scholarly journals Mars Global Ionosphere-Thermosphere Model: Solar cycle, seasonal, and diurnal variations of the Mars upper atmosphere

2015 ◽  
Vol 120 (2) ◽  
pp. 311-342 ◽  
Author(s):  
S. W. Bougher ◽  
D. Pawlowski ◽  
J. M. Bell ◽  
S. Nelli ◽  
T. McDunn ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Diurnal Variations ◽  
Upper Atmosphere ◽  
Seasonal And Diurnal Variations

Solar wind interaction with the Martian upper atmosphere: Crustal field orientation, solar cycle, and seasonal variations

2015 ◽  
Vol 120 (9) ◽  
pp. 7857-7872 ◽  
Author(s):  
Chuanfei Dong ◽  
Stephen W. Bougher ◽  
Yingjuan Ma ◽  
Gabor Toth ◽  
Yuni Lee ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Seasonal Variations ◽  
Upper Atmosphere ◽  
Solar Wind Interaction ◽  
Field Orientation ◽  
Crustal Field

Titan’s Ultraviolet Airglow Variability with Solar Cycle and Saturn Local Time

2020 ◽  
Author(s):  
Emilie Royer ◽  
Marielle Cooper ◽  
Joseph Ajello ◽  
Larry Esposito ◽  
Frank Crary
Keyword(s):  
Solar Cycle ◽  
Local Time ◽  
Solar Maximum ◽  
Incidence Angle ◽  
Upper Atmosphere ◽  
Particle Precipitation ◽  
Cassini Mission ◽  
Airglow Emissions ◽  
Airglow Intensity

<p>The Cassini spacecraft observed Titan’s upper atmosphere and its airglow emissions from 2005 to 2017. It is now established that the solar XUV radiation is the main source of dayglow, while magnetospheric particle precipitation principally acts on the nightside of the satellite. Nevertheless, one of the questions remaining unanswered after the end of the Cassini mission concerns the role and quantification of the magnetospheric particle precipitation and other minor sources such as micrometeorite precipitation and cosmic galactic ray at Titan. We report here on enhancements observed in Ultraviolet (UV) observations of Titan airglow made with the Cassini-Ultraviolet Imaging Spectrograph (UVIS). Enhancements are correlated with magnetospheric changing conditions occurring while the spacecraft, and thus Titan, are known to have crossed Saturn’s magnetopause and have been exposed to the magnetosheath environment. The processing and interpretation of 13+ years of airglow observations at Titan allows now for global studies of the upper atmosphere as a function of the Saturn Local Time (SLT) and the solar cycle.</p><p>Nitrogen airglow occur at about 1100 km of altitude in Titan’s upper atmosphere. Observations by the Cassini-UVIS instrument revealed the emission of the LBH band system, VK band system as well as Nitrogen atomic emission lines at 1085Å and 1493Å, as the prominent features of airglow emissions at Titan, as shown in Figures 1 and 2. Measurements were made at a wide range of solar incidence angles and Saturn Local Time (SLT), during the entire Cassini mission, allowing for the investigation of the upper atmosphere response to the magnetospheric environment and energetic particle precipitation. Additionally, observations were taken in a variety of solar condition, from solar maximum to minimum. UVIS observations of Titan around 12PM SLT (near Saturn’s magnetopause) present evidence of Titan’s upper atmosphere response to a fluctuating magnetospheric environment.</p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.9617eca672fe56938492951/sdaolpUECMynit/0202CSPE&app=m&a=0&c=975f92d7d9d43faa47cacd77ad47438f&ct=x&pn=gnp.elif" alt=""></p><p><strong>Figure 1.</strong> Airglow intensity as a function of the saturn Local Time (SLT), for observation taken close the Saturn’s magnetopause (12PM SLT, labelled ‘12h’) and observations taken around miadnight SLT (labelled ‘24h’). Dayglow spectra exhibit higher averaged airglow intensity than Nightglow spectra.</p><p>We present here comparisons of the spectral emissions from the dayglow (Solar incidence angle <110°) and nightglow (Solar incidence angle ≥110°) between a rayheight of 900-1200 km around noon (±1 h) and around midnight (±1 h) SLT, during solar minima and maxima conditions (Fig. 2). Results show an enhancement of the airglow brightness with increasing particle precipitation, especially at SLT close to noon (i.e. close to the magnetopause), during solar maximum and minimum. Correlation between the ratio of the V-K, LBH, and NI-1493Å emission peaks are also presented.</p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.2357e48772fe52168492951/sdaolpUECMynit/0202CSPE&app=m&a=0&c=2c6d843782e300fc27ec3db3de320caf&ct=x&pn=gnp.elif" alt=""></p><p><strong>Figure 2.</strong> Dayglow intensity as a function of the saturn Local Time (SLT) and solar cycle. Observations have been dispatched in four groups as a function of Titan’s orbital position within Saturn’s magnetosphere and maximum oe minimum stage of the solar cycle. Results suggest that solar maximum conditions around midgnight SLT favor the apparition of the brightest dayglow.</p><p>In the past decade, results from the Cassini-UVIS instrument greatly improved our understanding of airglow production at Titan. However, combining remote-sensing datasets, such as Cassini-UVIS data, with in-situ measurements taken by the Cassini Plasma Spectrometer (CAPS) instrument can provide us with a more rigorous assessment of the airglow contribution and correlations between data from simultaneous observations of in-situ Cassini instruments (CAPS, RPWS and MIMI) has been possible on few occasions. UVIS results present here will be put in context with results from in-situ simultaneous observations.</p><!-- COMO-HTML-CONTENT-END --> <p class="co_mto_htmlabstract-citationHeader"> <strong class="co_mto_htmlabstract-citationHeader-intro">How to cite:</strong> Royer, E., Cooper, M., Ajello, J., Esposito, L., and Crary, F.: Titan’s Ultraviolet Airglow Variability with Solar Cycle and Saturn Local Time, Europlanet Science Congress 2020, online, 21 September–9 Oct 2020, EPSC2020-415, 2020 </p>

scholarly journals The Thermosphere Responds to a Weaker Than Normal Solar Cycle

Eos ◽  
2019 ◽  
Vol 100 ◽  
Author(s):  
Aaron Sidder
Keyword(s):  
Nitric Oxide ◽  
Carbon Dioxide ◽  
Solar Cycle ◽  
Solar Radiation ◽  
Upper Atmosphere ◽  
Incoming Solar Radiation ◽  
Infrared Emissions

Infrared emissions from nitric oxide and carbon dioxide in Earth’s upper atmosphere, which are closely tied to incoming solar radiation, are drastically lower than in the previous solar cycle.

scholarly journals On the observed changes in upper stratospheric and mesospheric temperatures from UARS HALOE

2008 ◽  
Vol 26 (5) ◽  
pp. 1287-1297 ◽  
Author(s):  
E. Remsberg
Keyword(s):  
Time Series ◽  
Solar Cycle ◽  
Linear Regression ◽  
Linear Trend ◽  
Upper Atmosphere ◽  
Middle Latitudes ◽  
Solar Occultation ◽  
Decadal Scale ◽  
Low Latitudes ◽  
Pressure Altitude

Abstract. Temperature versus pressure or T(p) time series from the Halogen Occultation Experiment (HALOE) of the Upper Atmosphere Research Satellite (UARS) have been extended and re-analyzed for the period of 1991–2005 and for the upper stratosphere and mesosphere in 10-degree wide latitude zones from 60 S to 60 N. Even though sampling from a solar occultation experiment is somewhat limited, it is shown to be quite adequate for developing both the seasonal and longer-term variations in T(p). Multiple linear regression (MLR) techniques were used in the re-analyses for the seasonal and the significant interannual, solar cycle (SC-like or decadal-scale), and linear trend terms. Plots of the amplitudes and phases for the interannual (QBO and subbiennial) terms are provided. A simple SC-like term of 11-yr period was fitted to the time series residuals after accounting for the seasonal and interannual terms. Highly significant SC-like responses were found for both the upper mesosphere and the upper stratosphere. The phases of these SC-like terms were checked for their continuity with latitude and pressure-altitude; the larger amplitude responses are directly in-phase with that of standard proxies for the solar flux variations. The analyzed, max minus min, responses at low latitudes are of order 0.5 to 1 K, while at middle latitudes they are as large as 3 K in the upper mesosphere. Highly significant, linear cooling trends were found at middle latitudes of the middle to upper mesosphere (−1.5 to −2.0 K/decade), at tropical latitudes of the lower mesosphere (about −0.5 K/decade), and at 2 hPa (of order −1 K/decade). Both the diagnosed solar cycle responses and trends from HALOE for the mid to upper mesosphere at middle latitudes are larger than simulated with most models, perhaps an indication of decadal-scale dynamical forcings that are not being simulated so well.

Variations in the Ionospheric Peak Altitude at Mars in Response to Dust Storms

2019 ◽  
Author(s):  
Z Girazian ◽  
Z Luppen ◽  
D D Morgan ◽  
F Chu ◽  
L Montabone ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Zenith Angle ◽  
Dust Storm ◽  
Observational Studies ◽  
Solar Zenith Angle ◽  
Dust Storms ◽  
Upper Atmosphere ◽  
Mars Express

Previous observations have shown that, during Martian dust storms, the peak of the ionosphere rises in altitude. Observational studies of this type, however, have been extremely limited. Using 13 years of ionospheric peak altitude data from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on Mars Express, we study how the peak altitude responded to dust storms during six different Mars Years (MY). We find that the peak altitude increased during regional dust storms in MY 27 and MY 33, and during the global dust storm in MY 28. In contrast, we find that the peak altitude did not increase during regional dust storms in MY 29 and MY 32, nor during the global dust storm in MY 34. Our results suggest that the response of the upper atmosphere and ionosphere to dust storms is dependent on several factors, including latitude, solar zenith angle, solar cycle conditions, and the magnitude of the dust storm.

Ultraviolet Solar Spectral Irradiance Variation on Solar Cycle Timescales

2018 ◽  
Vol 13 (S340) ◽  
pp. 203-208 ◽  
Author(s):  
Martin Snow ◽  
Francis G. Eparvier ◽  
Jerald Harder ◽  
Andrew R. Jones ◽  
William E. McClintock ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Space Weather ◽  
Upper Atmosphere ◽  
Spectral Irradiance ◽  
The Sun ◽  
Robust Method ◽  
Solar Cycles ◽  
Solar Spectral Irradiance ◽  
Irradiance Variation ◽  
Earth Connection

AbstractUltraviolet (UV) Solar spectral Irradiance (SSI) has been measured from orbit on a regular basis since the beginning of the space age. These observations span four Solar Cycles, and they are crucial for our understanding of the Sun-Earth connection and space weather. SSI at these wavelengths are the main drivers for the upper atmosphere including the production and destruction of ozone in the stratosphere. The instruments that measure UV SSI not only require good preflight calibration, but also need a robust method to maintain that calibration on orbit. We will give an overview of the catalog of current and former UV SSI measurements along with the calibration philosophy of each instrument and an estimation of the uncertainties in the published irradiances.

scholarly journals Solar-cycle, seasonal, and asymmetric dependencies of thermospheric mass density disturbances due to magnetospheric forcing

2019 ◽  
Author(s):  
Andres Calabia ◽  
Shuanggen Jin
Keyword(s):  
Principal Component Analysis ◽  
Solar Cycle ◽  
High Frequency ◽  
Mass Density ◽  
Principal Component ◽  
Component Analysis ◽  
Upper Atmosphere ◽  
Local Solar Time ◽  
Short Term ◽  
Solar Time

Abstract. Short-term upper atmosphere variations due to magnetospheric forcing are very complex, and neither well understood nor capably modelled due to limited observations. In this paper, mass density variations from 2003–2013 of GRACE observations are isolated through the parameterization of annual, Local-Solar-Time (LST), and solar-cycle fluctuations using a Principal Component Analysis (PCA) technique and investigated in terms of magnetospheric drivers. The magnitude of high-frequency (

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