Quasi-biennial Variations Research Articles

Satellite Mapping of CO2 Emission from Forest Fires in Indonesia Using AIRS Measurements

Results from the analysis of the retrieved carbon dioxide (CO2) columns in the free troposphere are presented for one year (2005) obtained by the Atmospheric Infrared Sounder (AIRS) included on the EOS Aqua satellite launched on May 4, 2002. Providing information for several greenhouse gases, CO2, CH4, CO and O3 is one goal of the AIRS instrument as well as to improve weather prediction and study the water and energy cycle. Carbon Dioxide (CO2) is the most prominent Greenhouse gas in Earth's atmosphere and plays a key role in earth's climate. It is emitted into the air as humans exhale, from burning fossil fuels for energy and deforestation of the planet. The aim of this study is to generate Monthly CO2 Distribution maps and to investigate the effects of Indonesia forest fires on CO2 distributions over Peninsular Malaysia, north Sumatra and Singapore for 2005. The CO2 concentration map of the study area was generated by using mole_fraction of CO2 in free troposphere, obtained from AIRS/Aqua Level 3 monthly CO2 retrieval product (AIRS+AMSU) V005 (AIRX3C2M) at GES DISC. Considerable variations were demonstrated in the annual changes of rainfall and drought patterns in various seasons (dry & wet season). Variations in the biomass burning and CO2 emissions where noted over the study area, while the highest CO2 occurred over industrial and congested urban zones and a greater draw down of CO2 occurred in the pristine marine environment over northeast coasts of Sumatra during 2005. In particular, we observe a quasi-biennial variation in CO2 emissions from study area with two peaks, the natural peak occurring at the end of each dry season (February to April), when biomass burning occurs, and the second peak at wet season (July to September), because of the influence of Indonesia forest fire. Examining satellite measurements, the results showed that the enhanced CO2 emission correlates with occasions of less rainfall during dry season.

On the influence of the 11-year cycle of solar activity on quasi-biennial variations in ozone and temperature in the Canadian sector of the arctic

An analysis of the high-latitude ozone balloon sounding data derived from Canadian stations shows that, in the maximum of the 11-year cycle of solar activity (SA), the ozone content in the lower stratosphere is higher than in the SA minimum and, in the SA maximum, the lower stratosphere is warmer and the troposphere is colder than in the SA minimum. The ozone and temperature responses to the equatorial quasi-biennial oscillation (QBO) in the opposite phases of the 11-year cycle of SA show substantial differences: in the SA maximum, the QBO effects in the ozone and temperature cover a wider range of heights, the maxima of the effects manifest themselves at 5–10 km higher, and their amplitudes exceed the amplitudes of the effects in the SA minimum. The results indicate that the QBO is one of the “conductors” of the influence of the 11-year SA cycle in the Canadian sector of the Arctic.

Analysis of the quasi-biennial variability of carbon monoxide total column

On the basis of satellite observations of column carbon monoxide (CO) and total ozone (TO), an analysis has been performed of the connection of the interannual variability of CO with the quasi-biennial oscillation (QBO) of the equatorial stratospheric wind and the QBO of total ozone. It is found that the CO total colomn over most of the globe in the westerly phase of the QBO is greater than that in the easterly phase. The global distribution of the CO QBO amplitudes exhibits a local maximum over Indonesia, where the peak-to-peak amplitude of the CO QBO signal averages 15% of the local annual mean CO in this region. Analysis shows that the QBOs of CO are well synchronized with the QBO of wind at 50 hPa. At the same time, a joint analysis of the characteristics of the CO QBO and TO QBO demonstrates no direct photochemical coupling between of the quasi-biennial variations of TO and CO.

Quasibiennial variations in fractal dimension of solar total irradiance

Based on the Nimbus-7 (1978–1992) data and the parameters of solar activity (Wolf numbers W, solar radioemission F10.7) and the ionosphere (f2 index of the critical frequency of the ionospheric F2 layer normalized to noon), the fractal dimension (FD) of the variations in the solar total irradiance (L) has been determined on the moving annual interval using the Higuchi technique. It has been established that FD estimates substantially vary in time. Quasibiennial variations (QBVs), which similarly manifest themselves in all considered processes, are detected in these variations. It is interesting that all fractal QBVs are in phase with QBVs of solar irradiance (L) and are almost in antiphase with QBVs of initial (filtered) W, F10.7, and f2 indices. The presence of QBVs in the solar processes and in their FD and noncoincidence of the former with the latter in phase indicate that QBVs have a two-component structure. The obtained results also indicate that an analysis of the annual FD estimates of the solar and ionospheric processes in studying variations in these processes is reliable.

Certain regularities of solar activity variations during the 11-year cycle

The relationships between a number of the main characteristic parameters of the cycle—amplitude, half-width, and growth phase duration—and the approximation parameters, which make it possible to estimate the average behavior of 11-year activity, have been derived based on the obtained analytical representations of the regularities in the solar activity variations during the cycle. Quasibiennial variations proceeding against a background of the cycle are distinctly associated with the solar magnetic field structure and the structure representation variations in the corona and in the flux of the solar neutrino radiation. This makes it possible to state that all these processes are parts of the common physical mechanism of solar variability.

Spectral composition of the cyclic aperiodic (quasibiennial) variations in solar activity and the Earth’s atmosphere

Based on the published analysis of the average monthly variations in solar activity and temperature of the upper atmosphere in the region of the mesopause and lower thermosphere (after elimination of the average long-term variations during different 11-year cycles), it was indicated that the periods and amplitudes of the observed quasibiennial variations monotonically decrease in the course of time. The regularity of these variations is described by the Airy function, which represents a wave train with decreasing amplitude and period and reflects cyclic hydrodynamic processes in the Sun’s interior. A spectral analysis of the quasibiennial variations modelly described by the Airy function has been performed. It has been revealed that the period amplitudes near the average value for 2.25 years (27 months) are distributed normally with a dispersion of ∼0.5 years. According to several publications, similar periods are obtained by analyzing measurements of long-term variations in solar activity and parameters of the lower and middle atmosphere. This indicates that the values of the periods are obtained randomly. Therefore, a standard Fourier analysis does not make it possible to determine a real character of the quasibiennial variations since a real physical process is not revealed in the course of this analysis.

Antisymmetric transport of middle stratospheric methane with respect to the equator

Halogen Occultation Experiment (HALOE) data are used to study the quasi-biennial variability of CH4 mixing ratio in the middle stratosphere. The results of EOF analysis indicate that quasi-biennial period is principal for the interannual variability of methane. Antisymmetry with respect to the equator is significant for the methane QBO by explaining 59.3% variance, while the symmetric component only explains about 30%. The antisymmetry is more significant in 10°–20° latitude than between 10°S and 10°N. Analyses of the vertical motions show that anomalies of annual cycle play an important role in the antisymmetric distributions. Whereas, the zonal wind QBO is still the most important dynamical effect for the interannual variability of CH4 between 10°S–10°N.

Fractal dimension of changes in the solar magnetic field energy and quasi-biennial solar activity variations

Using the data of 1960–1999 on solar magnetic fields on the source surface and the Higuchi method, the fractal dimension of changes in the solar magnetic field energy at various heliolatitudes and in different time intervals is analyzed. The fractal dimension obtained on a moving 1-year interval displays substantial time variations. The 11-year cycle, which dominates at high latitudes, and quasi-biennial variations (QBVs), which dominate at low latitudes and are similar to QBVs of solar activity indices, are traced in these variations. Thus, solar QBVs that appear in all heliomagnetic activity indices are also present in the fractal structure of the solar magnetic field variations.

Quasi-biennial variations in ozone and meteorological parameters over western Europe from ozonesonde data

Quasi-biennial variations in vertical profiles of ozone, temperature, air pressure, and zonal and meridional wind velocities are analyzed from ozonesonde data obtained at the western European stations of Lindenberg, Hohenpeissenberg, and Payerne. The effect of quasi-biennial variations manifests itself variously in different variables and is nonuniform in altitude. The period of quasi-biennial variations is not constant, and the values of the mean period group mainly around 2 and 2.5 years. As in the North American region, the effects of quasi-biennial variations in different parameters of the stratosphere and troposphere over western Europe are due to a combination of the effects of the quasi-biennial oscillation (QBO) in the equatorial stratosphere, the El Nino-Southern Oscillation (ENSO), and the North Atlantic Oscillation (NAO). The observed 2.5-year variations in stratospheric ozone are related to the equatorial QBO to a larger extent in comparison with variations in other variables. It seems likely that a determining influence on variations in stratospheric wind and temperature is exerted by the ENSO. Variations in tropospheric and stratospheric parameters with a mean period of about 2 years are due to the ENSO and NAO effects.

Evolution of large-scale variations of lower-thermospheric parameters over Irkutsk

For the first time, using many years of measurements of lower-thermospheric parameters (the horizontal wind velocity for 1976–1995, and minimum reflection frequency for 1983–1991) over Irkutsk (52°N, 105°E), the dynamics of their large-scale variations was investigated. The study used a sliding multiple correlation periodogram analysis. Regular seasonal, semi-annual and annual variations were detected. Quasi-biennial variations are regarded as irregular variations with a constantly changing over a rather wide range period. Variations with similar periods were also detected in the planetary index of geomagnetic activity A p, and in the solar radio flux index F 10.7. Our correlation analysis indicates that large-scale variations of the wind velocity and f min in the lower thermosphere are correlated with those in the geomagnetic field. The large-scale variations under investigation characterize a regular long-term variability of lower-thermospheric parameters and can serve as climatic characteristics for the description of the climate of this atmospheric region.

Climatic change and interannual fluctuations in the long-term record of monthly precipitation for Seoul

We examine the characteristic climatic changes recorded in the long-term precipitation data for Seoul, Korea. Since precipitation data for Seoul has been accumulated for over 230 years, it is very useful in studying climatic changes in the monsoon region. The statistical test used to detect the change point was performed for the annual precipitation from April to November. It was found that statistically significant change points occurred in 1881 and 1952. On the basis of the results of the change point test, we examined the characteristic of the precipitation for the periods 1771–1881, 1882–1952, and 1953–2000. In change point detection test for monthly precipitation, it was found that there was no significant change point for the months June, July, and October. By means of comparing the statistics between different epochs, the modern precipitation climates during 1882–1952 and 1953–2000 are found to be more normal than the premodern ones. The ‘July–August or July, July/August interactive and September modes’ were classified through the empirical orthogonal function (EOF) structures and were identified as the principal modes in every epoch, whereas the ‘July mode’ was the most prevalent mode in every epoch. We present discussions on the synoptic meteorology that is probably responsible for these occurrences. The ‘September mode’ has significantly diminished and the ‘August mode’ has predominated during the modern era. It may be noteworthy to observe that the rainy season has been concentrated into a short time period. The quasi-biennial and interannual variability including ENSO groups of periods have been quite strong, but the outstanding periods in the long-period group were weak. Copyright © 2005 Royal Meteorological Society

Recent advances in wavelet analyses: Part 2—Amazon, Parana, Orinoco and Congo discharges time scale variability

This paper is devoted to illustrating new wavelet analysis methods in the field of hydrology. New wavelet indicators are applied to long-term hydrological and climatologic proxies. They are first applied to four Atlantic large river monthly discharges (Amazon, Parana, Orinoco and Congo) and then applied to two well-known long-term climatologic indexes: the Southern Oscillation and the North Atlantic Oscillation. This approach makes it possible to suggest physical explanations for time–scale dependant relationships. Six-month variability is present in all the rivers except in the Parana. In the Congo River this signal is near stationary with strong entropy. The strength of this scale coincides with higher discharge variability before 1920 and over the Orinoco basin with higher discharge values between 1940 and 1955. An annual cycle is present in all the rivers but is much stronger, along with the entropy, in the rivers with a large tropical basin, as in the Amazon and the Orinoco. This annual signal is not permanent in the Congo and much more intermittent in the Parana where the annual recharge appears as very irregular. A quasi biennial variability is apparent in all the equator ward rivers and a nearly permanent 2-year coherence is found between SOI and the Amazon discharge. A 3–6-year oscillation typical of ENSO variability is observed in all the rivers. It is intermittent, observed before 1930 in all the rivers and after 1980 mostly in the Amazon River. These peaks of activity correspond to periods of major SOI variability. An 8-year variability is particularly strong in the Parana River before 1940 and around 1970 and to a lesser extent in the Orinoco River during the low NAO index period, between 1940 and 1970. The Congo River exhibits that time–scale around 1970. A 13-year variability common to SOI, NAO and the South Atlantic Ocean circulation is observed in the Parana and Congo discharges. In all the rivers the greatest entropy is observed at bi and multi decadal time scales with the greatest coherence with both NAO and SOI. A near 20-year time–scale is observed in most of the series around 1970, although it is strongest in Amazon and Parana discharges. Finally, a 30-year time–scale is observed between 1940 and 1970. It is to be noted that most of the time–scale dominant activities, in all the rivers, may have been influenced by the interdecadal shifts that took place around 1940 and 1970 in the Pacific and in the Atlantic. Therefore, in this contribution, the application of new wavelet indicators (combined continuous and multi-resolution analysis, wavelet entropy, wavelet coherence, wavelet cross-correlation) leads to several improvements in the analysis of these global hydrological signal fluctuations and of their mutual time varying relationships. It is demonstrated that wavelets should be used more systematically in preference to the classical Fourier analysis, notably in hydrology.

Atmosphere–sea‐ice low‐frequency variability with a simple model of the southern hemisphere

AbstractA simple primitive‐equation general circulation model (SGCM) is used as a representation of an ‘aqua‐planet’ (with no orography) to model constant southern‐hemisphere‐winter conditions. The statistical significance of the decadal and quasi‐biennial variability is first assessed in a long‐time SGCM run by means of a frequency‐domain statistical decomposition. The modelled long‐wave atmospheric pattern is then associated with the observed southern‐hemisphere ‘annular mode’, as suggested by previous studies using the same SGCM.A simple linear relationship between the low‐level wind and the ice velocity is then introduced into the SGCM to investigate the feedbacks between the sea‐ice cover and the baroclinic waves. The zonal mean state reached by the sea‐ice cover in a long coupled run (a few hundred years) exhibits characteristics similar to the observations. Investigation of the low‐frequency variability in the coupled simulation leads to the following results: (1) statistically significant variability is observed on interdecadal, decadal, interannual and quasi‐biennial time‐scales; (2) interdecadal, decadal and quasi‐biennial signals are associated with the atmospheric annular mode that forces changes in the northward extent of the sea‐ice cover at all Southern Ocean longitudes; (3) the interannual signal (3–6 year period) exhibits spatio‐temporal patterns and propagation speed similar to the well‐known ‘Antarctic circumpolar wave’. Copyright © 2003 Royal Meteorological Society.

Quasi-Biennial Oscillations of Global Solar-Activity Indices

Quasi-biennial oscillations of solar activity are investigated using several global indices. The Singular Spectrum Analysis is used to separate out and study quasi-biennial oscillations; this method is one of the modifications of the main components method. The principal components of the solar cycle are stable 11-year, secular, and quasi-biennial variations. The periods and shapes of individual variations in each quasi-biennial train depend on the length and power of the particular 11-year cycle.

Quasi-biennial response of the upper atmospheric temperature on the same variations of the solar activity

On the basis of the data of the emission and radiophysical measurements some regularities of quasi-biennial oscillation (QBO) of the atmospheric temperature at heights of the mesopause and lower thermosphere are investigated. It is shown, that they are closely connected with quasi-biennial variations of solar activity and form within the limits of a cycle of solar activity the fading wave train of fluctuations. Such behaviour of the wave train can be good described by the Airy function. The wave train arises during an ending of previous cycle of solar activity. Within the maximum of solar activity the period of fluctuations is ∼38 months and linearly ( r = m 0.98) decreases up to ∼21 months to the end of a 11-year cycle.

Processes that Determine the Quasi-Biennial and Lower-Frequency Variability of the South Asian Monsoon.

The spatial and temporal structures of atmospheric circulation and SST associated with the Indian monsoon rainfall variability on quasi-biennial (2-3 year) and lower-frequency (3-7 year) time scales were investigated, using the domain-averaged Indian rainfall, the NCAR/NCEP reanalysis and Reynolds SST data. We took both time-filtering and composite analysis approaches. The results indicate that physical processes that determine the monsoon rainfall variation on the 2-3 year and 3-7 year time scales are different. The quasi-biennial variability of the monsoon is primarily determined by local processes in the Indian Ocean. Both local SST and moisture flux convergence anomalies are highly correlated with the monsoon at a lagged time of 3-6 months. It is argued that a positive SST anomaly in the Indian Ocean increases local moisture due to enhanced surface evaporation. The accumulation of these moistures leads to a strong monsoon through anomalous moisture advection by summer mean flows. The lower-frequency variability of the monsoon is primarily attributed to remote forcing mechanisms. Three possible processes may contribute to the monsoon variability on the 3-7 year time scale. The first is through the change of large-scale, east-west circulation induced by the eastern Pacific SST anomaly. The second is attributed to the effect of the SST anomaly in the Northwestern Pacific through enhanced (or suppressed) convective activity along the monsoon trough. The third is attributed to the tropical-midlatitude teleconnection-a strong north-south, land-ocean thermal contrast occurs six months prior to a wet monsoon, and it persists from the preceding winter to summer and is responsible for the monsoon intensity change.

Quasi-Biennial and Quasi-Decadal Variations in Snow Accumulation over Northern Eurasia and Their Connections to the Atlantic and Pacific Oceans

Abstract Spatial and temporal characteristics of winter snow depth variation over northern Eurasia and their connections to sea surface temperatures (SSTs) and associated atmospheric circulation anomalies, surface air temperatures, and precipitation are examined by using 60 yr (1936–95) of station data records. This study found that snow depth variation over the region east of the Caspian Sea and west of China, explaining 10.1% of total snow depth variance, has a quasi-biennial variability of about 2.5 yr. The snow depth variation over central European Russia and western-central Siberia, explaining 8.1% of the total snow depth variance, has a quasi-decadal variability of about 11.8 yr. The snow depth variation over the northern Ural Mountains, explaining 7.5% of the total snow depth variance has, variability of about 8 and 14 yr. The quasi-biennial snow depth variation is associated with SSTs over the northern North Pacific and tropical western Atlantic extending into the Gulf of Mexico. The associated at...

Characteristics of Winter Precipitation Variation over Northern Central Eurasia and Their Connections to Sea Surface Temperatures over the Atlantic and Pacific Oceans

Abstract This study reveals spatial and temporal characteristics of precipitation variability and their teleconnections to sea surface temperatures (SSTs) over the Atlantic and Pacific Oceans by analyzing 68 yr of recent precipitation records over the former Soviet Union. In addition to a general increasing trend of about 0.4 mm yr−1 or 6% decade−1 over much of the study region, three major modes of precipitation variation are identified. A quasi-biennial variation of 2–3 yr is found over the region surrounding the Caspian and Aral Seas. An El Nino timescale precipitation variation of 4–5 yr is present over southern central Siberia and is associated with eastern tropical Pacific SSTs. A quasi-decadal timescale variation of about 11–12 yr is evident over central European Russia. This quasi-decadal precipitation variation is closely linked to a major SST anomaly pattern of alternating latitudinal belts over the Atlantic and SST variations over the equatorial Pacific Ocean. These associations to SSTs are str...

Quasi-Biennial and Subbiennial Variations of Stratospheric Trace Constituents Derived from HALOE Observations

Interannual variability of trace constituents in the stratosphere is examined using methane, water vapor, and ozone data from the Halogen Occultation Experiment aboard the Upper Atmosphere Research Satellitein 1992‐ 99. Application of rotated principal component analysis to the dataset reveals dominant modes of variability consisting of annual, semiannual, and quasi-biennial oscillations (QBOs), together with ‘‘subbiennial’’ variations evidently due to nonlinear interaction between the annual cycle and QBO. The structure of quasi-biennial variability is approximately symmetric about the equator, while subbiennial variability, with certain exceptions, is approximately antisymmetric and confined mostly to the subtropics. The vertical structure and downward propagation of the ozone QBO at the equator is described by a pair of symmetric EOFs having separate amplitude maxima in the lower and upper stratosphere. A second pair of EOFs explains the seasonal dependence of subtropical ozone anomalies. For each tracer, the subtropical anomaly is larger in the Northern Hemisphere. A novel ‘‘phase diagram’’ illustrates the joint seasonal and QBO dependence of tracer anomalies. A pair of principal components are used to define the phase of the dynamical QBO. When plotted against the phase of the annual cycle, the QBO follows a diagonal trajectory with regular phase progression except for an occasional slowing of easterly shear-zone descent near 50 hPa. Tracer principal components of symmetric and antisymmetric EOFs, plotted along this trajectory, display the distinct signatures of quasi-biennial and subbiennial variation. Tracer anomalies reconstructed using an idealized representation of QBO and subbiennial harmonics display the seasonal synchronization and decadal modulation characteristic of QBO‐annual cycle interaction.

Quasi‐biennial variability in the Japan Sea

The TOPEX/Poseidon (T/P) altimetry reveals quasi‐biennial (QB) variability in the southern Japan Sea. Sea surface height anomalies of a biennial nature are most energetic in the Yamato Basin, the southeastern most part of the Japan Sea, where they can be as large as 20 cm and extend for 100–200 km. On the basis of the in situ measurements of Maizuru Marine Observatory, the 2–3 year variations are associated with thermohaline anomalies in the upper 300 m layer. The local QB oscillation is studied with a reduced gravity model of the Japan Sea. The model is forced by European Centre for Medium‐Range Weather Forecasting daily wind and seasonal inflows/outflows through the three major straits of the sea. The model sensitivity experiments suggest that the QB variability can be associated with the sea's response to wind forcing of particular years, more specifically, 1992 and 1996, and to some extent, 1994. An approximate Kaiman filter is employed for assimilation of the T/P altimeter data into the reduced gravity model. It filters out observational noise and intraseasonal sea level variability and allows the model to dynamically interpolate T/P observations. The results of the assimilation indicate that the QB anomalies are strongest at 37.5°N, 134.5°E and propagate west‐northwest with a speed of ∼0.01 m s‐1, contributing to variations of the Tsushima Warm Current.