On the spatial nonuniformity of some parameters of global variations in the recent climate

Abstract

The near-surface temperature began rising in the mid-1970s, and the planetary field of atmospheric pressure considerably rearranged. The average pressure fields and temperatures for two successive 25-year periods prior to and after the rearrangement are compared in this work. Temperature fluctuations between the periods are shown to be in good agreement with variations in the atmospheric circulation due to rearrangement of the barometric field. A decrease in the near-surface temperature average for the periods was observed in regions with an air mass influx from higher latitudes with an increase in wind speeds over the ocean. A rise in the temperature took place in reversed situations. Early in the 21st century, a gradual relapse of the system to the situation antedating the last quarter of the 20th century was noticed. According to [1], long-term atmospheric processes are inevitably global—only the planet as a whole can serve as a “natural synoptic region” for them. The processes correspond to the scale of the general circulation of the atmosphere. The global nature of climatic processes is evidenced by the observed quasi-synchronous changes in thermodynamic characteristics of the ocean‐atmosphere subsystem in the Pacific and Atlantic [2, 3] and Pacific and Indian [4, 5] oceans; in the high, middle, and low latitudes [6]; and in the Western and Eastern [7] hemispheres. Our investigations along with the study of individual properties and peculiarities of the climatic system are aimed at acquiring the whole pattern of its interdecadal variability and establishing general causes that form the basis of the observed climatic fluctuations, as well as physical mechanisms which maintain the variability. We consider in this work the peculiar features of the recent global climate dynamics in the period referred to as the global warming. Variations that took place in that period in the fields of the atmospheric pressure and near-surface temperature have been analyzed and natural processes that could cause those variations have been considered. Used as basic data in diagnostic calculations of oceanic and atmospheric climatically significant characteristics were global monthly fields of atmospheric pressure at sea level [http://www.cdc.noaa.gov/Pressure/Gridded/] and anomalies of the near-surface temperature [http://www. cru.uea/ak/cru/data/temperature/] for the period of 1950‐2007. Due to scanty data on observations north of 80 ° N and south of 70 ° S, the results of the analysis of the corresponding hydrometeorological fields in these zones should be taken with caution. The lack of data and, hence, inadequate reliability of the investigation results hold true for other regions as well, for instance, in central Africa. Global warming attracted particular attention in the 1970s, when a substantial rearrangement of the planetary field of atmospheric pressure took place [8‐10]. This situation formed the basis for the methods used in this work. To get nonrandom, statistically secured quantitative estimates of the above-mentioned rearrangement, we determined differences of global climatic fields of atmospheric pressure at sea level and the near-surface temperature averaged for two 25-year time intervals: 1975‐1999 and 1950‐1974. The field differences ∆ X ( ϕ , λ , z 0 ) were determined according to the formula