scholarly journals Methane as a diagnostic tracer of changes in the net circulation of the middle atmosphere

2014 ◽  
Vol 14 (17) ◽  
pp. 24183-24220
Author(s):  
E. E. Remsberg
Keyword(s):  
Time Series ◽  
Northern Hemisphere ◽  
Large Scale ◽  
Middle Atmosphere ◽  
Chemical Conversion ◽  
Global Scale ◽  
Positive Trend ◽  
Residual Circulation ◽  
Use Of Time ◽  
Extratropical Latitude

Abstract. This study makes use of time series of methane (CH4) data from the Halogen Occultation Experiment (HALOE) to determine whether there were any statistically significant changes of the net circulation within the stratosphere and lower mesosphere during 1992–2005. HALOE CH4 profiles in terms of mixing ratio vs. pressure-altitude are binned into subtropical and extratropical latitude zones of the southern and of the Northern Hemisphere, and their separate time series are then analyzed using multiple linear regression (MLR) techniques. A positive trend in the subtropics and a negative trend in the extratropics is interpreted as indicating an acceleration of the net circulation. A significant acceleration is found in the Northern Hemisphere from 20 hPa to 7 hPa, a likely indication of changes from the effects of wave activity during those years. No similar acceleration is found in the Southern Hemisphere. The trends from HALOE H2O are analyzed and compared with those from CH4 for consistency because H2O is a primary product in the upper stratosphere of the chemical conversion of CH4. The CH4 and H2O trends have a ratio of nearly 2 : 1, and they are anti-correlated most clearly near the stratopause in the southern extratropics. Seasonal anomalies are found in the HALOE CH4 time series of the lower mesosphere, and they are ascribed to wave-driven, secondary residual circulation cells associated with the descent of the SAO westerlies. The time series residuals for CH4 of the lower mesosphere also exhibit aperiodic structure, and it is anti-correlated with that of the tracer-like species HCl. Such structure indicates the effects of variations in the wave forcing. It is concluded that multi-year, global-scale distributions of CH4 are very useful for diagnosing large-scale changes of the net transport within the middle atmosphere.

scholarly journals Methane as a diagnostic tracer of changes in the Brewer–Dobson circulation of the stratosphere

2015 ◽  
Vol 15 (7) ◽  
pp. 3739-3754 ◽  
Author(s):  
E. E. Remsberg
Keyword(s):  
Time Series ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Lower Stratosphere ◽  
Middle Atmosphere ◽  
Wave Activity ◽  
Mixing Ratio ◽  
Use Of Time ◽  
Wave Induced ◽  
Middle Stratosphere

Abstract. This study makes use of time series of methane (CH4) data from the Halogen Occultation Experiment (HALOE) to detect whether there were any statistically significant changes of the Brewer–Dobson circulation (BDC) within the stratosphere during 1992–2005. The HALOE CH4 profiles are in terms of mixing ratio versus pressure altitude and are binned into latitude zones within the Southern Hemisphere and the Northern Hemisphere. Their separate time series are then analyzed using multiple linear regression (MLR) techniques. The CH4 trend terms for the Northern Hemisphere are significant and positive at 10° N from 50 to 7 hPa and larger than the tropospheric CH4 trends of about 3% decade−1 from 20 to 7 hPa. At 60° N the trends are clearly negative from 20 to 7 hPa. Their combined trends indicate an acceleration of the BDC in the middle stratosphere of the Northern Hemisphere during those years, most likely due to changes from the effects of wave activity. No similar significant BDC acceleration is found for the Southern Hemisphere. Trends from HALOE H2O are analyzed for consistency. Their mutual trends with CH4 are anti-correlated qualitatively in the middle and upper stratosphere, where CH4 is chemically oxidized to H2O. Conversely, their mutual trends in the lower stratosphere are dominated by their trends upon entry to the tropical stratosphere. Time series residuals for CH4 in the lower mesosphere also exhibit structures that are anti-correlated in some instances with those of the tracer-like species HCl. Their occasional aperiodic structures indicate the effects of transport following episodic, wintertime wave activity. It is concluded that observed multi-year, zonally averaged distributions of CH4 can be used to diagnose major instances of wave-induced transport in the middle atmosphere and to detect changes in the stratospheric BDC.

scholarly journals Estimating mass-wasting processes in active earth slides – earth flows with time-series of High-Resolution DEMs from photogrammetry and airborne LiDAR

2009 ◽  
Vol 9 (2) ◽  
pp. 433-439 ◽  
Author(s):  
A. Corsini ◽  
L. Borgatti ◽  
F. Cervi ◽  
A. Dahne ◽  
F. Ronchetti ◽  
...  
Keyword(s):  
Time Series ◽  
High Resolution ◽  
Large Scale ◽  
Airborne Lidar ◽  
Mitigation Measures ◽  
Mass Wasting ◽  
Aerial Photos ◽  
Use Of Time ◽  
Elevation Changes ◽  
Earth Flows

Abstract. This paper deals with the use of time-series of High-Resolution Digital Elevation Models (HR DEMs) obtained from photogrammetry and airborne LiDAR coupled with aerial photos, to analyse the magnitude of recently reactivated large scale earth slides – earth flows located in the northern Apennines of Italy. The landslides underwent complete reactivation between 2001 and 2006, causing civil protection emergencies. With the final aim to support hazard assessment and the planning of mitigation measures, high-resolution DEMs are used to identify, quantify and visualize depletion and accumulation in the slope resulting from the reactivation of the mass movements. This information allows to quantify mass wasting, i.e. the amount of landslide material that is wasted during reactivation events due to stream erosion along the slope and at its bottom, resulting in sediment discharge into the local fluvial system, and to assess the total volumetric magnitude of the events. By quantifying and visualising elevation changes at the slope scale, results are also a valuable support for the comprehension of geomorphological processes acting behind the evolution of the analysed landslides.

scholarly journals Renewed methane increase for five years (2007–2011) observed by solar FTIR spectrometry

2012 ◽  
Vol 12 (11) ◽  
pp. 4885-4891 ◽  
Author(s):  
R. Sussmann ◽  
F. Forster ◽  
M. Rettinger ◽  
P. Bousquet
Keyword(s):  
Time Series ◽  
Confidence Interval ◽  
Global Scale ◽  
Future Trend ◽  
Time Interval ◽  
Positive Trend ◽  
Time Period ◽  
New Period ◽  
Natural Wetlands ◽  
Surface Network

Abstract. Trends of column-averaged methane for the time period (1996, Sep 2011) are derived from the mid-infrared (mid-IR) solar FTIR time series at the Zugspitze (47.42° N, 10.98° E, 2964 m a.s.l.) and Garmisch (47.48° N, 11.06° E, 743 m a.s.l.). Trend analysis comprises a fit to the de-seasonalized time series along with bootstrap resampling for quantifying trend uncertainties. We find a positive trend during [1996, 1998] of 9.0 [3.2, 14.7] ppb yr−1 for Zugspitze (95% confidence interval), an insignificant growth during [1999, mid 2006] of 0.8 [−0.1, 1.7] ppb yr−1 (Zugspitze), and a significant renewed increase during [mid 2006, Sep 2011] of 5.1 [4.2, 6.0] ppb yr−1 for Garmisch, which is in agreement with 4.8 [3.8, 5.9] ppb yr−1 for Zugspitze. The agreement of methane trends at the two closely neighboring FTIR sites Zugspitze and Garmisch within the uncertainties indicates a good station-to-station consistency as a basis for future trend analyses by the ground-based mid-IR FTIR network on the global scale. Furthermore, the Zugspitze FTIR trend for the time interval [Jul 2006, Jun 2009] is found to agree with the trend derived from SCIAMACHY (WFM-DOAS v2.0.2) data within the 95% confidence intervals. In case a 1000-km pixel selection radius around the Zugspitze is used, the confidence interval is narrower for the FTIR trend (6.9 [4.2, 9.5] ppb yr−1) compared to SCIAMACHY (7.1 [5.1, 8.6] ppb yr−1). If, however, a loosened pixel selection is used (≈1000-km half-width latitudinal band), the SCIAMACHY trend significance interval is narrower (6.8 [5.1, 8.6] ppb yr−1) compared to Zugspitze FTIR (5.7 [3.0, 8.3] ppb yr−1). While earlier studies using surface network data revealed changes of 8.0 ± 0.6 ppb in 2007, 6.4 ± 0.6 ppb in 2008, and 4.7 ± 0.6 ppb in 2009 (Dlugokencky et al., 2011), our updated result proves that the renewed methane increase meanwhile has been persisting for >5 years [mid 2006, Sep 2011]. This is either the longest and largest positive trend anomaly since the beginning of systematic observations more than 25 years ago or the onset of a new period of strongly increasing CH4 levels in the atmosphere. Several scenarios have been developed to explain the persistent increase observed, mainly invoking an increase in emissions from natural wetlands, an increase in fossil fuel-related emissions or a decrease in OH concentrations. However, more work is needed to fully attribute this increase to a particular source or sink.

Baroclinic and Barotropic Annular Variability in the Northern Hemisphere

2015 ◽  
Vol 72 (3) ◽  
pp. 1117-1136 ◽  
Author(s):  
David W. J. Thompson ◽  
Ying Li
Keyword(s):  
Time Series ◽  
Kinetic Energy ◽  
Northern Hemisphere ◽  
Large Scale ◽  
Spectral Power ◽  
Principal Component ◽  
Eddy Kinetic Energy ◽  
Annular Mode ◽  
Teleconnection Patterns ◽  
Mean Kinetic Energy

Abstract Large-scale variability in the Northern Hemisphere (NH) circulation can be viewed in the context of three primary types of structures: 1) teleconnection patterns, 2) a barotropic annular mode, and 3) a baroclinic annular mode. The barotropic annular mode corresponds to the northern annular mode (NAM) and has been examined extensively in previous research. Here the authors examine the spatial structure and time-dependent behavior of the NH baroclinic annular mode (NBAM). The NAM and NBAM have very different signatures in large-scale NH climate variability. The NAM emerges as the leading principal component (PC) time series of the zonal-mean kinetic energy. It dominates the variance in the wave fluxes of momentum, projects weakly onto the eddy kinetic energy and wave fluxes of heat, and can be modeled as Gaussian red noise with a time scale of ~10 days. In contrast, the NBAM emerges as the leading PC time series of the eddy kinetic energy. It is most clearly identified when the planetary-scale waves are filtered from the data, dominates the variance in the synoptic-scale eddy kinetic energy and wave fluxes of heat, and has a relatively weak signature in the zonal-mean kinetic energy and the wave fluxes of momentum. The NBAM is marked by weak but significant enhanced spectral power on time scales of ~20–25 days. The NBAM is remarkably similar to its Southern Hemisphere counterpart despite the pronounced interhemispheric differences in orography and land–sea contrasts.

scholarly journals Large-scale characteristics of the distribution of blowing-snow sublimation

2008 ◽  
Vol 49 ◽  
pp. 11-16 ◽  
Author(s):  
Konosuke Sugiura ◽  
Tetsuo Ohata
Keyword(s):  
Northern Hemisphere ◽  
Land Surface ◽  
Large Scale ◽  
Hydrological Cycle ◽  
Analysis Data ◽  
Global Scale ◽  
Blowing Snow ◽  
Scale Characteristics ◽  
Global Datasets ◽  
Northern And Southern Hemispheres

AbstractTo consider the large-scale characteristics of blowing-snow sublimation and its importance in the hydrological cycle in the cryosphere, we investigated the sublimation of blowing snow particles on a global scale using the global datasets of the European Centre for Medium-RangeWeather Forecasts (ECMWF) re-analysis data and the International Satellite Land Surface Climatology Project (ISLSCP) Initiative I data for 1987. The sublimation fluxes of blowing snow particles were estimated globally with 2.5˚ resolution at 6 hour intervals. We found that the sublimation of blowing snow particles occurs more widely in the Northern Hemisphere than in the Southern Hemisphere, does not increase monotonously with latitude, and becomes more active in the polar coast regions and highlands, although the annual mean sublimation fluxes of the Northern and Southern Hemispheres are almost equal. In addition, we confirmed the characteristic seasonal changes in the area of sublimation in the Northern Hemisphere. Although we need to incorporate continuous parameters from systematic ground-based studies of the structure of blowing snow in specific fields to reduce uncertainty regarding the characteristics of blowing snow, our results point to a need to review the current understanding of the hydrological cycle.

Sea Surface Temperatures along the Coast of British Columbia: Regional Evidence for a Warming Trend

1990 ◽  
Vol 47 (2) ◽  
pp. 346-350 ◽  
Author(s):  
Howard J. Freeland
Keyword(s):  
British Columbia ◽  
Time Series ◽  
Large Scale ◽  
Southern Oscillation ◽  
Warming Trend ◽  
Global Scale ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Mean Values ◽  
Surface Temperatures

Sea-surface temperature has been measured at a large number of sites around the coast of British Columbia for periods well in excess of 50 yr. These time series are long enough to give clear evidence of a large scale secular warming. For the purposes of this paper the daily SST observations are decimated to monthly mean values. The observations are of particular value because observation methods have remained invariant throughout the observation period, and many of the stations are remote from civilisation allowing trends to be estimated that have not been contaminated with urbanization effects. Eighteen out of nineteen stations that are currently being sampled show a warming trend, the one that shows a cooling trend is the shortest time series, only in its eleventh year. The sea-surface temperatures at sites exposed to the Pacific Ocean show very high coherence with global scale air temperature variations but no relationship to the El Niño/Southern Oscillation signal.

scholarly journals Sentinel-1&2 Multitemporal Water Surface Detection Accuracies, Evaluated at Regional and Reservoirs Level

2021 ◽  
Vol 13 (16) ◽  
pp. 3279
Author(s):  
Santiago Peña-Luque ◽  
Sylvain Ferrant ◽  
Mauricio C. R. Cordeiro ◽  
Thomas Ledauphin ◽  
Jerome Maxant ◽  
...  
Keyword(s):  
Water Surface ◽  
Large Scale ◽  
Time Windows ◽  
Absolute Error ◽  
Water Shortage ◽  
Global Scale ◽  
Radar Detection ◽  
Advantages And Disadvantages ◽  
Use Of Time ◽  
The Impact

Water stock monitoring is a major issue for society on a local and global scale. Sentinel-1&2 satellites provide frequent acquisitions to track water surface dynamics, proxy variables to enable water surface volume monitoring. How do we combine such observations along time for each sensor? What advantages and disadvantages of single-date, monthly or time-windowed estimations? In this context, we analysed the impact of merging information through different types and lengths of time-windows. Satellite observations were processed separately on optical (Sentinel-2) and radar (Sentinel-1) water detectors at 10m resolution. The analysis has been applied at two scales. First, validating with 26 large scenes (110 × 110 km) in different climatic zones in France, time-windows yielded an improvement on radar detection (F1-score improved from 0.72 to 0.8 for 30 days on average logic) while optical performances remained stable (F1-score 0.89). Second, validating reservoir area estimations with 29 instrumented reservoirs (20–1250 ha), time-windows presented in all cases an improvement on both optical and radar error for any window length (5–30 days). The mean relative absolute error in optical area detection improved from 16.9% on single measurements to 12.9% using 15 days time-windows, and from 22.15% to 15.1% in radar detection). Regarding reservoir filling rates, we identified an increased negative bias for both sensors when the reservoir is nearly full. This work helped to compare accuracies of separate optical and radar capabilities, where optical statistically outperforms radar at both local and large scale to the detriment of less frequent measurements. Furthermore, we propose a geomorphological indicator of reservoirs to predict the quality of radar area monitoring (R2 = 0.58). In conclusion, we suggest the use of time-windows on operational water mapping or reservoir monitoring systems, using 10–20 days time-windows with average logic, providing more frequent and faster information to water managers in periods of crisis (e.g., water shortage) compared to monthly estimations.

Towards benefitting from diverse inferred features and foreseen behaviours of hydroclimatic variables in predictive modelling contexts

2021 ◽  
Author(s):  
Georgia Papacharalampous ◽  
Hristos Tyralis
Keyword(s):  
Time Series ◽  
Big Data ◽  
Time Series Analysis ◽  
Large Scale ◽  
Predictive Modelling ◽  
Global Scale ◽  
Multiple Models ◽  
Forecast Combinations ◽  
Hydroclimatic Variability ◽  
Hydroclimatic Variables

<p>We discuss possible pathways towards reducing uncertainty in predictive modelling contexts in hydrology. Such pathways may require big datasets and multiple models, and may include (but are not limited to) large-scale benchmark experiments, forecast combinations, and predictive modelling frameworks with hydroclimatic time series analysis and clustering inputs. Emphasis is placed on the newest concepts and the most recent methodological advancements for benefitting from diverse inferred features and foreseen behaviours of hydroclimatic variables, derived by collectively exploiting diverse essentials of studying and modelling hydroclimatic variability and change (from both the descriptive and predictive perspectives). Our discussions are supported by big data (including global-scale) investigations, which are conducted for several hydroclimatic variables at several temporal scales.</p>

scholarly journals On the spatio-temporal analysis of hydrological droughts from global hydrological models

2011 ◽  
Vol 8 (1) ◽  
pp. 619-652 ◽  
Author(s):  
G. A. Corzo Perez ◽  
M. H. J. van Huijgevoort ◽  
F. Voß ◽  
H. A. J. van Lanen
Keyword(s):  
Time Series ◽  
20Th Century ◽  
Large Scale ◽  
Southern Oscillation ◽  
Regional Scale ◽  
Spatial Coherence ◽  
Temporal Analysis ◽  
Global Scale ◽  
Scale Models ◽  
Spatio Temporal

Abstract. The recent concerns for world-wide extreme events related to climate change phenomena have motivated the development of large scale models that simulate the global water cycle. In this context, analyses of extremes is an important topic that requires the adaptation of methods used for river basin and regional scale models. This paper presents two methodologies that extend the tools to analyze spatio-temporal drought development and characteristics using large scale gridded time series of hydrometeorological data. The methodologies are distinguished and defined as non-contiguous and contiguous drought area analyses (i.e. NCDA and CDA). The NCDA presents time series of percentages of areas in drought at the global scale and for pre-defined regions of known hydroclimatology. The CDA is introduced as a complementary method that generates information on the spatial coherence of drought events at the global scale. Spatial drought events are found through CDA by clustering patterns (contiguous areas). In this study the global hydrological model WaterGAP was used to illustrate the methodology development. Global gridded time series (resolution 0.5°) simulated with the WaterGAP model from land points were used. The NCDA and CDA were applied to identify drought events in subsurface runoff. The percentages of area in drought calculated with both methods show complementary information on the spatial and temporal events for the last decades of the 20th century. The NCDA provides relevant information on the average number of droughts, duration and severity (deficit volume) for pre-defined regions (globe, 2 selected climate regions). Additionally, the CDA provides information on the number of spatially linked areas in drought as well as their geographic location on the globe. An explorative validation process shows that the NCDA results capture the overall spatio-temporal drought extremes over the last decades of the 20th century. Events like the El Niño Southern Oscillation (ENSO) in South America and the pan-European drought in 1976 appeared clearly in both analyses. The methodologies introduced provide an important basis for the global characterization of droughts, model inter-comparison, and spatial events validation.

scholarly journals Model simulation of the global circulation in the middle atmosphere for January conditions

2008 ◽  
Vol 15 ◽  
pp. 11-16 ◽  
Author(s):  
I. V. Mingalev ◽  
O. V. Mingalev ◽  
V. S. Mingalev
Keyword(s):  
Northern Hemisphere ◽  
Large Scale ◽  
Middle Atmosphere ◽  
Model Simulation ◽  
Vertical Component ◽  
Navier Stokes ◽  
Neutral Wind ◽  
Navier Stokes Equation ◽  
Polar Geophysical Institute ◽  
Global Circulation

Abstract. A mathematical model of the global neutral wind system of the Earth's atmosphere, developed earlier in the Polar Geophysical Institute (PGI), is utilized to simulate the large-scale global circulation of the middle atmosphere for January conditions. The utilized model enables to calculate not only the horizontal components but also the vertical component of the neutral wind velocity by means of a numerical solution of a generalized Navier-Stokes equation for compressible gas, so the hydrostatic equation is not applied. Global distributions of the horizontal and vertical wind, calculated for January conditions, are compared with simulation results, obtained earlier for conditions corresponding to summer in the northern hemisphere. It was found that the global distributions of the neutral wind, calculated both for winter and for summer periods in the northern hemisphere, in particular, the large-scale circumpolar vortices, are consistent with the planetary circulation of the atmosphere, obtained from observations.

Sign in / Sign up

Export Citation Format

Share Document