scholarly journals Investigating the Influence of Carbon Dioxide and the Stratosphere on the Long-Term Tropospheric Temperature Monitoring from HIRS

2010 ◽  
Vol 49 (9) ◽  
pp. 1927-1937 ◽  
Author(s):  
Eui-Seok Chung ◽  
Brian J. Soden
Keyword(s):  
Carbon Dioxide ◽  
Climate Model ◽  
Thermal Emission ◽  
Basic Result ◽  
Carbon Dioxide Concentration ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Tropospheric Temperature ◽  
Time Varying ◽  
Stratospheric Temperature

Abstract Contrary to a midtropospheric warming trend detected from Microwave Sounding Unit (MSU) measurements, High-Resolution Infrared Radiation Sounder (HIRS) temperature (15 μm) channels, sensitive to the thermal emission from the troposphere, produce distinct cooling trends for the period 1980–99. This apparent discrepancy in the tropospheric temperature trend is investigated through radiative transfer simulations using Geophysical Fluid Dynamics Laboratory climate model output and the profiles of the standard model atmospheres. Radiative simulations with time-invariant carbon dioxide concentration throughout the entire analysis period produce trends that are qualitatively similar to that obtained from the MSU observations, implying that the observed cooling trends of the HIRS temperature channels are attributable to increased carbon dioxide concentration over the 20-yr period. Additional simulations with the observed time-varying concentration of carbon dioxide confirm this basic result. Whereas temperature fluctuations dominate variability on monthly to interannual time scales, carbon dioxide changes dominate the decadal trends in both the observations and model simulations. Further simulations examined the sensitivity of the brightness temperature change with respect to the changes in tropospheric and stratospheric temperature. These calculations indicate that the influences of stratospheric temperature on the measured radiances are greater for the HIRS temperature channels relative to the MSU midtropospheric channel. These results highlight the contributions of time-varying carbon dioxide concentrations and stratospheric temperature to the HIRS 15-μm (temperature channel) radiance record and underscore the importance of accurately accounting for these changes when using HIRS measurements for long-term monitoring.

scholarly journals Space-based geoengineering: Challenges and requirements

2009 ◽  
Vol 224 (3) ◽  
pp. 571-580 ◽  
Author(s):  
C R McInnes
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Large Scale ◽  
Climate Model ◽  
Carbon Dioxide Concentration ◽  
Complex Solution ◽  
Lagrange Point ◽  
Simple Climate Model ◽  
Earth’S Climate

The prospect of engineering the Earth's climate (geoengineering) raises a multitude of issues associated with climatology, engineering on macroscopic scales, and indeed the ethics of such ventures. Depending on personal views, such large-scale engineering is either an obvious necessity for the deep future, or yet another example of human conceit. In this article a simple climate model will be used to estimate requirements for engineering the Earth's climate, principally using space-based geoengineering. Active cooling of the climate to mitigate anthropogenic climate change due to a doubling of the carbon dioxide concentration in the Earth's atmosphere is considered. This representative scenario will allow the scale of the engineering challenge to be determined. It will be argued that simple occulting discs at the interior Lagrange point may represent a less complex solution than concepts for highly engineered refracting discs proposed recently. While engineering on macroscopic scales can appear formidable, emerging capabilities may allow such ventures to be seriously considered in the long term. This article is not an exhaustive review of geoengineering, but aims to provide a foretaste of the future opportunities, challenges, and requirements for space-based geoengineering ventures.

scholarly journals Effect of Carbon Dioxide Concentration on Cereal Yield in Sudan

2019 ◽  
Vol 5 ◽  
pp. 1
Author(s):  
Ibrahim A. Onour ◽  
Keyword(s):  
Carbon Dioxide ◽  
Positive Impact ◽  
Carbon Dioxide Concentration ◽  
Cointegration Analysis ◽  
Short Term ◽  
Time Duration ◽  
Yield Increase ◽  
Research Findings ◽  
Bound Test

To estimate the long-term effect of carbon dioxide (CO2) emission on cereal yield in Sudan, we employed an autoregressive distributed lagged (ARDL) bound test for cointegration analysis. The ARDL results reveal evidence of cointegration between the dependent variable (cereals yield) and two independent variables (CO2 emission) and agricultural GDP. The estimation results of the error correction model indicate that change in CO2 has a positive and significant impact on the cereal yield in the long and short terms, as 1% increase in CO2 leads to a cereal yield increase by 3% in the short term and by 0.7% in the long term. This result adds two important findings to the existing literature: First, the positive impact of CO2 on cereal yield in Sudan supports previous research findings in other countries of warm and arid climates. Second, the effect of CO2 on cereal yield differs from short to long term, as our finding indicates that CO2 has a greater positive effect in the short term compared to that in the long term, implying that the effect of CO2 on cereal yields is not linear, as commonly perceived, but it decreases as time duration extends to longer periods. This may be due to the CO2 effect on global warming that emanates from cumulative CO2 concentration, which leaves a disproportionate impact on crops over time.

scholarly journals Detection and Correction of Diurnal Sampling Bias in HIRS/2 Brightness Temperatures

2007 ◽  
Vol 24 (8) ◽  
pp. 1425-1438 ◽  
Author(s):  
Darren L. Jackson ◽  
Brian J. Soden
Keyword(s):  
Climate Model ◽  
Sampling Bias ◽  
Observation Time ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Tropospheric Temperature ◽  
Brightness Temperatures ◽  
Channel Surface ◽  
Local Observation ◽  
Radiance Data ◽  
Climate Studies

Abstract Diurnal sampling biases arise in the High-Resolution Infrared Radiation Sounder (HIRS) satellite observations because some of the NOAA polar-orbiting satellites drift significantly from their original local observation time. Such bias adversely affects interpretation of these data for climate studies. Twenty-six years of HIRS/2 radiance satellite data (1979–2004) were examined by creating monthly mean gridded data that categorize the observations by local observing time through averaging ascending and descending orbits separately. Corresponding HIRS/2 simulated radiance data from the Geophysical Fluid Dynamics Laboratory (GFDL) climate model were constructed using HIRS/2 satellite sampling and were found to accurately represent the diurnal sampling bias. Correction of the HIRS/2 observations from the observed diurnal sampling bias was using the model simulations of HIRS brightness temperatures to adjust the observed brightness temperatures to the model daily mean. The diurnal bias was found to vary with channel, surface type, latitude, satellite, and cloud cover, but showed little dependence on satellite scan angle. Diurnal bias is most pronounced for ascending orbit observations of the afternoon [1400 local solar time (LST)] satellites with 60°N to 60°S domain averaged brightness temperatures variations up to 0.78 K yr−1. Lower tropospheric temperature and water vapor channels contained the largest bias, and biases over land were more than twice as large as those over the ocean. Brightness temperature adjustments of up to 10 K were needed in the most extreme situations.

scholarly journals Photosynthesis-dependent isoprene emission from leaf to planet in a global carbon-chemistry-climate model

2013 ◽  
Vol 13 (20) ◽  
pp. 10243-10269 ◽  
Author(s):  
N. Unger ◽  
K. Harper ◽  
Y. Zheng ◽  
N. Y. Kiang ◽  
I. Aleinov ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Climate Model ◽  
Carbon Dioxide Concentration ◽  
Canopy Temperature ◽  
Climate Simulation ◽  
Integration Time ◽  
Time Step ◽  
Global Database ◽  
Isoprene Emission ◽  
Isoprene Synthesis

Abstract. We describe the implementation of a biochemical model of isoprene emission that depends on the electron requirement for isoprene synthesis into the Farquhar–Ball–Berry leaf model of photosynthesis and stomatal conductance that is embedded within a global chemistry-climate simulation framework. The isoprene production is calculated as a function of electron transport-limited photosynthesis, intercellular and atmospheric carbon dioxide concentration, and canopy temperature. The vegetation biophysics module computes the photosynthetic uptake of carbon dioxide coupled with the transpiration of water vapor and the isoprene emission rate at the 30 min physical integration time step of the global chemistry-climate model. In the model, the rate of carbon assimilation provides the dominant control on isoprene emission variability over canopy temperature. A control simulation representative of the present-day climatic state that uses 8 plant functional types (PFTs), prescribed phenology and generic PFT-specific isoprene emission potentials (fraction of electrons available for isoprene synthesis) reproduces 50% of the variability across different ecosystems and seasons in a global database of 28 measured campaign-average fluxes. Compared to time-varying isoprene flux measurements at 9 select sites, the model authentically captures the observed variability in the 30 min average diurnal cycle (R2 = 64–96%) and simulates the flux magnitude to within a factor of 2. The control run yields a global isoprene source strength of 451 TgC yr−1 that increases by 30% in the artificial absence of plant water stress and by 55% for potential natural vegetation.

scholarly journals Understanding Recent Stratospheric Climate Change

2009 ◽  
Vol 22 (8) ◽  
pp. 1934-1943 ◽  
Author(s):  
David W. J. Thompson ◽  
Susan Solomon
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Lower Stratosphere ◽  
Climate Model ◽  
Longwave Radiation ◽  
Volcanic Eruptions ◽  
Stratospheric Temperature ◽  
Ozone Trends ◽  
Global Mean

Abstract The long-term, global-mean cooling of the lower stratosphere stems from two downward steps in temperature, both of which are coincident with the cessation of transient warming after the volcanic eruptions of El Chichón and Mount Pinatubo. Previous attribution studies reveal that the long-term cooling is linked to ozone trends, and modeling studies driven by a range of known forcings suggest that the steps reflect the superposition of the long-term cooling with transient variability in upwelling longwave radiation from the troposphere. However, the long-term cooling of the lower stratosphere is evident at all latitudes despite the fact that chemical ozone losses are thought to be greatest at middle and polar latitudes. Further, the ozone concentrations used in such studies are based on either 1) smooth mathematical functions fit to sparsely sampled observations that are unavailable during postvolcanic periods or 2) calculations by a coupled chemistry–climate model. Here the authors provide observational analyses that yield new insight into three key aspects of recent stratospheric climate change. First, evidence is provided that shows the unusual steplike behavior of global-mean stratospheric temperatures is dependent not only upon the trend but also on the temporal variability in global-mean ozone immediately following volcanic eruptions. Second, the authors argue that the warming/cooling pattern in global-mean temperatures following major volcanic eruptions is consistent with the competing radiative and chemical effects of volcanic eruptions on stratospheric temperature and ozone. Third, it is revealed that the contrasting latitudinal structures of recent stratospheric temperature and ozone trends are consistent with large-scale increases in the stratospheric overturning Brewer–Dobson circulation.

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