Stan Solomon

Climate Change in the Thermosphere and Ionosphere From the Early Twentieth Century to Early Twenty‐First Century Simulated by the Whole Atmosphere Community Climate Model—eXtended

whawkins — Fri, 02 Feb 2024 22:11:17 +0000

Climate Change in the Thermosphere and Ionosphere From the Early Twentieth Century to Early Twenty‐First Century Simulated by the Whole Atmosphere Community Climate Model—eXtended whawkins Fri, 02/02/2024 - 15:11

Author:

whawkins

Feb 2, 2024

Five-year zonal mean decadal value differences relative to the 1920s at March equinox (top) and June solstice (bottom) for neutral temperature on the 2.84×10-8 hPa pressure surface a) at ~295 km and e) at ~285 km, neutral density b) at ~377 km and f) at ~395 km, electron density c) at ~377 km and g) at ~395 km, and d) and h) electron column density.

Journal of Geophysical Research, Atmospheres: From seeing lower atmosphere computer climate models run for the past century, we decided to do the same for the upper atmosphere using the Whole Atmosphere Community Climate Model-eXtended (WACCM-X) for the decades from the 1920s to 2010s. In this higher region, the atmosphere is affected strongly by the Sun and removing the Sun’s effect is tricky in previous observation and model studies. We make the Sun’s effect small to see only effects from the Earth’s magnetic field and greenhouse gases. Earlier studies focused on recent decades show effects of greenhouse gas increases on the upper atmosphere but not for the early decades of the past century with greenhouse gas changes from less than 5% increase prior to the space age and the transition to the over 25% increase in the latter half of the 20th century. We cover this entire period and get results like those in studies before, with especially the temperature change matching very well with the greenhouse gas carbon dioxide change. Because WACCM-X performs well over the past century, it will be useful to predict what will happen in the century ahead as greenhouse gases increase and humans make efforts to reverse the increase.

Climate responses under an extreme quiet sun scenario

whawkins — Tue, 14 Feb 2023 17:32:02 +0000

Climate responses under an extreme quiet sun scenario whawkins Tue, 02/14/2023 - 10:32

Author:

whawkins

Feb 14, 2023

Understanding how climate may change under different solar conditions is both interesting and important. However it is difficult to clearly identify solar signal from the very large climate variability on broad time scales. In this study, we tackle this problem by providing a lower bound of the solar minimum condition according to our current understanding of solar physics. By specifying this extremely low solar minimum condition in a climate model that takes into consideration of the effects of ocean and middle atmosphere, we are able to identify significant climate responses, which are very different between the northern and southern hemispheres. We gain an understanding of the processes driving these responses, including how the lower and upper atmospheric processes may enhance/offset each other. By comparing these climate responses to those under nominal solar minimum conditions, we expose climate patterns that are hidden under the large climate variability in the latter.

Differences of average zonal mean zonal wind (color contours) between 50--200 year of HD and Smax simulations for (a) DJF and (c) JJA. Line contours are average zonal mean zonal wind from Smax simulations (contour intervals: 15 m/s. (b) and (d): similar to (a) and (c) but for average zonal mean temperature differences (color contour and grey line contours for differences less than 1 K, with 0.25 K intervals). Line contours are average zonal mean temperature from Smax simulations (contour intervals: 10 K). (e) and (g): similar to (a) and (c) but for average vertical EP flux component differences. The EP flux (unit: Pa m) is normalized by p^0.75 (p: atmosphere pressure) to better visualize the change at all altitudes (color contour). Line contours are average normalized vertical EP flux component from Smax simulations (contour intervals: 10x10^2). (f) and (h): similar to (a) and (c) but for average EP flux divergence differences (color contour). Line contours are average EP flux divergence from Smax simulations (contour intervals: 1 m/s/d).}

2022 Space Weather Summer School

whawkins — Tue, 30 Aug 2022 15:45:48 +0000

2022 Space Weather Summer School whawkins Tue, 08/30/2022 - 09:45

Author:

whawkins

Aug 30, 2022

FYI, we will not be holding a Space Weather Summer School in 2023. We hope to resume in 2024.

HAO held the latest in a series of successful Space Weather Summer Schools in Boulder, Colorado during the last 2 weeks of July. This unique educational workshop brought together 31 students mainly from the United States along with two students from abroad. Lecturers included experts in solar physics, solar wind, magnetsophere, and ionosphere-thermosphere in order to provide the students with a comprehensive background of the complete space weather system. In addition to lectures on the physics of the system, students learned from experts at the Space Weather Prediction Center about the challenges in making accurate space weather forecasts. Specialists provided an understanding of how space weather processes turn into impacts in human systems such as the power grid. Each day of the school included a computer-based laboratory exercise that let the students get hands-on experience with the models used to simulate space weather. HAO was pleased to once again provide students with an informative, comprehensive, and well well-appreciated introduction to space weather.

SWSS 2022 Group Photograph

Space Storms in the Upper Atmosphere and Ionosphere

kolinski — Mon, 22 Nov 2021 18:42:26 +0000

Space Storms in the Upper Atmosphere and Ionosphere kolinski Mon, 11/22/2021 - 11:42

NASA Features Research by HAO Scientist Xuguang Cai

kolinski — Thu, 18 Nov 2021 20:58:13 +0000

NASA Features Research by HAO Scientist Xuguang Cai kolinski Thu, 11/18/2021 - 13:58

Upper atmosphere radiance data assimilation: A feasibility study for GOLD far ultraviolet observations

kolinski — Thu, 18 Nov 2021 19:25:07 +0000

Upper atmosphere radiance data assimilation: A feasibility study for GOLD far ultraviolet observations kolinski Thu, 11/18/2021 - 12:25

Publication Name: Journal of Geophysical Research Space Physics; First HAO Author's Name: Stanley C. Solomon

Author:

kolinski

Nov 18, 2021

Availability of far ultraviolet observations of Earth’s dayglow by the NASA Global-scale Observations of the Limb and Disk (GOLD) mission presents an unparalleled opportunity for upper atmosphere radiance data assimilation.

Assimilation of the observed dayglow emissions can be formulated in a similar fashion to lower atmosphere radiance data assimilation approaches using the sensitivity of the Lyman-Birge-Hopfield (LBH) band emission to thermospheric temperature. To demonstrate such an approach, this paper presents a proof-of-concept implementation of an ensemble filter measurement update step using ensemble simulation of the thermosphere and LBH emission by the NOAA's Whole Atmosphere Model (WAM) and NCAR’s Global Airglow model.

Accuracy of temperature estimates in the measurement update step for four different assimilated observations.

Testing the approach with observing system simulation experiments has yielded the following findings: (1) Assimilation of GOLD LBH disk emission data can reduce the error in model temperature specification from forecast to analysis by 97% under geomagnetically quiet conditions and 87% under disturbed conditions, (2) The reduction in model uncertainty from forecast to analysis as a result of GOLD assimilation is ~20% in the lower thermosphere and ~25% in the upper thermosphere, and (3) Ingestion of three prominent LBH features, in comparison to the entire LBH spectrum, into the WAM leads to more accurate assimilation analyses. With the help of a radiance data assimilation approach, the utility of GOLD observations can be extended to reveal global, time-dependent, altitude-resolved thermospheric structure, offering the key to addressing a number of outstanding questions such as those relating to the properties of travelling atmospheric disturbances.

Link to paper: Upper atmosphere radiance data assimilation: A feasibility study for GOLD far ultraviolet observations

Global-scale Measurements of the Limb and Disk (GOLD) Mission Implementation: Instrument Design and Early Flight Performance

kolinski — Wed, 17 Nov 2021 20:03:40 +0000

Global-scale Measurements of the Limb and Disk (GOLD) Mission Implementation: Instrument Design and Early Flight Performance kolinski Wed, 11/17/2021 - 13:03

ublication Name: Journal of Geophysical Research Space Physics; First HAO Author's Name: Stan Solomon; Authors: McClintock, W. E., Richard Eastes, Alan Hoskins, Oswald Siegmund, Jason McPhate, Andrey Krywonos, Stanley Solomon, and Alan Burns

Author:

kolinski

Nov 17, 2021

The Global-scale Observations of the Limb and Disk (GOLD) is a NASA mission of opportunity designed to study how the Earth’s ionosphere-thermosphere system responds to geomagnetic storms, solar radiation and upward propagating tides on time scales as short as 30 minutes.

Sectional view of a GOLD spectroscopic imaging channel.

GOLD employs two identical ultraviolet spectrographs that make observations of the Earth’s thermosphere and ionosphere from a commercial communications satellite owned and operated by SES and located in geostationary orbit at 47.5° west longitude (near the mouth of the Amazon River). They make images of atomic oxygen 135.6 nm and N2 LBH radiances of the entire disk that is observable from geostationary orbit and on the near-equatorial limb. They also observe occultations of stars to measure molecular oxygen column densities on the limb. Here we describe the GOLD instrument including its optical system and detector. Its performance was characterized in the lab before launch. We compare measurements of laboratory sources made then to observations of the thermosphere after launch and find good agreement.

Link to paper: Global-scale Measurements of the Limb and Disk (GOLD) Mission Implementation: 1. Instrument Design and Early Flight Performance

Responses of the Thermosphere and Ionosphere System to Concurrent Solar Flares and Geomagnetic Storms

kolinski — Wed, 17 Nov 2021 17:13:03 +0000

Responses of the Thermosphere and Ionosphere System to Concurrent Solar Flares and Geomagnetic Storms kolinski Wed, 11/17/2021 - 10:13

Publication Name: JGR; Author's Names: Liying Qian, Wenbin Wang, Alan G. Burns, Phillip C. Chamberlin, Stanley C. Solomon

Author:

kolinski

Nov 17, 2021

We conducted numerical simulations to examine dayside thermosphere and ionosphere responses to concurrent solar flares and a geomagnetic storm during September 6th – September 11th, 2017, as well as the interplay of flare and storm effects. We found that E-region electron density response to the flares was much smaller inside the auroral oval than it was outside the auroral oval due to an extra source of ionization by auroral particle precipitation. During quiet times in this period, flare enhanced ionization, which decreased daytime eastward electric fields, caused an initial weakening of the vertical E x B drifts.

The simulated vertical E x B drift velocity (Wi), and the changes of the vertical drift velocity due to the flares, at 300 km and12:00 LT (September 6th – September 11th, 2017). (a) Wi using the flare spectrum and observed Kp; (b) Wi using the daily spectrum and observed Kp; (c) the difference between (a) and (b), which is the response to the flares in the presence of the storm; (d) the GOES X-ray energy flux in 0.1 – 0.8nm; (e) the Dst index. The vertical dashed lines indicate the flare peaks.

This weakening of the vertical E x B drifts was on the order of ~ 20% for an X8.2 flare in this period. During storm times, flare-induced initial changes of the vertical plasma drifts varied between being positive and being negative, depending on latitudes, due to storm-time disturbance dynamo effects. Storm effects also overall weakened flare effects on geopotential height, ionospheric F2 peak height hmF2, and ionospheric F2 peak electron density NmF2. In addition, storm effects changed the latitudinal distributions of flare effects on hmF2, NmF2, vertical plasma drifts, and O/N2. On the other hand, no major X-class flare occurred shortly before or during the storm. Model simulations indicate that the weaker C- and M- class flares that occurred before and during the storm had a minor effect on the amplitude of the large-scale traveling atmosphere disturbances generated by the storm.

Comparison of GOLD nighttime measurements with total electron content: preliminary results

kolinski — Tue, 16 Nov 2021 22:37:36 +0000

Comparison of GOLD nighttime measurements with total electron content: preliminary results kolinski Tue, 11/16/2021 - 15:37

ublication: Journal of Geophysical Research, Space Physics; Authors: Xuguang Cai, Alan G. Burns, Wenbin Wang, Anthea Coster, Liying Qian, Jing Liu, Stanley C. Solomon, Richard W. Eastes, Robert E. Daniell, William E. McClintock

Author:

kolinski

Nov 16, 2021

The National Aeronautics and Space Administration (NASA) Global‐scale Observations of the Limb and Disk (GOLD) has been imaging the thermosphere and ionosphere since October 2018. It provides continuous measurements over a large area from its geostationary orbit. The unambiguous 2-dimensional (2D) maps of OI 135.6 nm radiance retrieved from GOLD after sunset are compared with the total electron content (TEC) maps measured by GPS receivers in the American sector. The OI 135.6 nm radiance observed by GOLD is an indicator of the peak electron density of the ionosphere F2 region, while the TEC is the total electron density in the column.

The comparison between the GOLD map and TEC2 map on DOY 72 in 2019 23:10-23:40 (top) and 23:55-24:25 (bottom). The white part stands for the data unavailability and the pink line is the geomagnetic equator. The black points stand for the location of the peaks of the EIA.

Our comparisons show that the two datasets match each other very well in the equatorial ionization anomaly (EIA) morphology and its seasonal variability. Equatorial plasma bubbles (EPBs) are evident in GOLD nighttime OI 135.6 radiance. Corresponding depletions are shown in TEC maps, but without GOLD data as a reference, it is difficult to discern that the depletions are EPBs. In addition, both GOLD 135.6 radiance and TEC maps observed third peaks of electron density poleward of the southern EIA crests. Furthermore, both show that the ionosphere after sunset is quite dynamic and has strong day-to-day variability. In all, the GOLD and TEC have valuable synergy to allow us to gain a better understanding of the equatorial ionosphere.

Link to paper: Comparison of GOLD Nighttime Measurements With Total Electron Content: Preliminary Results

The 2‐D Evolution of Thermospheric ∑O/N2 Response to Weak Geomagnetic Activity During Solar‐Minimum Observed by GOLD

kolinski — Tue, 16 Nov 2021 22:34:30 +0000

The 2‐D Evolution of Thermospheric ∑O/N2 Response to Weak Geomagnetic Activity During Solar‐Minimum Observed by GOLD kolinski Tue, 11/16/2021 - 15:34

Publication Name: Geophysical Research Letters; First HAO Author's Name: Xuguang Cai; Other Authors: Alan G. Burns, Wenbin Wang, Liying Qian, Stanley C. Solomon Richard W. Eastes, Nicolas Pedatella, Robert E. Daniell, Will

Author:

kolinski

Nov 16, 2021

We conduct observational and modeling studies of thermospheric composition responses to weak geomagnetic activity (non-geomagnetic storms). We found that the thermospheric O and N 2 column density ratio (∑O/N 2 ) in part of the Northern Hemisphere measured by Global-scale Observations of the Limb and Disk (GOLD) exhibited large and long-lived depletions during weak geomagnetic activity in May and June 2019.

(top) The Kp and Dst index of three cases (DOY 145 to 148; DOY 153 to 156; DOY 162 to 165); (middle) latitude-longitude distribution of ∑O/N2 percentage difference between two quiet days in three cases; (bottom) percentage difference of ∑O/N2 between disturbed and quiet days in three cases. Corresponding local time is marked on longitude interval.

The depletions reached 30% of quiet time values, extended equatorward to 10°N, and lasted more than 10 hours. Furthermore, numerical simulation results are similar to these observations and indicate that the ∑O/N 2 depletions were pushed westward by zonal winds. The ∑O/N 2 evolution during weak geomagnetic activity suggests that the formation mechanism of the ∑O/N 2 depletions is similar to that during a geomagnetic storm. The effects of weak geomagnetic activity are often ignored, but, in fact, are important for understanding thermosphere neutral composition variability and hence the state of the thermosphere-ionosphere system.

2020 Cai The two dimensional Evolution

Stan Solomon

Climate Change in the Thermosphere and Ionosphere From the Early Twentieth Century to Early Twenty‐First Century Simulated by the Whole Atmosphere Community Climate Model—eXtended

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Climate responses under an extreme quiet sun scenario

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2022 Space Weather Summer School

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Space Storms in the Upper Atmosphere and Ionosphere

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NASA Features Research by HAO Scientist Xuguang Cai

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Upper atmosphere radiance data assimilation: A feasibility study for GOLD far ultraviolet observations

Recent News

Global-scale Measurements of the Limb and Disk (GOLD) Mission Implementation: Instrument Design and Early Flight Performance

Recent News

Responses of the Thermosphere and Ionosphere System to Concurrent Solar Flares and Geomagnetic Storms

Recent News

Comparison of GOLD nighttime measurements with total electron content: preliminary results

Recent News

The 2‐D Evolution of Thermospheric ∑O/N2 Response to Weak Geomagnetic Activity During Solar‐Minimum Observed by GOLD

Recent News