scholarly journals On the Zonal Near-Constancy of Fractional Solar Absorption in the Atmosphere

2016 ◽  
Vol 29 (9) ◽  
pp. 3423-3440 ◽  
Author(s):  
Maria Z. Hakuba ◽  
Doris Folini ◽  
Martin Wild
Keyword(s):  
Water Vapor ◽  
Global Scale ◽  
Solar Absorption ◽  
Clear Sky ◽  
Latitude Dependence ◽  
Zero Effect ◽  
Aerosol Effects ◽  
The Tropics ◽  
Water Vapor Path ◽  
Sky Conditions

Abstract Over Europe, a recent study found the fractional all-sky atmospheric solar absorption to be largely unaffected by variations in latitude, remaining nearly constant at its regional mean of 23% ± 1%, relative to the respective top-of-atmosphere insolation. The satellite-based CERES EBAF dataset (2000–10) confirms the weak latitude dependence within 23% ± 2%, representative of the near-global scale between 60°S and 60°N. Under clear-sky conditions, the fractional absorption follows the spatial imprint of the water vapor path, peaking in the tropics and decreasing toward the poles, accompanied by a slight hemispheric asymmetry. In the northern extratropics, the clear-sky absorption attains zonal near-constancy due to combined water vapor, surface albedo, and aerosol effects that are largely amiss in the Southern Hemisphere. In line with earlier studies, the CERES EBAF suggests an increase in atmospheric solar absorption due to clouds by on average 1.5% (5 W m−2) from 21.5% (78 W m−2) under clear-sky conditions to 23% (83 W m−2) under all-sky conditions (60°S–60°N). The low-level clouds in the extratropics act to enhance the absorption, whereas the high clouds in the tropics exhibit a near-zero effect. Consequently, clouds reduce the latitude dependence of fractional atmospheric solar absorption and yield a near-constant zonal mean pattern under all-sky conditions. In the GEWEX-SRB satellite product and the historical simulations from phase 5 of CMIP (CMIP5; 1996–2005, multimodel mean) the amount of insolation absorbed by the atmosphere is reduced by around −1.3% (5 W m−2) with respect to the CERES EBAF mean. The zonal variability and magnitude of the atmospheric cloud effect are, however, largely in line.

Aerosol Effects on Temperature Forecast in the COSMO-Ru Model

2021 ◽  
pp. 29-39
Author(s):  
A. A. Poliukhov ◽  
◽  
D. V. Blinov ◽  
◽  
Keyword(s):  
Air Temperature ◽  
Numerical Experiments ◽  
Surface Air Temperature ◽  
European Part ◽  
Clear Sky ◽  
Temperature Forecast ◽  
European Part Of Russia ◽  
Simulated Surface ◽  
Aerosol Effects ◽  
Sky Conditions

Aerosol effects on the forecast of surface temperature, as well as temperature at the levels of 850 and 500 hPa over Europe and the European part of Russia are studied using various aerosol climatologies: Tanre, Tegen, and MACv2. The numerical experiments with the COSMO-Ru model are performed for the central months of the seasons (January, April, July, and October) in 2017. It is found that a change in the simulated surface air temperature over land can reach 1C when using Tegen and MACv2 data as compared to Tanre. At 850 and 500 hPa levels, the changes do not exceed 0.4C. At the same time, it is shown that a decrease in the root-mean-square error of 2-m air temperature forecast at individual stations reaches 0.5C when using Tegen and MACv2 data and 1C for clear-sky conditions in Moscow.

scholarly journals Persistence and variability of Earth’s inter-hemispheric albedo symmetry in 19 years of CERES EBAF observations

2021 ◽  
pp. 1-62
Author(s):  
Aiden Jönsson ◽  
Frida A.-M. Bender
Keyword(s):  
Southern Oscillation ◽  
Global Scale ◽  
Coupled Models ◽  
Radiative Fluxes ◽  
Clear Sky ◽  
Data Record ◽  
Aerosol Sources ◽  
Mean Climate ◽  
The Tropics ◽  
Observational Record

AbstractDespite the unequal partitioning of land and aerosol sources between the hemispheres, Earth’s albedo is observed to be persistently symmetric about the equator. This symmetry is determined by the compensation of clouds to the clear-sky albedo. Here, the variability of this inter-hemispheric albedo symmetry is explored by decomposing observed radiative fluxes in the CERES EBAF satellite data record into components reflected by the atmosphere, clouds, and the surface. We find that the degree of inter-hemispheric albedo symmetry has not changed significantly throughout the observational record. The variability of the inter-hemispheric difference in reflected solar radiation (asymmetry) is strongly determined by tropical and subtropical cloud cover, particularly those related to non-neutral phases of the El Niño-Southern Oscillation (ENSO). As the ENSO is the most significant source of interannual variability in reflected radiation on a global scale, this underscores the inter-hemispheric albedo symmetry as a robust feature of Earth’s current annual mean climate. Comparing this feature in observations with simulations from coupled models reveals that the degree of modeled albedo symmetry is mostly dependent on biases in reflected radiation in the midlatitudes, and that models that overestimate its variability the most have larger biases in reflected radiation in the tropics. The degree of model albedo symmetry is improved when driven with historical sea surface temperatures, indicating that the degree of symmetry in Earth’s albedo is dependent on the representation of cloud responses to coupled ocean-atmosphere processes.

Modeling the aerosol effects on the light field below a tubular-pipe: A case of clear sky conditions

Solar Energy ◽  
2014 ◽  
Vol 107 ◽  
pp. 122-134 ◽  
Author(s):  
Miroslav Kocifaj ◽  
Ladislav Kómar ◽  
Igor Kohút
Keyword(s):  
Light Field ◽  
Clear Sky ◽  
Aerosol Effects ◽  
Sky Conditions

scholarly journals Carbon monoxide mixing ratios over Oklahoma between 2002 and 2009 retrieved from Atmospheric Emitted Radiance Interferometer spectra

2010 ◽  
Vol 3 (5) ◽  
pp. 1319-1331 ◽  
Author(s):  
L. Yurganov ◽  
W. McMillan ◽  
C. Wilson ◽  
M. Fischer ◽  
S. Biraud ◽  
...  
Keyword(s):  
Water Vapor ◽  
Great Plains ◽  
Microwave Radiometer ◽  
Precipitable Water ◽  
Retrieval Algorithm ◽  
Southern Great Plains ◽  
Diurnal Cycles ◽  
Mixing Ratios ◽  
Clear Sky ◽  
The Tropics

Abstract. CO mixing ratios for the lowermost 2-km atmospheric layer were retrieved from downwelling infrared (IR) radiance spectra of the clear sky measured between 2002 and 2009 by a zenith-viewing Atmospheric Emitted Radiance Interferometer (AERI) deployed at the Southern Great Plains (SGP) observatory of the Atmospheric Radiation Measurements (ARM) Program near Lamont, Oklahoma. A version of a published earlier retrieval algorithm was improved and validated. Archived temperature and water vapor profiles retrieved from the same AERI spectra through automated ARM processing were used as input data for the CO retrievals. We found the archived water vapor profiles required additional constraint using SGP Microwave Radiometer retrievals of total precipitable water vapor. A correction for scattered solar light was developed as well. The retrieved CO was validated using simultaneous independently measured CO profiles from an aircraft. These tropospheric CO profiles were measured from the surface to altitudes of 4572 m a.s.l. once or twice a week between March 2006 and December 2008. The aircraft measurements were supplemented with ground-based CO measurements using a non-dispersive infrared gas correlation instrument at the SGP and retrievals from the Atmospheric IR Sounder (AIRS) above 5 km to create full tropospheric CO profiles. Comparison of the profiles convolved with averaging kernels to the AERI CO retrievals found a squared correlation coefficient of 0.57, a standard deviation of ±11.7 ppbv, a bias of -16 ppbv, and a slope of 0.92. Averaged seasonal and diurnal cycles measured by the AERI are compared with those measured continuously in situ at the SGP in the boundary layer. Monthly mean CO values measured by the AERI between 2002 and 2009 are compared with those measured by the AIRS over North America, the Northern Hemisphere mid-latitudes, and over the tropics.

Precipitable water vapor over oceans from the Maritime Aerosol Network: Evaluation of global models and satellite products under clear sky conditions

2019 ◽  
Vol 215 ◽  
pp. 294-304
Author(s):  
Daniel Pérez-Ramírez ◽  
Alexander Smirnov ◽  
Rachel T. Pinker ◽  
Maksym Petrenko ◽  
Roberto Román ◽  
...  
Keyword(s):  
Water Vapor ◽  
Precipitable Water ◽  
Precipitable Water Vapor ◽  
Global Models ◽  
Clear Sky ◽  
Network Evaluation ◽  
Sky Conditions

scholarly journals Causes of Dimming and Brightening in China Inferred from Homogenized Daily Clear-Sky and All-Sky in situ Surface Solar Radiation Records (1958–2016)

2019 ◽  
Vol 32 (18) ◽  
pp. 5901-5913 ◽  
Author(s):  
Su Yang ◽  
Xiaolan L. Wang ◽  
Martin Wild
Keyword(s):  
Water Vapor ◽  
Solar Radiation ◽  
Water Vapor Pressure ◽  
Historical Records ◽  
Surface Solar Radiation ◽  
Clear Sky ◽  
The Past ◽  
Sky Conditions

AbstractThis paper presents a study on long-term surface solar radiation (SSR) changes over China under clear- and all-sky conditions and analyzes the causes of the “dimming” and “brightening.” To eliminate the nonclimatic signals in the historical records, the daily SSR dataset was first homogenized using quantile-matching (QM) adjustment. The results reveal rapid dimming before 2000 not only under all-sky conditions, but also under clear-sky conditions, at a decline rate of −9.7 ± 0.4 W m−2 decade−1 (1958–99). This is slightly stronger than that under all-sky conditions at −7.4 ± 0.4 W m−2 decade−1, since the clear-sky dimming stopped 15 years later. A rapid “wettening” of about 40-Pa surface water vapor pressure (SWVP) from 1985 to 2000 was found over China. It contributed 2.2% to the SSR decline under clear-sky conditions during the whole dimming period (1958–99). Therefore, water vapor cannot be the main cause of the long-term dimming in China. After a stable decade (1999–2008), an intensive brightening appeared under the clear-sky conditions at a rate of 10.6 ± 2.0 W m−2 decade−1, whereas a much weaker brightening (−0.8 ± 3.1 W m−2 decade−1) has been observed under all-sky conditions between 2008 and 2016. The remarkable divergence between clear- and all-sky trends in recent decades indicates that the clouds played two opposite roles in the SSR changes during the past 30 years, by compensating for the declining SSR under the cloud-free conditions in 1985–99 and by counteracting the increasing SSR under cloud-free conditions in 2008–16. Aerosols remain as the main cause of dimming and brightening over China in the last 60 years, although the clouds counteract the effects of aerosols after 2000.

scholarly journals Testing Climate Models Using Thermal Infrared Spectra

2008 ◽  
Vol 21 (9) ◽  
pp. 1863-1875 ◽  
Author(s):  
Stephen Leroy ◽  
James Anderson ◽  
John Dykema ◽  
Richard Goody
Keyword(s):  
Time Series ◽  
Water Vapor ◽  
Climate Models ◽  
Tropospheric Temperature ◽  
Strong Constraint ◽  
Detection Techniques ◽  
Clear Sky ◽  
Stratospheric Temperature ◽  
Occultation Data ◽  
The Tropics

Abstract An approach to test climate models with observations is presented. In this approach, it is possible to directly observe the longwave feedbacks of the climate system in time series of annual average outgoing longwave spectra. Tropospheric temperature, stratospheric temperature, water vapor, and carbon dioxide have clear and distinctive signatures in the infrared spectrum, and it is possible to detect trends of these signals unambiguously from trends in the outgoing longwave spectrum by optimal detection techniques. This approach is applied to clear-sky data in the tropics simulated from the output of an ensemble of climate models. Estimates of the water vapor–longwave feedback by this approach agree to within estimated errors with truth, and it is likely that an uncertainty of 50% can be obtained in 20 yr of a continuous time series. The correlation of tropospheric temperature and water vapor anomalies can provide a constraint on the water vapor–longwave feedback to 5% uncertainty in 20 yr, or 7% in 10 yr. Thus, it should be possible to place a strong constraint on climate models, which currently show a range of 30% in the water vapor–longwave feedback, in just 10 yr. These results may not hold in the presence of clouds, however, and so it may be necessary to supplement time series of outgoing longwave spectra with GPS radio occultation data, which are insensitive to clouds.

An Analysis of Nonovercast Sky Luminance Models Against Hong Kong Data

2006 ◽  
Vol 129 (4) ◽  
pp. 486-493 ◽  
Author(s):  
Danny H. W. Li ◽  
Chris C. S. Lau
Keyword(s):  
Hong Kong ◽  
Modern Architecture ◽  
Distribution Model ◽  
Position Change ◽  
Clear Sky ◽  
Luminance Distribution ◽  
Artificial Neural Network Ann ◽  
The Tropics ◽  
Sky Conditions ◽  
Solar Position

Daylighting is an important issue in modern architecture that has been characterized by the use of curtain walls in buildings. Nonovercast skies, including clear and partly cloudy days, are essential because they may occur more frequently for places such as in equatorial regions and the tropics. Better understanding of nonovercast sky luminance distribution is vital to estimate the dynamic variation in daylight illuminance as sky condition and solar position change. This paper presents the work on the evaluation of six clear sky and three partly cloudy sky models against three-year (1999–2001) measured Hong Kong sky luminance data. The general features and characteristics for the models were described and assessed. The nonovercast sky conditions were identified using the ratio of zenith luminance (Lz) to diffuse illuminance (Dv) and the ratio of global illuminance (Gv) to the extraterrestrial illuminance (Ev). Subsequent interpretations of the clear skies into high and low turbid types were conducted in conjunction with the cloud cover (CLD) and the luminous turbidity (Tv), and partly cloudy skies were further subdivided into thin and thick cloud modes using sunshine hour (SH) and global irradiance (GSI). A statistical analysis of the models revealed that the Gusev model (i.e., CIE (Internal Commission on Illumination) polluted sky No. 13) and the model by Chen et al. (1999, “Luminance Distribution Model of Intermediate Skies,” Zhaom Ing Gong Chen Xuebao, 10(1), pp. 59–63 (in Chinese)) developed using artificial neural network (ANN) theory with the measured data in Chongqing, China (29.6degN and 106.5degE) showed the best predictions for sky luminance at this location under the clear and partly cloudy sky conditions, respectively.

scholarly journals HIRS channel 12 brightness temperature dataset and its correlations with major climate indices

2013 ◽  
Vol 13 (14) ◽  
pp. 6907-6920 ◽  
Author(s):  
L. Shi ◽  
C. J. Schreck III ◽  
V. O. John
Keyword(s):  
Water Vapor ◽  
Brightness Temperature ◽  
Regional Climate ◽  
Climate Indices ◽  
Teleconnection Patterns ◽  
Clear Sky ◽  
Vapor Channel ◽  
Brightness Temperatures ◽  
Spatial Coverage ◽  
The Tropics

Abstract. A new version of the High-Resolution Infrared Radiation Sounder (HIRS) upper tropospheric water vapor channel (channel 12) brightness temperature dataset is developed using intersatellite calibrated data. In this dataset, only those pixels affected by upper tropospheric clouds are discarded. Compared to the previous version that was based on column-clear-sky data, the new version has much better daily spatial coverage. The HIRS observation patterns are compared to microwave sounder measurements. The differences between the two types of sounders vary with respect to brightness temperature with larger differences for higher (dry) values. Correlations between the HIRS upper tropospheric water vapor channel brightness temperatures and several major climate indices show strong signals during cold seasons. The selected climate indices track climate variation signals covering regions from the tropics to the poles. Qualitatively, moist signals are correlated with troughs and ascending branches of the circulation, while dry signals occur with ridges and descent. These correlations show the potential of using the upper tropospheric water vapor channel brightness temperature dataset together with a suite of many atmospheric variables to monitor regional climate changes and locate global teleconnection patterns.

Sign in / Sign up

Export Citation Format

Share Document