Changes In Precipitation Research Articles

Contribution of soil microbial necromass carbon to soil organic carbon in grassland under precipitation change and its influencing factors in loess hilly region, Northwest China.

To investigate the contribution of microbial necromass carbon (MNC) to soil organic carbon (SOC) and its influencing factors under precipitation changes in grassland, we conducted a precipitation experiment with seven different precipitation levels in the Bothriochloa ischaemum restoration area in the loess hilly region. We analyzed the contents and characteristics of fungal necromass carbon (FNC), bacterial necromass carbon (BNC), and MNC in different fractions of SOC under different treatments, including natural precipitation (CK), and increased and decreased 20%, 40%, 60% of natural precipitation (I20, I40, I60, D20, D40, D60) . The results showed that 1) MNC content in mineral organic carbon (MAOC) ranged from 1.62 g·kg-1 to 2.17 g·kg-1, which was higher than that in particulate organic carbon (POC) ranging from 0.69 g·kg-1 to 1.31 g·kg-1. The former was approximately 1.4 to 2.8 times as that of the latter. 2) FNC and MNC exhibited similar changes in both MAOC and POC fractions. BNC content in MAOC was approximately 1-3.1 times as that of FNC. FNC content in POC was generally higher than BNC except for I40 and I60 where BNC exceeded FNC. 3) Overall, both increases and decreases in precipitation resulted in elevated MNC/MAOC and BNC/MAOC ratios, but decreased MNC/POC and FNC/POC ratios. The MNC/MAOC ratios in I60 and D60 were 33.2% and 18.1% higher than CK, respectively. The BNC/MAOC ratios in D60, I40 and I60 were 28.0%, 23.0% and 19.1% higher than those in CK, respectively. Except for D60, the FNC/POC and MNC/POC ratios were significantly lower than CK under other treatments. In terms of POC fractions, the MNC/POC ratios of D40, D20, I20, I40 and I60 were 28.4%, 23.3%, 28.8%, 23.3% and 32.2% lower than that of CK, respectively. The FNC/POC ratio of D40, D20, I20, I40 and I60 was found to be lower by 23.3%, 16.1%, 21.0%, 27.0% and 31.0% compared to that of CK, respectively. 4) NH4+-N and pH were the primary factors influencing the content of MNC in different carbon fractions under varying precipitation conditions. In summary, alterations in precipitation (either increase or decrease) enhanced the contribution of BNC-dominated MNC to MAOC, but reduced the contribution of FNC-dominated MNC to POC. This study was of significance for understanding the distribution of microbial necromass across different organic carbon fractions under precipitation alterations.

Spatiotemporal variation of modern lake, stream, and soil water isotopes in Iceland

Abstract. As global warming progresses, changes in high-latitude precipitation are expected to impart long-lasting impacts on Earth systems, including glacier mass balance and ecosystem structures. Reconstructing past changes in high-latitude precipitation and hydroclimate from networks of continuous lake records offers one way to improve forecasts of precipitation and precipitation–evaporation balances, but these reconstructions are currently hindered by the incomplete understanding of controls on lake and soil water isotopes. Here, we study the distribution of modern water isotopes in Icelandic lakes, streams, and surface soils collected in 2002, 2003, 2004, 2014, 2019, and 2020 to understand the geographic, geomorphic, and environmental controls on their regional and interannual variability. We find that lake water isotopes in open-basin (through-flowing) lakes reflect local precipitation, with biases toward the cold season, particularly in lakes with sub-annual residence times. Closed-basin lakes have water isotope and deuterium excess values consistent with evaporative enrichment. Interannual and seasonal variabilities of lake water isotopes at repeatedly sampled sites are consistent with instrumental records of winter snowfall; summer relative humidity; and atmospheric circulation patterns, such as the North Atlantic Oscillation. Summer surface soil water isotopes span the entire range of seasonal precipitation values in Iceland and appear to be consistently overprinted by evaporative enrichment, which can occur throughout the year, although the sampling depths were shallower than rooting depths for many plant types. This dataset provides new insight into the functionality of water isotopes in Icelandic environments and offers renewed possibilities for optimized site selection and proxy interpretation in future paleohydrological studies on this North Atlantic outpost.

Spatially varying effect of soil moisture-atmosphere feedback on spring streamflow under future warming in China

Soil moisture–atmosphere feedback (SAF) is expected to accelerate warming in the future, but its influences on the terrestrial water cycle over non-traditional hotspots of land–atmosphere coupling (e.g., East Asia) remains elusive due to strong heterogeneity and uncertainties at model grid scales. Here we show robust evidence of the integral effects of SAF on streamflow under future warming across major river basins in China. Based on high-resolution hydrological modelings driven by CMIP6 simulations with/without land–atmosphere coupling, SAF is projected to significantly increase spring streamflow by 28–58% in mid-latitude China, but decrease it by 12–48% in other regions. Such contrary effects are attributed to the soil moisture-precipitation interaction, which causes spatially opposite changes in precipitation through thermodynamic (e.g., ascending/descending vertical motions) and thermal (e.g., weakened meridional water vapor transport) atmospheric adjustments. Our result highlights the importance of SAF in altering freshwater resources even in locations not typically considered to be SAF hotspots.

Monitoring the Net Primary Productivity of Togo’s Ecosystems in Relation to Changes in Precipitation and Temperature

Climate variability significantly impacts plant growth, making it crucial to monitor ecosystem performance for optimal carbon sequestration, especially in the context of rising atmospheric CO2 levels. Net Primary Productivity (NPP), which measures the net carbon flux between the atmosphere and plants, serves as a key indicator. This study uses the CASA (Carnegie–Ames–Stanford Approach) model, a radiation use efficiency method, to assess the spatio-temporal dynamics of NPP in Togo from 1987 to 2022 and its climatic drivers. The average annual NPP over 36 years is 4565.31 Kg C ha−1, with notable extremes in 2017 (6312.26 Kg C ha−1) and 1996 (3394.29 Kg C ha−1). Productivity in natural formations increased between 2000 and 2022. While climate change and land use negatively affect Total Production (PT) from 2000 to 2022, they individually enhance NPP variation (58.28% and 188.63%, respectively). NPP shows a strong positive correlation with light use efficiency (r2 = 0.75) and a moderate one with actual evapotranspiration (r2 = 0.43). Precipitation and potential evapotranspiration have weaker correlations (r2 = 0.20; 0.10), and temperature shows almost none (r2 = 0.05). These findings contribute to understanding ecosystem performance, supporting Togo’s climate commitments.

The LGM termination in the southeastern Tibetan plateau: View from high-frequency LGM glacier fluctuations in the Boshula mountain range

Climate processes that operated during the end of the Last Glacial Maximum (LGM) are remarkable for its global synchroneity. Atmospheric CO2 concentrations have been widely seen as its cause. However, the stepwise LGM deglaciation of mountain glaciers in both hemispheres complicates this view, and signifies additional factors that likely prompted the onset of LGM termination. Here, we examine LGM climate change in the Hengduan Mountains (HDM), southeastern Tibetan Plateau (TP), based on 10Be surface exposure dating of moraine boulders (n = 51). The timing of four moraine-building events is constrained to 22.8 ± 1.0 ka, 21.2 ± 0.6 ka, 20.4 ± 0.6 ka, and 19.2 ± 0.6 ka. These precisely-dated events provide convincing evidence of millennial-to centennial-scale glacial activities in the TP during the LGM. We show that these high-frequency glacier fluctuations likely reacted to a combination of changes in regional summer temperature related to sea surface temperatures as well as monsoon precipitation. The pronounced glacial retreat is dated at 19.2 ± 0.6 ka, representing the end of the LGM in the HDM. That is, the onset of LGM termination preceded the rapid CO2 rise at ∼18 ka. We suggest that the LGM termination in the southeastern TP was initiated by ice-sheet shrinkage, which induced changes in summer temperature and monsoon precipitation via ocean-atmosphere interactions.

Effects of precipitation changes and warming on vegetation–soil–microbial relationships in desert grasslands

Vegetation–soil–microbial relationships significantly affect global climatic and environmental changes. Fluctuations in temperature and precipitation caused by climate change are the driving forces of dynamic changes in vegetation–soil–microbial relationships. Our study was conducted in the desert grassland of Ningxia, China, and involved five levels of annual precipitation (33 % (R33), 66 % (R66), 100 % (RCK), 133 % (R133), and 166 % (R166)) and two temperature levels (within and outside the open-top chamber). Our objective was to determine how vegetation–soil–microbial relationships in desert grasslands respond to changes in precipitation and warming. Our results showed that precipitation was positively correlated with above-ground living and root biomass, and soil organic carbon. R166 had the strongest effect on the correlation between vegetation, soil, and microbes, whereas R33 had the weakest effect. Temperature was positively correlated with soil microbial α-diversity, and the effect of warming on the correlation among vegetation, soil, and microbes was less significant than under natural temperature. The combination of precipitation and warming was positively correlated with the above-ground living biomass and soil respiration. The correlation effects of the combination of precipitation and warming on vegetation, soil, and microbes were more substantial than those of precipitation and warming. Our findings provide a theoretical basis for the formulation of reasonable response strategies for desert steppe ecosystems.

Dominant Role of Eurasian Evaporation on the Moisture Sources of the Interannual Variations in Central Asian Summer Precipitation

Abstract The precipitation changes in arid and semiarid central Asia have great impacts on the local fragile ecosystem. The summer precipitation in central Asia shows obvious interannual variations, but the corresponding crucial moisture transporting processes remain unclear. Therefore, this study employs the Lagrangian flexible particle (FLEXPART) diffusion model to achieve this goal. Results show that the moisture of climatological summer precipitation in central Asia is mainly from the local regions, the surrounding western and northern Eurasian regions. The contribution of local evaporation from western central Asia is about 2 times that from eastern central Asia. At the interannual time scale, the moisture variations are mainly influenced by the local regions and western Eurasia, while the local evaporation is mainly from western central Asia. Totally, the Eurasian evaporation plays a dominant role in the interannual variations of central Asian summer precipitation by contributing more than 90% of the total moisture. The moisture transports associated with central Asian summer precipitation interannual variations are impacted by the anomalous cyclones over the western and northeastern parts of central Asia during the wet years, which enhance the moisture convergence and hence increase the summer precipitation in central Asia. The anomalous cyclone over the western part of central Asia is correlated with the changes in the intensity of Eurasian summer subtropical westerly jet (ESSWJ), while the anomalous cyclone over the northeastern part of central Asia is correlated with both ESSWJ and the British–Baikal Corridor pattern teleconnection in association with the polar front jet.

Understanding Observed Precipitation Change and the New Climate Normal from the Perspective of Daily Weather Types in the Southeast United States

Abstract Observed precipitation changes in the Southeast United States (SEUS) are spatially heterogeneous. Most of the inland SEUS and eastern Gulf Coast become drier, and the East Coast north of Charleston, South Carolina, and southern Florida become wetter from the old 30-yr period of 1961–90 to the recent period of 1991–2020. The observed climate change is examined from the perspective of daily weather types (WTs). A k-means clustering analysis has been conducted using daily 850-hPa circulation for 1948–2021. The obtained 10 WTs peak in different seasons, respectively. The frequencies and precipitation intensity of the WTs have been analyzed. A winter WT characterized by a western Appalachian trough (WAT) and a summer WT featuring North Atlantic subtropical high (NASH) have a rising trend of annual frequency from 1948 to 2021. An Appalachian high in the autumn has a decreasing frequency but becomes drier and stronger. Some precipitation intensity change and small location shift have also been observed. The drying up on the eastern Gulf Coast and the inland area of the SEUS is mainly caused by the weakened southwesterly low-level jet (LLJ) on the western flank of the NASH that reduces rain in the spring, the less frequent but stronger and drier Appalachian high in the summer and autumn, and the weaker and more western located Plains trough (PT) in the winter, spring, and autumn. The precipitation increase in the East Coast and southern Florida is majorly due to more frequent, stronger, and rainier troughs along the western Appalachian as well as the East Coast.

Spatial heterogeneity in the potential distribution of Aedes mosquitoes in India under current and future climatic scenarios

Aedes is the most globally distributed mosquito genus in the 21st century and transmits various arboviral diseases. The rapid expansion of Ae. Aegypti and Ae. albopictus breeding habitats is a significant threat to global public health, driven by temperature and precipitation changes. In this study, bioclimatic variables were employed to predict the spatial distribution of Ae. aegypti and Ae. albopictus in India. The reference coordinate points of (n = 583) Aedes occurrences at a scale of ∼1 km and nineteen bioclimatic factors were retrieved to train SDM (Species Distribution Models) for both species. Maximum entropy modelling was used to predict the species’ fundamental climatic niche distributions. Future projections were made using global climate models for 2021–2040 and 2081–2100 separately. The models performed reasonably well (AUC > 0.77). Both species thrived in reduced diurnal temperature and higher annual mean temperatures, with suitability increasing alongside precipitation. Ae. aegypti’s projected present and future distribution was broader than that of Ae. Albopictus. The expansion of Aedes suitability varied under different future climatic scenarios. Suitability for Ae. aegypti could expand from between 17.6 and 41.1 % in 2100 under SSP (shared socioeconomic pathways) scenarios 1 and 3, respectively, whereas for Ae. albopictus suitability increased from between 10.2 and 25 % under SSP scenarios 1 and 3 respectively. Preparing for future epidemics and outbreaks requires robust vector distribution models to identify high-risk areas, allocate resources for surveillance and control, and implement prevention strategies.

Vulnerability to extreme weather events: mapping future hazards in Wielkopolska region, Poland

The aim of this study is to assess future hazards due to extreme meteorological events in the Wielkopolska region, Poland, based on five climate model projections and three scenarios: SSP126, 370, and 585. The paper analyzes the changes of mean and extreme precipitation, mean and extreme temperatures, and humidity index, as well as changes in difference between maximum temperatures observed from day to day and changes in difference between mean atmospheric pressure at the sea level observed from day to day. Additionally, we look at possible future occurrence of wildfires due to changes in fire weather conditions. Based on climate model projections, future hazard due to extreme meteorological events in Wielkopolska region is to be more serious and will be most noticeable in the end of twenty-first century and for two higher scenarios: SSP370 and SSP585. For near future, 2021–2050, projected conditions of meteorological extremes for analyzed scenarios are quite consistent. Therefore, there is a strong need for implementing adaptation actions. Nevertheless, such activities are so far lacking, and several adaptation options are not present in local and national legislation, even though they are recognized as effective.

Mapping ecoregional vulnerability to climate change for Africa

African ecosystems are expected to be significantly affected by climate change, making it crucial to understand these changes for effective management. We provide a framework and application to assess ecoregional vulnerability to climate change, considering environmental exposure, sensitivity, and adaptive capacity. We assessed environmental exposure using projections for consecutive dry days, precipitation, and temperature changes. Sensitivity was determined based on forest fragmentation and grassland degradation. Adaptive capacity was represented by protected areas network and biodiversity intactness. These factors were combined to create overall vulnerability index and specific categories to guide management decisions. Under the SSP5 8.5 scenario, 16 % of ecoregions will be highly impacted by 2050, with vulnerable areas emerging in Montane forest-grassland and flooded savanna. Impacted ecoregions are disproportionately biodiverse. By intersecting the likely climate impacts and adaptive capacity, we highlight where conservation actions are needed to enhance the resilience of ecoregions to climate change.

Coupled adsorption/precipitation (Γ/Π) modelling of scale inhibitor transport in porous media using the coupled isotherm, AΓΠ(c)

Scale inhibitor (SI) “squeeze” treatments are widely used operations in production assurance to prevent inorganic scales as one of the main flow assurance problems. In these treatments, a high concentration SI slug is injected (“squeezed”) into the porous medium, retained in the formation rock, and is gradually produced back at relatively small concentrations that can prevent (or significantly reduce) scale formation. The retention of SI in the formation is governed by coupled mechanisms of adsorption (Γ) and precipitation (Π) of SI species in the system. To design such SI treatments in an optimized manner, it is important to have good mathematical models of both the transport and the coupled interactions of adsorption/precipitation (Γ/Π) processes. In this study, a 1D advection-dispersion-reaction transport model has been developed, considering the coupled Γ/Π retention processes, and it is used to model linear core flood systems. The parameters for the equilibrium Γ/Π model can be derived from the routine bulk SI “apparent adsorption” tests that are usually conducted before any treatments. From previous works, equilibrium adsorption isotherm, Γ(c), is used to describe the adsorption behavior in such systems. However, although the precipitation kinetics are “fast” (almost at equilibrium), the kinetics of SI dissolution are “slow” and is therefore modelled by a kinetic rate law. From the derived dimensionless form of the transport-Γ/Π model equations, it is shown that the system is governed by 4 dimensionless numbers, NA, NP, NPe and NDa, which are the adsorption number, the precipitation number, the Peclet number, and the Damköhler number, respectively. The shape of the adsorption isotherm also plays a very important part in the extent and form of the effluent SI returns from the linear system. The developed model was then employed to carry out a series of sensitivity calculations relating to coupled adsorption/precipitation (Γ/Π) processes. Both equilibrium and kinetic SI precipitation were modelled coupled with the equilibrium SI adsorption, and the effect of these processes on the form and extent of the SI effluents was assessed. A range of sensitivities was then carried out to determine the effect of a wide range of parameters, including the effects of flow rate and shut-in periods on the kinetic dissolution effluent behavior. The findings from this work present the most clear explanation to date of why and how “precipitation squeezes” can greatly extend squeeze lifetime. A novel feature of this analysis is to show how the role of precipitation and adsorption changes over the various stages of the return effluent by developing plots of the %SI adsorbed on the rock, in the precipitate, and the mobile fluid phase.

Spatiotemporal evolution of dry and wet and quantitative analysis of the influence of meteorological factors based on MI and the FAO P–M model

The frequent occurrence of extreme climate events disrupts the regional water budget balance and leads to changes in the dry and wet conditions of the surface, making the water surplus and deficit more complex and variable. To explore the quantitative relationship between the spatiotemporal evolution of dry and wet conditions and meteorological factors in the Hexi Corridor under changing environmental conditions, the relative moisture index (MI) and FAO Penman–Monteith (FAO P–M) model were combined to construct a partial differential quantitative attribution model for dry and wet variations affected by climate factors in the Hexi Corridor. The results show that: (1) MI in the Hexi Corridor increased significantly (Z = 2.341) during 1960–2019, showing a wet-trend change, and the degree of drought increased from southeast to northwest in the Hexi Corridor. (2) The order of drought degree in four seasons is as follows: winter (− 0.95), spring (− 0.93), autumn (− 0.89) and summer (− 0.83). (3) The frequency of extreme drought, severe drought, moderate drought, and mild drought within 60 years of 21 meteorological stations accounted for 28.38%, 50.48%, 8.85%, and 7.38%, respectively, and the frequency above severe drought was the highest. (4) The sensitivity of meteorological factors gradually increased from northwest to southeast, and MI was the most sensitive to the change of precipitation (P), followed by net radiation (Rn), wind speed (u2), mean temperature (Tmean), relative humidity (RH) and maximum temperature (Tmax). MI was the least sensitive to the change of minimum temperature (Tmin). P is the most important meteorological variable that contributes to the increase of MI, followed by u2, Tmean, and Tmin. Rn, Tmax, and RH have the least influence, and the total contribution of the seven meteorological factors is 85.59%. Compared with the reference evapotranspiration, P is the main factor affecting the dry and wet variations in Hexi Corridor.

The Yangtze River Delta experienced strong seasonality and regular summer upwelling during the warm mid-Holocene

The mid-Holocene climate optimum saw warm temperatures in large parts of China, but its impact on seasonal environmental changes is not fully understood yet. Here, we use high-resolution geochemical analyses of 7000 to 6000 year-old oyster shells from the Yangtze River Delta to reconstruct climatic and oceanographic patterns. The stable isotope (δ18O, δ13C) and clumped isotope data reflect prominent seasonal changes in temperature, precipitation, and river discharge. Summer months experienced warm temperatures and a distinct increase in rainfalls and river discharge. In contrast, winter months were characterized by a dry season, which might have been longer than today. Stable isotope data also indicate regular summer upwelling in the study area. These results partly disagree with available climate models raising doubts on the models’ reliability. Thus, our palaeo-proxy data offers the possibility to evaluate and correct climate models and thereby improve predictions for the future considering on-going global warming.

Spatial and Temporal Variations of Climate Resources during the Growing Season of Early-Season Rice in Hunan Province

The rising temperatures and changes in precipitation due to climate change have significantly impacted agricultural production. Evaluating the effects of climate change on rice production is crucial for improving rice cultivation techniques and ensuring food security. It is essential to comprehensively examine the climatic, spatial, and temporal variations during the duration of crop production. Previous research has mainly focused on different rice planting areas, rice types, and various growth stages of rice. However, more research is needed on the climatic changes during the crop-growing season in specific regions. Therefore, this study compiled complete daily meteorological data from 37 meteorological stations in Hunan Province from 1961 to 2020. The period from 1961 to 2020 was divided into three segments: 1961–1980 (a), 1981–2000 (b), and 2001–2020 (c), to analyze the characteristics of agricultural climate resource changes during different growth stages of early-season rice in Hunan Province. Results show that the heat resources were significantly increased (accumulated temperature growth rate of 43.36 °C/10a), the sunshine resources were decreased by −14.60 h/10a, and the precipitation resources were slightly increased by 6.85 mm/10a. The increase in heat resources mainly occurs during the vegetative growth stage of early-season rice. Additionally, the high-value regions of heat resources and precipitation in period c are 97.8% and 34.2% higher than the average values of periods a and b, respectively. In contrast, the regions with high sunshine hours significantly decreased in period c compared to periods a and b. In summary, the heat, sunshine, and water resources in the central and eastern regions of Hunan Province increase simultaneously, and appropriate cultivation measures should be adopted in the future to improve the yield and resource utilization efficiency of early-season rice in a double-cropping system.

Plant functional trait is a strong predictor of ecosystem productivity under altered precipitation in desert steppes

AbstractThe relationship between biodiversity and ecosystem function has always been one of the hot issues in the field of ecology. With the acceleration of global warming, the precipitation pattern has become one of the main drivers of biodiversity loss, which has a profound impact on ecosystem functional services and stability. However, the studies on the effects and mechanisms of plant community diversity and ecosystem productivity under precipitation changes in desert steppe are still unclear. According to the change rate (−41.1% to 39.2%) of precipitation in the study area in recent 50 years, five precipitation gradients (i.e., −40%, −20%, CK, +20% and +40%) were set to simulate the possible future precipitation pattern changes. Aboveground biomass increased with the increase of precipitation. Compared with CK, the aboveground biomass increased by 22.81% with +40% and decreased by 80.71% with −40%, and the negative impact of precipitation decrease on aboveground biomass was more significant. Through multiple stepwise regression analyses, species diversity, functional diversity and phylogenetic diversity were identified as the best models of aboveground biomass. The results showed that the aboveground biomass changes could be explained by 51.3%, 81.6%, 32.6% and 60% respectively. Combined with plant community diversity, the final index model was obtained through multiple stepwise regression analyses, which could explain 88.3% of changes in aboveground biomass. In this model, The average coefficient of specific leaf area and leaf thickness had a very high significance level, and these two functional traits of dominant species had a greater explanatory power for ecosystem system function. There was a nonlinear correlation between precipitation and aboveground biomass, and drought had a more significant negative effect on aboveground biomass. Compared with species diversity and phylogenetic diversity, plant functional traits can better explain ecosystem productivity. Selection effects are the main maintenance mechanism of desert steppe community productivity under the background of precipitation change.

Global and regional hydrological impacts of global forest expansion

Abstract. Large-scale reforestation, afforestation, and forest restoration schemes have gained global support as climate change mitigation strategies due to their significant carbon dioxide removal (CDR) potential. However, there has been limited research into the unintended consequences of forestation from a biophysical perspective. In the Community Earth System Model version 2 (CESM2), we apply a global forestation scenario, within a Paris Agreement-compatible warming scenario, to investigate the land surface and hydroclimate response. Compared to a control scenario where land use is fixed to present-day levels, the forestation scenario is up to 2 °C cooler at low latitudes by 2100, driven by a 10 % increase in evaporative cooling in forested areas. However, afforested areas where grassland or shrubland are replaced lead to a doubling of plant water demand in some tropical regions, causing significant decreases in soil moisture (∼ 5 % globally, 5 %–10 % regionally) and water availability (∼ 10 % globally, 10 %–15 % regionally) in regions with increased forest cover. While there are some increases in low cloud and seasonal precipitation over the expanded tropical forests, with enhanced negative cloud radiative forcing, the impacts on large-scale precipitation and atmospheric circulation are limited. This contrasts with the precipitation response to simulated large-scale deforestation found in previous studies. The forestation scenario demonstrates local cooling benefits without major disruption to global hydrodynamics beyond those already projected to result from climate change, in addition to the cooling associated with CDR. However, the water demands of extensive forestation, especially afforestation, have implications for its viability, given the uncertainty in future precipitation changes.

INVESTIGATION OF THE EFFECT OF ANNUAL AVERAGE TEMPERATURE AND PRECIPITATION CHANGES ON CORS-TR STATIONS: THE CASE OF KSTM STATION

In this study, the effects of meteorological changes on the point positioning of CORS-TR stations were investigated. For this purpose, KURU, SINP, BOYT, CORU, CANK, CMLD, KRBK, KSTM stations were selected. The KSTM station was taken as unknown and adjusted based on other stations. Seasonal normal values of KSTM station in Kastamonu province covering the years 2016-2020 were examined in terms of temperature and precipitation amount. These values were determined according to the minimum, maximum and average value criteria by using Türkiye State Meteorological Service data. For the calculations, IGS-standardized RINEX data of the stations for 5 years and 12 months between 2016 and 2020 and for 10 days on the 11th and 20th days of each month were used. All calculations were processed with Leica Geo Office v8.x. The calculated coordinates were compared with the current coordinates of CORS-TR at the same epoch and examined according to annual temperature and precipitation. In the analyzes, it was tested by statistical method whether all measurements were compatible. When it was examined whether the temperature changes were statistically significant, it was observed that the test values were calculated according to the temperature changes were below the test distribution limit at 95% confidence interval. When it was examined whether the precipitation changes were statistically significant, it was observed that the test values were calculated according to the precipitation changes were below the test distribution limit at 95% confidence interval.

Projection of precipitation under RCP4.5 and RCP 8.5 in central and southern regions of Iraq

Climate change has significant impacts on natural systems, especially in terms of altering hydrological patterns due to changing precipitation and melting snow and ice. This study examines projected changes in precipitation for central and southern Iraq under the RCP4.5 and RCP8.5 scenarios for the periods 2046–2065 and 2081–2100 using CMIP5 climate model HadGEM2-AO output. The results revealed that under RCP4.5, there was large spatial variation in the projected precipitation over the region during 2064-2065, ranging from as low as 27 mm in western part to as high as 1541 mm in the eastern part. The spatial variability as well as precipitation amount decreased considerably during 2081-2100 periods. Under RCP8.5 the projected precipitation was only 14-164 mm in 2046-2065 and 36-532 mm in 2081-2100 periods. Thus, under RCP8.5 scenario anticipated precipitation will be quite low.

Intra-growing season dry-wet spell pattern is a pivotal driver of maize yield variability in sub-Saharan Africa.

Climate variability plays a crucial role in the annual fluctuations of crop yields, posing a substantial threat to food security. Maize, the main cereal in sub-Saharan Africa, has shown varied yield trends during increasingly warmer growing seasons. Here we explore how sub-seasonal dry-wet spell patterns contribute to this variability, considering the spatial heterogeneity of crop responses, to map weather-related risks at a regional level. Our results show that shifts in specific dry-wet spell patterns across growth stages influence maize yield fluctuations in sub-Saharan Africa, explaining up to 50-60% of the interannual variation, which doubles that explained by mean changes in precipitation and temperature (30-35%). Precipitation primarily drives the onset of dry spells, while the influence of temperature increases with event intensity and peaks at the start of the growing season. Our large-scale, data-limited analysis approach has the potential to inform climate-smart agriculture in developing regions.