By how much does changing radiation from the sun influence the earth’s climate, presently and in the recent past, compared with other natural and anthropogenic processes? Current knowledge of the amplitudes and timescales of solar radiative output variability needed to address this question is described from contemporary solar monitoring and historical reconstructions. The 17-yr observational database of space-based solar monitoring exhibits an 11-yr irradiance cycle with amplitude of about 0.1%. Larger amplitude solar total radiative output changes—of 0.24% relative to present levels—are estimated for the seventeenth-century Maunder Minimum by parameterizing the variability mechanisms identified for the 11-yr cycle, using proxies of solar and stellar variability. The 11- and 22-yr periods evident in solar activity proxies appear in many climate and paleoclimate records, and some solar and climate time series correlate strongly over multidecadal and centennial timescales. These statistical relati...

Weather Cycles: Real or Imaginary?

Climate Forcing by Changing Solar Radiation

Four major circulation patterns, associated with daily precipitation in Portugal, are classified from daily sea level pressure fields over the northeastern Atlantic and western Europe, based on the K-means clustering algorithm coupled with principal component analysis A rainy pattern is clearly identified with a probability of rain of 746%, as well as two distinct dry patterns, one prevailing in summer and the other occurring frequently in winter; a blocking-like pattern with a probability of rain of 368% has also been identified These patterns are quasi-stationary, normally persisting for 1 week and sometimes even for 1 month, especially the dry ones; they represent the principal weather regimes associated with precipitation in Portugal



Interannual variations in monthly precipitation associated with the circulation patterns are also investigated; results show that these variations match fluctuations in the frequencies of occurrence of both the rainy and the dry patterns The decreasing trend of March monthly rainfall in southern Portugal is closely related to corresponding trends in the frequencies of both the rainy pattern and the summer dry pattern Long term trends are not significant either in other monthly rainfall sequences or in the frequencies of different circulation patterns Interannual variations seem, in most months, to be quasi-periodic Singular spectrum analysis (SSA) is performed on these sequences to detect quasi-periodic oscillations Relationships between oscillations in rainfall and in frequencies of occurrence of circulation patterns are studied Results show that four weather circulation patterns or weather regimes are important for investigating regional climate change in Portugal and its relationship with variability of large-scale atmospheric circulation © 1998 Royal Meteorological Society

Regional climate change in Portugal: precipitation variability associated with large‐scale atmospheric circulation

Climate Change: a Multidisciplinary Approach provides an up-to-date, concise and comprehensive presentation of our current knowledge of climate change and its implications for society. The book begins by giving a balanced coverage of the physical principles of the global climate, its behaviour on all timescales, and the evidence for and consequences of past change. It then reviews how we measure climate change and the statistical methods for analysing data, before exploring its causes and how we can model this behaviour. The final sections discuss predictions of future climate change and the economic and political debate surrounding its prevention and mitigation. This is a valuable undergraduate textbook for a wide range of courses, including meteorology, oceanography, environmental science, earth science, geography, history, agriculture and social science. It will also appeal to a wider general audience of readers in search of a better understanding of climate change.

Climate Change: A Multidisciplinary Approach

Low-frequency (interannual or longer period) climatic variability is of interest because of its significance for the understanding and prediction of protracted climatic anomalies. Closed basin lakes are sensitive to long-term climatic fluctuations and integrate out high-frequency variability. It is thus natural to examine the records of such lakes to better understand long-term climate dynamics. Here we use singular spectral analysis and multitaper spectral analysis to analyze the time series of Great Salt Lake (GSL) monthly volume change from 1848 to 1992 and monthly precipitation, temperature, and streamflow for nearby stations with 74 or more years of data. This analysis reveals high fractional variance in 15–18, 10–12, 3–7 and 2-year frequency bands, which seems to be consistent across time series. The putative decadal and interdecadal signals appear to be related to large-scale climate signals. The interannual signals are consistent with El Nino Southern Oscillation and quasi-biennial variability. Prospects for improved prediction of the GSL volume and of protracted wet/dry periods in the western United States are discussed.

https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1243&context=water_rep

Weather Cycles: Real or Imaginary?

Citations

Climate Forcing by Changing Solar Radiation

Regional climate change in Portugal: precipitation variability associated with large‐scale atmospheric circulation

Climate Change: A Multidisciplinary Approach

The Great Salt Lake: A Barometer of Low-Frequency Climatic Variability

Periodicity of climate conditions and solar variability derived from dendrochronological and other palaeoclimatic data in high latitudes