Modeling the microphysics of mesospheric ice particles: Assessment of current capabilities and basic sensitivities

We report on a thorough analysis of the Mars Pathfinder atmospheric structure investigation (ASI) accelerometer data spanning the altitude range 161–8.9 km. Entry, descent, and landing occurred within 850 km of the Viking 1 lander and somewhat later in northern summer. The early morning entry (0300 hours) provided the first opportunity to study Mars' nighttime atmospheric structure; the close proximity to the Viking 1 site has permitted a search for changes in atmospheric structure during the 21 years between the landings. Our results confirm and refine the major features of the atmospheric structure discovered in the initial analysis of the ASI results reported by Schofield et al. [1997]. The current analysis has yielded a much better definition of the temperature structure above 90 km altitude. Pathfinder measured a thermospheric peak temperature of 153°K at 134 km, which is 30°K colder than the value found by Viking 1. Between 110 and 88 km, Pathfinder found a broad, nearly isothermal plateau at 127°K, which correlates very well with a similar structure evident in Viking 1 data at the same pressures, although the Pathfinder layer is 25°K colder. At levels above 88 km, wavelike oscillations with a wavelength ∼5 km and amplitudes of 2–3°K are evident, possibly reflecting gravity or planetary wave activity. Between 90 and 60 km the average temperature is 20–30°K cooler than Viking 1 values. Large-amplitude (10–20°K) long-wavelength (20–40 km) oscillations, which show a remarkable correspondence to equivalent structures found in the Viking 1 profile at the same pressures, occur in this region and are likely due to a diurnal tidal mode. Between 85 and 77 km a minimum of one oscillation results in temperatures up to 7°K below the saturation temperature of CO2, well outside the uncertainties in the measurements and the vapor pressure curve and comparable to observed supersaturations of water in Earth's mesosphere. Between 55 and 16 km, temperatures are close to or warmer than Viking 1 values; superposed long-wavelength oscillations correspond well with similar structures observed by Viking 1. Between 16 and 9.9 km the temperature profile shows an unexpected strong thermal inversion, which may reflect radiative cooling due to a water cloud. At the base of the inversion, temperatures begin to increase abruptly until the last measurement at 8.9 km. The Viking-like temperatures in the lower atmosphere are consistent with the Viking-like dust optical depths observed by the Mars Pathfinder imager. The cool temperatures in the middle and upper atmosphere may be indicative of significant nighttime cooling at these levels, although other interpretations are possible.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1998JE900041

Results of the Mars Pathfinder atmospheric structure investigation

[1] Gravity waves (GWs) are a ubiquitious dynamical feature of the polar summer mesopause region During three summer campaigns, in 1991, 1993 and 1994, we launched seven sounding rockets from the north Norwegian island Andoya Each of these payloads carried an ionization gauge capable of measuring the total atmospheric density at a high spatial resolution From these measurements, temperature profiles were determined for altitudes between 70 and 110 km, with an altitude resolution of 200 m The temperature profiles reveal significant rms variations that are as large as 6 K at 80 km, 10 K at 85 km, and even 20 K at 95 km During three out of the seven launches a bright noctilucent cloud (NLC) was simultaneously detected by our ground-based lidar and by rocket-borne in situ experiments During these flights, the NLC is located close to a local temperature minimum below the mesopause We then estimated gravity wave parameters from accompanying falling sphere and chaff wind observations and found signatures that the wave periods during the NLC cases were on the order of 7–9 hours, with corresponding horizontal wavelengths of 600–1000 km Motivated by these observations, we used a microphysical model of NLC generation and growth to study the interaction between GWs and NLC Based on recently measured and modeled temperatures and water vapor mixing ratios, and our gravity wave parameter estimates, we find that the NLC layer indeed follows the motion of the cold phase of the wave by means of a complex interplay between ice crystal sedimentation, transport by the vertical wind, and simultaneous growth It turns out that the history of individual particles significantly influences the observed properties of NLC Furthermore, we find that GWs with periods longer than 65 hours amplify NLC while waves with shorter periods tend to destroy NLC In addition, we can only find a correlation between local temperature minima and the location of the NLC provided that the wave periods are longer than ∼6 hours, which is consistent with our wave parameter estimates

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2001JD001241

Small‐scale temperature variations in the vicinity of NLC: Experimental and model results

[1] In summertime, layers of icy particles form in the high-latitude mesopause region, causing the phenomena of noctilucent clouds and polar mesosphere summer echoes. We study the formation of these layers by means of a 3-D general circulation model of the middle atmosphere (COMMA/IAP) including new modules for the mesospheric chemistry and for the microphysics of icy particles. We initialize the mesopause region with an ensemble of two million particles and investigate their time-dependent transport in a 2-D Lagrangian way. We use the model to study in considerable detail ice particle formation by heterogeneous nucleation on smoke particles, freeze-drying of the mesopause region by formation of ice particles, and the influences of tidal waves and particle eddy diffusion on ice particle and noctilucent cloud (NLC) layer behavior. We present model results on the requirements for adequate size of smoke particles to act as condensation nuclei in the mesopause region (directly after initialization > 0.7 nm radius; after 8 hours > 2 nm), the types of ice particle trajectories, the timescale for growth of particles (6 to 8 hours to radii > 20 nm) and sublimation of ice particles (duration of sublimation phase typically 6 hours), the typical altitude range of maximum NLC brightness (82.5–83.0 km), the size distributions of ice particles (closer to Gaussian than lognormal in shape), the importance of the vertical component of the tidal winds on NLC layer behavior, and the dominance of semidiurnal over diurnal tidal effects. Furthermore, the model allows us to make predictions on a number of NLC features that are either currently under study or may become observable in the near future, such as properties of NLC at high arctic latitudes, and the development of layers with strongly enhanced water vapor mixing ratios near the lower border of the NLCs.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2001JA000316

Icy particles in the summer mesopause region: Three-dimensional modeling of their environment and two-dimensional modeling of their transport

[1] Previous satellite measurements have provided nearly complete seasonal and geographic coverage of polar mesospheric clouds (PMCs), but previous data sets have not been able to evaluate changes in PMC behavior on decadal timescales. The Solar Backscattered Ultraviolet (SBUV) series of ozone measuring instruments have been flying continuously since 1978. While the instrument design is not optimized for PMC detection, the radiance data can be analyzed to examine the occurrence frequency and intensity of relatively bright PMCs. In this paper, we present PMC results from five SBUV and SBUV/2 instruments covering more than 23 years (1978–2002), starting just before the maximum of solar cycle 21 and extending through the maximum of solar cycle 23. The overlapping data sets from nearly identical instruments give an accurate picture of long-term variations. Multiple linear regression fits are used to examine solar and secular correlations. PMC occurrence frequency is anticorrelated with solar Lyman alpha irradiance, with an approximate 0.5-year phase lag in the Northern Hemisphere (Rsolar = −0.87) and no phase lag in the Southern Hemisphere (Rsolar = −0.65). The distribution of cloud brightness by season appears to be changing over time. When the PMC brightness for each season is characterized using an exponential cumulative distribution function, the exponent decreases in magnitude by a factor of 2 from 1978 to 2002 in the Southern Hemisphere (Rtime = +0.85). This implies an increase in the relative proportion of the brightest PMCs. The secular brightness trend is less significant in the Northern Hemisphere (Rtime = +0.58). We discuss possible origins for these changes.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2002JD002398

Solar backscattered ultraviolet (SBUV) observations of polar mesospheric clouds (PMCs) over two solar cycles

a Numerical Model of Polar Mesospheric Cloud Formation and Evolution.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Eric Jon Jensen

Author Tools

Chat about Author

Papers

a Numerical Model of Polar Mesospheric Cloud Formation and Evolution.