Winds

Using a 3-dimensional atmospheric transport model driven by the ECMWF winds and the non-interannually varying seasonal biospheric flux from the CASA global ecosystem model, we show that a significant change in the downward-zero crossing day (DZCD) of the atmospheric CO2 seasonal cycle in the Northern Hemisphere above 30°N latitude can be obtained by year-to-year changes in the atmospheric transport alone. The transport model is able to reproduce both the trend and standard deviation of DZCD observed at Pt. Barrow. With only atmospheric transport changing from year to year, eastern North Atlantic, Europe, southern Eurasia, southeastern United States and western North America show DZCD starting earlier by 5-10 days after 21 years of model integration. If DZCD obtained from CO2 monitoring stations is going to be used as a proxy for determining the growing season length, then it is important to take into account of that portion caused by the atmospheric transport.

Desertification is the process that turns productive deserts into non-productive deserts as a result of poor land-management. Desertification reduces the ability of land to support life, affecting wild species, domestic animals, agricultural crops and humans. The reduction in plant cover that accompanies desertification leads to accelerated soil erosion by wind and water. South Africa is losing approximately 300–400 million tons of topsoil every year. As vegetation cover and soil layer are reduced, rain fall impact and run-off increases. This paper discusses the extent of desertification, its potential threat to sustained irrigated agriculture and possible measures adopted to control ongoing desertification processes to minimize the loss of agricultural productivity in an arid country such as the Kingdom of Saudi Arabia.

We have analyzed the seasonal variation of short-period (<2 h) gravity wave activity in the troposphere and lower stratosphere using the wind observations made with VHF radar at Gadanki (13.5
N, 79.2
E), India. Four years of high resolution (
3 min) wind data (2003–2006) have been used to study variance and momentum flux of short-period gravity waves. Both horizontal and vertical variances show annual variation. Variances in the upper troposphere (12–16 km) and lower stratosphere (18–21 km) are found to maximize in the wet months of June–July–August coinciding with the peaks of outgoing longwave radiation (OLR) and the rain rate (surface and Tropical Rainfall Measuring Mission [TRMM] 2 km rainfall). An additional strong peak of variance is observed in the height ranges of 4–12 km during spring which corresponds to TRMM storm height maximum. The measurements suggest deep convective activity to be the main source of short period gravity waves. Variances in the UTLS region are found to correlate well with square of wind shear indicating possible in situ generation of the gravity waves. Topographic generation of short period gravity waves does not seem to be important for this site. An interannual variability is observed in the measured wave activity. Zonal momentum flux shows annual variation with westward preference in the wet season whereas the meridional flux does not indicate any clear variation.

Variations in lake evaporation have a significant impact on the energy and water budgets of lakes. Understanding these variations and the role of climate is important for water resource management as well as predicting future changes in lake hydrology as a result of climate change. This study presents a comprehensive, 10-year analysis of seasonal, intraseasonal, and interannual variations in lake evaporation for Sparkling Lake in northern Wisconsin (USA). Meteorological and lake temperature measurements are made at a raft on the lake and are supplemented by radiation measurements from a nearby airport. The data are analyzed over 14-day periods from 1989 to 1998 (during the ice-free season) to provide bi-weekly energy budget estimates of evaporation rate (along with uncertainty estimates). The mean evaporation rate for Sparkling Lake over the study period is 3.1 mm day-1, with a coefficient of variation of 25%. Considerable variability in evaporation rates is found on a wide range of timescales, with seasonal changes having the highest coefficient of variation (18%), followed by the intraseasonal (15%) and interannual timescales (12%; for summer means). Intraseasonal changes in evaporation are primarily associated with synoptic weather variations, with high evaporation events tending to occur during incursions of cold, dry air (due, in part, to the thermal lag between air and lake temperatures). Seasonal variations in evaporation are largely driven by temperature and net radiation, but are out-of-phase with changes in wind speed. This presents challenges when calculating evaporation rates by means of the simpler mass-transfer technique. On interannual timescales, changes in summer evaporation rates are strongly associated with changes in net radiation and show only moderate connections to variations in temperature or humidity. Nonetheless, we are able to identify a simple, empirical relationship for estimating interannual evaporation rates that is more accurate than the mass transfer technique.

Both the seawater and the winds fall within the competence and sphere of responsibility of the gods. They activate their potency, initiate and control their action, and use them as remote tools to both provide help and punish the mortals. In this article, I wish to consider the way in which, in the Homeric episode of Odysseus' visit to Aeolus, the seawater and the winds, acting in full complicity in the middle of the storm, serve to signify the will of the gods and their sentences. ‘Primitive’ religious figure whose authority is limited to the control of the winds, Aeolus has neither power of judgment nor of decision to further Odysseus on his way home. Odysseus' right of νόστος thanks to the divine help is defined with respect to the θέμις. Therefore, Aeolus only respects the will of the gods with regard to the hero and their divine injunctions made through signs. As long as the gods oppose the return of Odysseus, as their sentence was expressed through the δύναμις specific to the elements they command, i.e. the winds and the aquatic elements, Aeolus does not have the right (θέμις) to help or send upon his way (ἀποπέμπω) a man abhorred by heaven, nor mortals whose impious acts are susceptible of harming the divine justice and the cosmic order.