Spatial Patterns of Climate Variability in Upper-Tropospheric Water Vapor Radiances from Satellite Data and Climate Model Simulations

Abstract Stratospheric water vapor concentrations and age of air are investigated in an ensemble of coupled chemistry-climate model simulations covering the period from 1960 to 2005. Observed greenhouse gas concentrations, halogen concentrations, aerosol amounts, and sea surface temperatures are all specified in the model as time-varying fields. The results are compared with two experiments (time-slice runs) with constant forcings for the years 1960 and 2000, in which the sea surface temperatures are set to the same climatological values, aerosol concentrations are fixed at background levels, while greenhouse gas and halogen concentrations are set to the values for the relevant years. The time-slice runs indicate an increase in stratospheric water vapor from 1960 to 2000 due primarily to methane oxidation. The age of air is found to be significantly less in the year 2000 run than the 1960 run. The transient runs from 1960 to 2005 indicate broadly similar results: an increase in water vapor and a decrease in age of air. However, the results do not change gradually. The age of air decreases significantly only after about 1975, corresponding to the period of ozone reduction. The age of air is related to tropical upwelling, which determines the transport of methane into the stratosphere. Oxidation of increased methane from enhanced tropical upwelling results in higher water vapor amounts. In the model simulations, the rate of increase of stratospheric water vapor during the period of enhanced upwelling is up to twice the long-term mean. The concentration of stratospheric water vapor also increases following volcanic eruptions during the simulations.

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Interannual Variations of Stratospheric Water Vapor in MLS Observations and Climate Model Simulations

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-14-0164.1 ◽

2014 ◽

Vol 71 (11) ◽

pp. 4072-4085 ◽

Cited By ~ 15

Author(s):

Yoshio Kawatani ◽

Jae N. Lee ◽

Kevin Hamilton

Keyword(s):

Water Vapor ◽

Climate Model ◽

Coupled Model ◽

Vertical Gradient ◽

Quasi Biennial Oscillation ◽

Model Simulations ◽

Stratospheric Water Vapor ◽

Budget Analysis ◽

Climate Model Simulations ◽

Interannual Fluctuations

Abstract By analyzing the almost-decade-long record of water vapor measurements from the Microwave Limb Sounder (MLS) instrument on the NASA Aura satellite and by detailed diagnostic analysis of the results from state-of-the art climate model simulations, this study confirmed the conceptual picture of the interannual variation in equatorial stratospheric water vapor discussed in earlier papers (e.g., Geller et al.). The interannual anomalies in water vapor are strongly related to the dynamical quasi-biennial oscillation (QBO), and this study presents the first QBO composite of the time–height structure of the equatorial water vapor anomalies. The anomalies display upward propagation below about 10 hPa in a manner analogous to the annual “tape recorder” effect, but at higher levels they show clear downward propagation. This study examined these variations in the Model for Interdisciplinary Research on Climate (MIROC)-AGCM and in four models in phase 5 of the Coupled Model Intercomparison Project (CMIP5) that simulate realistic QBOs. Diagnostic budget analysis of the MIROC-AGCM data and comparisons among the CMIP5 model results demonstrate (i) the importance of temperature anomalies at the tropopause induced by the QBO for lower-stratospheric water vapor variations and (ii) that upper-stratospheric water vapor anomalies are largely driven by advection of the mean vertical gradient of water content by the QBO interannual fluctuations in the vertical wind.

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Mechanisms of Global Warming Impacts on Robustness of Tropical Precipitation Asymmetry

Journal of Climate ◽

10.1175/2008jcli2154.1 ◽

2008 ◽

Vol 21 (21) ◽

pp. 5585-5602 ◽

Cited By ~ 16

Author(s):

Pei-Hua Tan ◽

Chia Chou ◽

Jien-Yi Tu

Keyword(s):

Global Warming ◽

Water Vapor ◽

Climate Model ◽

Hadley Circulation ◽

The Other ◽

Multimodel Ensemble ◽

Model Simulations ◽

Tropical Precipitation ◽

Precipitation Anomalies ◽

Climate Model Simulations

Abstract Hemispherically and temporally asymmetric tropical precipitation responses to global warming are evaluated in 13 different coupled atmosphere–ocean climate model simulations. In the late boreal summer, hemispherical averages of the tropical precipitation anomalies from the multimodel ensemble show a strong positive trend in the Northern Hemisphere and a weak negative trend in the Southern Hemisphere. In the late austral summer, on the other hand, the trends are reversed. This implies that the summer hemisphere becomes wetter and the winter hemisphere becomes a little drier in the tropics. Thus, the seasonal range of tropical precipitation, differences between wet and dry seasons, is increased. Zonal averages of the precipitation anomalies from the multimodel ensemble also reveal a meridional movement, which basically follows the seasonal migration of the main convection zone. Similar asymmetric features can be found in all 13 climate model simulations used in this study. Based on the moisture budget analysis, the vertical moisture advection associated with mean circulation is the main contribution for the robustness of the asymmetric distribution of the tropical precipitation anomalies. Under global warming, tropospheric water vapor increases as the temperature rises and most enhanced water vapor is in the lower troposphere. The ascending motion of the Hadley circulation then transports more water vapor upward, that is, anomalous moisture convergence, and enhances precipitation over the main convection zones. On the other hand, the thermodynamic effect associated with the descending motion of the Hadley circulation, that is, anomalous moisture divergence, reduces the precipitation over the descending regions.

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Dust-aerosol optical depth in CMIP6 models and implication for PV-power generation

10.5194/egusphere-egu21-2049 ◽

2021 ◽

Author(s):

Robert Scheele ◽

Stephanie Fiedler

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Satellite Data ◽

Power Plants ◽

Climate Model ◽

Dust Aerosol ◽

Model Simulations ◽

Desert Dust ◽

Dust Aerosols ◽

Climate Model Simulations

Renewable energy produced by photovoltaic (PV) power plants strongly depends on the meteorological conditions. Desert-dust aerosols impair the radiative transfer in the atmosphere, but their effect on PV power is poorly understood from a climatological perspective. Past climate model simulations are known to have a large spread in dust-aerosol loading. With the new CMIP6 model simulations now being available, we revisit the climate-model spread in representing desert-dust aerosols for 1985 to 2014, assess the dust-aerosol changes until 2100, and estimate the associated differences in the PV power potential. To this end, we evaluate the dust aerosol optical depth (DOD) in the CMIP6 historical simulations using modern reanalysis and satellite data. Our results highlight the persistent model spread for DOD in CMIP6, but a multi-model mean DOD close to the reanalysis and satellite data. We identify only slight changes in both the global and regional mean DOD in a green scenario (ssp126) at the end of the 21st century. For a future with continued strong warming (ssp245, ssp585), the simulations suggest an increase (decrease) in regional DOD associated with North-African, Transatlantic transport, and Australia (Taklamakan Desert) dust emissions. The differences in simulated DOD imply changes in the PV power potential for regions affected by dust aerosols. We compute the change in the PV power potential from surface irradiance, temperature, and wind speed in the CMIP6 scenarios against present-day. Our results point to a PV power&#160;potential&#160;for North Africa that is similarly affected by a future increase in temperature and decrease in irradiance associated with more dust aerosols. In mid-latitude regions of the northern hemisphere, a future change in PV power&#160;potential&#160;is controlled by changes of clouds and temperature. Our PV power estimates underline the impacts of the model uncertainty in DOD, the degree of future warming, and the unclear response of clouds and circulation to the warming.

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Temperature and Water Vapor Variance Scaling in Global Models: Comparisons to Satellite and Aircraft Data

Journal of the Atmospheric Sciences ◽

10.1175/2011jas3737.1 ◽

2011 ◽

Vol 68 (9) ◽

pp. 2156-2168 ◽

Cited By ~ 35

Author(s):

B. H. Kahn ◽

J. Teixeira ◽

E. J. Fetzer ◽

A. Gettelman ◽

S. M. Hristova-Veleva ◽

...

Keyword(s):

Water Vapor ◽

Spatial Resolution ◽

Climate Model ◽

Weather Prediction ◽

Atmospheric Model ◽

Small Scale ◽

Scaling Exponents ◽

Model Simulations ◽

Free Running ◽

Climate Model Simulations

Abstract Observations of the scale dependence of height-resolved temperature T and water vapor q variability are valuable for improved subgrid-scale climate model parameterizations and model evaluation. Variance spectral benchmarks for T and q obtained from the Atmospheric Infrared Sounder (AIRS) are compared to those generated by state-of-the-art numerical weather prediction “analyses” and “free-running” climate model simulations with spatial resolution comparable to AIRS. The T and q spectra from both types of models are generally too steep, with small-scale variance up to several factors smaller than AIRS. However, the two model analyses more closely resemble AIRS than the two free-running model simulations. Scaling exponents obtained for AIRS column water vapor (CWV) and height-resolved layers of q are also compared to the superparameterized Community Atmospheric Model (SP-CAM), highlighting large differences in the magnitude of CWV variance and the relative flatness of height-resolved q scaling in SP-CAM. Height-resolved q spectra obtained from aircraft observations during the Variability of the American Monsoon Systems Ocean–Cloud–Atmosphere–Land Study Regional Experiment (VOCALS-REx) demonstrate changes in scaling exponents that depend on the observations’ proximity to the base of the subsidence inversion with scale breaks that occur at approximately the dominant cloud scale (~10–30 km). This suggests that finer spatial resolution requirements must be considered for future satellite observations of T and q than those currently planned for infrared and microwave satellite sounders.

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Mechanisms for Global Warming Impacts on Precipitation Frequency and Intensity

Journal of Climate ◽

10.1175/jcli-d-11-00239.1 ◽

2012 ◽

Vol 25 (9) ◽

pp. 3291-3306 ◽

Cited By ~ 97

Author(s):

Chia Chou ◽

Chao-An Chen ◽

Pei-Hua Tan ◽

Kuan Ting Chen

Keyword(s):

Global Warming ◽

Water Vapor ◽

Climate Model ◽

Vertical Motion ◽

Heavy Precipitation ◽

Precipitation Frequency ◽

Dynamic Component ◽

Model Simulations ◽

Climate Model Simulations ◽

Dynamic Components

Global warming mechanisms that cause changes in frequency and intensity of precipitation in the tropics are examined in climate model simulations. Under global warming, tropical precipitation tends to be more frequent and intense for heavy precipitation but becomes less frequent and weaker for light precipitation. Changes in precipitation frequency and intensity are both controlled by thermodynamic and dynamic components. The thermodynamic component is induced by changes in atmospheric water vapor, while the dynamic component is associated with changes in vertical motion. A set of equations is derived to estimate both thermodynamic and dynamic contributions to changes in frequency and intensity of precipitation, especially for heavy precipitation. In the thermodynamic contribution, increased water vapor reduces the magnitude of the required vertical motion to generate the same strength of precipitation, so precipitation frequency increases. Increased water vapor also intensifies precipitation due to the enhancement of water vapor availability in the atmosphere. In the dynamic contribution, the more stable atmosphere tends to reduce the frequency and intensity of precipitation, except for the heaviest precipitation. The dynamic component strengthens the heaviest precipitation in most climate model simulations, possibly due to a positive convective feedback.

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Greenland temperature and precipitation over the last 20 000 years using data assimilation

Climate of the Past ◽

10.5194/cp-16-1325-2020 ◽

2020 ◽

Vol 16 (4) ◽

pp. 1325-1346

Author(s):

Jessica A. Badgeley ◽

Eric J. Steig ◽

Gregory J. Hakim ◽

Tyler J. Fudge

Keyword(s):

Data Assimilation ◽

Spatial Patterns ◽

Climate Model ◽

Ice Core ◽

Ice Sheet ◽

Proxy Data ◽

Model Simulations ◽

Temperature And Precipitation ◽

Climate Model Simulations ◽

Paleoclimate Data

Abstract. Reconstructions of past temperature and precipitation are fundamental to modeling the Greenland Ice Sheet and assessing its sensitivity to climate. Paleoclimate information is sourced from proxy records and climate-model simulations; however, the former are spatially incomplete while the latter are sensitive to model dynamics and boundary conditions. Efforts to combine these sources of information to reconstruct spatial patterns of Greenland climate over glacial–interglacial cycles have been limited by assumptions of fixed spatial patterns and a restricted use of proxy data. We avoid these limitations by using paleoclimate data assimilation to create independent reconstructions of mean-annual temperature and precipitation for the last 20 000 years. Our method uses oxygen isotope ratios of ice and accumulation rates from long ice-core records and extends this information to all locations across Greenland using spatial relationships derived from a transient climate-model simulation. Standard evaluation metrics for this method show that our results capture climate at locations without ice-core records. Our results differ from previous work in the reconstructed spatial pattern of temperature change during abrupt climate transitions; this indicates a need for additional proxy data and additional transient climate-model simulations. We investigate the relationship between precipitation and temperature, finding that it is frequency dependent and spatially variable, suggesting that thermodynamic scaling methods commonly used in ice-sheet modeling are overly simplistic. Our results demonstrate that paleoclimate data assimilation is a useful tool for reconstructing the spatial and temporal patterns of past climate on timescales relevant to ice sheets.

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Impact of Lagrangian transport on lower-stratospheric water vapor and radiative balance in a climate model

10.5194/egusphere-egu21-7571 ◽

2021 ◽

Author(s):

Edward Charlesworth ◽

Felix Plöger ◽

Patrick Jöckel

Keyword(s):

Water Vapor ◽

Climate Model ◽

Stratospheric Ozone ◽

Chem Phys ◽

Climate Feedback ◽

Lagrangian Transport ◽

Radiative Balance ◽

Model Simulations ◽

Stratospheric Water Vapor ◽

Climate Model Simulations

A robust result of climate model simulations is the moistening of the stratosphere. Many models show their strongest changes in stratospheric water vapor in the extratropical lowermost stratosphere, a change which could have substantial climate feedbacks (e.g. Banerjee et al. 2019). However, models are also heavily wet-biased in this region when compared to observations (Keeble et al. 2020), presenting some uncertainty on the robustness of these model results.In this study, we investigate the contribution of the choice of model transport scheme to this wet bias using a climate model (EMAC) coupled with two transport schemes: the standard EMAC flux-form semi-Lagrangian (FFSL) scheme and the fully-Lagrangian scheme of CLaMS. This experiment has the advantage of analytical clarity in that the dynamical fields driving both transport schemes are identical. Prior work using this tool has shown large differences in transport timecales within the extratropical lowermost stratosphere depending on the transport scheme used (Charlesworth et al. 2020).&#160;These results also suggested that EMAC-CLaMS should reduce the transport of water vapor into this region, but calculations of water vapor fields using this tool were not performed until now. We present the results of that work, comparing the water vapor fields calculated using EMAC-CLaMS and EMAC-FFSL online. Two model simulations were performed, wherein each water vapor field was used to drive radiation calculations, such that the radiative consequences of applying one transport scheme or the other could be assessed.References:Banerjee, A., Chiodo, G., Previdi, M. et al. Stratospheric water vapor: an important climate feedback. Clim Dyn 53, 1697&#8211;1710 (2019). https://doi.org/10.1007/s00382-019-04721-4Keeble, J., Hassler, B., Banerjee, A., Checa-Garcia, R., Chiodo, G., Davis, S., Eyring, V., Griffiths, P. T., Morgenstern, O., Nowack, P., Zeng, G., Zhang, J., Bodeker, G., Cugnet, D., Danabasoglu, G., Deushi, M., Horowitz, L. W., Li, L., Michou, M., Mills, M. J., Nabat, P., Park, S., and Wu, T.: Evaluating stratospheric ozone and water vapor changes in CMIP6 models from 1850&#8211;2100, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2019-1202, in review, 2020.&#160;Charlesworth, E. J., Dugstad, A.-K., Fritsch, F., J&#246;ckel, P., and Pl&#246;ger, F.: Impact of Lagrangian transport on lower-stratospheric transport timescales in a climate model, Atmos. Chem. Phys., 20, 15227&#8211;15245, https://doi.org/10.5194/acp-20-15227-2020, 2020.&#160;

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