Process-Based Decomposition of the Decadal Climate Difference between 2002–13 and 1984–95

2017 ◽  
Vol 30 (12) ◽  
pp. 4373-4393 ◽  
Author(s):  
Xiaoming Hu ◽  
Yana Li ◽  
Song Yang ◽  
Yi Deng ◽  
Ming Cai
Keyword(s):  
Radiative Transfer ◽  
Heat Storage ◽  
Decomposition Analysis ◽  
Arctic Region ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Model Calculations ◽  
Surface Warming ◽  
Decadal Climate

This study examines at the process level the climate difference between 2002–13 and 1984–95 in ERA-Interim. A linearized radiative transfer model is used to calculate the temperature change such that its thermal radiative cooling would balance the energy flux perturbation associated with the change of an individual process, without regard to what causes the change of the process in the first place. The global mean error of the offline radiative transfer model calculations is 0.09 K, which corresponds to the upper limit of the uncertainties from a single term in the decomposition analysis. The process-based decomposition indicates that the direct effect of the increase of CO2 (0.15 K) is the largest contributor to the global warming between the two periods (about 0.27 K). The second and third largest contributors are the cloud feedback (0.14 K) and the combined effect of the oceanic heat storage and evaporation terms (0.11 K), respectively. The largest warming associated with the oceanic heat storage term is found in the tropical Pacific and Indian Oceans, with relatively weaker warming over the tropical Atlantic Ocean. The increase in atmospheric moisture adds another 0.1 K to the global surface warming, but the enhancement in tropical convections acts to reduce the surface warming by 0.17 K. The ice-albedo and atmospheric dynamical feedbacks are the two leading factors responsible for the Arctic polar warming amplification (PWA). The increase of atmospheric water vapor over the Arctic region also contributes substantially to the Arctic PWA pattern.

Radiative forcing over the Arctic of aerosols from the August 2017 Canadian and Greenlandic wildfires

2021 ◽  
Author(s):  
Filippo Calì Quaglia ◽  
Daniela Meloni ◽  
Alcide Giorgio di Sarra ◽  
Tatiana Di Iorio ◽  
Virginia Ciardini ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Radiative Forcing ◽  
Solar Zenith Angle ◽  
Surface Albedo ◽  
High Arctic ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Layer ◽  
Radiative Effect

<p>Extended and intense wildfires occurred in Northern Canada and, unexpectedly, on the Greenlandic West coast during summer 2017. The thick smoke plume emitted into the atmosphere was transported to the high Arctic, producing one of the largest impacts ever observed in the region. Evidence of Canadian and Greenlandic wildfires was recorded at the Thule High Arctic Atmospheric Observatory (THAAO, 76.5°N, 68.8°W, www.thuleatmos-it.it) by a suite of instruments managed by ENEA, INGV, Univ. of Florence, and NCAR. Ground-based observations of the radiation budget have allowed quantification of the surface radiative forcing at THAAO. </p><p>Excess biomass burning chemical tracers such as CO, HCN, H2CO, C2H6, and NH3 were  measured in the air column above Thule starting from August 19 until August 23. The aerosol optical depth (AOD) reached a peak value of about 0.9 on August 21, while an enhancement of wildfire compounds was  detected in PM10. The measured shortwave radiative forcing was -36.7 W/m2 at 78° solar zenith angle (SZA) for AOD=0.626.</p><p>MODTRAN6.0 radiative transfer model (Berk et al., 2014) was used to estimate the aerosol radiative effect and the heating rate profiles at 78° SZA. Measured temperature profiles, integrated water vapour, surface albedo, spectral AOD and aerosol extinction profiles from CALIOP onboard CALIPSO were used as model input. The peak  aerosol heating rate (+0.5 K/day) was  reached within the aerosol layer between 8 and 12 km, while the maximum radiative effect (-45.4 W/m2) is found at 3 km, below the largest aerosol layer.</p><p>The regional impact of the event that occurred on August 21 was investigated using a combination of atmospheric radiative transfer modelling with measurements of AOD and ground surface albedo from MODIS. The aerosol properties used in the radiative transfer model were constrained by in situ measurements from THAAO. Albedo data over the ocean have been obtained from Jin et al. (2004). Backward trajectories produced through HYSPLIT simulations (Stein et al., 2015) were also employed to trace biomass burning plumes.</p><p>The radiative forcing efficiency (RFE) over land and ocean was derived, finding values spanning from -3 W/m2 to -132 W/m2, depending on surface albedo and solar zenith angle. The fire plume covered a vast portion of the Arctic, with large values of the daily shortwave RF (< -50 W/m2) lasting for a few days. This large amount of aerosol is expected to influence cloud properties in the Arctic, producing significant indirect radiative effects.</p>

scholarly journals Accounting for the effect of horizontal gradients in limb measurements of scattered sunlight

2007 ◽  
Vol 7 (6) ◽  
pp. 16155-16183 ◽  
Author(s):  
J. Puķīte ◽  
S. Kühl ◽  
T. Deutschmann ◽  
U. Platt ◽  
T. Wagner
Keyword(s):  
Monte Carlo ◽  
Radiative Transfer ◽  
Scattered Light ◽  
Trace Gases ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Boreal Winter ◽  
Transfer Model ◽  
Measurement Sensitivity ◽  
Horizontal Gradients

Abstract. Limb measurements provided by the SCanning Imaging Absorption spectrometer for Atmospheric CHartographY (SCIAMACHY) on the ENVISAT satellite allow retrieving stratospheric profiles of various trace gases on a global scale, among them BrO for the first time. For limb observations in the UV/VIS spectral region the instrument measures scattered light with a complex distribution of light paths: the light is measured at different elevation angles and can be scattered or absorbed in the atmosphere or reflected by the ground. By means of spectroscopy and radiative transfer modelling the measurements can be inverted to retrieve the vertical distribution of stratospheric trace gases. A full spherical 3-D Monte Carlo radiative transfer model "Tracy-II" is applied in this study. The Monte Carlo method benefits from conceptual simplicity and allows realizing the concept of full spherical geometry of the atmosphere and also its 3-D properties, which is important for a realistic description of the limb geometry. Furthermore it allows accounting for horizontal gradients in the distribution of trace gases. In this study the effect ofhorizontal inhomogeneous distributions of trace gases on the retrieval of profiles from limb measurements of scattered UV/VIS light is investigated. We introduce a method to correct for this effect by combining consecutive limb scanning sequences and utilizing the overlap in their measurement sensitivity regions. It is found that if horizontal inhomogenity is not properly accounted for, typical errors of 20% for NO2 and up to 50% for OClO around the altitude of the profile peak can arise for measurements close to the Arctic polar vortex boundary in boreal winter.

scholarly journals Detection of the Depth-Hoar Layer in the Snow-Pack of the Arctic Coastal Plain of Alaska, U.S.A., Using Satellite Data

1986 ◽  
Vol 32 (110) ◽  
pp. 87-94 ◽  
Author(s):  
D. K. Hall ◽  
A. T. C. Chang ◽  
J. L. Foster
Keyword(s):  
Radiative Transfer ◽  
Coastal Plain ◽  
Crystal Size ◽  
Microwave Radiometer ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Snow Pack ◽  
Arctic Coastal Plain ◽  
Crystal Diameter

AbstractThe snow-pack on the Arctic Coastal Plain of Alaska has a well-developed depth-hoar layer which forms each year at the base of the snow-pack due to upward vapor transfer resulting from a temperature gradient in the snow-pack. The thickness of the depth-hoar layer tends to increase inland where greater temperature extremes (in particular, lower minimum temperatures) permit larger temperature gradients to develop within the snow-pack. Brightness temperature (TB) data were analyzed from October through May for four winters using the 37 GHz horizontally polarized Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR). By mid-winter each year, a decrease in TB of approximately 20K was found between coastal and inland sites on the Arctic Coastal Plain of Alaska. Modeling has indicated that a thicker depth-hoar layer in the inland sites could be responsible for the lower TBs. The large grain-sizes of the depth-hoar crystals scatter the upwelling radiation moreso than do smaller crystals, and greater scattering lowers the microwave TB. Using a two-layered radiative transfer model, the crystal diameter in the top layer was assumed to be 0.50 mm. The crystals in the depth-hoar layer may be 5–10 mm in diameter but the effective crystal diameter used in the radiative-transfer model is 1.40 mm. The crystal size used in the model had to be adjusted downward, relative to the actual crystal size, because the hollow, cup-shaped depth-hoar crystals are not as effective at scattering the microwave radiation as are spherical crystals that are assumed in the model. In the model, when the thickness of the depth-hoar layer was increased from 5 cm to 10 cm, a 21K decrease in TB resulted. This is comparable to the decrease in TB observed from coastal to inland sites in the study area.

scholarly journals Parameterizing radiative transfer to convert MAX-DOAS dSCDs into near-surface box-averaged mixing ratios

2013 ◽  
Vol 6 (6) ◽  
pp. 1521-1532 ◽  
Author(s):  
R. Sinreich ◽  
A. Merten ◽  
L. Molina ◽  
R. Volkamer
Keyword(s):  
Boundary Layer ◽  
Radiative Transfer ◽  
Mexico City ◽  
Vertical Gradient ◽  
Radiative Transfer Model ◽  
Optical Absorption Spectroscopy ◽  
Transfer Model ◽  
Model Calculations ◽  
Near Surface ◽  
Mixing Ratios

Abstract. We present a novel parameterization method to convert multi-axis differential optical absorption spectroscopy (MAX-DOAS) differential slant column densities (dSCDs) into near-surface box-averaged volume mixing ratios. The approach is applicable inside the planetary boundary layer under conditions with significant aerosol load, and builds on the increased sensitivity of MAX-DOAS near the instrument altitude. It parameterizes radiative transfer model calculations and significantly reduces the computational effort, while retrieving ~ 1 degree of freedom. The biggest benefit of this method is that the retrieval of an aerosol profile, which usually is necessary for deriving a trace gas concentration from MAX-DOAS dSCDs, is not needed. The method is applied to NO2 MAX-DOAS dSCDs recorded during the Mexico City Metropolitan Area 2006 (MCMA-2006) measurement campaign. The retrieved volume mixing ratios of two elevation angles (1° and 3°) are compared to volume mixing ratios measured by two long-path (LP)-DOAS instruments located at the same site. Measurements are found to agree well during times when vertical mixing is expected to be strong. However, inhomogeneities in the air mass above Mexico City can be detected by exploiting the different horizontal and vertical dimensions probed by the MAX-DOAS and LP-DOAS instruments. In particular, a vertical gradient in NO2 close to the ground can be observed in the afternoon, and is attributed to reduced mixing coupled with near-surface emission inside street canyons. The existence of a vertical gradient in the lower 250 m during parts of the day shows the general challenge of sampling the boundary layer in a representative way, and emphasizes the need of vertically resolved measurements.

scholarly journals A synthetic data set of high-spectral resolution infrared spectra for the Arctic atmosphere

2016 ◽  
Author(s):  
C. J. Cox ◽  
P. M. Rowe ◽  
S. P. Neshyba ◽  
V. P. Walden
Keyword(s):  
Remote Sensing ◽  
Radiative Transfer ◽  
Infrared Spectra ◽  
Spectral Resolution ◽  
High Spectral Resolution ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Data Set ◽  
Atmospheric State

Abstract. Retrievals of cloud microphysical and macrophysical properties from ground-based and satellite-based infrared remote sensing instruments are critical for understanding clouds. However, retrieval uncertainties are difficult to quantify without a standard for comparison. This is particularly true over the polar regions where surface-based data for a cloud climatology are sparse, yet clouds represent a major source of uncertainty in weather and climate models. We describe a synthetic high-spectral resolution infrared data set that is designed to facilitate validation and development of cloud retrieval algorithms for surface- and satellite-based remote sensing instruments. Since the data set is calculated using pre-defined cloudy atmospheres, the properties of the cloud and atmospheric state are known a priori. The atmospheric state used for the simulations is drawn from radiosonde measurements made at the North Slope of Alaska (NSA) Atmospheric Radiation Measurement (ARM) site at Barrow, Alaska (71.325° N, 156.615° W), a location that is generally representative of the western Arctic. The cloud properties for each simulation are selected from statistical distributions derived from past field measurements. Upwelling (at 60 km) and downwelling (at the surface) infrared spectra are simulated for 222 cloudy cases from 50–3000 cm−1 (3.3 to 200 μm) at monochromatic (line-by-line) resolution at a spacing of ~ 0.01 cm−1 using the Line-by-line Radiative Transfer Model (LBLRTM) and the discrete-ordinate-method radiative transfer code (DISORT). These spectra are freely available for interested researchers from the ACADIS data repository (doi:10.5065/D61J97TT).

scholarly journals A case study on biomass burning aerosols: effects on solar UV irradiance, retrieval of aerosol single scattering albedo

2008 ◽  
Vol 8 (5) ◽  
pp. 17987-18005 ◽  
Author(s):  
A. Bagheri ◽  
B. Kjeldstad ◽  
B. Johnsen
Keyword(s):  
Radiative Transfer ◽  
Uv Radiation ◽  
Biomass Burning ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Uv Irradiance ◽  
Surface Measurements

Abstract. The aerosol optical depth (AOD) from biomass burning aerosols from eastern Europe was measured in Trondheim, Norway (63.43° N , 10.43° E) in May 2006. The event was observed as far as the Arctic. In the first part of this paper, the surface measurements of direct and global UV radiation (and retrieved AOD) are used to simulate the data using a radiative transfer model. Measured and simulated data were used to study the effect of biomass aerosol on the levels of surface UV radiation. We found reductions of up to 31%, 15% and 2% in direct, global and diffuse surface UV irradiance (at 350 nm, SZA=50°±0.5°) as compared to typical aerosol conditions. In the second part of our study, surface measurements of global and direct irradiance at five wavelength in UVB and UVA (305, 313, 320, 340 and 380 nm) were coupled with a radiative transfer model to produce values of aerosol single scattering albedo, ω. The aerosol single scattering albedo for biomass aerosols is compared to ω for background aerosols. The values of ω for biomass aerosols were 0.76 at 305 nm, 0.75 at 313 nm, 0.79 at 320 nm, 0.72 at 340 nm and 0.80 at 380 nm.

scholarly journals Accounting for the effect of horizontal gradients in limb measurements of scattered sunlight

2008 ◽  
Vol 8 (12) ◽  
pp. 3045-3060 ◽  
Author(s):  
J. Puķīte ◽  
S. Kühl ◽  
T. Deutschmann ◽  
U. Platt ◽  
T. Wagner
Keyword(s):  
Monte Carlo ◽  
Radiative Transfer ◽  
Scattered Light ◽  
Trace Gases ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Boreal Winter ◽  
Transfer Model ◽  
Measurement Sensitivity ◽  
Horizontal Gradients

Abstract. Limb measurements provided by the SCanning Imaging Absorption spectrometer for Atmospheric CHartographY (SCIAMACHY) on the ENVISAT satellite allow retrieving stratospheric profiles of various trace gases on a global scale, among them BrO for the first time. For limb observations in the UV/VIS spectral region the instrument measures scattered light with a complex distribution of light paths: the light is measured at different tangent heights and can be scattered or absorbed in the atmosphere or reflected by the ground. By means of spectroscopy and radiative transfer modelling these measurements can be inverted to retrieve the vertical distribution of stratospheric trace gases. The fully spherical 3-D Monte Carlo radiative transfer model "Tracy-II" is applied in this study. The Monte Carlo method benefits from conceptual simplicity and allows realizing the concept of full spherical geometry of the atmosphere and also its 3-D properties, which is important for a realistic description of the limb geometry. Furthermore it allows accounting for horizontal gradients in the distribution of trace gases. In this study the effect of horizontally inhomogeneous distributions of trace gases along flight/viewing direction on the retrieval of profiles is investigated. We introduce a tomographic method to correct for this effect by combining consecutive limb scanning sequences and utilizing the overlap in their measurement sensitivity regions. It is found that if horizontal inhomogenity is not properly accounted for, typical errors of 20% for NO2 and up to 50% for OClO around the altitude of the profile peak can arise for measurements close to the Arctic polar vortex boundary in boreal winter.

scholarly journals Regional radiative impact of volcanic aerosol from the 2009 eruption of Mt. Redoubt

2012 ◽  
Vol 12 (8) ◽  
pp. 3699-3715 ◽  
Author(s):  
C. L. Young ◽  
I. N. Sokolik ◽  
J. Dufek
Keyword(s):  
Radiative Transfer ◽  
Environmental Conditions ◽  
Radiative Forcing ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Layer ◽  
Volcanic Aerosol ◽  
High Northern Latitude ◽  
Arctic Environment

Abstract. High northern latitude eruptions have the potential to release volcanic aerosol into the Arctic environment, perturbing the Arctic's climate system. We present assessments of shortwave (SW), longwave (LW) and net direct aerosol radiative forcing efficiencies and atmospheric heating/cooling rates caused by volcanic aerosol from the 2009 eruption of Mt. Redoubt by performing radiative transfer modeling constrained by NASA A-Train satellite data. The optical properties of volcanic aerosol were calculated by introducing a compositionally resolved microphysical model developed for both ash and sulfates. Two compositions of volcanic aerosol were considered in order to examine a fresh, ash rich plume and an older, ash poor plume. Optical models were incorporated into a modified version of the SBDART radiative transfer model. Our results indicate that environmental conditions, such as surface albedo and solar zenith angle (SZA), can influence the sign and the magnitude of the radiative forcing at the top of the atmosphere (TOA) and at the surface and the magnitude of the forcing in the aerosol layer. We find that a fresh, thin plume (~2.5–7 km) at an AOD (550 nm) range of 0.18–0.58 and SZA = 55° over snow cools the surface and warms the TOA, but the opposite effect is seen for TOA by the same layer over ocean. The layer over snow also warms by 64 W m−2AOD−1 more than the same plume over seawater. The layer over snow at SZA = 75° warms the TOA 96 W m−2AOD−1 less than it would at SZA = 55° over snow, and there is instead warming at the surface. We also find that plume aging can alter the magnitude of the radiative forcing. An aged plume over snow at SZA = 55° would warm the TOA and layer by 146 and 143 W m−2AOD−1 less than the fresh plume, while the aging plume cools the surface 3 W m−2AOD−1 more. Comparing results for the thin plume to those for a thick plume (~3–20 km), we find that the fresh, thick plume with AOD(550 nm) = 3, over seawater, and SZA = 55° heats the upper part of the plume in the SW ~28 K day−1 more and cools in the LW by ~6.3 K day−1 more than a fresh, thin plume under the same environmental conditions. We compare our assessments with those reported for other aerosols typical to the Arctic environment (smoke from wildfires, Arctic haze, and dust) to demonstrate the importance of volcanic aerosols.

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