scholarly journals A net decrease in the Earth's cloud plus aerosol reflectivity during the past 33 yr (1979–2011) and increased solar heating at the surface

2012 ◽  
Vol 12 (12) ◽  
pp. 31991-32038 ◽  
Author(s):  
J. R. Herman ◽  
M. T. DeLand ◽  
L.-K. Huang ◽  
G. Labow ◽  
D. Larko ◽  
...  
Keyword(s):  
Time Series ◽  
Southern Oscillation ◽  
Weighted Average ◽  
Equatorial Region ◽  
The Us ◽  
Surface Reflectivity ◽  
Zonal Average ◽  
Decadal Climate ◽  
Highly Correlated

Abstract. Measured upwelling radiances from Nimbus-7 SBUV, seven NOAA SBUV/2 and the AURA-OMI instruments have been used to calculate the 340 nm Lambertian Equivalent Reflectivity (LER) of the Earth from 1979 to 2011 after applying a new common calibration. The 340 nm LER is highly correlated with cloud and aerosol cover because of the low surface reflectivity of the land and oceans (typically 2 to 6 RU, where 1 RU = 0.01 = 1.0%) relative to the much higher reflectivity of clouds plus aerosols (typically 10 to 90 RU). Because of the nearly constant seasonal and long-term 340 nm surface reflectivity, the 340 nm LER can be used to estimate changes in cloud plus aerosol amount associated with seasonal and interannual variability and decadal climate change. The annual motion of the Intertropical Convergence Zone, episodic El Nino Southern Oscillation ENSO, and latitude dependent seasonal cycles are apparent in the LER time series. LER trend estimates from 5° zonal average and from 2° × 5° latitude × longitude time series show that there has been a global net decrease in cloud plus aerosol reflectivity. The decrease in global cos2 (latitude) weighted average LER from 60° S to 60° N is 0.79 ± 0.03 RU over 33 yr, corresponding to a 3.6 ± 0.2% change in LER. Based on energy balance partitioning (Trenberth et al., 2009) this corresponds to an increase of 2.7 W m−2 of solar energy reaching the Earth's surface (an increase of 1.4% or 2.3 W m−2) absorbed by the surface, which is partially offset by an increase in longwave cooling to space. Most of the decreases in cloud reflectivity occur over land, with the largest decreases occurring over the US (−0.97 RU decade−1), Brazil (−0.9 RU decade−1), and Central Europe (−1.35 RU decade−1). There are reflectivity increases near the west coast of Peru and Chile (0.8 ± 0.1 RU decade−1) over parts of India, China, and Indochina, and almost no change over Australia. The largest Pacific Ocean change is −2 ± 0.1 RU decade−1 over the central equatorial region associated with ENSO. An area in Central Greenland shows a decrease in reflectivity of −0.3 ± 0.03 RU decade−1 caused by cloud and possible surface changes.

scholarly journals A net decrease in the Earth's cloud, aerosol, and surface 340 nm reflectivity during the past 33 yr (1979–2011)

2013 ◽  
Vol 13 (16) ◽  
pp. 8505-8524 ◽  
Author(s):  
J. Herman ◽  
M. T. DeLand ◽  
L.-K. Huang ◽  
G. Labow ◽  
D. Larko ◽  
...  
Keyword(s):  
Time Series ◽  
West Coast ◽  
Southern Oscillation ◽  
Weighted Average ◽  
Equatorial Region ◽  
The West ◽  
Surface Reflectivity ◽  
Zonal Average ◽  
Decadal Climate ◽  
Highly Correlated

Abstract. Measured upwelling radiances from Nimbus-7 SBUV (Solar Backscatter Ultraviolet) and seven NOAA SBUV/2 instruments have been used to calculate the 340 nm Lambertian equivalent reflectivity (LER) of the Earth from 1979 to 2011 after applying a common calibration. The 340 nm LER is highly correlated with cloud and aerosol cover because of the low surface reflectivity of the land and oceans (typically 2 to 6 RU, reflectivity units, where 1 RU = 0.01 = 1.0%) relative to the much higher reflectivity of clouds plus nonabsorbing aerosols (typically 10 to 90 RU). Because of the nearly constant seasonal and long-term 340 nm surface reflectivity in areas without snow and ice, the 340 nm LER can be used to estimate changes in cloud plus aerosol amount associated with seasonal and interannual variability and decadal climate change. The annual motion of the Intertropical Convergence Zone (ITCZ), episodic El Niño Southern Oscillation (ENSO), and latitude-dependent seasonal cycles are apparent in the LER time series. LER trend estimates from 5° zonal average and from 2° × 5° , latitude × longitude, time series show that there has been a global net decrease in 340 nm cloud plus aerosol reflectivity. The decrease in cos2(latitude) weighted average LER from 60° S to 60° N is 0.79 ± 0.03 RU over 33 yr, corresponding to a 3.6 ± 0.2% decrease in LER. Applying a 3.6% cloud reflectivity perturbation to the shortwave energy balance partitioning given by Trenberth et al. (2009) corresponds to an increase of 2.7 W m−2 of solar energy reaching the Earth's surface and an increase of 1.4% or 2.3 W m−2 absorbed by the surface, which is partially offset by increased longwave cooling to space. Most of the decreases in LER occur over land, with the largest decreases occurring over the US (−0.97 RU decade−1), Brazil (−0.9 RU decade−1), and central Europe (−1.35 RU decade−1). There are reflectivity increases near the west coast of Peru and Chile (0.8 ± 0.1 RU decade−1), over parts of India, China, and Indochina, and almost no change over Australia. The largest Pacific Ocean change is −2 ± 0.1 RU decade−1 over the central equatorial region associated with ENSO. There has been little observed change in LER over central Greenland, but there has been a significant decrease over a portion of the west coast of Greenland. Similar significant decreases in LER are observed over a portion of the coast of Antarctica for longitudes −160° to −60° and 80° to 150°.

Following the infection dynamics of the tropical trematode Oligogonotylus mayae in its intermediate and definitive hosts for 13 years

2020 ◽  
Vol 94 ◽  
Author(s):  
A.L. May-Tec ◽  
N.A. Herrera-Castillo ◽  
V.M. Vidal-Martínez ◽  
M.L. Aguirre-Macedo
Keyword(s):  
Time Series ◽  
Cross Correlation ◽  
Southern Oscillation ◽  
Fish Host ◽  
Snail Host ◽  
Monthly Data ◽  
Infection Dynamics ◽  
Infection Parameters ◽  
Over Time

Abstract We present a time series of 13 years (2003–2016) of continuous monthly data on the prevalence and mean abundance of the trematode Oligogonotylus mayae for all the hosts involved in its life cycle. We aimed to determine whether annual (or longer than annual) environmental fluctuations affect these infection parameters of O. mayae in its intermediate snail host Pyrgophorus coronatus, and its second and definitive fish host Mayaheros urophthalmus from the Celestun tropical coastal lagoon, Yucatan, Mexico. Fourier time series analysis was used to identify infection peaks over time, and cross-correlation among environmental forcings and infection parameters. Our results suggest that the transmission of O. mayae in all its hosts was influenced by the annual patterns of temperature, salinity and rainfall. However, there was a biannual accumulation of metacercarial stages of O. mayae in M. urophthalmus, apparently associated with the temporal range of the El Niño-Southern Oscillation (five years) and the recovery of the trematode population after a devasting hurricane. Taking O. mayae as an example of what could be happening to other trematodes, it is becoming clear that environmental forcings acting at long-term temporal scales affect the population dynamics of these parasites.

scholarly journals Multidecadal change in streamflow associated with anthropogenic disturbances in the tropical Andes

2015 ◽  
Vol 19 (10) ◽  
pp. 4201-4213 ◽  
Author(s):  
A. Molina ◽  
V. Vanacker ◽  
E. Brisson ◽  
D. Mora ◽  
V. Balthazar
Keyword(s):  
Time Series ◽  
Land Cover ◽  
Land Cover Change ◽  
Agricultural Land ◽  
Southern Oscillation ◽  
Anthropogenic Disturbances ◽  
Tropical Andes ◽  
Water Users ◽  
Native Forests

Abstract. Andean headwater catchments are an important source of freshwater for downstream water users. However, few long-term studies exist on the relative importance of climate change and direct anthropogenic perturbations on flow regimes in these catchments. In this paper, we assess change in streamflow based on long time series of hydrometeorological data (1974–2008) and land cover reconstructions (1963–2009) in the Pangor catchment (282 km2) located in the tropical Andes. Three main land cover change trajectories can be distinguished during the period 1963–2009: (1) expansion of agricultural land by an area equal to 14 % of the catchment area (or 39 km2) in 46 years' time, (2) deforestation of native forests by 11 % (or −31 km2) corresponding to a mean rate of 67 ha yr−1, and (3) afforestation with exotic species in recent years by about 5 % (or 15 km2). Over the time period 1963–2009, about 50 % of the 64 km2 of native forests was cleared and converted to agricultural land. Given the strong temporal variability of precipitation and streamflow data related to El Niño–Southern Oscillation, we use empirical mode decomposition techniques to detrend the time series. The long-term increasing trend in rainfall is remarkably different from the observed changes in streamflow, which exhibit a decreasing trend. Hence, observed changes in streamflow are not the result of long-term change in precipitation but very likely result from anthropogenic disturbances associated with land cover change.

scholarly journals Longer spring snowmelt: spatial and temporal variations of snowmelt trends detected by passive microwave from 1988 to 2010 in the Yukon River Basin

2012 ◽  
Vol 6 (1) ◽  
pp. 715-735
Author(s):  
K. A. Semmens ◽  
J. M. Ramage
Keyword(s):  
Time Series ◽  
River Basin ◽  
Southern Oscillation ◽  
Temporal Variations ◽  
Yukon River ◽  
Time Period ◽  
Yukon River Basin ◽  
Microwave Imager ◽  
Highly Correlated ◽  
Melt Duration

Abstract. Brightness temperature (Tb) data from the Special Sensor Microwave Imager (SSM/I) 37 V-GHz frequency provides a time series from 1988 to 2010 that enables the assessment of snowmelt timing trends (onset, end of melt-refreeze, and duration) for the Yukon River Basin. Tb and diurnal amplitude variation (DAV) thresholds determine dates of melt onset and melt-freeze end (end of high DAV), defined as the first date when thresholds are met for more than three of five consecutive days. Temporal and spatial trends in melt onset and end of melt-refreeze date are determined with varying time period intervals and for each sub-basin and elevation class. Earlier melt onset trends are found in the highest elevations and northernmost sub-basins (Porcupine, Chandalar, and Koyukuk Rivers). Significant later (>0.75 d yr−1) end of melt-refreeze and longer melt duration trends are found in a majority of the sub-basins. Moving interval trends suggest interannual variability within the time series and a power spectrum analysis reveals peak frequencies and periods of 5–7 and ~11 years, possibly related to El Nino- Southern Oscillation and the solar cycle, respectively. Latitude and elevation display the dominant controls on timing variance and spring solar flux is highly correlated with melt timing in middle elevations.

scholarly journals Trend analysis of the 20 years time series of stratospheric ozone profiles observed by the GROMOS microwave radiometer at Bern

2015 ◽  
Vol 15 (12) ◽  
pp. 16371-16400
Author(s):  
L. Moreira ◽  
K. Hocke ◽  
E. Eckert ◽  
T. von Clarmann ◽  
N. Kämpfer
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
Southern Oscillation ◽  
Stratospheric Ozone ◽  
Microwave Radiometer ◽  
Atmospheric Composition ◽  
Quasi Biennial Oscillation ◽  
Ozone Trend ◽  
Long Term Trend

Abstract. The ozone radiometer GROMOS (GROund-based Millimeterwave Ozone Spectrometer) performs continuous observations of stratospheric ozone profiles since 1994 above Bern, Switzerland. GROMOS is part of the Network for the Detection of Atmospheric Composition Change (NDACC). From November 1994 to October 2011, the ozone line spectra were measured by a filter bench (FB). In July 2009, a Fast-Fourier-Transform spectrometer (FFTS) has been added as backend to GROMOS. The new FFTS and the original FB measured in parallel for over two years. The ozone profiles retrieved separately from the ozone line spectra of FB and FFTS agree within 5 % at pressure levels from 30 to 0.5 hPa, from October 2009 to August 2011. A careful harmonisation of both time series has been carried out by taking the FFTS as the reference instrument for the FB. This enables us to assess the long-term trend derived from more than 20 years of stratospheric ozone observations at Bern. The trend analysis has been performed by using a robust multilinear parametric trend model which includes a linear term, the solar variability, the El Niño–Southern Oscillation (ENSO) index, the quasi-biennial oscillation (QBO), the annual and semi-annual oscillation and several harmonics with period lengths between 3 and 24 months. Over the last years, some experimental and modelling trend studies have shown that the stratospheric ozone trend is levelling off or even turning positive. With our observed ozone profiles, we are able to support this statement by reporting a statistically significant trend of +3.14 % decade-1 at 4.36 hPa, covering the period from January 1997 to January 2015, above Bern. Additionally, we have estimated a negative trend over this period of −3.94 % decade-1 at 0.2 hPa.

An Empirical Decomposition of Deep Groundwater Time Series and Possible Link to Climate Variability

2013 ◽  
Vol 16 (1) ◽  
pp. 87-103
Keyword(s):  
Time Series ◽  
Climate Variability ◽  
Polynomial Interpolation ◽  
Southern Oscillation ◽  
Global Climate ◽  
Deep Groundwater ◽  
Anthropogenic Effect ◽  
Cyclic Patterns ◽  
History Of

<p>Deep groundwater data reflects hydrological processes, climate change and variability, as well as any anthropogenic influence. Decomposition of deep groundwater signal examines the history of the groundwater region. Detrending is a vital step in decomposition of groundwater time series because it is expected to remove anthropogenic effects and long-term cyclic patterns. Eight detrending methods were applied to long-term groundwater records monitored in the Lower Chao Phraya basin in Thailand. Detrended residuals and subsequently periodograms of the residuals were computed by applying the Fourier series analysis. The result from this study indicates that the 5th order polynomial interpolation provides the trendlines that significantly relate to the groundwater withdrawal background. The detrended residual function is imbedded with two major cyclic patterns, which can be the result from global climate variability, e.g. Indian Ocean Dipole and the El Niño Southern Oscillation. The magnitude of deep groundwater dynamics as the result from the anthropogenic effect is much greater than that of the climate variability in this region. In addition, this study demonstrates that caution must be exercised when fitting groundwater time series with different detrending techniques can yield mistaken cyclic patterns and may infer to different climate variability phenomenon.</p>

scholarly journals Interpreting the time variability of world-wide GPS and GOME/SCIAMACHY integrated water vapour retrievals, using reanalyses as auxiliary tools

2018 ◽  
Author(s):  
Roeland Van Malderen ◽  
Eric Pottiaux ◽  
Gintautas Stankunavicius ◽  
Steffen Beirle ◽  
Thomas Wagner ◽  
...  
Keyword(s):  
Time Series ◽  
Linear Regression ◽  
Multiple Linear Regression ◽  
Water Vapour ◽  
Southern Oscillation ◽  
Linear Trend ◽  
Time Variability ◽  
The North ◽  
Integrated Water Vapour

Abstract. This study investigates different aspects of the Integrated Water Vapour (IWV) variability at 118 globally distributed Global Positioning System (GPS) sites, using additionally UV/VIS satellite retrievals by GOME, SCIAMACHY and GOME-2 (denoted as GOMESCIA below), and ERA-Interim reanalysis output at these site locations. Apart from some spatial representativeness issues at especially coastal and island sites, those three datasets correlate rather well, the lowest correlation found between GPS and GOMESCIA (0.865 on average). In this paper, we first study the geographical distribution of the frequency distributions of the IWV time series, and subsequently analyse the seasonal IWV cycle and linear trend differences among the three different datasets. Finally, both the seasonal behaviour and the long-term variability are fitted together by means of a stepwise multiple linear regression of the station’s time series, with a selection of regionally dependent candidate explanatory variables. Overall, the variables that are most frequently used and explain the largest fractions of the IWV variability are the surface temperature and precipitation. Also the surface pressure and tropopause pressure (in particular for higher latitude sites) are important contributors to the IWV time variability. All these variables also seem to account for the sign of long-term trend in the IWV time series to a large extent, when considered as explanatory variable. Furthermore, the multiple linear regression linked the IWV variability at some particular regions to teleconnection patterns or climate/oceanic indices like the North Oscillation index for West USA, the El Niňo Southern Oscillation (ENSO) for East Asia, the East Atlantic (associated with the North Atlantic Oscillation, NAO) index for Europe.

scholarly journals Trend analysis of the 20-year time series of stratospheric ozone profiles observed by the GROMOS microwave radiometer at Bern

2015 ◽  
Vol 15 (19) ◽  
pp. 10999-11009 ◽  
Author(s):  
L. Moreira ◽  
K. Hocke ◽  
E. Eckert ◽  
T. von Clarmann ◽  
N. Kämpfer
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
Southern Oscillation ◽  
Stratospheric Ozone ◽  
Microwave Radiometer ◽  
Atmospheric Composition ◽  
Quasi Biennial Oscillation ◽  
Ozone Trend ◽  
Long Term Trend

Abstract. The ozone radiometer GROMOS (GROund-based Millimeter-wave Ozone Spectrometer) has been performing continuous observations of stratospheric ozone profiles since 1994 above Bern, Switzerland (46.95° N, 7.44° E, 577 m). GROMOS is part of the Network for the Detection of Atmospheric Composition Change (NDACC). From November 1994 to October 2011, the ozone line spectra were measured by a filter bench (FB). In July 2009, a fast Fourier transform spectrometer (FFTS) was added as a back end to GROMOS. The new FFTS and the original FB measured in parallel for over 2 years. The ozone profiles retrieved separately from the ozone line spectra of FB and FFTS agree within 5 % at pressure levels from 30 to 0.5 hPa, from October 2009 to August 2011. A careful harmonisation of both time series has been carried out by taking the FFTS as the reference instrument for the FB. This enables us to assess the long-term trend derived from stratospheric ozone observations at Bern. The trend analysis was performed by using a robust multilinear parametric trend model which includes a linear term, the solar variability, the El Niño–Southern Oscillation (ENSO) index, the quasi-biennial oscillation (QBO), the annual and semi-annual oscillation and several harmonics with period lengths between 3 and 24 months. Over the last years, some experimental and modelling trend studies have shown that the stratospheric ozone trend is levelling off or even turning positive. With our observed ozone profiles, we are able to support this statement by reporting a statistically significant trend of +3.14 % decade−1 at 4.36 hPa (37.76 km), covering the period from January 1997 to January 2015, above Bern. Additionally, we have estimated a negative trend over this period of −3.94 % decade−1 at 0.2 hPa (59 km).

scholarly journals Matching the forecast horizon with the relevant spatial and temporal processes and data sources

2019 ◽  
Author(s):  
Peter B. Adler ◽  
Ethan P. White ◽  
Michael H. Cortez
Keyword(s):  
Time Series ◽  
Initial Conditions ◽  
Environmental Gradients ◽  
Weighted Average ◽  
Forecast Horizon ◽  
Ecological Processes ◽  
Ecological Selection ◽  
Time Series Approach ◽  
New Research

AbstractMost phenomenological, statistical models used to generate ecological forecasts take either a time-series approach, based on long-term data from one location, or a space-for-time approach, based on data describing spatial patterns across environmental gradients. Here we consider how the forecast horizon determines whether more accurate predictions come from the time-series approach, the space-for-time approach, or a combination of the two. We use two simulated case studies to show that forecasts for short and long forecast horizons need to focus on different ecological processes, which are reflected in different kinds of data. In the short-term, dynamics reflect initial conditions and fast processes such as birth and death, and the time-series approach makes the best predictions. In the long-term, dynamics reflect the additional influence of slower processes such as evolutionary and ecological selection, colonization and extinction, which the space-for-time approach can effectively capture. At intermediate time-scales, a weighted average of the two approaches shows promise. However, making this weighted model operational will require new research to predict the rate at which slow processes begin to influence dynamics.

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