scholarly journals The 11-Yr Solar Cycle in ERA-40 Data: An Update to 2008

2010 ◽  
Vol 23 (8) ◽  
pp. 2213-2222 ◽  
Author(s):  
Thomas H. A. Frame ◽  
Lesley J. Gray
Keyword(s):  
Solar Cycle ◽  
Linear Regression ◽  
Zonal Wind ◽  
Volcanic Aerosol ◽  
Mount Pinatubo ◽  
Aerosol Forcing ◽  
Stratospheric Temperature ◽  
Temperature Trends ◽  
Solar Signal ◽  
Using Data

Abstract Multiple linear regression is used to diagnose the signal of the 11-yr solar cycle in zonal-mean zonal wind and temperature in the 40-yr ECMWF Re-Analysis (ERA-40) dataset. The results of previous studies are extended to 2008 using data from ECMWF operational analyses. This analysis confirms that the solar signal found in previous studies is distinct from that of volcanic aerosol forcing resulting from the eruptions of El Chichón and Mount Pinatubo, but it highlights the potential for confusion of the solar signal and lower-stratospheric temperature trends. A correction to an error that is present in previous results of Crooks and Gray, stemming from the use of a single daily analysis field rather than monthly averaged data, is also presented.

scholarly journals Meteor radar quasi two-day wave observations over 10 years at Collm (51.3° N, 13.0° E)

2015 ◽  
Vol 15 (6) ◽  
pp. 9631-9659
Author(s):  
F. Lilienthal ◽  
C. Jacobi
Keyword(s):  
Solar Cycle ◽  
Zonal Wind ◽  
Wind Shear ◽  
Meteor Radar ◽  
Annual Variability ◽  
Summer Maximum ◽  
Using Data ◽  
Clear Relation ◽  
Phase Differences

Abstract. The quasi two-day wave (QTDW) at 82–97 km altitude over Collm (51° N, 13° E) has been observed using a~VHF meteor radar. The long-term mean amplitudes calculated using data between September 2004 and August 2014 show a strong summer maximum and a much weaker winter maximum. In summer, the meridional amplitude is slightly larger than the zonal one with about 15 m s−1 at 91 km height. Phase differences are slightly greater than 90° on an average. The periods of the summer QTDW vary between 43 and 52 H during strong bursts, while in winter the periods tend to be more diffuse. On an average, the summer QTDW is amplified after a maximum of zonal wind shear which is connected with the summer mesospheric jet and there is a possible correlation of the summer mean amplitudes with the backgound wind shear. QTDW amplitudes exhibit considerable inter-annual variability, however, a clear relation between the 11 year solar cycle and the QTDW is not found.

scholarly journals Solar cycle in current reanalyses: (non)linear attribution study

2014 ◽  
Vol 14 (22) ◽  
pp. 30879-30912
Author(s):  
A. Kuchar ◽  
P. Sacha ◽  
J. Miksovsky ◽  
P. Pisoft
Keyword(s):  
Solar Cycle ◽  
Linear Regression ◽  
Middle Atmosphere ◽  
Polar Vortex ◽  
Support Vector ◽  
Satellite Measurements ◽  
Attribution Analysis ◽  
Nonlinear Approach ◽  
Hypothetical Mechanism ◽  
Solar Signal

Abstract. This study focusses on the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the influence of the 11 year solar cycle. It is based on attribution analysis using multiple nonlinear techniques (Support Vector Regression, Neural Networks) besides the traditional linear approach. The analysis was applied to several current reanalysis datasets for the 1979–2013 period, including MERRA, ERA-Interim and JRA-55, with the aim to compare how this type of data resolves especially the double-peaked solar response in temperature and ozone variables and the consequent changes induced by these anomalies. Equatorial temperature signals in the lower and upper stratosphere were found to be sufficiently robust and in qualitative agreement with previous observational studies. The analysis also pointed to the solar signal in the ozone datasets (i.e. MERRA and ERA-Interim) not being consistent with the observed double-peaked ozone anomaly extracted from satellite measurements. Consequently the results obtained by linear regression were confirmed by the nonlinear approach through all datasets, suggesting that linear regression is a relevant tool to sufficiently resolve the solar signal in the middle atmosphere. Furthermore, the seasonal dependence of the solar response was also discussed, mainly as a source of dynamical causalities in the wave propagation characteristics in the zonal wind and the induced meridional circulation in the winter hemispheres. The hypothetical mechanism of a weaker Brewer Dobson circulation was reviewed together with discussion of polar vortex stability.

scholarly journals The 11-year solar cycle in current reanalyses: a (non)linear attribution study of the middle atmosphere

2015 ◽  
Vol 15 (12) ◽  
pp. 6879-6895 ◽  
Author(s):  
A. Kuchar ◽  
P. Sacha ◽  
J. Miksovsky ◽  
P. Pisoft
Keyword(s):  
Solar Cycle ◽  
Linear Regression ◽  
Middle Atmosphere ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Support Vector ◽  
Data Sets ◽  
Nonlinear Approach ◽  
Hypothetical Mechanism ◽  
Solar Signal

Abstract. This study focusses on the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the influence of the 11-year solar cycle. It is based on attribution analysis using multiple nonlinear techniques (support vector regression, neural networks) besides the multiple linear regression approach. The analysis was applied to several current reanalysis data sets for the 1979–2013 period, including MERRA, ERA-Interim and JRA-55, with the aim to compare how these types of data resolve especially the double-peaked solar response in temperature and ozone variables and the consequent changes induced by these anomalies. Equatorial temperature signals in the tropical stratosphere were found to be in qualitative agreement with previous attribution studies, although the agreement with observational results was incomplete, especially for JRA-55. The analysis also pointed to the solar signal in the ozone data sets (i.e. MERRA and ERA-Interim) not being consistent with the observed double-peaked ozone anomaly extracted from satellite measurements. The results obtained by linear regression were confirmed by the nonlinear approach through all data sets, suggesting that linear regression is a relevant tool to sufficiently resolve the solar signal in the middle atmosphere. The seasonal evolution of the solar response was also discussed in terms of dynamical causalities in the winter hemispheres. The hypothetical mechanism of a weaker Brewer–Dobson circulation at solar maxima was reviewed together with a discussion of polar vortex behaviour.

scholarly journals Meteor radar quasi 2-day wave observations over 10 years at Collm (51.3° N, 13.0° E)

2015 ◽  
Vol 15 (17) ◽  
pp. 9917-9927 ◽  
Author(s):  
F. Lilienthal ◽  
Ch. Jacobi
Keyword(s):  
Solar Cycle ◽  
Zonal Wind ◽  
Wind Shear ◽  
Meteor Radar ◽  
Background Wind ◽  
Annual Variability ◽  
Summer Maximum ◽  
Using Data ◽  
Phase Differences

Abstract. The quasi 2-day wave (QTDW) at 82–97 km altitude over Collm (51° N, 13° E) has been observed using a VHF meteor radar. The long-term mean amplitudes calculated using data between September 2004 and August 2014 show a strong summer maximum and a much weaker winter maximum. In summer, the meridional amplitude is slightly larger than the zonal one with about 15 m s−1 at 91 km height. Phase differences are slightly greater than 90° on an average. The periods of the summer QTDW vary between 43 and 52 h during strong bursts, while in winter the periods tend to be more diffuse. On average, the summer QTDW is amplified after a maximum of zonal wind shear which is connected with the summer mesospheric jet and there is a possible correlation of the summer mean amplitudes with the background wind shear. QTDW amplitudes exhibit considerable inter-annual variability; however, a relationship between the 11-year solar cycle and the QTDW is not found.

scholarly journals Stratospheric Temperature Trends over 1979–2015 Derived from Combined SSU, MLS, and SABER Satellite Observations

2016 ◽  
Vol 29 (13) ◽  
pp. 4843-4859 ◽  
Author(s):  
William J. Randel ◽  
Anne K. Smith ◽  
Fei Wu ◽  
Cheng-Zhi Zou ◽  
Haifeng Qian
Keyword(s):  
Solar Cycle ◽  
Lower Stratosphere ◽  
Stratospheric Ozone ◽  
Volcanic Eruptions ◽  
Weighting Functions ◽  
Stratospheric Temperature ◽  
Temperature Trends ◽  
Decadal Scale ◽  
Data Record ◽  
The Tropics

Abstract Temperature trends in the middle and upper stratosphere are evaluated using measurements from the Stratospheric Sounding Unit (SSU), combined with data from the Aura Microwave Limb Sounder (MLS) and Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) instruments. Data from MLS and SABER are vertically integrated to approximate the SSU weighting functions and combined with SSU to provide a data record spanning 1979–2015. Vertical integrals are calculated using empirically derived Gaussian weighting functions, which provide improved agreement with high-latitude SSU measurements compared to previously derived weighting functions. These merged SSU data are used to evaluate decadal-scale trends, solar cycle variations, and volcanic effects from the lower to the upper stratosphere. Episodic warming is observed following the volcanic eruptions of El Chichón (1982) and Mt. Pinatubo (1991), focused in the tropics in the lower stratosphere and in high latitudes in the middle and upper stratosphere. Solar cycle variations are centered in the tropics, increasing in amplitude from the lower to the upper stratosphere. Linear trends over 1979–2015 show that cooling increases with altitude from the lower stratosphere (from ~−0.1 to −0.2 K decade−1) to the middle and upper stratosphere (from ~−0.5 to −0.6 K decade−1). Cooling in the middle and upper stratosphere is relatively uniform in latitudes north of about 30°S, but trends decrease to near zero over the Antarctic. Mid- and upper-stratospheric temperatures show larger cooling over the first half of the data record (1979–97) compared to the second half (1998–2015), reflecting differences in upper-stratospheric ozone trends between these periods.

scholarly journals Radiosonde stratospheric temperatures at Dumont d'Urville (Antarctica): trends and link with polar stratospheric clouds

2010 ◽  
Vol 10 (8) ◽  
pp. 3813-3825 ◽  
Author(s):  
C. David ◽  
P. Keckhut ◽  
A. Armetta ◽  
J. Jumelet ◽  
M. Snels ◽  
...  
Keyword(s):  
Significant Trend ◽  
Positive Trend ◽  
International Geophysical Year ◽  
Stratospheric Temperature ◽  
Temperature Trends ◽  
Mean Temperature ◽  
Climate Evolution ◽  
Data Gap ◽  
Using Data ◽  
Stratospheric Clouds

Abstract. Temperature profiles measurements are performed daily (00:00 UT) in Dumont d'Urville (66°40' S, 140°01' E) by Météo-France, using standard radiosondes, since the International Geophysical Year in 1957. Yet, due to a 16 years data gap between 1963 and 1978, the entire dataset is only used for a qualitative overview. Only the most recent series, between 1979 and 2008, is used to investigate the inter-annual stratospheric temperatures variability. Over Dumont d'Urville, at the edge of the vortex, the annual mean temperature cooling of about 1 K/decade at 20 km is the result of the cooling trends between 0.5 and 1.4 K/decade, in summer and autumn and a warming of about 1.1 K/decade in spring. These values are consistent with values obtained using data from inner vortex stations, but with smaller amplitude. No statistically significant trend is detected in winter. We propose here the first attempt to link stratospheric temperature trends to Polar Stratospheric Cloud (PSC) trends in Antarctica based on the only continuous 20 years database of PSC lidar detection. Despite the absence of mean temperature trend during winter, the occurrence of temperatures below the NAT threshold between 1989 and 2008 reveals a significant trend of about +6%/decade. The PSCs occurrences frequency exhibits a concomitant trend of about +3%/decade, although not statistically significant. Yet, this is consistent with results obtained in the Northern Hemisphere. Such a possible positive trend in PSC occurrence has to be further explored to be confirmed or invalidated. If confirmed, this PSC trend is likely to have strong impacts, both on ozone recovery and climate evolution in Antarctica. The study also reveals the importance of trends on extreme temperatures, and not only on mean temperatures.

scholarly journals How can we understand the global distribution of the solar cycle signal on the Earth's surface?

2016 ◽  
Vol 16 (20) ◽  
pp. 12925-12944 ◽  
Author(s):  
Kunihiko Kodera ◽  
Rémi Thiéblemont ◽  
Seiji Yukimoto ◽  
Katja Matthes
Keyword(s):  
Solar Cycle ◽  
Surface Temperature ◽  
Zonal Wind ◽  
High Solar Activity ◽  
Mean Flow ◽  
Central Pacific ◽  
Solar Signal ◽  
The Tropics ◽  
Solar Influence ◽  
The Impact

Abstract. To understand solar cycle signals on the Earth's surface and identify the physical mechanisms responsible, surface temperature variations from observations as well as climate model data are analysed to characterize their spatial structure. The solar signal in the annual mean surface temperature is characterized by (i) mid-latitude warming and (ii) no overall tropical warming. The mid-latitude warming during solar maxima in both hemispheres is associated with a downward penetration of zonal mean zonal wind anomalies from the upper stratosphere during late winter. During the Northern Hemisphere winter this is manifested by a modulation of the polar-night jet, whereas in the Southern Hemisphere, the upper stratospheric subtropical jet plays the major role. Warming signals are particularly apparent over the Eurasian continent and ocean frontal zones, including a previously reported lagged response over the North Atlantic. In the tropics, local warming occurs over the Indian and central Pacific oceans during high solar activity. However, this warming is counterbalanced by cooling over the cold tongue sectors in the southeastern Pacific and the South Atlantic, and results in a very weak zonally averaged tropical mean signal. The cooling in the ocean basins is associated with stronger cross-equatorial winds resulting from a northward shift of the ascending branch of the Hadley circulation during solar maxima. To understand the complex processes involved in the solar signal transfer, results of an idealized middle atmosphere–ocean coupled model experiment on the impact of stratospheric zonal wind changes are compared with solar signals in observations. Model integration of 100 years of strong or weak stratospheric westerly jet condition in winter may exaggerate long-term ocean feedback. However, the role of ocean in the solar influence on the Earth's surface can be better seen. Although the momentum forcing differs from that of solar radiative forcing, the model results suggest that stratospheric changes can influence the troposphere, not only in the extratropics but also in the tropics through (i) a downward migration of wave–zonal mean flow interactions and (ii) changes in the stratospheric mean meridional circulation. These experiments support earlier evidence of an indirect solar influence from the stratosphere.

scholarly journals How can we understand the solar cycle signal on the Earth's surface?

2016 ◽  
Author(s):  
Kunihiko Kodera ◽  
Rémi Thiéblemont ◽  
Seiji Yukimoto ◽  
Katja Matthes
Keyword(s):  
Solar Cycle ◽  
Surface Temperature ◽  
Zonal Wind ◽  
High Solar Activity ◽  
Late Winter ◽  
Mean Flow ◽  
Central Pacific ◽  
Solar Signal ◽  
The Tropics ◽  
The Impact

Abstract. To understand solar cycle signals on the Earth's surface and identify the physical mechanisms responsible, surface temperature variations from observations as well as climate model data are analyzed to characterize their spatial structure. The solar signal in the annual mean surface temperature is characterized by (i) mid-latitude warming and (ii) no warming in the tropics. The mid-latitude warming during solar maxima in both hemispheres is associated with a downward penetration of zonal mean zonal wind anomalies from the upper stratosphere during late winter. During Northern Hemisphere winter this is manifested in a modulation of the polar-night jet whereas in the Southern Hemisphere the subtropical jet plays the major role. Warming signals are particularly apparent over the Eurasian continent and ocean frontal zones, including a previously reported lagged response over the North Atlantic. In the tropics, local warming occurs over the Indian and central Pacific oceans during high solar activity. However, this warming is counter balanced by cooling over the cold tongue sectors in the southeastern Pacific and the South Atlantic, and results in a very weak zonally averaged tropical mean signal. The cooling in the ocean basins is associated with stronger cross-equatorial winds resulting from a northward shift of the ascending branch of the Hadley circulation during solar maxima. To understand the complex processes involved in the solar signal transfer, results of an idealized middle atmosphere–ocean coupled model experiment on the impact of stratospheric zonal wind changes are compared with solar signals in observations. The model results suggest that both tropical and extra-tropical solar surface signals can result from circulation changes in the upper stratosphere through (i) a downward migration of wave–zonal mean flow interactions and (ii) changes in the stratospheric mean meridional circulation. These experiments support earlier evidence of an indirect solar influence from the stratosphere.

scholarly journals The sunspot cycle, the QBO, and the total ozone over Northeastern Europe: a connection through the dynamics of stratospheric circulation

1997 ◽  
Vol 15 (12) ◽  
pp. 1595-1603 ◽  
Author(s):  
B. Soukharev
Keyword(s):  
Solar Cycle ◽  
Zonal Wind ◽  
Total Ozone ◽  
Sunspot Cycle ◽  
Correlation Method ◽  
Quasi Biennial Oscillation ◽  
Sunspot Numbers ◽  
Stratospheric Circulation ◽  
Solar Signal ◽  
Northeastern Europe

Abstract. The interaction between the factors of the quasi-biennial oscillation (QBO) and the 11-year solar cycle is considered as an separate factor influencing the interannual January-March variations of total ozone over Northeastern Europe. Linear correlation analysis and the running correlation method are used to examine possible connections between ozone and solar activity at simultaneous moment the QBO phase. Statistically significant correlations between the variations of total ozone in February and, partially, in March, and the sunspot numbers during the different phases of QBO are found. The running correlation method between the ozone and the equatorial zonal wind demonstrates a clear modulation of 11-y solar signal for February and March. Modulation is clearer if the QBO phases are defined at the level of 50 hPa rather than at 30 hPa. The same statistical analyses are conducted also for possible connections between the index of stratospheric circulation C1 and sunspot numbers considering the QBO phase. Statistically significant connections are found for February. The running correlations between the index C1 and the equatorial zonal wind show the clear modulation of 11-y solar signal for February and March. Based on the obtained correlations between the interannual variations of ozone and index C1, it may be concluded that a connection between solar cycle – QBO – ozone occurs through the dynamics of stratospheric circulation.

scholarly journals Relationship between MODIS Derived NDVI and Yield of Cereals for Selected European Countries

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 340
Author(s):  
Ewa Panek ◽  
Dariusz Gozdowski
Keyword(s):  
Linear Regression ◽  
Grain Yield ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Arable Land ◽  
Early Spring ◽  
European Countries ◽  
Yield Prediction ◽  
Country Level ◽  
Using Data

In this study, the relationships between normalized difference vegetation index (NDVI) obtained based on MODIS satellite data and grain yield of all cereals, wheat and barley at a country level were analyzed. The analysis was performed by using data from 2010–2018 for 20 European countries, where percentage of cereals is high (at least 35% of the arable land). The analysis was performed for each country separately and for all of the collected data together. The relationships between NDVI and cumulative NDVI (cNDVI) were analyzed by using linear regression. Relationships between NDVI in early spring and grain yield of cereals were very strong for Croatia, Czechia, Germany, Hungary, Latvia, Lithuania, Poland and Slovakia. This means that the yield prediction for these countries can be as far back as 4 months before the harvest. The increase of NDVI in early spring was related to the increase of grain yield by about 0.5–1.6 t/ha. The cumulative of averaged NDVI gives more stable prediction of grain yield per season. For France and Belgium, the relationships between NDVI and grain yield were very weak.

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