scholarly journals On the Detection of Robust Multidecadal Changes in Earth’s Outgoing Longwave Radiation Spectrum

2016 ◽  
Vol 29 (13) ◽  
pp. 4939-4947 ◽  
Author(s):  
R. J. Bantges ◽  
H. E. Brindley ◽  
X. H. Chen ◽  
X. L. Huang ◽  
J. E. Harries ◽  
...  
Keyword(s):  
Outgoing Longwave Radiation ◽  
Radiative Forcing ◽  
Radiation Spectrum ◽  
Spectral Response ◽  
Longwave Radiation ◽  
Step Change ◽  
Feedback Type ◽  
Atmospheric Window ◽  
Infrared Spectrometer ◽  
Global Mean

Abstract Differences between Earth’s global mean all-sky outgoing longwave radiation spectrum as observed in 1970 [Interferometric Infrared Spectrometer (IRIS)], 1997 [Interferometric Monitor for Greenhouse Gases (IMG)], and 2012 [Infrared Atmospheric Sounding Instrument (IASI)] are presented. These differences are evaluated to determine whether these are robust signals of multidecadal radiative forcing and hence whether there is the potential for evaluating feedback-type responses. IASI–IRIS differences range from +2 K in the atmospheric window (800–1000 cm−1) to −5.5 K in the 1304 cm−1 CH4 band center. Corresponding IASI–IMG differences are much smaller, at 0.2 and −0.8 K, respectively. More noticeably, IASI–IRIS differences show a distinct step change across the 1042 cm−1 O3 band that is not seen in IASI–IMG comparisons. This step change is a consequence of a difference in behavior when moving from colder to warmer scenes in the IRIS data compared to IASI and IMG. Matched simulations for the relevant periods using ERA reanalyses mimic the spectral behavior shown by IASI and IMG rather than by IRIS. These findings suggest that uncertainties in the spectral response of IRIS preclude the use of these data for quantitative assessments of forcing and feedback processes.

scholarly journals Estimating the Earth’s Outgoing Longwave Radiation Measured from a Moon-Based Platform

2021 ◽  
Vol 13 (11) ◽  
pp. 2201
Author(s):  
Hanlin Ye ◽  
Huadong Guo ◽  
Guang Liu ◽  
Jinsong Ping ◽  
Lu Zhang ◽  
...  
Keyword(s):  
Outgoing Longwave Radiation ◽  
Large Scale ◽  
Single Point ◽  
Longwave Radiation ◽  
Earth Observation ◽  
Artificial Satellites ◽  
Earth Observations ◽  
The Earth ◽  
Observation Geometry ◽  
Global Mean

Moon-based Earth observations have attracted significant attention across many large-scale phenomena. As the only natural satellite of the Earth, and having a stable lunar surface as well as a particular orbit, Moon-based Earth observations allow the Earth to be viewed as a single point. Furthermore, in contrast with artificial satellites, the varied inclination of Moon-based observations can improve angular samplings of specific locations on Earth. However, the potential for estimating the global outgoing longwave radiation (OLR) from the Earth with such a platform has not yet been fully explored. To evaluate the possibility of calculating OLR using specific Earth observation geometry, we constructed a model to estimate Moon-based OLR measurements and investigated the potential of a Moon-based platform to acquire the necessary data to estimate global mean OLR. The primary method of our study is the discretization of the observational scope into various elements and the consequent integration of the OLR of all elements. Our results indicate that a Moon-based platform is suitable for global sampling related to the calculation of global mean OLR. By separating the geometric and anisotropic factors from the measurement calculations, we ensured that measured values include the effects of the Moon-based Earth observation geometry and the anisotropy of the scenes in the observational scope. Although our results indicate that higher measured values can be achieved if the platform is located near the center of the lunar disk, a maximum difference between locations of approximately 9 × 10−4 W m−2 indicates that the effect of location is too small to remarkably improve observation performance of the platform. In conclusion, our analysis demonstrates that a Moon-based platform has the potential to provide continuous, adequate, and long-term data for estimating global mean OLR.

scholarly journals Evaluation of ACCMIP outgoing longwave radiation from tropospheric ozone using TES satellite observations

2013 ◽  
Vol 13 (8) ◽  
pp. 4057-4072 ◽  
Author(s):  
K. W. Bowman ◽  
D. T. Shindell ◽  
H. M. Worden ◽  
J.F. Lamarque ◽  
P. J. Young ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Outgoing Longwave Radiation ◽  
Radiative Forcing ◽  
Climate Models ◽  
Climate Model ◽  
Longwave Radiation ◽  
Satellite Observations ◽  
Ensemble Mean ◽  
High Bias

Abstract. We use simultaneous observations of tropospheric ozone and outgoing longwave radiation (OLR) sensitivity to tropospheric ozone from the Tropospheric Emission Spectrometer (TES) to evaluate model tropospheric ozone and its effect on OLR simulated by a suite of chemistry-climate models that participated in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The ensemble mean of ACCMIP models show a persistent but modest tropospheric ozone low bias (5–20 ppb) in the Southern Hemisphere (SH) and modest high bias (5–10 ppb) in the Northern Hemisphere (NH) relative to TES ozone for 2005–2010. These ozone biases have a significant impact on the OLR. Using TES instantaneous radiative kernels (IRK), we show that the ACCMIP ensemble mean tropospheric ozone low bias leads up to 120 mW m−2 OLR high bias locally but zonally compensating errors reduce the global OLR high bias to 39 ± 41 m Wm−2 relative to TES data. We show that there is a correlation (R2 = 0.59) between the magnitude of the ACCMIP OLR bias and the deviation of the ACCMIP preindustrial to present day (1750–2010) ozone radiative forcing (RF) from the ensemble ozone RF mean. However, this correlation is driven primarily by models whose absolute OLR bias from tropospheric ozone exceeds 100 m Wm−2. Removing these models leads to a mean ozone radiative forcing of 394 ± 42 m Wm−2. The mean is about the same and the standard deviation is about 30% lower than an ensemble ozone RF of 384 ± 60 m Wm−2 derived from 14 of the 16 ACCMIP models reported in a companion ACCMIP study. These results point towards a profitable direction of combining satellite observations and chemistry-climate model simulations to reduce uncertainty in ozone radiative forcing.

scholarly journals Attribution of Chemistry-Climate Model Initiative (CCMI) ozone radiative flux bias from satellites

2020 ◽  
Vol 20 (1) ◽  
pp. 281-301 ◽  
Author(s):  
Le Kuai ◽  
Kevin W. Bowman ◽  
Kazuyuki Miyazaki ◽  
Makoto Deushi ◽  
Laura Revell ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Outgoing Longwave Radiation ◽  
Radiative Forcing ◽  
General Circulation ◽  
Climate Model ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Longwave Radiation ◽  
Geophysical Fluid Dynamics Laboratory

Abstract. The top-of-atmosphere (TOA) outgoing longwave flux over the 9.6 µm ozone band is a fundamental quantity for understanding chemistry–climate coupling. However, observed TOA fluxes are hard to estimate as they exhibit considerable variability in space and time that depend on the distributions of clouds, ozone (O3), water vapor (H2O), air temperature (Ta), and surface temperature (Ts). Benchmarking present-day fluxes and quantifying the relative influence of their drivers is the first step for estimating climate feedbacks from ozone radiative forcing and predicting radiative forcing evolution. To that end, we constructed observational instantaneous radiative kernels (IRKs) under clear-sky conditions, representing the sensitivities of the TOA flux in the 9.6 µm ozone band to the vertical distribution of geophysical variables, including O3, H2O, Ta, and Ts based upon the Aura Tropospheric Emission Spectrometer (TES) measurements. Applying these kernels to present-day simulations from the Chemistry-Climate Model Initiative (CCMI) project as compared to a 2006 reanalysis assimilating satellite observations, we show that the models have large differences in TOA flux, attributable to different geophysical variables. In particular, model simulations continue to diverge from observations in the tropics, as reported in previous studies of the Atmospheric Chemistry Climate Model Intercomparison Project (ACCMIP) simulations. The principal culprits are tropical middle and upper tropospheric ozone followed by tropical lower tropospheric H2O. Five models out of the eight studied here have TOA flux biases exceeding 100 mW m−2 attributable to tropospheric ozone bias. Another set of five models have flux biases over 50 mW m−2 due to H2O. On the other hand, Ta radiative bias is negligible in all models (no more than 30 mW m−2). We found that the atmospheric component (AM3) of the Geophysical Fluid Dynamics Laboratory (GFDL) general circulation model and Canadian Middle Atmosphere Model (CMAM) have the lowest TOA flux biases globally but are a result of cancellation of opposite biases due to different processes. Overall, the multi-model ensemble mean bias is -133±98 mW m−2, indicating that they are too atmospherically opaque due to trapping too much radiation in the atmosphere by overestimated tropical tropospheric O3 and H2O. Having too much O3 and H2O in the troposphere would have different impacts on the sensitivity of TOA flux to O3 and these competing effects add more uncertainties on the ozone radiative forcing. We find that the inter-model TOA outgoing longwave radiation (OLR) difference is well anti-correlated with their ozone band flux bias. This suggests that there is significant radiative compensation in the calculation of model outgoing longwave radiation.

scholarly journals Outgoing Longwave Radiation due to Directly Transmitted Surface Emission

2012 ◽  
Vol 69 (6) ◽  
pp. 1865-1870 ◽  
Author(s):  
S. M. S. Costa ◽  
K. P. Shine
Keyword(s):  
Outgoing Longwave Radiation ◽  
Ad Hoc ◽  
Longwave Radiation ◽  
Detailed Calculation ◽  
Surface Emission ◽  
Clear Sky ◽  
Atmospheric Window ◽  
The Tropics ◽  
The Continuum

Abstract A frequently used diagram summarizing the annual- and global-mean energy budget of the earth and atmosphere indicates that the irradiance reaching the top of the atmosphere from the surface, through the midinfrared atmospheric window, is 40 W m−2; this can be compared to the total outgoing longwave radiation (OLR) of about 235 W m−2. The value of 40 W m−2 was estimated in an ad hoc manner. A more detailed calculation of this component, termed here the surface transmitted irradiance (STI), is presented, using a line-by-line radiation code and 3D climatologies of temperature, humidity, cloudiness, etc. No assumption is made as to the wavelengths at which radiation from the surface can reach the top of the atmosphere. The role of the water vapor continuum is highlighted. In clear skies, if the continuum is excluded, the global- and annual-mean STI is calculated to be about 100 W m−2 with a broad maximum throughout the tropics and subtropics. When the continuum is included, the clear-sky STI is reduced to 66 W m−2, with a distinctly different geographic distribution, with a minimum in the tropics and local peaks over subtropical deserts. The inclusion of clouds reduces the STI to about 22 W m−2. The actual value is likely somewhat smaller due to processes neglected here, and an STI value of 20 W m−2 (with an estimated uncertainty of about ±20%) is suggested to be much more realistic than the previous estimate of 40 W m−2. This indicates that less than one-tenth of the OLR originates directly from the surface.

The Earth's outgoing longwave radiation spectrum as seen by REFIR

2005 ◽  
Author(s):  
Maxwell Bolton ◽  
John Harries ◽  
Luca Palchetti ◽  
Rolando Rizzi ◽  
M. Caldwell
Keyword(s):  
Outgoing Longwave Radiation ◽  
Radiation Spectrum ◽  
Longwave Radiation

scholarly journals Earth’s outgoing longwave radiation linear due to H2O greenhouse effect

2018 ◽  
Vol 115 (41) ◽  
pp. 10293-10298 ◽  
Author(s):  
Daniel D. B. Koll ◽  
Timothy W. Cronin
Keyword(s):  
Greenhouse Effect ◽  
Outgoing Longwave Radiation ◽  
Radiative Forcing ◽  
Extrasolar Planets ◽  
Thermal Emission ◽  
Longwave Radiation ◽  
Future Climate Change ◽  
Spectral Window ◽  
Wide Range ◽  
Earth’S Climate

Satellite measurements and radiative calculations show that Earth’s outgoing longwave radiation (OLR) is an essentially linear function of surface temperature over a wide range of temperatures (≳60 K). Linearity implies that radiative forcing has the same impact in warmer as in colder climates and is thus of fundamental importance for understanding past and future climate change. Although the evidence for a nearly linear relation was first pointed out more than 50 y ago, it is still unclear why this relation is valid and when it breaks down. Here we present a simple semianalytical model that explains Earth’s linear OLR as an emergent property of an atmosphere whose greenhouse effect is dominated by a condensable gas. Linearity arises from a competition between the surface’s increasing thermal emission and the narrowing of spectral window regions with warming and breaks down at high temperatures once continuum absorption cuts off spectral windows. Our model provides a way of understanding the longwave contribution to Earth’s climate sensitivity and suggests that extrasolar planets with other condensable greenhouse gases could have climate dynamics similar to Earth’s.

scholarly journals Latitude–Height Structure of the Atmospheric Angular Momentum Cycle Associated with the Madden–Julian Oscillation

2007 ◽  
Vol 135 (4) ◽  
pp. 1564-1575 ◽  
Author(s):  
Joseph Egger ◽  
Klaus Weickmann
Keyword(s):  
Angular Momentum ◽  
Principal Components ◽  
Outgoing Longwave Radiation ◽  
Opposite Sign ◽  
Longwave Radiation ◽  
Empirical Orthogonal Functions ◽  
Madden Julian Oscillation ◽  
Orthogonal Functions ◽  
Tropical Troposphere ◽  
Global Mean

Abstract The angular momentum cycle of the Madden–Julian oscillation is analyzed by regressing the zonally averaged axial angular momentum (AAM) budget including fluxes and torques against the first two principal components P1 and P2 of the empirical orthogonal functions (EOFs) of outgoing longwave radiation (OLR). The maximum of P1 coincides with an OLR minimum near 150°E and a shift from anomalously negative AAM to positive AAM in the equatorial troposphere. AAM anomalies of one sign develop first in the upper-equatorial troposphere and then move downward and poleward to the surface of the subtropics within two weeks. During the same time the opposite sign AAM anomaly develops in the upper-equatorial troposphere. The tropical troposphere is warming when P1 approaches its maximum while the stratosphere is cooling. The torques are largest in the subtropics and are linked with the downward and poleward movement of AAM anomalies. The evolution is conveniently summarized using a time–height depiction of the global mean AAM and vertical flux anomaly.

scholarly journals The link between outgoing longwave radiation and the altitude at which a spaceborne lidar beam is fully attenuated

2017 ◽  
Vol 10 (12) ◽  
pp. 4659-4685 ◽  
Author(s):  
Thibault Vaillant de Guélis ◽  
Hélène Chepfer ◽  
Vincent Noel ◽  
Rodrigo Guzman ◽  
Philippe Dubuisson ◽  
...  
Keyword(s):  
Outgoing Longwave Radiation ◽  
Climate Model ◽  
Radiant Energy ◽  
Longwave Radiation ◽  
Energy System ◽  
Lidar Measurement ◽  
Radiative Effect ◽  
Simple Formulation ◽  
Cloud Radiative Effect ◽  
Global Mean

Abstract. According to climate model simulations, the changing altitude of middle and high clouds is the dominant contributor to the positive global mean longwave cloud feedback. Nevertheless, the mechanisms of this longwave cloud altitude feedback and its magnitude have not yet been verified by observations. Accurate, stable, and long-term observations of a metric-characterizing cloud vertical distribution that are related to the longwave cloud radiative effect are needed to achieve a better understanding of the mechanism of longwave cloud altitude feedback. This study shows that the direct measurement of the altitude of atmospheric lidar opacity is a good candidate for the necessary observational metric. The opacity altitude is the level at which a spaceborne lidar beam is fully attenuated when probing an opaque cloud. By combining this altitude with the direct lidar measurement of the cloud-top altitude, we derive the effective radiative temperature of opaque clouds which linearly drives (as we will show) the outgoing longwave radiation. We find that, for an opaque cloud, a cloud temperature change of 1 K modifies its cloud radiative effect by 2 W m−2. Similarly, the longwave cloud radiative effect of optically thin clouds can be derived from their top and base altitudes and an estimate of their emissivity. We show with radiative transfer simulations that these relationships hold true at single atmospheric column scale, on the scale of the Clouds and the Earth's Radiant Energy System (CERES) instantaneous footprint, and at monthly mean 2° × 2° scale. Opaque clouds cover 35 % of the ice-free ocean and contribute to 73 % of the global mean cloud radiative effect. Thin-cloud coverage is 36 % and contributes 27 % of the global mean cloud radiative effect. The link between outgoing longwave radiation and the altitude at which a spaceborne lidar beam is fully attenuated provides a simple formulation of the cloud radiative effect in the longwave domain and so helps us to understand the longwave cloud altitude feedback mechanism.

scholarly journals Comparison of Spectrally Resolved Outgoing Longwave Radiation over the Tropical Pacific between 1970 and 2003 Using IRIS, IMG, and AIRS

2007 ◽  
Vol 20 (15) ◽  
pp. 3982-4001 ◽  
Author(s):  
J. A. Griggs ◽  
J. E. Harries
Keyword(s):  
Greenhouse Gas ◽  
Outgoing Longwave Radiation ◽  
Radiative Forcing ◽  
Direct Method ◽  
Longwave Radiation ◽  
Difference Spectrum ◽  
Reanalysis Data ◽  
Temperature Structure ◽  
The Difference ◽  
Spectrally Resolved

Abstract The observation of changes in the earth’s spectrally resolved outgoing longwave radiation (OLR) provides a direct method of determining changes in the radiative forcing of the climate system. An earlier study showed that satellite-observed changes in the clear-sky outgoing longwave spectrum between 1997 and 1970 from the Infrared Interferometer Spectrometer (IRIS) and Interferometic Monitor of Greenhouse Gases (IMG) instruments could be related to changes in greenhouse gas composition. The authors present a new study that extends this to 2003, through the first use of a new, independent source of global atmospheric infrared spectra, from the Atmospheric Infrared Sounder (AIRS) experiment. AIRS is a dispersion grating spectrometer, while the other two were Fourier transform spectrometers, and this is taken into account in the analysis. The observed difference spectrum between the years 2003 and 1970 generally shows the signatures of greenhouse gas forcing, and also shows the sensitivity of the signatures to interannual variations in temperature. The new 2003 data support the conclusions found in the earlier work, though, interestingly, the methane (CH4) Q branch centered at 1304 cm−1 exhibits more complex behavior, showing a decrease in intensity in the difference spectrum between 1997 and 2003. Sensitivity analysis indicates that this is due to changes in temperature structure, superposed on an underlying increase in CH4. Radiative transfer calculations based on reanalysis data are used to simulate the changes in the OLR spectrum; limitations in such data and possible variations that could account for several observed effects are discussed.

Sign in / Sign up

Export Citation Format

Share Document