Temporal variability of inferred surface energy fluxes derived from the ERA5 energy budget

2020 ◽  
Author(s):  
Johannes Mayer ◽  
Michael Mayer ◽  
Leopold Haimberger
Keyword(s):  
Surface Energy ◽  
Energy Budget ◽  
Temporal Variability ◽  
Heat Content ◽  
Global Ocean ◽  
High Temporal Resolution ◽  
Energy Fluxes ◽  
Ocean Heat Uptake ◽  
Surface Energy Fluxes ◽  
Global Mean

<p>We use the new Copernicus ERA5 reanalysis dataset to evaluate the global atmospheric energy budget using a consistent diagnostic framework and  improved numerical methods. A main outcome of this work are mass consistent divergences of moist static plus kinetic energy fluxes. These divergences are combined with top-of-the-atmosphere fluxes based on satellite observations and reconstructions back to 1985 to obtain net surface energy fluxes (F<sub>S</sub>) with unprecedented accuracy. The global mean of these F<sub>S</sub> fields is unbiased by construction. Hence, this product is well-suited for climate studies and model evaluations.  Here, the temporal variability and stability of inferred F<sub>S</sub>, the land-ocean energy transport and the corresponding water cycle are presented and compared with previous evaluations, which used ERA-Interim. </p><p>The inferred F<sub>S</sub> fields exhibit a much smaller noise level, and sampling errors are drastically reduced due to the high temporal resolution (hourly) of the ERA5 dataset. Energy budget residuals over land are on the order of 17.0 Wm<sup>-2</sup>, which represents a 63 % reduction compared to ERA-Interim. We also present time series of F<sub>S</sub> averaged over the global ocean. Its global mean is 2.0 Wm<sup>-2</sup>, which is in much better agreement with ocean heat uptake than widely used satellite-derived surface flux products. Moreover, it exhibits reasonable temporal stability at least from 2000 onwards. We compare the annual cycles of F<sub>S</sub> over the ocean and ocean heat content variations derived from ocean reanalysis products and find good agreement. Overall, our results demonstrate clear improvements over earlier evaluations, but more work is needed to optimally use the available data and further reduce uncertainties.</p>

Comparing inferred surface energy fluxes with observation-based flux estimates over the ocean

2021 ◽  
Author(s):  
Johannes Mayer ◽  
Michael Mayer ◽  
Leopold Haimberger
Keyword(s):  
Surface Energy ◽  
Energy Budget ◽  
North Atlantic ◽  
Surface Flux ◽  
Surface Fluxes ◽  
Energy Fluxes ◽  
Surface Energy Fluxes ◽  
The North ◽  
The North Atlantic ◽  
Good Agreement

<p>We combine atmospheric energy transports from ECMWF's latest reanalysis dataset ERA5 with observation-based TOA fluxes from CERES-EBAF to infer net surface energy fluxes (FS<sub>inf</sub>) for the period 1985-2018. We present an extensive comparison at scales ranging from global to local using 15 in-situ buoy measurements, parameterized surface fluxes from ERA5, and previous evaluations of FS<sub>inf</sub> using ERA-Interim. We also combine FS<sub>inf</sub> with various estimates of the ocean heat content tendency (OHCT) and observation-based oceanic heat transports from RAPID and moorings in Fram Strait and Barents Sea Opening to evaluate the oceanic energy budget in the North Atlantic Ocean basin.</p><p>Our results show that the indirectly estimated FS<sub>inf</sub> has a 1985-2018 ocean mean of 1.7 W m<sup>-2</sup> (see J.Mayer et al. (2021); under review), which is in good agreement with the long-term mean OHCT derived from ocean reanalyses as well as independent surface flux estimates presented in recent literature (e.g., von Schuckmann et al. (2020); https://doi.org/10.5194/essd-12-2013-2020), suggesting an only small global ocean mean bias of FS<sub>inf</sub>. Moreover, our FS<sub>inf</sub> product is temporally more stable than parameterized surface fluxes from ERA5 and previous FS<sub>inf</sub> estimates using ERA-Interim, at least from 2000 onwards. The evaluation of the oceanic energy budget in the North Atlantic shows good agreement between FS<sub>inf</sub> and observation-based divergence of oceanic heat transports and OHCT such that its residual is on the order of <0.2 PW (~7 W m<sup>-2</sup>). Even on station-scale, FS<sub>inf</sub> agrees reasonably well with buoy-based surface flux measurements with a bias of 19.7 W m<sup>-2</sup> over all 15 buoys  (compared to 21.7 W m<sup>-2</sup> for parameterized surface fluxes), with largest biases in the Indian Ocean. This assessment demonstrates that our inferred surface flux estimate using ERA5 data outperforms parameterized fluxes from the model on all considered spatial scales (global-regional-local) in terms of bias and temporal stability and thus is well-suited for climate studies and model evaluations.</p><p> </p>

scholarly journals Applications of an Updated Atmospheric Energetics Formulation

2018 ◽  
Vol 31 (16) ◽  
pp. 6263-6279 ◽  
Author(s):  
Kevin E. Trenberth ◽  
John T. Fasullo
Keyword(s):  
Surface Energy ◽  
Mass Balance ◽  
Energy Budget ◽  
Temperature Scale ◽  
Hydrological Cycle ◽  
Heat Content ◽  
Total Surface Energy ◽  
Surface Energy Fluxes ◽  
Atmospheric Energetics ◽  
New Formulation

As observations and atmospheric reanalyses have improved, the diagnostics that can be computed with confidence also increase. Accordingly, a new formulation of the energetics of the atmosphere is laid out, with a view to advancing diagnostic studies of Earth’s energy budget and flows. It is utilized to produce assessments of the vertically integrated divergences in both the atmosphere and ocean. Careful conservation of mass is required, with special attention given to the hydrological cycle and redistribution of mass associated with precipitation and evaporation, and a new method for ensuring this is developed. It guarantees that the atmospheric divergence is associated with moisture and precipitation, unlike previous methods. A new term, identified as associated with the enthalpy of precipitation, is included in a preliminary way. It is sensitive to the formulation, and the use of temperature in degrees Celsius instead of Kelvin greatly reduces errors and produces the extra term with values up to about ±5 W m−2. New results for 2000 to 2016 are presented for the vertical-mean and annual-mean diabatic atmospheric heating, atmospheric moistening, and total atmospheric energy divergence. Results for the atmospheric divergence are combined with top-of-atmosphere radiation observations to deduce total surface energy fluxes. Along with estimates of changes in ocean heat content, the Atlantic Ocean meridional heat transports are recomputed for March 2000 through 2013. The new results are compared with previous estimates and an assessment is made of the effects of the new mass balance, change in temperature scale, and the extra precipitation enthalpy term.

Interannual Variability in Arctic Surface Energy Fluxes and their Drivers

2021 ◽  
Author(s):  
Raleigh Grysko ◽  
Jacqueline Oehri ◽  
Gabriela Schaepman-Strub
Keyword(s):  
Surface Energy ◽  
Interannual Variability ◽  
Energy Budget ◽  
Climate Warming ◽  
Atmospheric Stability ◽  
Surface Energy Budget ◽  
The Arctic ◽  
Energy Fluxes ◽  
Surface Energy Fluxes ◽  
Arctic Surface

<div> <p>The Arctic is undergoing amplified climate warming, and temperature and precipitation are predicted to increase even more in the future. Increased climate warming is indicative of changes in the surface energy budget, which lies at the heart of the carbon and water budget. The surface energy budget is an important driver of many earth system processes, and yet has received little attention in the past.</p> </div><div> <p>The goal of this study is to further develop our understanding in the spatio-temporal variability of Arctic surface energy fluxes. Specifically, we will investigate the magnitude and dependence on changes in energy flux drivers interannually at different sites across the Arctic. We used<span> </span><em>in situ</em><span> </span>data from 10 sites gathered from the FLUXNET2015, Arctic Observatory Network, and European Fluxes Database Center repositories. All study sites are of 60° N or higher and spread across the Arctic. The chosen sites include Chokurdakh, Russia (147.5° E, 70.8° N), Cherskiy, Russia (161.3° E, 68.6° N), Kaamanen,, Finland (27.3° E, 69.1° N), Imnavait Creek, USA (-149.3° E, 68.6° N), Zackenberg Heath, Greenland (-20.6° E, 74.5° N), Tiksi, Russia (128.9° E, 71.6° N), Sodankyla, Finland (26.6° E, 67.4° N), Poker Flat, USA (-147.5° E, 65.1° N), Nuuk, Greenland (-51.4° E, 64.1° N), and Samoylov, Russia (126.5° E, 72.4° N). Using these data, we analyzed the interannual variability of surface energy fluxes including net radiation, sensible, latent, and ground heat fluxes, and Bowen ratio including their dependence on potential drivers, such as temperature, wind speed, atmospheric stability, and vapor pressure deficit.</p> </div><p>Our results on interannual variability in surface energy fluxes and flux drivers inform long term climate model simulations across the Arctic, which is critical for the improved prediction of the state and development of the surface energy budget and drivers under current and future conditions in this vulnerable, rapidly changing, and understudied region.</p>

Estimating Global Ocean Heat Content Changes in the Upper 1800 m since 1950 and the Influence of Climatology Choice*

2014 ◽  
Vol 27 (5) ◽  
pp. 1945-1957 ◽  
Author(s):  
John M. Lyman ◽  
Gregory C. Johnson
Keyword(s):  
Heat Content ◽  
Ocean Heat Content ◽  
Global Ocean ◽  
Ocean Temperature ◽  
Vertical Separation ◽  
Ocean Heat Uptake ◽  
Expendable Bathythermograph ◽  
Heat Uptake ◽  
The Mean

Abstract Ocean heat content anomalies are analyzed from 1950 to 2011 in five distinct depth layers (0–100, 100–300, 300–700, 700–900, and 900–1800 m). These layers correspond to historic increases in common maximum sampling depths of ocean temperature measurements with time, as different instruments—mechanical bathythermograph (MBT), shallow expendable bathythermograph (XBT), deep XBT, early sometimes shallower Argo profiling floats, and recent Argo floats capable of worldwide sampling to 2000 m—have come into widespread use. This vertical separation of maps allows computation of annual ocean heat content anomalies and their sampling uncertainties back to 1950 while taking account of in situ sampling advances and changing sampling patterns. The 0–100-m layer is measured over 50% of the globe annually starting in 1956, the 100–300-m layer starting in 1967, the 300–700-m layer starting in 1983, and the deepest two layers considered here starting in 2003 and 2004, during the implementation of Argo. Furthermore, global ocean heat uptake estimates since 1950 depend strongly on assumptions made concerning changes in undersampled or unsampled ocean regions. If unsampled areas are assumed to have zero anomalies and are included in the global integrals, the choice of climatological reference from which anomalies are estimated can strongly influence the global integral values and their trend: the sparser the sampling and the bigger the mean difference between climatological and actual values, the larger the influence.

scholarly journals Comparison of FASST and SNTHERM in Three Snow Accumulation Regimes

2008 ◽  
Vol 9 (6) ◽  
pp. 1443-1463 ◽  
Author(s):  
Susan Frankenstein ◽  
Anne Sawyer ◽  
Julie Koeberle
Keyword(s):  
Surface Energy ◽  
Single Layer ◽  
Soil Strength ◽  
Snow Accumulation ◽  
Dynamic State ◽  
Energy Fluxes ◽  
One Dimensional ◽  
Surface Energy Fluxes ◽  
Snow Model ◽  
Surface Ice

Abstract Numerical experiments of snow accumulation and depletion were carried out as well as surface energy fluxes over four Cold Land Processes Experiment (CLPX) sites in Colorado using the Snow Thermal model (SNTHERM) and the Fast All-Season Soil Strength model (FASST). SNTHERM is a multilayer snow model developed to describe changes in snow properties as a function of depth and time, using a one-dimensional mass and energy balance. The model is intended for seasonal snow covers and addresses conditions found throughout the winter, from initial ground freezing in the fall to snow ablation in the spring. It has been used by many researchers over a variety of terrains. FASST is a newly developed one-dimensional dynamic state-of-the-ground model. It calculates the ground’s moisture content, ice content, temperature, and freeze–thaw profiles as well as soil strength and surface ice and snow accumulation/depletion. Because FASST is newer and not as well known, the authors wanted to determine its use as a snow model by comparing it with SNTHERM, one of the most established snow models available. It is demonstrated that even though FASST is only a single-layer snow model, the RMSE snow depth compared very favorably against SNTHERM, often performing better during the accumulation phase. The surface energy fluxes calculated by the two models were also compared and were found to be similar.

scholarly journals Simulated Sensitivity of Tropical Cyclone Size and Structure to the Atmospheric Temperature Profile

2016 ◽  
Vol 73 (11) ◽  
pp. 4553-4571 ◽  
Author(s):  
Diana R. Stovern ◽  
Elizabeth A. Ritchie
Keyword(s):  
Tropical Cyclone ◽  
Surface Energy ◽  
Temperature Profile ◽  
Convective Available Potential Energy ◽  
Atmospheric Temperature ◽  
Outer Core ◽  
Specific Humidity ◽  
Energy Fluxes ◽  
Surface Energy Fluxes ◽  
Size And Structure

Abstract This study uses the WRF ARW to investigate how different atmospheric temperature environments impact the size and structure development of a simulated tropical cyclone (TC). In each simulation, the entire vertical virtual temperature profile is either warmed or cooled in 1°C increments from an initial specified state while the initial relative humidity profile and sea surface temperature are held constant. This alters the initial amount of convective available potential energy (CAPE), specific humidity, and air–sea temperature difference such that, when the simulated atmosphere is cooled (warmed), the initial specific humidity and CAPE decrease (increase), but the surface energy fluxes from the ocean increase (decrease). It is found that the TCs that form in an initially cooler environment develop larger wind and precipitation fields with more active outer-core rainband formation. Consistent with previous studies, outer-core rainband formation is associated with high surface energy fluxes, which leads to increases in the outer-core wind field. A larger convective field develops despite initializing in a low CAPE environment, and the dynamics are linked to a wider field of surface radial inflow. As the TC matures and radial inflow expands, large imports of relative angular momentum in the boundary layer continue to drive expansion of the TC’s overall size.

Sign in / Sign up

Export Citation Format

Share Document