Long-term atmospheric variability on Uranus and Neptune

Icarus ◽  
2007 ◽  
Vol 186 (1) ◽  
pp. 291-301 ◽  
Author(s):  
H.B. Hammel ◽  
G.W. Lockwood
Keyword(s):  
Atmospheric Variability

scholarly journals Consistency and quality assessment of the Metop-A/IASI and Metop-B/IASI operational trace gas products (O<sub>3</sub>, CO, N<sub>2</sub>O, CH<sub>4</sub>, and CO<sub>2</sub>) in the subtropical North Atlantic

2016 ◽  
Vol 9 (5) ◽  
pp. 2315-2333 ◽  
Author(s):  
Omaira Elena García ◽  
Eliezer Sepúlveda ◽  
Matthias Schneider ◽  
Frank Hase ◽  
Thomas August ◽  
...  
Keyword(s):  
North Atlantic ◽  
Pearson Correlation ◽  
Trace Gases ◽  
Temporal Stability ◽  
Trace Gas ◽  
Atmospheric Variability ◽  
Annual Cycles ◽  
Long Term Trends ◽  
Atmospheric Variations

Abstract. This paper presents the tools and methodology for performing a routine comprehensive monitoring of consistency and quality of IASI (Infrared Atmospheric Sounding Interferometer) trace gas Level 2 (L2) products (O3, CO, N2O, CH4, and CO2) generated at EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites) using ground-based observations at the Izaña Atmospheric Observatory (IZO, Tenerife). As a demonstration the period 2010–2014 was analysed, covering the version 5 of the IASI L2 processor. Firstly, we assess the consistency between the total column (TC) observations from the IASI sensors on board the EUMETSAT Metop-A and Metop-B meteorological satellites (IASI-A and IASI-B respectively) in the subtropical North Atlantic region during the first 2 years of IASI-B operations (2012–2014). By analysing different timescales, we probe the daily and annual consistency of the variability observed by IASI-A and IASI-B and thereby assess the suitability of IASI-B for continuation of the IASI-A time series. The continuous intercomparison of both IASI sensors also offers important diagnostics for identifying inconsistencies between the data records and for documenting their temporal stability. Once the consistency of IASI sensors is documented we estimate the overall accuracy of all the IASI trace gas TC products by comparing to coincident ground-based Fourier transform infrared spectrometer (FTS) measurements performed at IZO from 2010 to 2014. The IASI L2 products reproduce the ground-based FTS observations well at the longest temporal scales, i.e. annual cycles and long-term trends for all the trace gases considered (Pearson correlation coefficient, R, larger than 0.95 and 0.75 for long-term trends and annual cycles respectively) with the exception of CO2. For CO2 acceptable agreement is only achieved for long-term trends (R ∼ 0.70). The differences observed between IASI and FTS observations can be in part attributed to the different vertical sensitivities of the two remote sensing instruments and also to the degree of maturity of the IASI products: O3 and CO are pre-operational, while N2O, CH4, and CO2 are, for the period covered by this study, aspirational products only and are not considered mature. Regarding shorter timescales (single or daily measurements), only the O3 product seems to show good sensitivity to actual atmospheric variations (R ∼ 0.80), while the CO product is only moderately sensitive (R ∼ 0.50). For the remainder of the trace gases, further improvements would be required to capture the day-to-day real atmospheric variability.

scholarly journals Simulating the effects of weather and climate on large wildfires in France

2018 ◽  
Author(s):  
Renaud Barbero ◽  
Thomas Curt ◽  
Anne Ganteaume ◽  
Eric Maillé ◽  
Marielle Jappiot ◽  
...  
Keyword(s):  
Linear Models ◽  
Weather Conditions ◽  
Historical Period ◽  
Natural Ecosystem ◽  
Atmospheric Variability ◽  
Modeling Framework ◽  
Weather And Climate ◽  
Change Context ◽  
Spatio Temporal

Abstract. Large wildfires across parts of France can cause devastating damages which put lives, infrastructures, and natural ecosystem at risk. One of the most challenging questions in the climate change context is how these large wildfires relate to weather and climate and how they might change in a warmer world. Such projections rely on the development of a robust modeling framework linking wildfires to atmospheric variability. Drawing from a MODIS product and a gridded meteorological dataset, we derived a suite of biophysical and fire danger indices and developed generalized linear models simulating the probability of large wildfires (> 100 ha) at 8-km spatial and daily temporal resolutions across the entire country over the MODIS period. The models were skillful in reproducing the main spatio-temporal patterns of large wildfires across different environmental regions. Long-term drought was found to be a significant predictor of large wildfires in flammability-limited systems such as the Alpine and Southwest regions. In the Mediterranean, large wildfires were found to be associated with both short-term fire weather conditions and longer-term soil moisture deficits, collectively facilitating the occurrence of large wildfires. Simulated probabilities during the day of large wildfires were on average 2–3 times higher than normal with respect to the mean seasonal cycle. The model has wide applications, including improving our understanding of the drivers of large wildfires over the historical period and providing a basis to estimate future changes to large wildfire from climate scenarios.

scholarly journals Assessment of Sun photometer Langley calibration at the high-elevation sites Mauna Loa and Izaña

2018 ◽  
Author(s):  
Carlos Toledano ◽  
Ramiro González ◽  
David Fuertes ◽  
Emilio Cuevas ◽  
Thomas F. Eck ◽  
...  
Keyword(s):  
Near Infrared ◽  
Quality Criteria ◽  
High Elevation ◽  
High Mountain ◽  
Atmospheric Variability ◽  
Mauna Loa ◽  
Clear Sky ◽  
Calibration Uncertainty

Abstract. The aim of this paper is to analyze the suitability of the high-mountain stations Mauna Loa and Izaña for Langley plot calibration of Sun photometers. Thus the aerosol optical depth (AOD) characteristics and seasonality, as well as the cloudiness, have been investigated in order to provide a robust estimation of the calibration accuracy, as well as the number of days that are suitable for Langley calibrations. The data used for the investigations belong to AERONET and GAW-PFR networks, which maintain reference Sun photometers at these stations with long measurement records: 22 years at Mauna Loa and 15 years at Izaña. In terms of clear sky and stable aerosol conditions, Mauna Loa (3397 m a.s.l.) exhibits on average of 377 Langleys (243 morning and 134 afternoon) per year suitable for Langley plot calibration, whereas Izaña (2373 m a.s.l.) shows 343 Langleys (187 morning and 155 afternoon) per year. The background AOD (500 nm wavelength) values, on days that are favorable for Langley calibrations, are in the range 0.01–0.02 throughout the year, with well-defined seasonality that exhibits a spring maximum at both stations plus a slight summer increase at Izaña. The statistical analysis of the long-term determination of extraterrestrial signals yields to a calibration uncertainty of ~ 0.2–0.5 %, being this uncertainty smaller in the near infrared and larger in the ultraviolet wavelengths. This is due to atmospheric variability that cannot be reduced based only on quality criteria of individual Langely plots.

scholarly journals Extreme Wave Storms and Atmospheric Variability at the Spanish Coast of the Bay of Biscay

Atmosphere ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 316 ◽  
Author(s):  
Domingo Rasilla ◽  
Juan García-Codron ◽  
Carolina Garmendia ◽  
Sixto Herrera ◽  
Victoria Rivas
Keyword(s):  
Low Frequency ◽  
Bay Of Biscay ◽  
Extreme Wave ◽  
Atmospheric Variability ◽  
Spatial And Temporal Scales ◽  
Teleconnection Patterns ◽  
Spanish Coast ◽  
Pressure Anomaly ◽  
Anomaly Index

This paper examines the characteristics and long-term variability of storminess for the Spanish coast of the Bay of Biscay for the period 1948 to 2015, by coupling wave (observed and modelled) and atmospheric datasets. The diversity of atmospheric mechanisms that are responsible for wave storms are highlighted at different spatial and temporal scales: synoptic (cyclone) and low frequency (teleconnection patterns) time scales. Two types of storms, defined mostly by wave period and storm energy, are distinguished, resulting from the distance to the forcing cyclones, and the length of the fetch area. No statistically significant trends were found for storminess and the associated atmospheric indices over the period of interest. Storminess reached a maximum around the decade of the 1980s, while less activity occurred at the beginning and end of the period of study. In addition, the results reveal that only the WEPI (West Europe Pressure Anomaly Index), EA (Eastern Atlantic), and EA/WR (Eastern Atlantic/Western Russia) teleconnection patterns are able to explain a substantial percentage of the variability in storm climate, suggesting the importance of local factors (W-E exposition of the coast) in controlling storminess in this region.

scholarly journals Can Australian Multiyear Droughts and Wet Spells Be Generated in the Absence of Oceanic Variability?

2016 ◽  
Vol 29 (17) ◽  
pp. 6201-6221 ◽  
Author(s):  
Andréa S. Taschetto ◽  
Alex Sen Gupta ◽  
Caroline C. Ummenhofer ◽  
Matthew H. England
Keyword(s):  
Southern Oscillation ◽  
Rainfall Variability ◽  
Gaussian White Noise ◽  
Atmospheric Variability ◽  
Tropical Oceans ◽  
Rainfall Anomalies ◽  
Wet Spells ◽  
Australian Rainfall ◽  
Oceanic Variability

Abstract Anomalous conditions in the tropical oceans, such as those related to El Niño–Southern Oscillation and the Indian Ocean dipole, have been previously blamed for extended droughts and wet periods in Australia. Yet the extent to which Australian wet and dry spells can be driven by internal atmospheric variability remains unclear. Natural variability experiments are examined to determine whether prolonged extreme wet and dry periods can arise from internal atmospheric and land variability alone. Results reveal that this is indeed the case; however, these dry and wet events are found to be less severe than in simulations incorporating coupled oceanic variability. Overall, ocean feedback processes increase the magnitude of Australian rainfall variability by about 30% and give rise to more spatially coherent rainfall impacts. Over mainland Australia, ocean interactions lead to more frequent extreme events, particularly during the rainy season. Over Tasmania, in contrast, ocean–atmosphere coupling increases mean rainfall throughout the year. While ocean variability makes Australian rainfall anomalies more severe, droughts and wet spells of duration longer than three years are equally likely to occur in both atmospheric- and ocean-driven simulations. Moreover, they are essentially indistinguishable from what one expects from a Gaussian white noise distribution. Internal atmosphere–land-driven megadroughts and megapluvials that last as long as ocean-driven events are also identified in the simulations. This suggests that oceanic variability may be less important than previously assumed for the long-term persistence of Australian rainfall anomalies. This poses a challenge to accurate prediction of long-term dry and wet spells for Australia.

scholarly journals South African EUCAARI – measurements: a site with high atmospheric variability

2010 ◽  
Vol 10 (12) ◽  
pp. 30691-30729 ◽  
Author(s):  
L. Laakso ◽  
V. Vakkari ◽  
H. Laakso ◽  
A. Virkkula ◽  
M. Kulmala ◽  
...  
Keyword(s):  
Optical Properties ◽  
South African ◽  
Atmospheric Aerosols ◽  
Number Concentration ◽  
Multiple Sources ◽  
Atmospheric Variability ◽  
Air Masses ◽  
Aerosol Number Concentration ◽  
A Site

Abstract. In this paper, new long-term measurements of chemical composition and physical properties of atmospheric aerosols carried out on the eastern brink of the heavily polluted Highveld area in South Africa are introduced. As expected, a high variability of aerosol properties was observed. Optical properties of aerosol particles were found to be closely correlated with particulate mass and number concentration in the case of polluted air masses. In contrast, in clean conditions there was no clear connection between optical properties and aerosol number concentration due to the presence of multiple sources including new particle formation.

scholarly journals Relativistic magnetospheric electrons: Lower ionospheric conductivity and long-term atmospheric variability

1990 ◽  
Vol 10 (10) ◽  
pp. 229-233 ◽  
Author(s):  
D.N. Baker ◽  
J.B. Blake ◽  
R.W. Klebesadel ◽  
D.D. Sentman ◽  
D.J. Gorney ◽  
...  
Keyword(s):  
Atmospheric Variability ◽  
Ionospheric Conductivity

scholarly journals Spectral UV measurements in Austria from 1994 to 2006: investigations of short- and long-term changes

2008 ◽  
Vol 8 (1) ◽  
pp. 2403-2428
Author(s):  
S. Simic ◽  
P. Weihs ◽  
A. Vacek ◽  
H. Kromp-Kolb ◽  
M. Fitzka
Keyword(s):  
Trend Test ◽  
Atmospheric Variability ◽  
Short Term ◽  
Time Period ◽  
Uv Irradiance ◽  
Long Term Changes ◽  
Long Term Trends ◽  
Short And Long Term ◽  
Double Monochromator

Abstract. Influences of atmospheric variability on short- and long-term changes of spectral UV irradiance measured at the Sonnblick observatory (47.03 N, 12.57 E, 3106 m) during the period from 1994 to 2006 is studied. Measurements are performed with a Brewer ozone single spectrophotometer and with a Bentham DM150 spectroradiometer (double monochromator). The influence of ozone, albedo and clouds on UV variability is evaluated separately using 10-year climatology. It is found that the effect of total ozone on short-term variability of UV irradiance at 305 nm can be more than 200% and on average more than 50%. Clouds can cause variability of 150% or more and on average 35%. Variability caused by albedo is maximum 32%. Long-term trends are investigated for the time period from 1994 to 2006 using the non-parametric Mann-Kendall trend test. Significant downwards trends (99% confidence level) were found for solar zenith angle 55° at wavelengths from 305 nm to 324 nm and CIE.

scholarly journals Jupiter’s Atmospheric Variability from Long-term Ground-based Observations at 5 μm

2019 ◽  
Vol 158 (3) ◽  
pp. 130 ◽  
Author(s):  
Arrate Antuñano ◽  
Leigh N. Fletcher ◽  
Glenn S. Orton ◽  
Henrik Melin ◽  
Steve Milan ◽  
...  
Keyword(s):  
Atmospheric Variability
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