Climate functions for the use in multi-disciplinary optimisation in the pre-design of supersonic business jet

Abstract Mitigation of climate change is a challenge to science and society. Here, we establish a methodology, applicable in multi-disciplinary optimisation (MDO) during aircraft pre-design, allowing a minimisation of the aircraft’s potential climate impact. In this first step we consider supersonic aircraft flying at a cruise altitude between 45kfeet (~13·5km, 150hPa) and 67kfeet (~20·5km, 50hPa). The methodology is based on climate functions, which give a relationship between 4 parameters representing an aircraft/engine configuration and an expected impact on global mean near surface temperature as an indicator for the impact on climate via changes in the greenhouse gases carbon dioxide, water vapour, ozone and methane. These input parameters are cruise altitude pressure, fuel consumption, fuel flow and Mach number. The climate functions for water vapour and carbon dioxide are independent from the chosen engine, whereas the climate functions for ozone and methane depend on engine parameters describing the nitrogen oxide emissions. Ten engine configurations are taken into account, which were considered in the framework of the EU-project HISAC. An analysis of the reliability of the climate functions with respect to the simplified climate-chemistry model AirClim and a detailed analysis of the climate functions is given.

Download Full-text

Estimates of the climate impact of future small-scale supersonic transport aircraft – results from the HISAC EU-project

The Aeronautical Journal ◽

10.1017/s000192400000364x ◽

2010 ◽

Vol 114 (1153) ◽

pp. 199-206 ◽

Cited By ~ 7

Author(s):

V. Grewe ◽

M. Plohr ◽

G. Cerino ◽

M. Di Muzio ◽

Y. Deremaux ◽

...

Keyword(s):

Water Vapour ◽

Climate Impact ◽

Climate Impacts ◽

Atmospheric Composition ◽

Small Scale ◽

Near Surface ◽

Transport Aircraft ◽

Supersonic Transport ◽

Global Mean Temperature ◽

Eu Project

Abstract The climate impacts of three fleets of supersonic small-scale transport aircraft (S4TA) are simulated. Based on characteristic aircraft parameters, which were developed within the EU-project HISAC, emissions along geographically representative trajectories are calculated and in addition the resulting changes in the atmospheric composition (carbon dioxide, ozone layer, water vapour) and climate (near surface global mean temperature) are deduced. We assume a fleet development with an entry in service in 2015, a full fleet in 2050. The results show a temperature increase of 0·08mK (0·07-0·10mK) with only small but statistically significant variations between the configurations, leading to a minimum climate impact for a weight optimised and hence lower flying aircraft. A climate impact ratio of 3·0 ± 0·4 between a S4TA and its subsonic counterpart is calculated, which is considerable less than for previous supersonic fleets because of a lower flight altitude, leading to smaller water vapour impacts.

Download Full-text

Field measurements of windbreak effects on airflow, turbulent exchanges and microclimates

Australian Journal of Experimental Agriculture ◽

10.1071/ea02004 ◽

2002 ◽

Vol 42 (6) ◽

pp. 665 ◽

Cited By ~ 19

Author(s):

H. A. Cleugh

Keyword(s):

Wind Speed ◽

Water Vapour ◽

Incident Angle ◽

Surface Wind ◽

Field Measurements ◽

Experimental Program ◽

Near Surface ◽

Speed Reduction ◽

Temperature And Humidity ◽

The Impact

While there has been considerable research into airflow around windbreaks, the interaction of this airflow with the exchanges of heat and water vapour has received far less attention. Yet, the effects of windbreaks on microclimates, water use and agricultural productivity depend, in part, on this interaction. A field and wind tunnel experimental program was conducted to quantify the effects of windbreaks on microclimates and evaporation fluxes. This paper describes the field measurements, which were conducted over a 6-week period at a tree windbreak site located in undulating terrain in south-east Australia. The expected features of airflow around porous windbreaks were observed despite the less than ideal nature of the site. As predicted from theory, the air temperature and humidity were elevated, by day, in the quiet zone and the location of the peak increase in temperature and humidity coincided with the location of the minimum wind speed. However, this increase in temperature and humidity was small in size and restricted to the zone within 10 windbreak heights (H) of the windbreak. This pattern contrasts with that for the near surface wind speeds, which were reduced by up to 80% in a sheltered zone that extended from 5 H upwind to over 25 H downwind of the windbreak. Similar differences were found between the turbulent scalar (heat, water vapour) and velocity terms. While both are reduced in the quiet zone, the turbulent scalar terms near the surface were substantially enhanced at the location where the wake zone begins. Here the mean wind speed is reduced by 50% and the turbulent velocity terms return to their upwind values. Wind speed reductions varied linearly with [cos (90 – α)], where α is the incident angle of the wind, for sites located 6 H downwind. This means that the spatial pattern of wind speed reduction applies to all wind directions, provided that distance downwind is expressed in terms of streamwise distance. However, shelter in the near-break region is slightly increased as the wind blows more obliquely towards the windbreak. The atmospheric demand in the quiet zone was reduced when the humidity of the upwind air was low. In such conditions, windbreaks can 'protect' growing crops from the impact of dry air with high atmospheric demand. The corollary is that in humid conditions, the atmospheric demand in the quiet zone can be increased as a result of shelter.

Download Full-text

Assessing the Climate Impact of Formation Flights

Aerospace ◽

10.3390/aerospace7120172 ◽

2020 ◽

Vol 7 (12) ◽

pp. 172 ◽

Cited By ~ 1

Author(s):

Katrin Dahlmann ◽

Sigrun Matthes ◽

Hiroshi Yamashita ◽

Simon Unterstrasser ◽

Volker Grewe ◽

...

Keyword(s):

Climate Impact ◽

Climate Impacts ◽

Response Model ◽

Climate Response ◽

Surface Temperature Change ◽

Near Surface ◽

Average Decrease ◽

Co2 Effects ◽

Saturation Effects ◽

The Impact

An operational measure that is inspired by migrant birds aiming toward the mitigation of aviation climate impact is to fly in aerodynamic formation. When this operational measure is adapted to commercial aircraft it saves fuel and is, therefore, expected to reduce the climate impact of aviation. Besides the total emission amount, this mitigation option also changes the location of emissions, impacting the non-CO2 climate effects arising from NOx and H2O emissions and contrails. Here, we assess these non-CO2 climate impacts with a climate response model to assure a benefit for climate not only due to CO2 emission reductions, but also due to reduced non-CO2 effects. Therefore, the climate response model AirClim is used, which includes CO2 effects and also the impact of water vapor and contrail induced cloudiness as well as the impact of nitrogen dioxide emissions on the ozone and methane concentration. For this purpose, AirClim has been adopted to account for saturation effects occurring for formation flight. The results of the case studies show that the implementation of formation flights in the 50 most popular airports for the year 2017 display an average decrease of fuel consumption by 5%. The climate impact, in terms of average near surface temperature change, is estimated to be reduced in average by 24%, with values of individual formations between 13% and 33%.

Download Full-text

Aircraft type influence on contrail properties

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-11965-2013 ◽

2013 ◽

Vol 13 (23) ◽

pp. 11965-11984 ◽

Cited By ~ 31

Author(s):

P. Jeßberger ◽

C. Voigt ◽

U. Schumann ◽

I. Sölch ◽

H. Schlager ◽

...

Keyword(s):

Climate Impact ◽

Linear Increase ◽

Meteorological Conditions ◽

Analytical Relationship ◽

Fuel Flow ◽

Research Aircraft ◽

Meteorological Influences ◽

Aircraft Type ◽

Passenger Aircraft ◽

The Impact

Abstract. The investigation of the impact of aircraft parameters on contrail properties helps to better understand the climate impact from aviation. Yet, in observations, it is a challenge to separate aircraft and meteorological influences on contrail formation. During the CONCERT campaign in November 2008, contrails from 3 Airbus passenger aircraft of types A319-111, A340-311 and A380-841 were probed at cruise under similar meteorological conditions with in situ instruments on board DLR research aircraft Falcon. Within the 2 min-old contrails detected near ice saturation, we find similar effective diameters Deff (5.2–5.9 μm), but differences in particle number densities nice (162–235 cm−3) and in vertical contrail extensions (120–290 m), resulting in large differences in contrail optical depths τ at 550 nm (0.25–0.94). Hence larger aircraft produce optically thicker contrails. Based on the observations, we apply the EULAG-LCM model with explicit ice microphysics and, in addition, the Contrail and Cirrus Prediction (CoCiP) model to calculate the aircraft type impact on young contrails under identical meteorological conditions. The observed increase in τ for heavier aircraft is confirmed by the models, yet for generally smaller τ. CoCiP model results suggest that the aircraft dependence of climate-relevant contrail properties persists during contrail lifetime, adding importance to aircraft-dependent model initialization. We finally derive an analytical relationship between contrail, aircraft and meteorological parameters. Near ice saturation, contrail width × τ scales linearly with the fuel flow rate, as confirmed by observations. For higher relative humidity with respect to ice (RHI), the analytical relationship suggests a non-linear increase in the form (RHI-12/3. Summarized, our combined results could help to more accurately assess the climate impact from aviation using an aircraft-dependent contrail parameterization.

Download Full-text

Aircraft type influence on contrail properties

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-13915-2013 ◽

2013 ◽

Vol 13 (5) ◽

pp. 13915-13966 ◽

Cited By ~ 7

Author(s):

P. Jeßberger ◽

C. Voigt ◽

U. Schumann ◽

I. Sölch ◽

H. Schlager ◽

...

Keyword(s):

Climate Impact ◽

Linear Increase ◽

Meteorological Conditions ◽

Analytical Relationship ◽

Fuel Flow ◽

Research Aircraft ◽

Meteorological Influences ◽

Aircraft Type ◽

Passenger Aircraft ◽

The Impact

Abstract. The investigation of the impact of aircraft parameters on contrail properties helps to better understand the climate impact from aviation. Yet, in observations, it is a challenge to separate aircraft and meteorological influences on contrail formation. During the CONCERT campaign in November 2008, contrails from 3 Airbus passenger aircraft of type A319-111, A340-311 and A380-841 were probed at cruise under similar meteorological conditions with in-situ instruments on board the DLR research aircraft Falcon. Within the 2 min old contrails detected near ice saturation, we find similar effective diameters Deff (5.2–5.9 μm), but differences in particle number densities nice (162–235 cm−3) and in vertical contrail extensions (120–290 m), resulting in large differences in contrail optical depths τ (0.25–0.94). Hence larger aircraft produce optically thicker contrails. Based on the observations, we apply the EULAG-LCM model with explicit ice microphysics and in addition the Contrail and Cirrus Prediction model CoCiP to calculate the aircraft type impact on young contrails under identical meteorological conditions. The observed increase in τ for heavier aircraft is confirmed by the models, yet for generally smaller τ. An aircraft dependence of climate relevant contrail properties persists during contrail lifetime, adding importance to aircraft dependent model initialization. We finally derive an analytical relationship between contrail, aircraft and meteorological parameters. Near ice saturation, contrail width × τ scales linearly with fuel flow rate as confirmed by observations. For higher saturation ratios approximations from theory suggest a non-linear increase in the form (RHI–1)2/3. Summarized our combined results could help to more accurately assess the climate impact from aviation using an aircraft dependent contrail parameterization.

Download Full-text

BAYWRF: a high-resolution present-day climatological atmospheric dataset for Bavaria

Earth System Science Data ◽

10.5194/essd-12-3097-2020 ◽

2020 ◽

Vol 12 (4) ◽

pp. 3097-3112

Author(s):

Emily Collier ◽

Thomas Mölg

Keyword(s):

Climate Change ◽

High Resolution ◽

Large Scale ◽

Wrf Model ◽

Atmospheric Model ◽

Climate Impact ◽

Reanalysis Data ◽

Near Surface ◽

Local Climate ◽

The Impact

Abstract. Climate impact assessments require information about climate change at regional and ideally also local scales. In dendroecological studies, this information has traditionally been obtained using statistical methods, which preclude the linkage of local climate changes to large-scale drivers in a process-based way. As part of recent efforts to investigate the impact of climate change on forest ecosystems in Bavaria, Germany, we developed a high-resolution atmospheric modelling dataset, BAYWRF, for this region over the thirty-year period of September 1987 to August 2018. The atmospheric model employed in this study, the Weather Research and Forecasting (WRF) model, was configured with two nested domains of 7.5 and 1.5 km grid spacing centred over Bavaria and forced at the outer lateral boundaries by ERA5 reanalysis data. Using an extensive network of observational data, we evaluate (i) the impact of using grid analysis nudging for a single-year simulation of the period of September 2017 to August 2018 and (ii) the full BAYWRF dataset generated using nudging. The evaluation shows that the model represents variability in near-surface meteorological conditions generally well, although there are both seasonal and spatial biases in the dataset that interested users should take into account. BAYWRF provides a unique and valuable tool for investigating climate change in Bavaria with high interdisciplinary relevance. Data from the finest-resolution WRF domain are available for download at daily temporal resolution from a public repository at the Open Science Framework (Collier, 2020; https://doi.org/10.17605/OSF.IO/AQ58B).

Download Full-text

Fire emission heights in the climate system – Part 2: Impact on transport, Black Carbon concentrations and radiation

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-6695-2015 ◽

2015 ◽

Vol 15 (5) ◽

pp. 6695-6744 ◽

Cited By ~ 2

Author(s):

A. Veira ◽

S. Kloster ◽

N. A. J. Schutgens ◽

J. W. Kaiser

Keyword(s):

Black Carbon ◽

Radiative Forcing ◽

General Circulation ◽

Circulation Model ◽

Climate Impact ◽

Atmospheric Radiation ◽

Plume Height ◽

Near Surface ◽

The Impact ◽

Emission Height

Abstract. Wildfires represent a major source for aerosols impacting atmospheric radiation, atmospheric chemistry and cloud micro-physical properties. Although former studies indicated that the height of the aerosol–radiation interaction crucially affects the overall climate impact, the importance of fire emission heights in particular remains to be quantified. In this study we use the general circulation model ECHAM6 extended by the aerosol module HAM2 to investigate the impact of wildfire emission heights on atmospheric long-range transport, Black Carbon (BC) concentrations and atmospheric radiation. We simulate the wildfire aerosol release using either various versions of a semi-empirical plume height parametrization or prescribed standard emission heights in ECHAM6-HAM2. Extreme scenarios of near-surface or free-tropospheric only injections provide lower and upper constraints on the emission height climate impact. We find relative changes in mean global atmospheric BC burden of up to 7.9±4.4% caused by average changes in emission heights of 1.5–3.5 km. Regionally, changes in BC burden exceed 30–40% in the major biomass burning regions. The model evaluation of Aerosol Optical Thickness (AOT) against MODIS, AERONET and CALIOP observations indicates that the implementation of a plume height parametrization slightly reduces the ECHAM6-HAM2 biases regionally, but on the global scale these improvements in model performance are small. For prescribed emission release at the surface, wildfire emissions entail a total sky Top Of Atmosphere (TOA) Radiative Forcing (RF) of −0.16±0.06 W m−2. The application of a plume height parametrization which agrees reasonably well with observations introduces a slightly stronger negative TOA RF of −0.20±0.07 W m−2. The standard ECHAM6-HAM2 model in which 25% of the wildfire emissions are injected into the free troposphere and 75% into the planetary boundary layer, leads to a TOA RF of −0.24±0.06 W m−2. Overall, we conclude that simple plume height parametrizations provide sufficient representations of emission heights for global climate modeling. Significant improvements in aerosol wildfire modeling likely depend on better emission inventories and aerosol process modeling rather than on improved emission height parametrizations.

Download Full-text

Agricultural management effects on mean and extreme temperature trends

10.5194/esd-2020-35 ◽

2020 ◽

Author(s):

Aine M. Gormley-Gallagher ◽

Sebastian Sterl ◽

Annette L. Hirsch ◽

Sonia I. Seneviratne ◽

Edouard L. Davin ◽

...

Keyword(s):

Water Vapour ◽

Radiative Forcing ◽

Regional Scale ◽

Agricultural Management ◽

Climate Projections ◽

Spatial Average ◽

Local Cooling ◽

Near Surface ◽

Regional Trends ◽

The Impact

Abstract. Regression-based trend analysis is applied to observations and present-day ensemble simulations with the Community Earth System Model to assess if climate models overestimate warming trends because theoretical constant levels of irrigation and conservation agriculture (CA) are excluded. At the regional scale, an irrigation- and CA-induced acceleration of the annual mean near-surface air temperature (T2m) warming trends and the annual maximum daytime temperature (TXx) warming trends were evident. Estimation of the impact of irrigation and CA on the spatial average of the warming trends indicated that irrigation and CA have a pulse cooling effect on T2m and TXx, after which the warming trends increase at a greater rate than the control simulations. This differed at the local (subgrid) scale under irrigation where surface temperature cooling and the dampening of warming trends were both evident. As the local surface warming trends, in contrast to regional trends, do not account for atmospheric (water vapour) feedbacks, their dampening confirms the importance of atmospheric feedbacks (water vapour forcing) in explaining the enhanced regional trends. At the land surface, the positive radiative forcing signal is too weak to offset the local cooling from the irrigation-induced increase in the evaporative fraction. Our results underline that agricultural management has complex and nonnegligible impacts on the local climate and highlights the need to account for land management in climate projections.

Download Full-text

A strategy for climate evaluation of aircraft technology: an efficient climate impact assessment tool – AirClim

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-12185-2007 ◽

2007 ◽

Vol 7 (4) ◽

pp. 12185-12229 ◽

Cited By ~ 4

Author(s):

V. Grewe ◽

A. Stenke

Keyword(s):

Climate Change ◽

Radiative Forcing ◽

Climate Impact ◽

Climate Impacts ◽

Assessment Tools ◽

Nox Emissions ◽

Near Surface ◽

Temperature Changes ◽

Concentration Changes ◽

The Impact

Abstract. Climate change is a challenge to society and to cope with requires assessment tools which are suitable to evaluate new technology options with respect to their impact on climate. Here we present AirClim, a model which comprises a linearisation of the processes occurring from the emission to an estimate in near surface temperature change, which is presumed to be a reasonable indicator for climate change. The model is designed to be applicable to aircraft technology, i.e.~the climate agents CO2, H2O, CH4 and O3 (latter two resulting from NOx-emissions) and contrails are taken into account. It employs a number of precalculated atmospheric data and combines them with aircraft emission data to obtain the temporal evolution of atmospheric concentration changes, radiative forcing and temperature changes. The linearisation is based on precalculated data derived from 25 steady-state simulations of the state-of-the-art climate-chemistry model E39/C, which include sustained normalised emissions at various atmospheric regions. The results show that strongest climate impacts from ozone changes occur for emissions in the tropical upper troposphere (60 mW/m²; 80 mK for 1 TgN emitted), whereas from methane in the middle tropical troposphere (–2.7% change in methane lifetime; –30 mK per TgN). The estimate of the temperature changes caused by the individual climate agents takes into account a perturbation lifetime, related to the region of emission. A comparison of this approach with results from the TRADEOFF and SCENIC projects shows reasonable agreement with respect to concentration changes, radiative forcing, and temperature changes. The total impact of a supersonic fleet on radiative forcing (mainly water vapour) is reproduced within 5%. For subsonic air traffic (sustained emissions after 2050) results show that although ozone-radiative forcing is much less important than that from CO2 for the year 2100. However the impact on temperature is of comparable size even when taking into account temperature decreases from CH4. That implies that all future measures for climate stabilisation should concentrate on both CO2 and NOx emissions. A direct comparison of super- with subsonic aircraft (250 passengers, 5400 nm) reveals a 5 times higher climate impact of supersonics.

Download Full-text

Climate impact of supersonic air traffic: an approach to optimize a potential future supersonic fleet – results from the EU-project SCENIC

Atmospheric Chemistry and Physics ◽

10.5194/acp-7-5129-2007 ◽

2007 ◽

Vol 7 (19) ◽

pp. 5129-5145 ◽

Cited By ~ 23

Author(s):

V. Grewe ◽

A. Stenke ◽

M. Ponater ◽

R. Sausen ◽

G. Pitari ◽

...

Keyword(s):

Radiative Forcing ◽

Climate Models ◽

Climate Impact ◽

Ozone Layer ◽

Climate Impacts ◽

Atmospheric Composition ◽

Base Case ◽

Case Scenario ◽

Near Surface ◽

Supersonic Aircraft

Abstract. The demand for intercontinental transportation is increasing and people are requesting short travel times, which supersonic air transportation would enable. However, besides noise and sonic boom issues, which we are not referring to in this investigation, emissions from supersonic aircraft are known to alter the atmospheric composition, in particular the ozone layer, and hence affect climate significantly more than subsonic aircraft. Here, we suggest a metric to quantitatively assess different options for supersonic transport with regard to the potential destruction of the ozone layer and climate impacts. Options for fleet size, engine technology (nitrogen oxide emission level), cruising speed, range, and cruising altitude, are analyzed, based on SCENIC emission scenarios for 2050, which underlay the requirements to be as realistic as possible in terms of e.g., economic markets and profitable market penetration. This methodology is based on a number of atmosphere-chemistry and climate models to reduce model dependencies. The model results differ significantly in terms of the response to a replacement of subsonic aircraft by supersonic aircraft, e.g., concerning the ozone impact. However, model differences are smaller when comparing the different options for a supersonic fleet. Those uncertainties were taken into account to make sure that our findings are robust. The base case scenario, where supersonic aircraft get in service in 2015, a first fleet fully operational in 2025 and a second in 2050, leads in our simulations to a near surface temperature increase in 2050 of around 7 mK and with constant emissions afterwards to around 21 mK in 2100. The related total radiative forcing amounts to 22 mWm2 in 2050, with an uncertainty between 9 and 29 mWm2. A reduced supersonic cruise altitude or speed (from Mach 2 to Mach 1.6) reduces both, climate impact and ozone destruction, by around 40%. An increase in the range of the supersonic aircraft leads to more emissions at lower latitudes since more routes to SE Asia are taken into account, which increases ozone depletion, but reduces climate impact compared to the base case.

Download Full-text