variability and predictability
of seasonal Sahel rainfall. Geophys. Res. Lett., 19, 905-908
For further information
see:
Description of the work package in the orginal
proposal
Detailed
first annual report (available only to PROMISE partners or by permission
of the lead contractor)
Detailed second year report
(available only to PROMISE partners or by permission of the lead contractor)
Detailed third year report
(available only to PROMISE partners or by permission of the lead contractor)
Final report
or:
contact the lead contractor, Roy Kershaw at rkershaw@meto.gov.uk
contact Emily Black at emily@met.reading.ac.uk
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