Sentences with phrase «observed cloud cover»

There is however separate proof that a casual link exists between cosmic rays and climate, and independently that cosmic rays left a fingerprint in the observed cloud cover variations.

Radiative effects of surface - observed cloud cover anomalies, called «cloud cover radiative forcing (CCRF) anomalies,» are estimated based on a linear relationship to climatological cloud radiative forcing per unit cloud cover.

I am happy to agree with WebHubTelescope that the changes in observed cloud cover may be a result of increases in CO2.

Thus the study shows that that iRAM simulates recently observed cloud cover changes in this the eastern Pacific more accurately than the GCMs, and iRAM also successfully simulates the main features of the observed interannual variation of clouds in this region, including the evolution of the clouds through the El Niño Southern Oscillation (ENSO) cycle.

Not exact matches

Using data from earth - observing satellites and high - resolution climate models, the authors found a consistent decrease in summer cloud cover since 1995.

Of particular importance are vertically extended polar stratospheric clouds that have been observed to cover wide areas of the Arctic.

However, radiation changes at the top of the atmosphere from the 1980s to 1990s, possibly related in part to the El Niño - Southern Oscillation (ENSO) phenomenon, appear to be associated with reductions in tropical upper - level cloud cover, and are linked to changes in the energy budget at the surface and changes in observed ocean heat content.

Our understanding of these phenomena and our ability to model them are primitive,...» While there are doubts about the link between cosmic rays and cloud cover, there is an observed significant link between (low) cloud cover and solar radiation within the last two sun cycles.

Once the limitations of our study (short coverage, limited precision, viewing angle) are considered, this frequency indicates that most (and probably all) brown dwarfs have intrinsically patchy cloud covers and display rotational variability when observed at sub-percent accuracy.

Unless low - level cloud albedo substantially decreased during this time period, the reduced solar absorption caused by the reported enhancement of cloud cover would have resulted in cooling of the climate system that is inconsistent with the observed temperature record.»

«the variation of ionization by galactic cosmic rays over the decadal solar cycle does not entail a response... that would explain observed variations in global cloud cover»

«Global mean time series of surface - and satellite - observed low - level and total cloud cover exhibit very large discrepancies, however, implying that artifacts exist in one or both data sets... The surface - observed low - level cloud cover time series averaged over the global ocean appears suspicious because it reports a very large 5 % - sky - cover increase between 1952 and 1997.

«we estimate that less than 23 %, at the 95 % confidence level, of the 11 - year cycle changes in the globally averaged cloud cover observed in solar cycle 22 is due to the change in the rate of ionization from the solar modulation of cosmic rays.»

This coastal cloud cover is frequently observed reaching as far inland as Poway and in some cases, San Diego Country Estates.

«A number of studies have suggested that long - term irradiance - based measurements of cloud cover from satellite may be unreliable due to the inclusion of artifacts, difficulties in observing low - cloud, biases connected to view angles, and calibration issues [1, 2, 3, 4].

No matter what (unknown) physical process causes the changes in cloud cover, these changes are observed during a sun cycle.

Our understanding of these phenomena and our ability to model them are primitive,...» While there are doubts about the link between cosmic rays and cloud cover, there is an observed significant link between (low) cloud cover and solar radiation within the last two sun cycles.

One only needs to increase the direct insolation variance with a factor 3 - 5 (e.g. by observed variations in cloud cover, see also my comment # 18)...

The sun doesn't vary enough for this and the observed variations of cloud cover and albedo do not match the solar cycle.

So if there were, say, a decadal - scale 1 % -2 % reduction in cloud cover that allowed more SW radiation to penetrate into the ocean (as has been observed since the 1980s), do you think this would have an impact of greater magnitude on the heat in the oceans than a change of, say, +10 ppm (0.00001) in the atmospheric CO2 concentration?

Hansen et al. (1995) demonstrate that tropospheric aerosols plus increases in continental cloud cover, possibly associated with aerosols, could account for the observed decrease in DTR.

This discrepancy is associated with simulated increases in daily maximum temperature being larger than observed, and could be associated with simulated increases in cloud cover being smaller than observed (Braganza et al., 2004; see Section 3.4.3.1 for observations), a result supported by other analyses (Dai et al., 1999; Stone and Weaver, 2002, 2003).

A 1 % decrease in cloud cover has a slightly higher radiative effect as all the observed loss of Arctic sea ice to date has had.

(Ramanathan and Inamdar 1989) So a 1 % decrease in cloud cover has a slightly higher radiative effect as all the observed loss of Arctic sea ice to date has had.

From the figures I took an average value of 0.45 — but, hey, if you prefer to assume 0.35, that's OK, because it will not change the conclusion that the observed Arctic sea ice melt has not appreciably changed our planet's total albedo, and that a very small change in cloud cover would have a far greater effect.

Consistency between EECRA upper - level cloud cover anomalies and those from the International Satellite Cloud Climatology Project (ISCCP) during 1984 — 1997 suggests the surface - observed trends are cloud cover anomalies and those from the International Satellite Cloud Climatology Project (ISCCP) during 1984 — 1997 suggests the surface - observed trends are Cloud Climatology Project (ISCCP) during 1984 — 1997 suggests the surface - observed trends are real.

He says that the increased solar brightness over the past 20 years has not been enough to cause the observed climate changes, but believes that the impact of intense sunshine on the ozone layer and cloud cover could be affecting the climate more than the sunlight itself.

The closest effect to a «greenhouse» anyone can observe is heavy cloud cover.

«This study examines variability in zonal mean surface - observed upper - level (combined midlevel and high - level) and low - level cloud cover over land during 1971 — 1996 and over ocean during 1952 — 1997.

Statistical analysis of observed daily cloud cover and sulfate surface concentrations in Europe and North America indicates a significant negative correlation between clouds and sulfate.

The reduction in surface - observed upper - level cloud cover between the 1980s and 1990s is also consistent with the decadal increase in all - sky outgoing longwave radiation reported by the Earth Radiation Budget Satellite (ERBS).

The tutorial covers the following four topics: determining satellite overpass time, observing cloud properties, transmitting results to NASA, and comparing results with satellite - retrieved properties.

NRF is influenced by seasonal variations related to the tilt of the Earth's axis and degree of cloud cover as well as Earth's surface features... (View More) Using measurements taken by the CERES instrument, students will observe and analyze NRF patterns.

Between days − 5 to +3 (after the first appear - ance of significant cloud changes) the observed correlation coefficient between SLAT and cloud cover was found to be R = − 0.91.

However, there have been several studies comparing observed changes in cloud cover to cloud simulations in climate models.

We had the warm ENSO period of the 1980s / 1990s (which led to the all - time record warm year 1998), an observed decrease in late 20th C cloud cover (and albedo), the highest solar activity for several thousand years, etc..

Craig Loehle Your still making an assumption that CO2 was the main driver of recent warming when the observations show a 4 - 5 % reduction of cloud cover during the 1990s that was responsible at least 75 % (0.3 degC or 0.7 W / m2) of the observed warming in the satellite period.

This suggests that the aerosol indirect effect and in particular the increase of cloud cover can serve as a possible explanation to the observed changes in surface illumination.

If this hypothesis is validated it could be a «paradigm buster», in that it would provide a mechanism for the observed reaction of our climate to changes in cloud cover (Spencer) and the empirically observed correlation between solar activity and temperature (Svensmark), which lies beyond the measured impact of direct solar irradiance alone.

The authors are very careful not to describe the observed change in cloud cover as a «feedback».

I wasn't aware how much error there was in cloud cover with far fewer clouds predicted by the physics models than the clouds actually observed, except in the very high latitudes where they predict far more than actually observed.

It is well known that the solar magnetic cycle strongly modulates the cosmic ray flux observed on Earth and there have been a number of papers concerning apparent correlations between cosmic rays and cloud cover.

Cloud cover changes that HAVE been observed show a minor increase, but < 10 % of the temperature change can be attributed to that.

It is logical to presume that changes in Earth's albedo are due to increases and decreases in low cloud cover, which in turn is related to the climate change that we have observed during the 20th Century, including the present global cooling.

«the variation of ionization by galactic cosmic rays over the decadal solar cycle does not entail a response... that would explain observed variations in global cloud cover»

«Global mean time series of surface - and satellite - observed low - level and total cloud cover exhibit very large discrepancies, however, implying that artifacts exist in one or both data sets... The surface - observed low - level cloud cover time series averaged over the global ocean appears suspicious because it reports a very large 5 % - sky - cover increase between 1952 and 1997.

Unless low - level cloud albedo substantially decreased during this time period, the reduced solar absorption caused by the reported enhancement of cloud cover would have resulted in cooling of the climate system that is inconsistent with the observed temperature record.»

The observed relationships between cloud cover and regional meteorological conditions provide a more complete way of testing the realism of the cloud simulation in current - generation climate models.