‘The time series of total and low-level cloud cover averaged over the
NE Pacific (115° to 145°W, 15° to 25°N) are displayed in Fig. 1, A and
B. Both COADS and adjusted ISCCP data sets show a shift toward more
total cloud cover in the late 1990s, and the shift is dominated by low-
level cloud cover in the adjusted ISCCP data (bars, in Fig. 1B). The
longer COADS total cloud time series indicates that a similar-
magnitude shift toward reduced cloud cover occurred in the mid-1970s,
and this earlier shift was also dominated by marine stratiform clouds
(bars, Fig. 1A).’
‘Our observational analysis indicates that increased SST and weaker
subtropical highs
(Fig. 4A) will act to reduce NE Pacific cloud cover…’
http://meteora.ucsd.edu/~jnorris/reprints/PacCloudFeedback.pdf
‘Tropical and subtropical low-level marine clouds consist of optically
thick stratocumulus clouds, which usually form over the regions
associated with relatively cold sea surface temperatures (SST) and the
atmospheric subsidence, and optically thin shallow cumuli in the
tradewind regime. These low-level clouds play a pivotal role in the
global climate system not only by affecting radiative budgets but also
by promoting heat and moisture exchange between the sea-surface, the
boundary layer, and the overlying troposphere.’
Ping, Z., Hack, J., Keilh, J and Zhu, P, Bretherton, C. 2007, Climate
sensitivity of tropical and subtropical marine low cloud amount to
ENSO and global warming due to doubled CO2 - JGR, VOL. 112, 2007)
‘One important development since the TAR is the apparent unexpectedly
large changes in tropical mean radiation flux reported by ERBS
(Wielicki et al., 2002a,b). It appears to be related in part to
changes in the nature of tropical clouds (Wielicki et al., 2002a),
based on the smaller changes in the clear-sky component of the
radiative fluxes (Wong et al., 2000; Allan and Slingo, 2002), and
appears to be statistically distinct from the spatial signals
associated with ENSO (Allan and Slingo, 2002; Chen et al., 2002). A
recent reanalysis of the ERBS active-cavity broadband data corrects
for a 20 km change in satellite altitude between 1985 and 1999 and
changes in the SW filter dome (Wong et al., 2006). Based upon the
revised (Edition 3_Rev1) ERBS record (Figure 3.23), outgoing LW
radiation over the tropics appears to have increased by about 0.7 W m–
2 while the reflected SW radiation decreased by roughly 2.1 W m–2 from
the 1980s to 1990s (Table 3.5).
'The most accurate of the data sets in Table 3.5 is believed to be the
ERBS Edition 3 Rev 1 active-cavity wide field of view data (Wielicki
et al., 2005). The ERBS stability is estimated as better than 0.5 W m–
2 over the 1985 to 1999 period and the spatial and temporal sampling
noise is less than 0.5 W m–2 on annual time scales (Wong et al.,
2006). The outgoing LW radiation changes from ERBS are similar to the
decadal changes in the HIRS Pathfinder and ISCCP FD records, but
disagree with the AVHRR Pathfinder data (Wong et al., 2006). The AVHRR
Pathfinder data also do not support the TOA SW radiation trends.
However, calibration issues, conversion from narrow to broadband, and
satellite orbit changes are thought to render the AVHRR record less
reliable for decadal changes compared to ERBS (Wong et al., 2006).
Estimates of the stability of the ISCCP time series for long-term TOA
flux records are 3 to 5 W m–2 for SW radiative flux and 1 to 2 W m–2
for LW radiative flux (Brest et al., 1997), although the time series
agreement of the ISCCP and ERBS records are much closer than these
estimated calibration drift uncertainties (Zhang et al., 2004c).'
‘As noted in Section 3.4.3, the low-latitude changes in the radiation
budget appear consistent with reduced cloud fraction from ISCCP.
Detailed radiative transfer computations, using ISCCP cloud products
along with additional global data sets, show broad agreement with the
ERBS record of tropical radiative fluxes (Hatzianastassiou et al.,
2004; Zhang et al., 2004c; Wong et al., 2006). However, the decrease
in reflected SW radiation from the 1980s to the 1990s may be
inconsistent with the increase in total and low cloud cover over
oceans reported by surface observations (Norris, 2005a), which show
increased low cloud occurrence. The degree of inconsistency, however,
is difficult to ascertain without information on possible changes in
low-level cloud albedo.’
My note here is that there is a consensus on why cloud cover is
influenced by SST - and the biggest factor in variable sea surface
temperature is ENSO.
'In summary, although there is independent evidence for decadal
changes in TOA radiative fluxes over the last two decades, the
evidence is equivocal. Changes in the planetary and tropical TOA
radiative fluxes are consistent with independent global ocean heat-
storage data, and are expected to be dominated by changes in cloud
radiative forcing. To the extent that they are real, they may simply
reflect natural low-frequency variability of the climate system.'
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-4-4-1.html
Really - just picking a paragraph on some supposed inconsistency of
satellite and surface observations is BS. Anything that doesn't fit
the preconceived notions isn't real?
Cheers
Robert
> > Robert- Hide quoted text -