Search Constraints
1 - 5 of 5
Number of results to display per page
View results as:
Search Results
-
- Creator:
- Steiner, Allison and Bryan, Alex
- Description:
- Included are RegCM simulations driven by three different types of boundary conditions 1. ERA - present day only (1979-2005) 2. GFDL - present day (1978-2005) and future (2041-2065) 3. HadGEM - present day (1978-2005) and future (2041-2065) Each directory has three files with monthly averaged values: ATM: includes 4D (t,z,y,x) atmospheric fields (pressure, winds, temperature, specific humidity, cloud water) and some 3D fields (t,y,x) precipitation, soil temperature, soil water SRF: includes 3D (t,y,x) surface variables (surface pressure, 10m winds, drag coefficient, surface temperature, 2m air temperature, soil moisture, precipitation, runoff, snow, sensible heat flux, latent heat flux, surface radiation components (SW, LW), PBL height, albedo, sunshine duration) RAD: includes 4D radiative transfer variables (SW and LW heating, TOA fluxes, cloud fraction, ice water content) clm_h0 files: CLM land surface files, includes canopy variables, surface fluxes, soil moisture by layers, etc. "
- Keyword:
- climate
- Citation to related publication:
- Bryan, A. M., A. L. Steiner, and D. J. Posselt (2015), Regional modeling of surface-atmosphere interactions and their impact on Great Lakes hydroclimate, J. Geophys. Res. Atmos., 120, 1044–1064. https://doi.org/10.1002/2014JD022316
- Discipline:
- Science
-
- Creator:
- Flanner, Mark
- Description:
- Greenhouse gas (GHG) additions to Earth’s atmosphere initially reduce global outgoing longwave radiation (OLR), thereby warming the planet. In select environments with temperature inversions, however, increased GHG concentrations can actually increase local OLR. Negative top-of-atmosphere and effective radiative forcing (ERF) from this situation give the impression that local surface temperatures could cool in response to GHG increases. Here we consider an extreme scenario in which GHG concentrations are increased only within the warmest layers of winter near-surface inversions of the Arctic and Antarctic. We find, using a fully coupled Earth system model, that the underlying surface warms despite the GHG addition exerting negative ERF and cooling the troposphere in the vicinity of the GHG increase. This unique radiative forcing and thermal response is facilitated by the high stability of the polar winter atmosphere, which inhibits thermal mixing and amplifies the impact of surface radiative forcing on surface temperature. These findings also suggest that strategies to exploit negative ERF via injections of short-lived GHGs into inversion layers would likely be unsuccessful in cooling the planetary surface. and Note: A revised data description file was added to this work on April 11, 2018 containing additional information about the data set than was provided in the original description. Additional keywords and a full citation to the related article were added as well.
- Keyword:
- climate, greenhouse gas, polar inversion layers, radiative forcing (and/or effective radiative forcing), and MODTRAN simulation
- Discipline:
- Science
-
- Creator:
- Ward, Jamie L ., Flanner, Mark G., Bergin, Mike, Dibb, Jack E., Polashenski, Chris M., Soja, Amber J., and Thomas, Jennie L.
- Description:
- Biomass burning produces smoke aerosols that are emitted into the atmosphere. Some smoke constituents, notably black carbon (BC), are highly effective light-absorbing aerosols (LAA). Emitted LAA can be transported to high albedo regions like the Greenland Ice Sheet (GrIS) and affect local snowmelt. In the summer, the effects of LAA in Greenland are uncertain. To explore how LAA affect GrIS snowmelt and surface energy flux in the summer, we conduct idealized global climate model simulations with perturbed aerosol amounts and properties in the GrIS snow and overlying atmosphere. The in-snow and atmospheric aerosol burdens we select range from background values measured on the GrIS to unrealistically high values. This helps us explore the linearity of snowmelt response and to achieve high signal-to-noise ratios. With LAA operating only in the atmosphere, we find no significant change in snowmelt due to the competing effects of surface dimming and tropospheric warming. Regardless of atmospheric LAA presence, in-snow BC-equivalent mixing ratios greater than ~60 ng/g produce statistically significant snowmelt increases over much of the GrIS. We find that net surface energy flux changes correspond well to snowmelt changes for all cases. The dominant component of surface energy flux change is solar energy flux, but sensible and longwave energy fluxes respond to temperature changes. Atmospheric LAA dampen the magnitude of solar radiation absorbed by in-snow LAA when both varieties are simulated. In general, the significant melt and surface energy flux changes we simulate occur with LAA quantities that have never been recorded in Greenland.
- Keyword:
- climate, Greenland Ice Sheet, black carbon, biomass burning, snowmelt, and surface energy balance
- Discipline:
- Science
-
- Creator:
- Yang, Emily G, Kort, Eric A, Wu, Dien, Lin, John C, Oda, Tomohiro, Ye, Xinxin, and Lauvaux, Thomas
- Description:
- This data set supports a study that seeks to evaluate global fossil fuel CO2 emissions inventory representations of CO2 emissions of five cities in the Middle East, and assess the ability of satellite observations to inform this evaluation. Improved observational understanding of urban CO2 emissions, a large and dynamic global source of fossil CO2, can provide essential insights for both carbon cycle science and mitigation decision making. In this study we compare three distinct global CO2 emissions inventory representations of urban CO2 emissions for five Middle Eastern cities (Riyadh, Mecca, Tabuk, Jeddah, and Baghdad) and use independent satellite observations from the Orbiting Carbon Observatory-2 (OCO-2) satellite to evaluate the inventory representations of afternoon emissions. We use the column version of the Stochastic Time-Inverted Lagrangian Transport (X-STILT) model to account for atmospheric transport and link emissions to observations. We compare XCO2 simulations with observations to determine optimum inventory scaling factors. Applying these factors, we find that the average summed emissions for all five cities are 100 MtC/y (50-151, 90% CI), which is 2.0 (1.0, 3.0) times the average prior inventory magnitudes. The total adjustment of the emissions of these cities comes out to ~7% (0%, 14%) of total Middle Eastern emissions (~700 MtC/y). We find our results to be insensitive to the prior spatial distributions in inventories of the cities’ emissions, facilitating robust quantitative assessments of urban emission magnitudes without accurate high-resolution gridded inventories. and There are three files included in this data set, and all data are in tab-delimited form. The first file, xco2_lat.zip, contains 26 separate text files, each named by the city and date of the corresponding OCO-2 overpass. Each of these 26 files includes overpass-specific data, with modeled and observed XCO2 values binned by 0.1 degree of latitude. The file overpass_scaling_factors.txt provides the scaling factors for each overpass used in this study. The file city_estimates.txt provides the scaled emissions estimates for each city (or sum of cities) as well as the lower and upper bounds of the 90% confidence intervals, for each inventory.
- Keyword:
- greenhouse gases, carbon dioxide, urban, cities, satellite, remote sensing, Lagrangian modeling, emissions inventories, carbon cycle, and climate
- Citation to related publication:
- Yang, E. G., Kort, E. A., Wu, D., Lin, J. C., Oda, T., Ye, X., & Lauvaux, T. (2020). Using space‐based observations and Lagrangian modeling to evaluate urban carbon dioxide emissions in the Middle East. Journal of Geophysical Research: Atmospheres, 125, e2019JD031922. https://doi.org/10.1029/2019JD031922
- Discipline:
- Science
-
- Creator:
- Mark Flanner
- Description:
- This dataset includes spectrally-resolved optical properties for volcanic ash particles from the 2010 Eyjafjallajökull volcanic eruptions. These properties were used in the climate simulations described by Flanner et al. (2014, doi:10.1002/2014JD021977) to quantify ash radiative forcing from the eruptions.
- Keyword:
- ash, volcano, aerosols, Eyjafjallajökull, climate, and radiative transfer
- Citation to related publication:
- Flanner, M.G., Gardner, A.S., Eckhardt, S., Stohl, A., & Perket, J. (2014). Aerosol radiative forcing from the 2010 Eyjafjallajökull volcanic eruptions. Journal of Geophysical Research: Atmospheres. https://doi.org/10.1002/2014JD021977
- Discipline:
- Science