Comparison of the observed and calculated clear sky greenhouse effect: Implications for climate studies

1992 ◽  
Vol 97 (D9) ◽  
pp. 10037-10049 ◽  
Author(s):  
J. T. Kiehl ◽  
B. P. Briegleb
Keyword(s):  
Greenhouse Effect ◽  
Clear Sky ◽  
Climate Studies

scholarly journals Diurnal variations in the UV albedo of arctic snow

2008 ◽  
Vol 8 (21) ◽  
pp. 6551-6563 ◽  
Author(s):  
O. Meinander ◽  
A. Kontu ◽  
K. Lakkala ◽  
A. Heikkilä ◽  
L. Ylianttila ◽  
...  
Keyword(s):  
High Surface ◽  
Measured Temperature ◽  
Snow Melt ◽  
Clear Sky ◽  
Different Types ◽  
Essential Parameter ◽  
Surface Reflectivity ◽  
Climate Studies ◽  
Radiative Transfer Modeling ◽  
Surface Layer Thickness

Abstract. The relevance of snow for climate studies is based on its physical properties, such as high surface reflectivity. Surface ultraviolet (UV) albedo is an essential parameter for various applications based on radiative transfer modeling. Here, new continuous measurements of the local UV albedo of natural Arctic snow were made at Sodankylä (67°22'N, 26°39'E, 179 m a.s.l.) during the spring of 2007. The data were logged at 1-min intervals. The accumulation of snow was up to 68 cm. The surface layer thickness varied from 0.5 to 35 cm with the snow grain size between 0.2 and 2.5 mm. The midday erythemally weighted UV albedo ranged from 0.6 to 0.8 in the accumulation period, and from 0.5 to 0.7 during melting. During the snow melt period, under cases of an almost clear sky and variable cloudiness, an unexpected diurnal decrease of 0.05 in albedo soon after midday, and recovery thereafter, was detected. This diurnal decrease in albedo was found to be asymmetric with respect to solar midday, thus indicating a change in the properties of the snow. Independent UV albedo results with two different types of instruments confirm these findings. The measured temperature of the snow surface was below 0°C on the following mornings. Hence, the reversible diurnal change, evident for ~1–2 h, could be explained by the daily metamorphosis of the surface of the snowpack, in which the temperature of the surface increases, melting some of the snow to liquid water, after which the surface freezes again.

scholarly journals Model-dependence of the CO<sub>2</sub> threshold for melting the hard Snowball Earth

2011 ◽  
Vol 7 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Y. Hu ◽  
J. Yang ◽  
F. Ding ◽  
W. R. Peltier
Keyword(s):  
Surface Temperature ◽  
Greenhouse Effect ◽  
Surface Albedo ◽  
Snowball Earth ◽  
Pressure Broadening ◽  
Near Surface ◽  
Induced Absorption ◽  
Cloud Forcing ◽  
Clear Sky ◽  
Convective Model

Abstract. One of the critical issues of the Snowball Earth hypothesis is the CO2 threshold for triggering the deglaciation. Using Community Atmospheric Model version 3.0 (CAM3), we study the problem for the CO2 threshold. Our simulations show large differences from previous results (e.g. Pierrehumbert, 2004, 2005; Le Hir et al., 2007). At 0.2 bars of CO2, the January maximum near-surface temperature is about 268 K, about 13 K higher than that in Pierrehumbert (2004, 2005), but lower than the value of 270 K for 0.1 bar of CO2 in Le Hir et al. (2007). It is found that the difference of simulation results is mainly due to model sensitivity of greenhouse effect and longwave cloud forcing to increasing CO2. At 0.2 bars of CO2, CAM3 yields 117 Wm−2 of clear-sky greenhouse effect and 32 Wm−2 of longwave cloud forcing, versus only about 77 Wm−2 and 10.5 Wm−2 in Pierrehumbert (2004, 2005), respectively. CAM3 has comparable clear-sky greenhouse effect to that in Le Hir et al. (2007), but lower longwave cloud forcing. CAM3 also produces much stronger Hadley cells than that in Pierrehumbert (2005). Effects of pressure broadening and collision-induced absorption are also studied using a radiative-convective model and CAM3. Both effects substantially increase surface temperature and thus lower the CO2 threshold. The radiative-convective model yields a CO2 threshold of about 0.21 bars with surface albedo of 0.663. Without considering the effects of pressure broadening and collision-induced absorption, CAM3 yields an approximate CO2 threshold of about 1.0 bar for surface albedo of about 0.6. However, the threshold is lowered to 0.38 bars as both effects are considered.

scholarly journals Uncertainty of the CO<sub>2</sub> threshold for melting a hard Snowball Earth

2010 ◽  
Vol 6 (4) ◽  
pp. 1337-1350 ◽  
Author(s):  
Y. Hu ◽  
J. Yang
Keyword(s):  
Greenhouse Effect ◽  
Atmospheric Model ◽  
Snowball Earth ◽  
Near Surface ◽  
Cloud Forcing ◽  
Clear Sky ◽  
Critical Issues ◽  
Simulation Results ◽  
High Level ◽  
Hadley Cells

Abstract. One of the critical issues of the Snowball Earth hypothesis is how high level of CO2 is required for triggering the deglaciation. Using Community Atmospheric Model version 3 (CAM3), we study the problem for the CO2 threshold. Our simulations show large differences from previous results (Pierrehumbert, 2004, 2005). At 0.2 bars of CO2, the January maximum near-surface temperature is about 268 K, about 13 K higher than that in Pierrehumbert (2004, 2005), but lower than the value of 270 K for 0.1 bar of CO2 in Le Hir et al. (2007). It is found that the diversity of simulation results is mainly due to model sensitivity of greenhouse effect and longwave cloud forcing to increasing CO2. At 0.2 bar of CO2, CAM3 yields 117 Wm −2 of clear-sky greenhouse effect and 32 Wm−2 of longwave cloud forcing, versus only about 77 Wm−2 and 10.5 Wm−2 in Pierrehumbert (2004, 2005), respectively. CAM3 has comparable clear-sky greenhouse effect to that in Le Hir et al. (2007), but lower longwave cloud forcing. CAM3 also produces much stronger Hadley cells than in Pierrehumbert (2005).

Satellite measurements of the clear-sky greenhouse effect from tropospheric ozone

2008 ◽  
Vol 1 (5) ◽  
pp. 305-308 ◽  
Author(s):  
Helen M. Worden ◽  
Kevin W. Bowman ◽  
John R. Worden ◽  
Annmarie Eldering ◽  
Reinhard Beer
Keyword(s):  
Greenhouse Effect ◽  
Tropospheric Ozone ◽  
Satellite Measurements ◽  
Clear Sky

scholarly journals Quantifying the Drivers of the Clear Sky Greenhouse Effect, 2000–2016

2019 ◽  
Vol 124 (21) ◽  
pp. 11354-11371 ◽  
Author(s):  
Shiv Priyam Raghuraman ◽  
David Paynter ◽  
V. Ramaswamy
Keyword(s):  
Greenhouse Effect ◽  
Clear Sky

scholarly journals The Super Greenhouse Effect in a Changing Climate

2016 ◽  
Vol 29 (15) ◽  
pp. 5469-5482 ◽  
Author(s):  
Graeme L. Stephens ◽  
Brian H. Kahn ◽  
Mark Richardson
Keyword(s):  
Greenhouse Effect ◽  
Climate Model ◽  
Coupled Model ◽  
Sensitivity Analyses ◽  
Meridional Heat Transport ◽  
Feedback Analysis ◽  
Surface Warming ◽  
Clear Sky ◽  
Order Of Magnitude ◽  
Ir Emission

Abstract In all outputs of the 1% yr−1 increase in CO2 climate model experiments archived under the World Climate Research Programme’s (WCRP) phase 5 of the Coupled Model Intercomparison Project (CMIP5), regions exist in the low latitudes where both the clear-sky and all-sky OLR decrease with surface warming. These are identified as regions of positive longwave feedback and are regions of a super greenhouse effect (SGE). These SGE regions are identified from feedback analysis of the 4 × CO2 abrupt experiments of CMIP5, and despite their existence, there is little agreement across models as to the magnitude of the effect. The general effects of clouds on the SGE are to amplify the clear-sky SGE, but there is also poor agreement on the magnitude of the amplification that varies by an order of magnitude across models. Sensitivity analyses indicate that localized SGE regions are spatially aligned with a large moistening of the upper troposphere. The reduction in clear-sky OLR arises from a reduction in emission in the far IR with nonnegligible contributions from mid-IR emission from the midtroposphere. When viewed in the broader context of meridional heat transport, it is found that of the 1.03-PW rate of heat gained globally, 0.8 PW is absorbed in the tropics and is contributed almost equally by reductions in clear-sky longwave emission (i.e., the clear-sky SGE) and increased absorbed clear-sky solar radiation associated with increased water vapor. The processes that define the clear-sky SGE are shown to be fundamental to the way models accumulate heat and then transport it poleward.

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