Search results for "Seasonality"
showing 10 items of 229 documents
Some aspects of the seasonal variation of carbon dioxide and ozone
1968
An attempt is made to estimate the seasonal source function, Q , of CO 2 on the basis of data for the biosphere, provided by Lieth, and for other sources. The variation of soil respiration appears to be the most uncertain factor. The resulting CO 2 variations in the atmosphere are calculated for horizontal exchange coefficients, K , which vary with latitude. Comparison with observations given by Bolin & Keeling shows that the results are not very sensitive with respect to the assumed variations of Q and of K with latitude. Previous results on the 0 3 budget are used to calculate seasonal variations of tropospheric 0 3 for stratospheric injection rates, and K values which vary with latitude.…
Global ozone budget and exchange between stratosphere and troposphere
1962
A survey of existing data reveals that tropospheric ozone is fairly uniformly distributed within the hemispheres, but that the hemispheres are well separated. Within the northern hemisphere representative data of tropospheric ozone exhibit a uniform seasonal variation the phase of which is delayed by about 2 months with respect to the injection into the troposphere. It is suggested that this delay is controlled by the rate of destruction of ozone within the troposphere. On the basis of this concept and additional reasonable assumptions it is possible to give a quantitative analysis of the ozone budget and of the seasonal variation of the exchange between stratosphere and troposphere. Calcul…
Vegetation fire emissions and their impact on air pollution and climate
2009
Gaseous and particulate emissions from vegetation fires substantially modify the atmospheric chemical composition, degrade air quality and can alter weather and climate. The impact of vegetation fire emissions on air pollution and climate has been recognised in the late 1970s. The application of satellite data for fire-related studies in the beginning of the 21th century represented a major break through in our understanding of the global importance of fires. Today the location and extent of vegetation fires, burned area and emissions released from fires are determined from satellite products even though many uncertainties persist. Numerous dedicated experimental and modeling studies contri…
Quantifying transport into the lowermost stratosphere using simultaneous in-situ measurements of SF<sub>6</sub> and CO&am…
2009
Abstract. The seasonality of transport and mixing of air into the lowermost stratosphere (LMS) is studied using distributions of mean age of air and a mass balance approach, based on in-situ observations of SF6 and CO2 during the SPURT (Spurenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region) aircraft campaigns. Combining the information of the mean age of air and the water vapour distributions we demonstrate that the tropospheric air transported into the LMS above the extratropical tropopause layer (ExTL) originates predominantly from the tropical tropopause layer (TTL). The concept of our mass balance is based on simultaneous measurements of the two pas…
Recent temporal and spatial temperature changes in Egypt
2005
In order to detect and to estimate trends of temperature change in Egypt, trend analyses applying the least-squares method and the non-parametric Mann–Kendall test for trends were carried out at six stations for the period 1941–2000 (60 years), and at nine stations for the period 1971–2000 (30 years). According to the trend computations for the period 1941–2000, variable temperature trends over time and space have been observed. Decreasing trends of the mean annual temperature were observed in northern Egypt and (weakly) increasing trends in southern Egypt. Seasonally, positive trends prevailed in summer compared with negative trends in winter. For the recent period, 1971–2000, positive tre…
Diurnal and seasonal variation of monoterpene and sesquiterpene emissions from Scots pine (Pinus sylvestris L.)
2006
Abstract Recent research pointed out the question of missing OH reactivity in a forest system and the question for unknown highly reactive biogenic emissions. In this study we show that coniferous forests are an important source of highly reactive hydrocarbons, the sesquiterpenes. We investigated the seasonality of terpene emissions from Scots pine to work out influences on atmospheric chemistry in different seasons for both mono- and sesquiterpenes. Especially sesquiterpenes (C15) change dramatically in their contribution to the terpene emissions of Scots pine. Fourteen sesquiterpenes and oxygenated compounds were found in the emissions. In spring, the pattern was most complex with all 14 …
Characterization of the inter-annual, seasonal, and diurnal variations of condensation particle concentrations at Neumayer, Antarctica
2011
Continuous condensation particle (CP) observations were conducted from 1984 through 2009 at Neumayer Station under stringent contamination control. During this period, the CP concentration (median 258 cm<sup>−3</sup>) showed no significant long term trend but exhibited a pronounced seasonality characterized by a stepwise increase starting in September and reaching its annual maximum of around 10<sup>3</sup> cm<sup>−3</sup> in March. Minimum values below 10<sup>2</sup> cm<sup>&ndash;3</sup> were observed during June/July. Dedicated time series analyses in the time and frequency domain revealed no significant correlations between…
Spatial distribution of the precipitation in Dobruja (Romania/Black Sea)
2000
An original dataset for the Dobruja, a low plateau region of southeastern Romania, is used to perform a statistical study of the spatial distribution of rainfall at annual and seasonal time-scales. A principal component analysis (PCA) is carried out to identify the precipitation regimes. The high eigenvalue of PC1 attests of the prevailing temperate-continental regime, with a relatively dry winter opposed to a late spring and early summer rainfall maximum. PC2 shows the specific pattern of the coast, with a small secondary maximum in November. In spite of the relatively flat topography, annual rainfall is characterized by a strong gradient between the coast and the interior. Particularly lo…
Spatio-temporal variability of fog-water collection in the eastern Iberian Peninsula: 2003-2012
2019
Abstract Among the different inputs involved in the hydrological system, fog water measured by man-made passive devices is one of the most unknown components, although it could be an additional water resource for specific environmental applications (forest restoration, forest firefighting, etc.). Focusing on the Mediterranean Iberian Peninsula, the aim of this work is to quantify fog-water collected by a 24-fog-stations network spread across three latitudinal sectors with different locations (coastal, pre-littoral and inland), and to determine the most productive sites. Measurements from the network show that distance-to-sea, latitude or elevation differences between stations are factors af…
The orthogonal structure of Monsoon rainfall variation over Sri Lanka
1992
The spatial organization of Monsoon rainfall over Sri Lanka is examined using Orthogonal Factor Analysis (OFA) on long-term mean monthly rainfall data. Three types of orthogonal structure of Monsoon regime in Sri Lanka have been identified. Interpretation of orthogonal factor scores revealed that a large amount of rainfall occurs from March to October in the southwestern parts of Sri Lanka, from December to February in the eastern parts, and in November in the northern and mid-western parts which are all represented by high positive factor scores. Orthogonal factor scores for the first three factors account for 93.6% of the total variance of mean monthly rainfall and clearly indicate that t…