scholarly journals Ice supersaturation and the potential for contrail formation in a changing climate

2015 ◽  
Vol 6 (2) ◽  
pp. 555-568 ◽  
Author(s):  
E. A. Irvine ◽  
K. P. Shine
Keyword(s):  
Northern Hemisphere ◽  
21St Century ◽  
Coupled Model ◽  
Air Traffic ◽  
Polar Regions ◽  
Upper Troposphere ◽  
Percentage Points ◽  
Using Data ◽  
Projected Changes ◽  
The Tropics

Abstract. Ice supersaturation (ISS) in the upper troposphere and lower stratosphere is important for the formation of cirrus clouds and long-lived contrails. Cold ISS (CISS) regions (taken here to be ice-supersaturated regions with temperature below 233 K) are most relevant for contrail formation. We analyse projected changes to the 250 hPa distribution and frequency of CISS regions over the 21st century using data from the Representative Concentration Pathway 8.5 simulations for a selection of Coupled Model Intercomparison Project Phase 5 models. The models show a global-mean, annual-mean decrease in CISS frequency by about one-third, from 11 to 7% by the end of the 21st century, relative to the present-day period 1979–2005. Changes are analysed in further detail for three subregions where air traffic is already high and increasing (Northern Hemisphere mid-latitudes) or expected to increase (tropics and Northern Hemisphere polar regions). The largest change is seen in the tropics, where a reduction of around 9 percentage points in CISS frequency by the end of the century is driven by the strong warming of the upper troposphere. In the Northern Hemisphere mid-latitudes the multi-model-mean change is an increase in CISS frequency of 1 percentage point; however the sign of the change is dependent not only on the model but also on latitude and season. In the Northern Hemisphere polar regions there is an increase in CISS frequency of 5 percentage points in the annual mean. These results suggest that, over the 21st century, climate change may have large impacts on the potential for contrail formation; actual changes to contrail cover will also depend on changes to the volume of air traffic, aircraft technology and flight routing.

scholarly journals Ice-supersaturation and the potential for contrail formation in a changing climate

2015 ◽  
Vol 6 (1) ◽  
pp. 317-349 ◽  
Author(s):  
E. A. Irvine ◽  
K. P. Shine
Keyword(s):  
Northern Hemisphere ◽  
Air Traffic ◽  
First Century ◽  
Cmip5 Models ◽  
Polar Regions ◽  
Upper Troposphere ◽  
Twenty First Century ◽  
Using Data ◽  
Projected Changes ◽  
The Tropics

Abstract. Ice-supersaturation (ISS) in the upper-troposphere and lower stratosphere is important for the formation of cirrus cloud and long-lived contrails. We analyse projected changes to 250 hPa ISS distribution and frequency over the twenty-first century using data from the RCP8.5 simulations of a selection of CMIP5 models. The models show a global-mean annual-mean decrease in ISS frequency of 4% by the end of the twenty-first century, relative to the present-day period 1979–2005. Changes are analysed in further detail for three sub-regions where air traffic is already high and increasing (Northern Hemisphere mid-latitudes) or expected to increase (tropics and Northern Hemisphere polar regions). The largest change is seen in the tropics, where a reduction of around 9% in ISS frequency by the end of the century is driven by the strong warming of the upper troposphere. In the Northern Hemisphere mid-latitudes the multi-model mean change is an increase in ISS frequency of 1%; however the sign of the change is not only model-dependent but also has a strong latitudinal and seasonal dependence. In the Northern Hemisphere polar regions there is an increase in ISS frequency of 5% in the annual-mean. These results suggest that over the 21st century climate change may have large impacts on the potential for contrail formation; actual changes to contrail cover will also depend on changes to the volume of air traffic, aircraft technology and flight routing.

scholarly journals Seasonal impact of biogenic VSL bromine on the evolution of mid-latitude lowermost stratospheric ozone during the 21<sup>st</sup> century

2020 ◽  
Author(s):  
Javer A. Barrera ◽  
Rafael P. Fernandez ◽  
Fernando Iglesias-Suarez ◽  
Carlos A. Cuevas ◽  
Jean-Francois Lamarque ◽  
...  
Keyword(s):  
21St Century ◽  
Total Ozone ◽  
Stratospheric Ozone ◽  
Polar Regions ◽  
Total Ozone Column ◽  
Seasonal Impact ◽  
The Tropics ◽  
The Impact ◽  
Ozone Column ◽  
Modelling Study

Abstract. Biogenic very short-lived bromine (VSLBr) represents, nowadays, ~ 25 % of the total stratospheric bromine loading. Owing to their much shorter lifetime compared to anthropogenic long-lived bromine (LLBr, e.g., halons) and chlorine (LLCl, e.g., chlorofluorocarbons) substances, the impact of VSLBr on ozone peaks at the extratropical lowermost stratosphere, a key climatic and radiative atmospheric region. Here we present a modelling study of the evolution of stratospheric ozone and its chemical losses in extra-polar regions during the 21st century, under two different scenarios: considering and neglecting the additional stratospheric injection of 5 ppt biogenic VSLBr naturally released from the ocean. Our analysis shows that the inclusion of VSLBr result in a realistic stratospheric bromine loading and improves the quantitative 1980–2015 model-satellite agreement of total ozone column (TOC) in the mid-latitudes. We show that the overall ozone response to VSLBr within the mid-latitudes follows the stratospheric abundances evolution of long-lived inorganic chlorine and bromine throughout the 21st century. Additional ozone losses due to VSLBr are maximised during the present-day period (1990–2010), with TOC differences of −8 DU (−3 %) and −5.5 DU (−2 %) for the southern (SH-ML) and northern (NH-ML) mid-latitudes, respectively. Moreover, the projected TOC differences at the end of the 21st century are at least half of the values found for the present-day period. In the tropics, a small (

scholarly journals Climate change projections over Indus basin using CMIP6 model simulations

2021 ◽  
Author(s):  
KOTESWARARAO KUNDETI ◽  
Lakshmi Kumar T.V ◽  
Ashwini Kulkarni ◽  
Chowdary J.S ◽  
Srinivas Desamsetti
Keyword(s):  
Climate Change ◽  
21St Century ◽  
Minimum Temperature ◽  
Coupled Model ◽  
Baseline Period ◽  
Indus Basin ◽  
Climate Indices ◽  
Data Sets ◽  
Projected Changes ◽  
Precipitation And Temperature

Abstract Indus basin is one of the most vulnerable regions due to climate change. This article presents the projected changes in precipitation and temperature over the Indus Basin using statistically downscaled, bias-corrected Coupled Model Intercomparison Project-6 (CMIP6) data sets for different shared socioeconomic pathways (SSP2-4.5 and SSP5-8.5) in response to global warming. The future changes in precipitation and temperature extremes for different epochal periods of the 21st century are outlined. The spatial variations of precipitation, maximum and minimum temperature obtained from the Multi-Model Mean (MMM) of CMIP6 models showed a good agreement with observations such as APHRODITE (precipitation), CPC (temperature) for the base period 1995 to 2014 over the Indus Basin. Our results suggest that there is a general increase in precipitation/ maximum and minimum temperature over the Upper Indus Basin/Lower Indus Basin by the end of the 21st century. It is also noted that the spatial variability of extreme climate indices is high during June to September (JJAS) than December to January (DJF). By the end of the century projections show that the precipitation changes are about 85% in JJAS and 40% in DJF with reference to the baseline (1995–2014) period over Indus Basin region. The temperature extreme indices are also increasing in future compare to the baseline period.

scholarly journals Global large-scale stratosphere-troposphere exchange in modern reanalyses

2016 ◽  
Author(s):  
Alexander C. Boothe ◽  
Cameron R. Homeyer
Keyword(s):  
Large Scale ◽  
Lower Stratosphere ◽  
Radiative Properties ◽  
Lapse Rate ◽  
Polar Regions ◽  
Transport Mechanisms ◽  
Upper Troposphere ◽  
Long Term Changes ◽  
The Tropics

Abstract. Stratosphere-troposphere exchange (STE) has important and significant impacts on the chemical and radiative properties of the upper troposphere and lower stratosphere. This study presents a 15-year climatology of global large-scale STE from four modern reanalyses: ERA-Interim, JRA-55, MERRA-2, and MERRA-1. STE is separated into four categories for analysis to identify the significance of known transport mechanisms: 1) vertical stratosphere-to-troposphere transport (STT), 2) vertical troposphere-to-stratosphere transport (TST), 3) lateral STT (that occurring between the tropics and the extratropics and across the tropopause "break"), and 4) lateral TST. In addition, this study employs a method to identify STE as that which crosses the lapse-rate tropopause (LRT), while most previous studies have used a potential vorticity (PV) isosurface as the troposphere-stratosphere boundary. PV-based and LRT based STE climatologies are compared using the same reanalysis output (ERA-Interim). The comparison reveals quantitative and qualitative differences, particularly in the geographic representation of TST in the polar regions. Based upon spatiotemporal integrations, we find STE to be STT-dominant in ERA-Interim and JRA-55 and TST-dominant in the MERRA reanalyses. Time series during the 15-year analysis period show long-term changes that are argued to correspond with changes in the Brewer-Dobson circulation.

Mapping the Cosmos

2020 ◽  
pp. 284-290
Author(s):  
Nicholas Mee
Keyword(s):  
Milky Way ◽  
Spherical Surface ◽  
Logarithmic Scale ◽  
Wide Field ◽  
Polar Regions ◽  
Milky Way Galaxy ◽  
Buckminster Fuller ◽  
Barred Spiral Galaxy ◽  
Using Data ◽  
The Tropics

There is no way to transcribe the features of the Earth’s spherical surface onto a flat map without some distortion. All maps distort the geography of the sphere. The familiar Mercator maps inflate regions close to the poles compared to regions in the tropics. In 1973, Arno Peters promoted the Gall–Peters projection that compensates for the expansion of polar regions compared to the tropics. Buckminster Fuller invented a map called the Dymaxion in which the globe is projected onto an icosahedron, which is then unfolded into an icosahedral net. Another interesting projection is the Pierce Quincuncial projection invented by Charles Sanders Pierce. The Milky Way galaxy was recently mapped using data from NASA’s Wide-field Infra-red Survey Explorer (WISE) and shown to be a barred spiral galaxy. Pablo Carlos Budassi has created a map of the entire visible universe using NASA images by representing radial distances on a logarithmic scale.

scholarly journals Global large-scale stratosphere–troposphere exchange in modern reanalyses

2017 ◽  
Vol 17 (9) ◽  
pp. 5537-5559 ◽  
Author(s):  
Alexander C. Boothe ◽  
Cameron R. Homeyer
Keyword(s):  
Large Scale ◽  
Lower Stratosphere ◽  
Radiative Properties ◽  
Lapse Rate ◽  
Polar Regions ◽  
Transport Mechanisms ◽  
Upper Troposphere ◽  
Subtropical Jet ◽  
The Tropics

Abstract. Stratosphere–troposphere exchange (STE) has important impacts on the chemical and radiative properties of the upper troposphere and lower stratosphere. This study presents a 15-year climatology of global large-scale STE from four modern reanalyses: ERA-Interim, JRA-55, MERRA-2, and MERRA. STE is separated into three regions (tropics, subtropics, and extratropics) and two transport directions (stratosphere-to-troposphere transport or STT and troposphere-to-stratosphere transport or TST) in an attempt to identify the significance of known transport mechanisms. The extratropics and tropics are separated by the tropopause break. Any STE occurring between the tropics and the extratropics through the tropopause break is considered subtropical exchange (i.e., in the vicinity of the subtropical jet). In addition, this study employs a method to identify STE as that which crosses the lapse-rate tropopause (LRT), while most previous studies have used a potential vorticity (PV) isosurface as the troposphere–stratosphere boundary. PV-based and LRT-based STE climatologies are compared using the ERA-Interim reanalysis output. The comparison reveals quantitative and qualitative differences, particularly for TST in the polar regions. Based upon spatiotemporal integrations, we find STE to be STT dominant in ERA-Interim and JRA-55 and TST dominant in MERRA and MERRA-2. The sources of the differences are mainly attributed to inconsistencies in the representation of STE in the subtropics and extratropics. Time series during the 15-year analysis period show long-term changes that are argued to correspond with changes in the Brewer–Dobson circulation.

scholarly journals The total ozone field separated into meteorological regimes – Part II: Northern Hemisphere mid-latitude total ozone trends

2006 ◽  
Vol 6 (12) ◽  
pp. 5183-5191 ◽  
Author(s):  
R. D. Hudson ◽  
M. F. Andrade ◽  
M. B. Follette ◽  
A. D. Frolov
Keyword(s):  
Northern Hemisphere ◽  
Total Ozone ◽  
Linear Trend ◽  
Polar Vortex ◽  
Polar Front ◽  
Relative Area ◽  
Upper Troposphere ◽  
Ozone Trends ◽  
Change In The Mean ◽  
Using Data

Abstract. Previous studies have presented clear evidence that the Northern Hemisphere total ozone field can be separated into distinct regimes (tropical, midlatitude, polar, and arctic) the boundaries of which are associated with the subtropical and polar upper troposphere fronts, and in the winter, the polar vortex. This paper presents a study of total ozone variability within these regimes, from 1979–2003, using data from the TOMS instruments. The change in ozone within each regime for the period January 1979–May 1991, a period of rapid total ozone change, was studied in detail. Previous studies had observed a zonal linear trend of −3.15% per decade for the latitude band 25°–60° N. When the ozone field is separated by regime, linear trends of −1.4%, 2.3%, and 3.0%, per decade for the tropical, midlatitude, and polar regimes, respectively, are observed. The changes in the relative areas of the regimes were also derived from the ozone data. The relative area of the polar regime decreased by about 20%; the tropical regime increased by about 10% over this period. No significant change was detected for the midlatitude regime. From the trends in the relative area and total ozone it is deduced that 35% of the trend between 25° and 60° N, from January 1979–May 1991 is due to movement of the upper troposphere fronts. The changes in the relative areas can be associated with a change in the mean latitude of the subtropical and polar fronts within the latitude interval 25° to 60° N. Over the period from January 1979 to May 1991, both fronts moved northward by 1.1±0.2 degrees per decade. Over the entire period of the study, 1979–2003, the subtropical front moved northward at a rate of 1.1±0.1 degrees per decade, while the polar front moved by 0.5±0.1 degrees per decade.

scholarly journals The total ozone field separated into meteorological regimes. Part II: Northern Hemisphere mid-latitude total ozone trends

2006 ◽  
Vol 6 (4) ◽  
pp. 6183-6209 ◽  
Author(s):  
R. D. Hudson ◽  
M. F. Andrade ◽  
M. B. Follette ◽  
A. D. Frolov
Keyword(s):  
Northern Hemisphere ◽  
Total Ozone ◽  
Linear Trend ◽  
Polar Vortex ◽  
Polar Front ◽  
Upper Troposphere ◽  
Time Period ◽  
Ozone Trends ◽  
The Mean ◽  
Using Data

Abstract. Previous studies have presented clear evidence that the Northern Hemisphere total ozone field can be separated into distinct regimes (tropical, midlatitude, polar, and arctic) the boundaries of which are associated with the subtropical and polar upper troposphere fronts,and in the winter, the polar vortex. This paper presents a study of total ozone variability within these regimes, from 1979–2003, using data from the TOMS instruments. The change in ozone within each regime for the period January 1979–May 1991, a period of rapid total ozone change, was studied in detail. Previous studies had observed a zonal linear trend of –3.15% per decade for the latitude band 25°–60° N. When the ozone field is separated by regime, smaller linear trends (–2.5%, –2.2%, and –1.9% per decade for the polar, midlatitude, and tropical regimes, respectively) are observed. The trend in the zonal total ozone is larger because the relative areas of the regimes also changed over this time period. The relative area of the polar regime decreased by about 15%; the tropical regime increased by about 10% over this period. The changes in the relative areas can be associated with a change of the mean latitude of the sub-tropical and polar fronts within the latitude interval 25° to 60° N. Over the period from January 1979-May 1991, both fronts moved northward by 1.1±0.2 degrees per decade. Over the entire period of the study the subtropical front moved northward at a rate of 1.1±0.1 degree per decade, while the polar front moved by only 0.5±0.1 degrees per decade.

scholarly journals An annual cycle of long lived stratospheric gases from MIPAS

2007 ◽  
Vol 7 (7) ◽  
pp. 1879-1897 ◽  
Author(s):  
M. N. Juckes
Keyword(s):  
Standard Deviation ◽  
Water Vapour ◽  
Polar Regions ◽  
Upward Motion ◽  
High Quality ◽  
Height Range ◽  
Water Vapour Concentration ◽  
Vapour Concentration ◽  
Using Data ◽  
The Tropics

Abstract. MIPAS, on ENVISAT, has made high quality observations of ozone, methane and water vapour. Gridded fields, at 4 hourly intervals and, have been calculated for all of 2003 using data assimilation with isentropic advection as a constraint. The gridded fields are validated against independent measurements (from 7 other instruments in the case of ozone, 3 for water vapour and one for methane). For ozone the results are in agreement with previously published results. For water vapour the bias relative to HALOE is below 10% between 20 and 48 km, and the standard deviation is below 12% in this range. Departures from SAGE II and POAM III are substantially larger. The methane analysis has a bias of less than 5% relative to HALOE between 23 and 40 km, with a standard deviation less than 10% in this height range. The water vapour field clearly reflects the upward motion in the lower tropical stratosphere, while both water vapour and methane show the signature of advection higher up. In the polar regions the descent in the vortex is clearly visible, with strong descent in autumn giving way to weaker descent through the winter. Descent rates of around 10−3ms−1 are found during the formation of the polar vortices, slowing to around 3×10−4ms−1 during the winter. Ascent of around 2×10−4ms−1 in the tropics is revealed by the water vapour and total observed hydrogen fields (4 times the methane plus twice the water vapour concentration). The total observed hydrogen is depleted in the polar upper stratosphere when air is advected down from the upper mesosphere.

scholarly journals New observations of NO<sub>2</sub> in the upper troposphere from TROPOMI

2021 ◽  
Vol 14 (3) ◽  
pp. 2389-2408
Author(s):  
Eloise A. Marais ◽  
John F. Roberts ◽  
Robert G. Ryan ◽  
Henk Eskes ◽  
K. Folkert Boersma ◽  
...  
Keyword(s):  
Transport Model ◽  
Polar Regions ◽  
Chemical Transport Model ◽  
Ozone Monitoring Instrument ◽  
Upper Troposphere ◽  
Mauna Loa ◽  
Mixing Ratios ◽  
Spatial Coverage ◽  
The Tropics ◽  
Improve Representation

Abstract. Nitrogen oxides (NOx≡NO+NO2) in the NOx-limited upper troposphere (UT) are long-lived and so have a large influence on the oxidizing capacity of the troposphere and formation of the greenhouse gas ozone. Models misrepresent NOx in the UT, and observations to address deficiencies in models are sparse. Here we obtain a year of near-global seasonal mean mixing ratios of NO2 in the UT (450–180 hPa) at 1∘×1∘ by applying cloud-slicing to partial columns of NO2 from TROPOMI. This follows refinement of the cloud-slicing algorithm with synthetic partial columns from the GEOS-Chem chemical transport model. TROPOMI, prior to cloud-slicing, is corrected for a 13 % underestimate in stratospheric NO2 variance and a 50 % overestimate in free-tropospheric NO2 determined by comparison to Pandora total columns at high-altitude free-tropospheric sites at Mauna Loa, Izaña, and Altzomoni and MAX-DOAS and Pandora tropospheric columns at Izaña. Two cloud-sliced seasonal mean UT NO2 products for June 2019 to May 2020 are retrieved from corrected TROPOMI total columns using distinct TROPOMI cloud products that assume clouds are reflective boundaries (FRESCO-S) or water droplet layers (ROCINN-CAL). TROPOMI UT NO2 typically ranges from 20–30 pptv over remote oceans to >80 pptv over locations with intense seasonal lightning. Spatial coverage is mostly in the tropics and subtropics with FRESCO-S and extends to the midlatitudes and polar regions with ROCINN-CAL, due to its greater abundance of optically thick clouds and wider cloud-top altitude range. TROPOMI UT NO2 seasonal means are spatially consistent (R=0.6–0.8) with an existing coarser spatial resolution (5∘ latitude × 8∘ longitude) UT NO2 product from the Ozone Monitoring Instrument (OMI). UT NO2 from TROPOMI is 12–26 pptv more than that from OMI due to increase in NO2 with altitude from the OMI pressure ceiling (280 hPa) to that for TROPOMI (180 hPa), but possibly also due to altitude differences in TROPOMI and OMI cloud products and NO2 retrieval algorithms. The TROPOMI UT NO2 product offers potential to evaluate and improve representation of UT NOx in models and supplement aircraft observations that are sporadic and susceptible to large biases in the UT.

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