Electron Precipitation at an Auroral Latitude – Saskatoon, L = 4.4. II. Fluxes of Precipitating Electrons

1974 ◽  
Vol 52 (19) ◽  
pp. 1879-1884 ◽  
Author(s):  
A. H. Manson ◽  
Z. M. Khan
Keyword(s):  
Ionospheric Disturbance ◽  
Differential Absorption ◽  
Satellite Measurements ◽  
Electron Densities ◽  
Characteristic Energy ◽  
Mean Values ◽  
Absorption Experiment ◽  
Ambient Electron ◽  
Auroral Latitude ◽  
Good Agreement

Measurements of ambient electron densities have been made by the differential absorption experiment, on a number of aurorally disturbed nights in 1971. The measured values of the intensity of the green line (5577 Å) emission, and of the ambient electron densities, are then compared with theoretical estimates of these two variables. An exponential energy spectrum is used in the calculation, and fluxes of precipitated electrons (> 40 keV) and values for the e folding energies (E0) thereby become available. Comparisons of mean values with satellite measurements made under similar magnetic conditions, show good agreement. Calculations are also made for two specific nights, (January 26–28, 1971). Characteristic energies are typically 5 keV during the maximum of the magnetic and photometric disturbances, and increase to values of 10–15 keV near sunrise when the ionospheric disturbance (< 90 km) is greatest. The calculation is shown to be sensitive to changes in characteristic energy of the spectrum.

scholarly journals Types of pulsating aurora: Comparison of model and EISCAT electron density observations

2021 ◽  
Author(s):  
Fasil Tesema ◽  
Noora Partamies ◽  
Daniel K. Whiter ◽  
Yasunobu Ogawa
Keyword(s):  
Energetic Particle ◽  
Energy Input ◽  
Energy Deposition ◽  
Common Phenomenon ◽  
Ion Chemistry ◽  
Satellite Measurements ◽  
Electron Densities ◽  
Significant Difference ◽  
Energetic Particle Precipitation ◽  
Good Agreement

Abstract. Energetic particle precipitation associated with pulsating aurora (PsA) can reach down to lower mesospheric altitude and deplete ozone. It is well documented that pulsating aurora is a common phenomenon during substorm recovery phases. This indicates that using magnetic indices to model the chemistry induced by PsA electrons could underestimate the energy deposition in the atmosphere. Integrating satellite measurements of precipitating electrons in models is considered to be an alternative way to account for such underestimation. One way to do this is to test and validate existing ion chemistry models using integrated measurements from satellite and ground-based observations. By using satellite measurements, an average/typical spectrum of PsA electrons can be constructed and used as an input in models to study the effects of the energetic electrons in the atmosphere. In this study, we compare electron densities from EISCAT radars with auroral ion chemistry and the energetics model by using pulsating aurora spectra derived from POES satellites as an energy input for the model. We found a good agreement between the model and EISCAT electron densities in the region dominated by patchy pulsating aurora. However, the magnitude of the observed electron densities suggests a significant difference in the flux of precipitating electrons for different pulsating aurora types (structures) observed.

scholarly journals Types of pulsating aurora: comparison of model and EISCAT electron density observations

2022 ◽  
Vol 40 (1) ◽  
pp. 1-10
Author(s):  
Fasil Tesema ◽  
Noora Partamies ◽  
Daniel K. Whiter ◽  
Yasunobu Ogawa
Keyword(s):  
Energetic Particle ◽  
Energy Deposition ◽  
Radar System ◽  
Ion Chemistry ◽  
Satellite Measurements ◽  
Electron Densities ◽  
Incoherent Scatter ◽  
Significant Difference ◽  
Energetic Particle Precipitation ◽  
Good Agreement

Abstract. Energetic particle precipitation associated with pulsating aurora (PsA) can reach down to lower mesospheric altitudes and deplete ozone. It is well documented that pulsating aurora is a common phenomenon during substorm recovery phases. This indicates that using magnetic indices to model the chemistry induced by PsA electrons could underestimate the energy deposition in the atmosphere. Integrating satellite measurements of precipitating electrons in models is considered to be an alternative way to account for such an underestimation. One way to do this is to test and validate the existing ion chemistry models using integrated measurements from satellite and ground-based observations. By using satellite measurements, an average or typical spectrum of PsA electrons can be constructed and used as an input in models to study the effects of the energetic electrons in the atmosphere. In this study, we compare electron densities from the EISCAT (European Incoherent Scatter scientific radar system) radars with auroral ion chemistry and the energetics model by using pulsating aurora spectra derived from the Polar Operational Environmental Satellite (POES) as an energy input for the model. We found a good agreement between the model and EISCAT electron densities in the region dominated by patchy pulsating aurora. However, the magnitude of the observed electron densities suggests a significant difference in the flux of precipitating electrons for different pulsating aurora types (structures) observed.

scholarly journals Simulating the climatic mass balance of Svalbard glaciers from 2003 to 2013 with a high-resolution coupled atmosphere-glacier model

2015 ◽  
Vol 9 (5) ◽  
pp. 5775-5815
Author(s):  
K. S. Aas ◽  
T. Dunse ◽  
E. Collier ◽  
T. V. Schuler ◽  
T. K. Berntsen ◽  
...  
Keyword(s):  
Mass Balance ◽  
Detailed Comparison ◽  
Climate Projections ◽  
Grid Spacing ◽  
Satellite Measurements ◽  
Mean Values ◽  
Ice Cap ◽  
A Site ◽  
Model Temperature ◽  
Good Agreement

Abstract. In this study we simulate the climatic mass balance of Svalbard glaciers with a coupled atmosphere-glacier model with 3 km grid spacing, from September 2003 to September 2013. We find a mean specific net mass balance of −167 mm w.e. yr−1, corresponding to a mean annual mass loss of about 5.7 Gt, with large interannual variability. Our results are compared with a comprehensive set of mass balance, meteorological and satellite measurements. Model temperature biases of 0.17 and −1.9 °C are found at two glacier automatic weather station sites. Simulated climatic mass balance is mostly within about 0.1 m w.e. yr−1 of stake measurements, and simulated winter accumulation at the Austfonna ice cap shows mean absolute errors of 0.05 and 0.06 m w.e. yr−1 when compared to radar-derived values for the selected years 2004 and 2006. Comparison of surface height changes from 2003 to 2008 from model, and satellite altimetry reveals good agreement in both mean values and regional differences. The largest deviations from observations are found for winter accumulation at Hansbreen (up to around 1 m w.e. yr−1), a site where sub-grid topography and wind redistribution of snow are important factors. Comparison with simulations using a 9 km grid spacing reveal considerable differences on regional and local scales. In addition, the 3 km grid spacing allows for a much more detailed comparison with observations than what is possible with a 9 km grid spacing. Further decreasing the grid spacing to 1 km appears to be less significant, although in general precipitation amounts increase with resolution. Altogether, the model compares well with observations and offers possibilities for studying glacier climatic mass balance on Svalbard both historically as well as based on climate projections.

scholarly journals The climatic mass balance of Svalbard glaciers: a 10-year simulation with a coupled atmosphere–glacier mass balance model

2016 ◽  
Vol 10 (3) ◽  
pp. 1089-1104 ◽  
Author(s):  
Kjetil S. Aas ◽  
Thorben Dunse ◽  
Emily Collier ◽  
Thomas V. Schuler ◽  
Terje K. Berntsen ◽  
...  
Keyword(s):  
Mass Balance ◽  
Detailed Comparison ◽  
Balance Model ◽  
Climate Projections ◽  
Glacier Mass Balance ◽  
Grid Spacing ◽  
Satellite Measurements ◽  
Mean Values ◽  
Ice Cap ◽  
A Site

Abstract. In this study we simulate the climatic mass balance of Svalbard glaciers with a coupled atmosphere–glacier model with 3 km grid spacing, from September 2003 to September 2013. We find a mean specific net mass balance of −257 mm w.e. yr−1, corresponding to a mean annual mass loss of about 8.7 Gt, with large interannual variability. Our results are compared with a comprehensive set of mass balance, meteorological, and satellite measurements. Model temperature biases of 0.19 and −1.9 °C are found at two glacier automatic weather station sites. Simulated climatic mass balance is mostly within about 100 mm w.e. yr−1 of stake measurements, and simulated winter accumulation at the Austfonna ice cap shows mean absolute errors of 47 and 67 mm w.e. yr−1 when compared to radar-derived values for the selected years 2004 and 2006. Comparison of modeled surface height changes from 2003 to 2008, and satellite altimetry reveals good agreement in both mean values and regional differences. The largest deviations from observations are found for winter accumulation at Hansbreen (up to around 1000 mm w.e. yr−1), a site where sub-grid topography and wind redistribution of snow are important factors. Comparison with simulations using 9 km grid spacing reveal considerable differences on regional and local scales. In addition, 3 km grid spacing allows for a much more detailed comparison with observations than what is possible with 9 km grid spacing. Further decreasing the grid spacing to 1 km appears to be less significant, although in general precipitation amounts increase with resolution. Altogether, the model compares well with observations and offers possibilities for studying glacier climatic mass balance on Svalbard both historically as well as based on climate projections.

scholarly journals The high Arctic in extreme winters: vortex, temperature, and MLS and ACE-FTS trace gas evolution

2008 ◽  
Vol 8 (3) ◽  
pp. 505-522 ◽  
Author(s):  
G. L. Manney ◽  
W. H. Daffer ◽  
K. B. Strawbridge ◽  
K. A. Walker ◽  
C. D. Boone ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
High Arctic ◽  
Trace Gas ◽  
Satellite Measurements ◽  
Broadband Emission ◽  
Gas Measurements ◽  
Chemistry Experiment ◽  
Very High ◽  
Good Agreement

Abstract. The first three Arctic winters of the ACE mission represented two extremes of winter variability: Stratospheric sudden warmings (SSWs) in 2004 and 2006 were among the strongest, most prolonged on record; 2005 was a record cold winter. Canadian Arctic Atmospheric Chemistry Experiment (ACE) Validation Campaigns were conducted at Eureka (80° N, 86° W) during each of these winters. New satellite measurements from ACE-Fourier Transform Spectrometer (ACE-FTS), Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), and Aura Microwave Limb Sounder (MLS), along with meteorological analyses and Eureka lidar temperatures, are used to detail the meteorology in these winters, to demonstrate its influence on transport, and to provide a context for interpretation of ACE-FTS and validation campaign observations. During the 2004 and 2006 SSWs, the vortex broke down throughout the stratosphere, reformed quickly in the upper stratosphere, and remained weak in the middle and lower stratosphere. The stratopause reformed at very high altitude, near 75 km. ACE measurements covered both vortex and extra-vortex conditions in each winter, except in late-February through mid-March 2004 and 2006, when the strong, pole-centered vortex that reformed after the SSWs resulted in ACE sampling only inside the vortex in the middle through upper stratosphere. The 2004 and 2006 Eureka campaigns were during the recovery from the SSWs, with the redeveloping vortex over Eureka. 2005 was the coldest winter on record in the lower stratosphere, but with an early final warming in mid-March. The vortex was over Eureka at the start of the 2005 campaign, but moved away as it broke up. Disparate temperature profile structure and vortex evolution resulted in much lower (higher) temperatures in the upper (lower) stratosphere in 2004 and 2006 than in 2005. Satellite temperatures agree well with lidar data up to 50–60 km, and ACE-FTS, MLS and SABER show good agreement in high-latitude temperatures throughout the winters. Consistent with a strong, cold upper stratospheric vortex and enhanced radiative cooling after the SSWs, MLS and ACE-FTS trace gas measurements show strongly enhanced descent in the upper stratospheric vortex in late January through March 2006 compared to that in 2005.

scholarly journals Tropospheric BrO column densities in the Arctic derived from satellite: retrieval and comparison to ground-based measurements

2012 ◽  
Vol 5 (11) ◽  
pp. 2779-2807 ◽  
Author(s):  
H. Sihler ◽  
U. Platt ◽  
S. Beirle ◽  
T. Marbach ◽  
S. Kühl ◽  
...  
Keyword(s):  
Boundary Layer ◽  
The Arctic ◽  
Trace Gas ◽  
Natural Phenomenon ◽  
Satellite Measurements ◽  
Surface Layers ◽  
Vertical Column ◽  
Near Surface ◽  
The Vertical Distribution ◽  
Good Agreement

Abstract. During polar spring, halogen radicals like bromine monoxide (BrO) play an important role in the chemistry of tropospheric ozone destruction. Satellite measurements of the BrO distribution have become a particularly useful tool to investigate this probably natural phenomenon, but the separation of stratospheric and tropospheric partial columns of BrO is challenging. In this study, an algorithm was developed to retrieve tropospheric vertical column densities of BrO from data of high-resolution spectroscopic satellite instruments such as the second Global Ozone Monitoring Experiment (GOME-2). Unlike recently published approaches, the presented algorithm is capable of separating the fraction of BrO in the activated troposphere from the total BrO column solely based on remotely measured properties. The presented algorithm furthermore allows to estimate a realistic measurement error of the tropospheric BrO column. The sensitivity of each satellite pixel to BrO in the boundary layer is quantified using the measured UV radiance and the column density of the oxygen collision complex O4. A comparison of the sensitivities with CALIPSO LIDAR observations demonstrates that clouds shielding near-surface trace-gas columns can be reliably detected even over ice and snow. Retrieved tropospheric BrO columns are then compared to ground-based BrO measurements from two Arctic field campaigns in the Amundsen Gulf and at Barrow in 2008 and 2009, respectively. Our algorithm was found to be capable of retrieving enhanced near-surface BrO during both campaigns in good agreement with ground-based data. Some differences between ground-based and satellite measurements observed at Barrow can be explained by both elevated and shallow surface layers of BrO. The observations strongly suggest that surface release processes are the dominating source of BrO and that boundary layer meteorology influences the vertical distribution.

scholarly journals Analysis of a Regional Scale Chemical-Transport Model to Investigate the Potential Capability of Satellites for Identifying a Widespread Air Pollution Event

2017 ◽  
Author(s):  
Jason Welsh ◽  
Jack Fishman
Keyword(s):  
Transport Model ◽  
Regional Scale ◽  
Ozone Production ◽  
Metropolitan Region ◽  
Trace Gas ◽  
Chemical Transport Model ◽  
Satellite Measurements ◽  
Pollution Event ◽  
Surface O3 ◽  
Good Agreement

We use a regional scale photochemical transport model to investigate the surface concentrations and column integrated amounts of ozone (O3) and nitrogen dioxide (NO2) during a pollution event that occurred in the St. Louis metropolitan region in 2012. These trace gases will be two of the primary constituents that will be measured by TEMPO, an instrument on a geostationary platform, which will result in a dataset that has hourly temporal resolution during the daytime and ~4 km spatial resolution. Although air quality managers are most concerned with surface concentrations, satellite measurements provide a quantity that reflects a column amount, which may or may not be directly relatable to what is measured at the surface. The model results provide good agreement with observed surface O3 concentrations, which is the only trace gas dataset that can be used for verification. The model shows that a plume of O3 extends downwind from St. Louis and contains an integrated amount of ozone of ~ 16 DU (1 DU = 2.69 x 1016 mol. cm-2), a quantity that is two to three times lower than what was observed by satellite measurements during two massive pollution episodes in the 1980s. Based on the smaller isolatable emissions coming from St. Louis, this quantity is not unreasonable, but may also reflect the reduction of photochemical ozone production due to the implementation of emission controls that have gone into effect in the past few decades.

scholarly journals Variations of carbon monoxide in the atmosphere of Antarctica according to ground-based and satellite measurements

2019 ◽  
pp. 97-106 ◽  
Author(s):  
V. P. Ustinov ◽  
E. L. Baranova ◽  
K. N. Visheratin ◽  
M. I. Grachev ◽  
A. V. Kalsin
Keyword(s):  
Satellite Data ◽  
Total Content ◽  
Mixing Ratio ◽  
Satellite Measurements ◽  
Average Volume ◽  
Average Deviation ◽  
Average Value ◽  
Surface Measurements ◽  
Good Agreement ◽  
Measurement Period

The results of systematic (2003–2017) measurements of the total content and the volume mixing ratio of CO at Novolazarevskaya station with a spectrometer with a resolution of 0.2 cm– 1 are presented. The inverse problem of determining the total CO content, as well as interfering gases (H2O and N2O), was solved using the SFIT4 software package. Data analysis showed that over the measurement period the average total CO content at Novolazarevskaya amounted to (8 ± 2) 1017 molec/cm2, and the average volume mixing ratio amounted to (37 ± 8) ppb. The obtained data are compared with variations in the total content of CO in Arrival-Heights station, with MOPITT satellite data, as well as with surface values of CO concentration at Syova station. The maximum values of CO are observed in September, the minimum — in January–February. For all the considered series, the trends are insignificant, while there are periods of increased CO content (2010). In recent years (2014–2017) there is a tendency towards an increase in the minimum values of CO. For  Novolazarevskaya and  Arrival-Heights satellite data are characterized by the excess of over ground data, amounting to 19% and 14%, respectively, while there is a seasonal dependence of the deviation with the minimum in December–January. Surface measurements of the total CO content are in fairly good agreement at Novolazarevskaya and Arrival-Heights, and since 2010 the average deviation is 2.4%. The average value of the concentration of CO on Syova 51 ppb is higher than the average volume mixing ratio at Novolazarevskaya. According to the spectral, wavelet and composite analyzes, in all the considered series there are oscillations in the range of 6–45 months with closely coinciding periods and phases.

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