By using a hybrid model tier-1 that is coupled in the Indo-Pacific tropical ocean, we perform a set of 10 ensemble
runs with different initial condition for two-season period that starts from November 1st and May 1st respectively in 1982
though 2004. The tier-1.5 that is only coupled from India Ocean to dateline and prescribes model monthly climatology
plus observed SSTA in east tropical Pacific is also used to perform another suite of 10 ensemble runs with same initial
conditions. The sensitivity of Asia monsoon and Australian monsoon to SST in central and eastern tropical Pacific has
been investigated. The results of experiments suggest that, 1) the climatology precipitation bias has close relationship
with climatology SST bias which possibly cause overabundant rainfall over Arab Sea and Bay of Bengal, northward shift
rain belt over West Pacific in summer, deficient rainfall of ITCZ over tropical Pacific in summer, too long south branch
of ITCZ over southern Pacific in winter. 2) To east of dateline, the precipitation external variance and internal variance
in tier-1.5 are much larger than those in tier-1.5. 3) The similar signal to noise ratio or error to external ratio as well as
anomaly correlation over Asia monsoon region between in tier-1 and tier-1.5 suggests that precipitation predictability
over Asia monsoon region has little relationship with the improvement of central and east Pacific SST. 4) The
improvement spatial correlation in winter by tier-1.5 over El Nino region during La Nina year, especially when the cold
SST over Nino3.4 turn into warm SST suggest that the winter precipitation predictability over El Nino region can
possible be improved by SST predictability.
KEYWORDS: Wave propagation, Convection, Atmospheric propagation, Climatology, Physics, Data centers, System on a chip, Environmental sensing, Data modeling, Atmospheric modeling
By using GEOS data assimilation system, we investigate the influence of TRMM precipitation products on the
structure and underlying physics of ISO in a GCM assimilation system. We get the following conclusion: 1) In 1998
summer, the strong ISO is apparently in Asia monsoon region off equator and and east equatorial Pacific region .2) 20-
30-day eastward propagation is the dominant mode of ISO near equator. 30-60-day northeastward propagation is the
dominant mode of ISO north of equator averaged over 10°N-25°N. 3) For 20-30-day eastward propagation near equator,
the wavenumver 1 intensity of control run is usually weaker than that of assimilation run and observation. For 30-60-day
northward propagation averaged over 60°E-140°E, the wavenumber 1 intensity of control run is usually stronger than
that of assimilation run and observation. 4)By comparing the correlation coefficients and RMS of Kelvin wave structure
for geopotential height and wind vector at 150hPa between control run and observation with assimilation run with
observation, we can conclude that the assimilation run are more resemble observation, especially near equator. 5) For
assimilation run, the convection, which occurred between high and low geopotential height at 150hPa or between
easterly and westerly and the two anticyclone at 150hPa off equator, are more organized than that for control run
compared with observation. The better Kelvin wave features for the eastward-propagating MJO in the tropic from the
assimilation with TRMM precipitation imply that latent heating is very important in exciting equatorial MJO.
Using the humidity profiles from Atmospheric Infrared Sounder (AIRS) data set, rainfall from TRMM GPI and
winds from QSCAT as well as SST from Aqua/AMSR_E, We analyze the structure of summer quasi biweekly mode
(QBM) over western Pacific region in 2003-2004. We find that the signal of 10-20d oscillation in western Pacific
originates from Philippine Sea, which propagates northwestward to south of China. The AIRS data reveal much larger
tropospheric moisture perturbations than those depicted in ECMWF analysis. It also reveals that the boundary-layer
moisture leads the mid-troposphere moisture during the QBM propagation. The positive SST anomaly may play an
important role to moistening the boundary-layer, which preconditions the QBM propagation. Therefore, the 10-20d SST
anomaly could positively feed back to the atmosphere through moistening the boundary layer, destabilizing the
troposphere, and contributing to the northwestward propagation of the QBM in western North Pacific. On the other hand,
the salient feature that the boundary-layer moisture anomaly leads mid-troposphere moisture does not exist in ECMWF
analysis.
By using the humidity from AIRS data set, rainfall from TRMM GPI and wind from QSCAT wind as well as SST
from Aqua/AMSR_E, We analyze the structure of summer intraseasonal oscillation (ISO) over western Pacific region in
2004. We find the signal of 20-90d oscillation in western Pacific originated from equatorial India ocean, which
propagate eastward to Philippine sea, then propagate northwestward to south of China. The AIRS humidity data shows
that the boundary layer moisture lead the mid-troposphere moisture during the ISO propagation. The positive SST
anomaly may play an important role to moistening the boundary layer and induces the ISO propagation. Therefore, the
intraseasonal SST anomaly could positively feed back to the atmosphere through moistening the boundary layer,
destabilizing the troposphere, and contributing to the northwestward propagation of the ISO in western North Pacific.
The character that the boundary moisture anomaly leads mid-troposphere moisture above ABL is not revealed by
miosture depicted in ECMWF.
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