Differences and similarities between precipitation patterns of different climates

In recent years water-related issues are increasing globally, some researchers even argue that the global hydrological cycle is accelerating, while the number of meteorological extremities is growing. With the help of large number of available measured data, these changes can be examined with advanced mathematical methods. In the outlined research we were able to collect long precipitation datasets from two different climatical regions, one sample area being Ecuador, the other one being Kenya. Using the methodology of spectral analysis based on the discrete Fourier-transformation, several deterministic components were calculated locally in the otherwise stochastic time series, while by the comparison of the results, also with previous calculations from Hungary, several global precipitation cycles were defined in the time interval between 1980 and 2019. The results of these calculations, the described local, regional, and global precipitation cycles can be a helpful tool for groundwater management, as precipitation is the major resource of groundwater recharge, as well as with the help of these deterministic cycles, precipitation forecasts can be delivered for the areas.

Responses of Soil Microbes to Hydrological Perturbations in Tropical Forest Soils

<p>Model projections predict that climate change impacts on the tropics will include an increased frequency of drought and precipitation cycles. Such environmental fluctuations at the soil pore-scale play an important role in shaping microbial adaptive capacity, and trait composition of a community, which feeds back on to the breakdown and formation of soil organic matter (SOM). Understanding the factors controlling the carbon balance of humid tropical forest soils remains a social imperative. Microbial feedback to SOM pools is critical. Herein, we examine the microbial response to drought perturbations across  3 different, but complementary scales. At the largest scale, we explored the impacts of drought across a 1 m precipitation gradient spanning four sites from the Caribbean coast to the interior of Panama. At each site 4, throughfall exclusion plots (10 x 10 m) were established to reduce precipitation by 50 %. In addition, 4 corresponding control plots were also constructed. At the meso-scale, we incubated intact soil cores from one of these sites (P12) under 3 different hydrological treatments (control, drought, rewetting-drying cycles) for over a 5-month period. For the field and meso-scale experiments, we evaluated changes imparted by hydrological perturbations using multi-omic approaches, and physico-chemical measurements.   In order to identify the traits involved in response to drought at the field and meso-scale, we isolated a range of bacteria to subject to stress at the scale of the single-cell and simple communities.  Cell extracts were subjected to osmotic or matric stress and the short-term physiological responses determined using non-destructive synchrotron radiation-based Fourier Transform-Infrared spectromicroscopy. Through this approach, we identified changes in metabolic allocation within different cells, in particular to the secondary metabolome of the different bacteria. Our contribution will discuss the outcomes of these multi-scale experiments.  Specifically focusing on how shifts in the microbial community and physiological changes may influence tropical soil carbon stability under future scenarios of altered drought and precipitation cycles.</p>

Precipitation cycles in Turkey

Turkey is located in the temperate zone; thus, it is influenced by regionally different air masses during summers and winters, resulting in different precipitation regimes. Often, systems with varying masses of air repeatedly affect Turkey; however, at times, these periods are disrupted and difficult to predict. This study analyzes whether a certain periodicity exists in the seasonal and annual total precipitation of 74 meteorological stations in Turkey using periodograms. The analyses conducted herein showed more than one period in the series; therefore, this study was extended, and the first six periods were examined. As a result, we found 2-, 3-, 4-, and 5-year precipitation cycles (PCs) in the short term; 6-, 7-, and 8-year PCs in the medium term; and 11-, 12-, 14-, 17-, and 21-year PCs in the long term in Turkey’s PC. While seasonal distributions exhibited similarities, there were significant differences in the seasonal frequencies owing to seasonal variations in the systems affecting Turkey. The cycles vary by region, and some of these cycles can be found in each region. Three cycles have been identified in Turkey according to frequency and length, namely: (1) short-term cycle across Turkey; (2) Eastern and Central Anatolia, the Black Sea, and Aegean regions; and (3) borders of Central Anatolian and the eastern Mediterranean region. A cluster identifies unrelated locations as the affected local factors. Cycles are connected to the NAO, whereas solar activity is observed throughout Turkey. The analysis showed that certain cycles were repeated and were not dominant in each period, with the best example of this cycle as the 7–14–21 consecutive cycles.

Anthropogenic impact on inorganic soil C: Impact of Irrigated Agriculture on Carbonates Dynamics in Semiarid Land

<p>In many semiarid Mediterranean soils, carbonates can constitute a significant proportion of the soil mass. Unlike other soil inorganic components, carbonates can react in the short term to changes in the soil water regime and the physical-chemical conditions of the soil solution. The introduction of irrigation can be associated to such changes, as it changes the water balance, the composition of the soil solution, and the concentration of CO<sub>2</sub> in the soil atmosphere.</p><p>To gain knowledge on the importance of the effect of irrigation on carbonates dynamics in the tilled layer of agricultural Mediterranean soils, we conducted a three-step study embracing field observations and numerical simulation.</p><p>In the first step, carbonates stocks and size-distribution were quantified for two different situations (irrigation and non-irrigation) in paired plots of three irrigation districts in Navarre (Spain). Our results, showed that although the net annual balance of total carbonates-C between irrigated and non-irrigated plots was neutral, carbonates concentration was lower with irrigation in the finest (< 50 μm) soil fractions (25.6 ± 2.6 carbonates 100 g<sup>−1</sup> without irrigation for 19.3 ± 2.1 with irrigation, on average).</p><p>In a second step, numerical simulations of the geochemical interactions between soil carbonates, the soil solution and irrigation water were run using actual soil characteristics and soil solution data from the tilled layer (0-30 cm) of two paired plots 9 years after irrigation started. A sensitivity analysis was also conducted to investigate the potential impact of water quality and crop types as sources of variability in the model outputs. The modelling results showed annual losses of carbonates-C in the range of 12.06-13.52 g m<sup>−2</sup> year<sup>−1</sup> in the studied depth under irrigation, depending on the quality of irrigation water, for 0.46 g m<sup>−2</sup> without irrigation.</p><p>Lastly, and because the acceleration of carbonate dissolution/precipitation cycles, together with the addition of calcium in fertilizers and irrigation water, can cause an increase in the formation of pedogenic carbonates, their proportion was estimated in paired plots from carbonates-C isotopic signatures: a preferential accumulation of pedogenic carbonates in the finest size fractions (87-92%) was observed with irrigation (61-74% without irrigation).</p><p><em>Future investigations</em></p><p>New field observations and numerical simulations will be done in an experimental plot in  which corn (Zea mays L.) has been grown since 2010 with and without irrigation. A numerical model will be developed to study the expected changes in the carbonate dissolution/precipitation cycles in semi-arid Mediterranean areas and these results will be compared with the concentration and characteristics of carbonates (size distribution and isotopic signature as an indicator of their geological or pedogenic origin) in the experimental plot.</p><p>Finally, the model will be validated at a regional scale, using a network of real representative agricultural plots in which there has been a change in land use from unirrigated to irrigated land in Navarre.</p><p> </p>

Diurnal Cycle of Surface Winds in the Maritime Continent Observed through Satellite Scatterometry

The diurnal cycle of surface winds throughout the Maritime Continent plays a significant role in the formation of precipitation over the islands of the region and over the surrounding seas. This study investigates the connection between the diurnal cycles of surface wind and offshore precipitation using data from four satellite scatterometer instruments and two satellite precipitation radar instruments. For the first time, data from three scatterometer instruments are combined to yield a more temporally complete picture of the surface wind diurnal cycles over the Maritime Continent’s surrounding seas. The results indicate that land–sea breezes typically propagate over 400 km offshore, produce mean wind perturbations of between 1 and 5 m s−1, and propagate as gravity waves at 25–30 m s−1. Diurnal precipitation cycles are affected through gravity wave propagation processes associated with the land–sea breezes, and through the convergence of land breezes from nearby islands. These observational results are then compared with previous mesoscale modeling results. It is shown that land–sea breezes occur too early, and are too intense in these modeling results, and this may partly explain why these modeling results also exhibit an early, overly intense diurnal precipitation cycle. This study also investigates variations in the diurnal cycle of surface winds at seasonal and intraseasonal time scales. Previous work has suggested that seasonal and intraseasonal variations in surface heating affect the land–sea breeze circulation and diurnal precipitation cycles; we argue that variations in background winds also play a defining role in modulating coastally influenced local winds.

Analysis of precipitation cycles based on MEM in the Yellow River basin

Using the monthly precipitation series of 32 meteorological stations in the Yellow River basin from 1951 to 2003, the precipitation cycles were discussed using the Maximum Entropy Method (MEM), the spatial distribution of the precipitation cycles were analysed, and the possible driving factors of the cycles investigated. The results show that the precipitation in the Yellow River has decadal (60a), inter-decadal (25a and 14a) and inter-annual cycles (9a and 3a). The main oscillations over the whole basin are 3a and 9a. There are clearer inter-decadal variations in the riverhead area with much greater water resources, and north of the region of LanHe main stream. The decadal signals are detected in the inner area with less precipitation and Wei River basin. These differences are possibly related to some physical processes, such as the mutual action of sea and atmosphere, and solar activities.