Evaporation Trends Research Articles

Application of Developing Artificial Intelligence (AI) Techniques to Model Pan Evaporation Trends in Slovak River Sub-Basins

The modeling of pan evaporation (Ep) trends in Slovak river sub-basins was conducted using advanced artificial intelligence (AI) techniques algorithms to accurately calculate evaporation rates based on daily climate data from 2010 to 2023 across eight sub-basins in the Slovak Republic. The AI modeling results reveal that the Bodrog, Hornád, Ipeľ, Morava, Slaná, and Váh river basins are experiencing increases in evaporation, while the Dunaj and Hron rivers show declining trends. This divergence may indicate varying ecological factors influencing the evaporation dynamics of each river. A comprehensive set of 28 machine learning (ML) and deep learning (DL) models was employed, including ML techniques such as linear regression, tree-based, support vector machines (both with and without kernels), ensemble, and Gaussian process methods; as well as DL approaches like neural networks (narrow, medium, wide, bilayered, and trilayered). Among these, stepwise linear regression provided the most optimal fit. The minimum redundancy maximum relevance (mRMR) method was utilized for feature selection to balance relevance and redundancy effectively. The results suggest that emphasizing relative humidity (RH) and minimum temperature (tmin) significantly enhances accuracy, highlighting the critical roles of these factors in modeling pan evaporation trends. The results offer precise evaporation analyses to improve water management and lessen scarcity.

Increasing warm-season evaporation rates across European lakes under climate change

Lakes represent a vital source of freshwater, accounting for 87% of the Earth’s accessible surface freshwater resources and providing a range of ecosystem services, including water for human consumption. As climate change continues to unfold, understanding the potential evaporative water losses from lakes becomes crucial for effective water management strategies. Here we investigate the impacts of climate change on the evaporation rates of 23 European lakes and reservoirs of varying size during the warm season (July–September). To assess the evaporation trends, we employ a 12-member ensemble of model projections, utilizing three one-dimensional process-based lake models. These lake models were driven by bias-corrected climate simulations from four General Circulation Models (GCMs), considering both a historical (1970–2005) and future (2006–2099) period. Our findings reveal a consistent projection of increased warm-season evaporation across all lakes this century, though the magnitude varies depending on specific factors. By the end of this century (2070–2099), we estimate a 21%, 30% and 42% average increase in evaporation rates in the studied European lakes under RCP (Representative Concentration Pathway) 2.6, 6.0 and 8.5, respectively. Moreover, future projections of the relationship between precipitation (P) and evaporation (E) in the studied lakes, suggest that P-E will decrease this century, likely leading to a deficit in the availability of surface water. The projected increases in evaporation rates underscore the significance of adapting strategic management approaches for European lakes to cope with the far-reaching consequences of climate change.

The Evolution of the Hunga Hydration in a Moistening Stratosphere

AbstractThe 2022 Hunga eruption caused unprecedented stratospheric hydration. Aura Microwave Limb Sounder (MLS) measurements show that the stratospheric water vapor mass remains essentially unchanged as of early 2024 and that the Hunga hydration occurred atop a robust (possibly accelerating) moistening trend in the stratosphere. Enhanced by the excess Hunga water vapor, dehydration via polar stratospheric cloud sedimentation in the 2023 Antarctic vortex exceeded climatological values by 50%. Simple projections based on modeled exponential decay illustrate that the timing of the return to humidity levels that would have been expected absent the Hunga hydration depends on the ongoing stratospheric water vapor trend. With the Hunga hydration compounding an underlying moistening trend, the stratosphere could remain anomalously humid for an extended period.

On the effect of the processing parameters in microstructure and thermomechanical properties of LPBF NiTi shape memory alloys

Recent studies have shown that variations in the parameters of the laser powder bed fusion (LPBF) process significantly impact the microstructure and thermomechanical properties of NiTi shape memory alloys (SMAs). Understanding how parameter selection influences the final NiTi SMA properties enables the strategic design of additively manufactured (AM) components with tailored mechanical and transformation behavior, suitable for specific applications in a plethora of scientific fields. However, the connection between processing and thermomechanical properties of NiTi SMAs is still not completely understood. This study investigates the effects of AM parameters laser power (72–185 W), scanning speed (668-1739 mm/s), and hatch spacing (28–85 μm) on a near equiatomic NiTi powder. Low porosity levels are found in the samples additively manufactured (AM) with the different LPBF parameter combinations. The findings also reveal that transformation temperatures and nickel evaporation trends correlate directly with volumetric energy density (VED). Additionally, the amount of Ti2Ni precipitates increases with higher VED. Thermal cycles under constant stress, training, and two-way shape memory effect tests have been performed; the results demonstrate a strain recovery ratio of 2–3.5% for most of the samples. The results arising from this study pave the way for the engineering of customized materials with tailored properties from the same alloy metal powder.

Evolution characteristics and attribution analysis of runoff in the coal mining area in northwest China: A case study of the Kuye River Basin

ABSTRACT The Kuye River Basin is the main coal-producing area in northwest China, and it is also a typical arid and semi-arid area. Under the combined influence of climate change and human activities, the runoff of the basin decreases noticeably. The Mann–Kendall trend test, the Hurst index, cumulative anomaly, and wavelet analysis were used to analyze the runoff evolution characteristics of the Kuye River, and the contributions of climate change and human activities to the runoff reduction were quantitatively separated by the slope-changing ratio of the cumulative quantity. The results showed that the runoff decreased significantly from 1970 to 2020, and there was an obvious abrupt change in 1996, while the change trends in precipitation and evaporation were not significant. The contributions of climate change and human activities to runoff reduction were 22.71 and 77.29%, respectively, and human activities have become the dominant factor in runoff variations. Coal mining and the implementation of soil and water conservation measures are considered to be the main human activities contributing to the reduction in runoff. In particular, mining activities reduce groundwater recharge to rivers, which provides a profound understanding of the effect of human activities in mining areas on runoff variation.

Climate variability and hydrology impacts in east Africa’s Rwenzori Mountains

Study regionThe eastern flank of the 4 km Rwenzori Mountains and the Mobuku catchment 0.25–0.4 N, 29.85–30.1E are the geographic area for detailed analysis. Research focusHydro-climate variability is studied using high resolution satellite- and model- assimilated products in the period 1980–2023. The Mobuku catchment receives rainfall of 3–6 mm/day which generates an eastward discharge of 100 m3/s that declines rapidly downstream, thereby limiting hydro-power availability. New insightsLong-term trends in cloud fraction and potential evaporation reveal a tendency for drying associated with increasing easterly winds, subsidence near the mountain top, and warming of +.04 C/year that is melting glaciers. These constrain runoff on the eastern flank of the Rwenzori Mountains. Low river flows in Dec-Mar correspond with dry air intrusions from the northeast. High river flows in Jul-Nov are modulated by sea temperatures in the Indian Ocean that oscillate east-west at ∼3 year interval. Improved understanding of climate variability will contribute to better management of Uganda’s hydro-power resources.

Trend Analysis of Climatic Variables in the Cross River Basin, Nigeria

There have been several incidences of flood recently, which are believed to be aggravated by increased climatic variables as a result of perceived changes in climatic conditions (due to climate change) in the Cross River Basin. The basin is the most extensively developed and used river basin in the management of the water resources of the Cross River and Akwa Ibom States in Nigeria. In this paper, 30 years (from 1992 to 2021) of hydro-meteorological data (annual average rainfall, maximum and minimum temperatures, hu midity, duration of sunlight (sunshine hours), evaporation, wind speed, soil temperature, cloud cover, solar radiation, and atmospheric pressure) from four stations in the Cross River Basin were obtained from the Nigerian Meteorological Agency (NIMET), Abuja and subjected to trend detection analysis using the Mann–Kendall test to determine the trend in climatic parameters. The results indicate that there is a significant upward trend in annual rainfall in Ogoja but a downward trend in Calabar. The evaporation trend is significantly downward in Eket, whereas in Calabar, there is an upward trend in solar radiation. Generally, there is a significant rise in annual maximum temperature across the basin. Serial correlation and segmented regression analyses were performed to measure the impact of fluctuations in monthly and long-term Tahiti and Darwin’s Sea level pressures on the climatic variables at the Cross River Basin catchment. These analyses were necessary to determine the extent of the influence of the El Nino Southern Oscillation climatic cycle. The analyses show no significant association between the El Niño Southern Oscillation (ENSO) and rainfall or between the ENSO and runoff in the catchment. This implies that the impact of the ENSO on rainfall and runoff in the Cross River Basin catchment is not considerable. The intercepts derived from the segmented regression in Eket and Ogoja show significant positive trends in both areas for rainfall and runoff. The trends in intercepts suggest that there are external factors influencing rainfall and runoff other than ENSO events, thus strengthening the assertion of climate change. Results from this study will facilitate the understanding of the variability in climatic parameters by stakeholders in the basin, researchers, policymakers, and water resource managers.

Orinoco revisited: Comprehensive analysis of the Orinoco River basin present and future hydroclimate

The Orinoco River basin, ranked as South America’s third-largest catchment, is pivotal in contributing to the Atlantic Ocean’s water volume. This study provides a comprehensive update on the basin’s surface water balance, examining trends using gridded precipitation and total evaporation datasets. We also explore projected changes in precipitation until the end of the 21st century, focusing on the RCP8.5 climate change scenario. To achieve this, we utilize data from regional climate models designed by the CORDEX-CORE experiment, selecting an ensemble that excels in performance across South America and Central America. We estimate the accuracy of reference datasets in capturing water balance dynamics. We identify increasing trends in precipitation and total evaporation across most of the basin, enhancing our understanding of its long-term hydrological balance. Notably, the Andean and Guianese sectors of the basin contribute equally to half of the mean surface runoff, although the latter encompasses only 30% of the total area. This underscores the key role of the Guianese shield sub-basins. In regional climate modeling, despite some underestimation, the model runs for the CORDEX South America domain simulate effectively the precipitation across the basin. Regarding climate scenarios, our analysis using the RCP8.5 scenario projects an average annual precipitation reduction of around 45% for the entire basin. These findings emphasize the urgency of adopting measures to mitigate potential adverse effects on the Orinoco River basin’s hydrological sustainability in response to evolving climate patterns.

Evaporation Trends for Elemental Tellurium Recovery in a Te–Cu2S System Produced from a Sustainable Sulfidation-Vacuum Distillation Process

Evaporation Trends for Elemental Tellurium Recovery in a Te–Cu2S System Produced from a Sustainable Sulfidation-Vacuum Distillation Process

Air–sea interactions in stable atmospheric conditions: lessons from the desert semi-enclosed Gulf of Eilat (Aqaba)

Abstract. Accurately quantifying air–sea heat and gas exchange is crucial for comprehending thermoregulation processes and modeling ocean dynamics; these models incorporate bulk formulae for air–sea exchange derived in unstable atmospheric conditions. Therefore, their applicability in stable atmospheric conditions, such as desert-enclosed basins in the Gulf of Eilat/Aqaba (coral refugium), Red Sea, and Persian Gulf, is unclear. We present 2-year eddy covariance results from the Gulf of Eilat, a natural laboratory for studying air–sea interactions in stable atmospheric conditions, which are directly related to ocean dynamics. The measured mean evaporation, 3.22 m yr−1, approximately double that previously estimated by bulk formulae, exceeds the heat flux provided by radiation. Notably, in arid environments, the wind speed seasonal trend drives maximum evaporation in summer, with a minimum winter rate. The higher evaporation rate appears when elevated wind, particularly in the afternoon, coincides with an increase in vapor pressure difference. The inability of the bulk formulae approach to capture the seasonal (opposite from our measurements) and annual trend of evaporation is linked to errors in quantifying the atmospheric boundary layer stability parameter. Most of the year, there is a net cooling effect of surface water (−79 W m−2), primarily through evaporation. The substantial heat deficit is compensated by the advection of heat via northbound currents from the Red Sea, which we indirectly quantify from energy balance considerations. Cold and dry synoptic-scale winds induce extreme heat loss through air–sea fluxes and are correlated with the destabilization of the water column during winter and initiation of vertical water-column mixing.

Stream macroinvertebrate communities in restored and impacted catchments respond differently to climate, land-use, and runoff over a decade

Identifying which environmental drivers underlie degradation and improvements of ecological communities is a fundamental goal of ecology. Achieving this goal is a challenge due to diverse trends in both environmental conditions and ecological communities across regions, and it is constrained by the lack of long-term parallel monitoring of environmental and community data needed to study causal relationships. Here, we identify key environmental drivers using a high-resolution environmental - ecological dataset, an ensemble of the Soil and Water Assessment Tool (SWAT+) model, and ecological models to investigate effects of climate, land-use, and runoff on the decadal trend (2012−2021) of stream macroinvertebrate communities in a restored urban catchment and an impacted catchment with mixed land-uses in Germany. The decadal trends showed decreased precipitation, increased temperature, and reduced anthropogenic land-uses, which led to opposing runoff trends – with decreased runoff in the restored catchment and increased runoff in the impacted catchment. The two catchments also varied in decadal trends of taxonomic and trait composition and metrics. The most significant improvements over time were recorded in communities of the restored catchment sites, which have become wastewater free since 2007 to 2009. Within the restored catchment sites, community metric trends were primarily explained by land-use and evaporation trends, while community composition trends were mostly associated with precipitation and runoff trends. Meanwhile, the communities in the impacted catchment did not undergo significant changes between 2012 and 2021, likely influenced by the effects of prolonged droughts following floods after 2018. The results of our study confirm the significance of restoration and land-use management in fostering long-term improvements in stream communities, while climate change remains a prodigious threat. The coupling of long-term biodiversity monitoring with concurrent sampling of relevant environmental drivers is critical for preventative and restorative management in ecology.

Spatiotemporal variation of the major meteorological elements in an agricultural region: A case study of Linyi City, Northern China

<abstract> <p>Evaporation is a key element of the water and energy cycle and is essential in determining the spatial and temporal variations of meteorological elements. In particular, evaporation is crucial for thoroughly understanding the climate variations of a region. In this study, we discussed evaporation, precipitation, and temperature by adopting Linyi City in Shandong Province, China, which is an important agricultural region, as a research case. Linear regression analysis, the empirical orthogonal decomposition function, and the Morlet wavelet function were used to reveal the trends, spatiotemporal modes, and multi-time scale characteristics of the three climate factors and provide a theoretical basis for the efficient use of climate resources in the future development of regional agriculture. Results showed that the precipitation (2.09 mm/a) and temperature (0.04 ℃/a) in Linyi City exhibited a synchronous growth trend. Conversely, evaporation (−6.47 mm/a) showed a decreasing trend and the evaporation paradox because of the considerable decrease in evaporation energy. Regional development of water-consuming agriculture in consideration of global warming is a key point for improving water use efficiency in Linyi City. In terms of spatial distribution, precipitation was dominated by the first mode wherein low precipitation was observed at the early stage, and high precipitation occurred at the late stage. The first mode was supplemented by the second mode wherein an inverse phase change occurred in the southeast-northwest direction. Large interannual fluctuations were observed only in Yinan County. Temperature exhibited a pattern of warming change with high homogeneity. Evaporation demonstrated obvious heterogeneity and was dominated by two major modes, and the difference in evaporation between Junan County and the other regions of Linyi City was large. Therefore, the local regional climate changes in Yinan and Junan should be given attention. All three meteorological elements showed interannual and interdecadal variations in the short (5 a), medium (16 a), and long (25 a) terms, with precipitation, temperature, and evaporation dominated by 16 a, 24 a, and 31 a, respectively. In the short-term future, the regional precipitation and temperature in Linyi will experience decrements that are above the multiyear average, and evaporation will increase to above the multiyear average. Given the changing trends of precipitation, temperature, and evaporation, urgent requirements for the regional development of efficient water-saving irrigation and the promotion of digital agriculture should be proposed.</p> </abstract>

Multi-decadal variability controls short-term stratospheric water vapor trends

Stratospheric water vapor increases are expected in response to greenhouse gas-forced climate warming, and these changes act as a positive feedback to surface climate. Previous efforts at inferring trends from the 3–4 decade-long observational stratospheric water vapor record have yielded conflicting results. Here we show that a robust multi-decadal variation of water vapor concentrations exists in most parts of the stratosphere based on satellite observations and atmospheric model simulations, which clearly divides the past 40 years into two wet decades (1986–1997; 2010–2020) and one dry decade (1998–2009). This multi-decadal variation, especially pronounced in the lower to middle stratosphere and in the northern hemisphere, is associated with decadal temperature anomalies (±0.2 K) at the cold point tropopause and a hemispheric asymmetry in changes of the Brewer-Dobson circulation modulating methane oxidation. Multi-decadal variability must be taken into account when evaluating stratospheric water vapor trends over recent decades.

Characterizing the tropospheric water vapor spatial variation and trend using 2007–2018 COSMIC radio occultation and ECMWF reanalysis data

Abstract. Atmospheric water vapor plays a crucial role in the global energy balance, hydrological cycle, and climate system. High-quality and consistent water vapor data from different sources are vital for weather prediction and climate research. This study assesses the consistency between the Formosa Satellite Mission 3–Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC) radio occultation (RO) and European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis Model 5 (ERA5) water vapor datasets. Comparisons are made across different atmospheric pressure levels (300, 500, and 850 hPa) from 2007 to 2018. Generally, the two datasets show good spatial and temporal agreement. COSMIC's global water vapor retrieval is slightly lower than ERA5's at 500 and 850 hPa, with distinct latitudinal differences between hemispheres. COSMIC exhibits global water vapor increasing trends of 3.47 ± 1.77 % per decade, 3.25 ± 1.25 % per decade, and 2.03 ± 0.65 % per decade at 300, 500, and 850 hPa, respectively. Significant regional variability in water vapor trends, encompassing notable increasing and decreasing patterns, is observable in tropical and subtropical regions. At 500 and 850 hPa, strong water vapor increasing trends are noted in the equatorial Pacific Ocean and the Laccadive Sea, while decreasing trends are evident in the Indo-Pacific Ocean region and the Arabian Sea. Over land, substantial increasing trends at 850 hPa are observed in the southern United States, contrasting with decreasing trends in southern Africa and Australia. The differences between the water vapor trends of COSMIC and ERA5 are primarily negative in the tropical regions at 850 hPa. However, the water vapor increasing trends at 850 hPa estimated from COSMIC are significantly higher than the ones derived from ERA5 data for two low-height stratocumulus-cloud-rich ocean regions west of Africa and South America. These regions with notable water vapor trend differences are located in the Intertropical Convergence Zone (ITCZ) area with frequent occurrences of convection, such as deep clouds. The difference in characterizing water vapor distribution between RO and ERA5 in deep cloud regions may cause such trend differences. The assessment of spatiotemporal variability in RO-derived water vapor and reanalysis of atmospheric water vapor data helps ensure the quality of these datasets for climate studies.

Changes in the Global Water Exchange by the Results of Historical Experiments on Climate Models under CMIP-6 Project

Long-term (up to 165 years) series of globally averaged values of the main water exchange components, obtained as the result of historic experiments on several dozen (from 34 to 41) climate models of CMIP-6 project, are analyzed. The examined characteristics include variations of evaporation from ocean surface, precipitation over the ocean, effective evaporation from the ocean (total horizontal moisture transfer in the atmosphere from the ocean to land), and total model river runoff from the continents. It is shown that the model precipitation over the ocean effectively filters out the monotonic positive trend in evaporation from the ocean and, therefore, increases the stationarity of the total chain of global water exchange, including long-term changes in the global river runoff.

Observed decreasing trend in pan evaporation in a tropical rainforest region during 1959–2021

Abstract Pan evaporation (Epan) is a critical measure of the atmospheric evaporation demand. Analyzing meteorological data from the Tropical Rainforest Comprehensive Meteorological Observation Field in the Xishuangbanna Tropical Botanical Garden (XTBG Meteorological Observing Station) based on physical models is helpful to improve our understanding of the state of the hydrological cycle in the Xishuangbanna tropical rainforest region. In this study, we investigated the long-term trend in Epan using the observation data from 1959 to 2021. Moreover, correlation analyses of Epan were performed, such as trend test, assessment of periodic properties and abrupt change analysis. Then, D20 Epan data and related meteorological data from 1979 to 2008 were used to drive Penman‒Monteith and PenPan models for simulating Epan. The partial derivative attribution method was used to analyze the dominant factors affecting Epan. The results showed that Epan exhibits obvious periodic changes, the 19a is the first primary period. In addition, there was a clear ‘evaporation paradox’ phenomenon in Xishuangbanna. Epan showed a decreasing trend during both 1959–2008 and 2009–2018, and the decreasing trend reached a significant level with a rate of −3.404 mm·a−2 during 1959–2008. Through comparative analysis, the PenPan model was considered more suitable for simulating Epan in Xishuangbanna. In order to identify the main meteorological factors influencing Epan, complete data from the D20 pan monitoring period, namely, 1979–2008, were selected for attribution calculations. The variations in the net radiation and saturated vapor pressure deficit are the main triggers that explain the ‘evaporation paradox’ phenomenon in Xishuangbanna.

Current Climatic Trends in Evaporation and Soil Moisture Changes in the South of European Russia

Current Climatic Trends in Evaporation and Soil Moisture Changes in the South of European Russia

Current and future water balance of a mountain subcatchment of Issyk-Kul Lake, Tien Shan range, Kyrgyzstan

Snow and ice dominated basins are particularly vulnerable to climate change but estimating their hydrological balance remains challenging in data-scarce regions like the Tien Shan mountains. With the overall aim of modeling of the large Issyk-Kul Lake basin in Kyrgyzstan, this article focuses on the hydrological balance of the Chon Kyzyl-Suu basin, a representative sub-catchment of the lake basin. The study involved two steps: first, calibration/validation of a distributed hydrological snow model, second, assessment of future trends in runoff, evaporation, snow melt and glacier melt under different climate scenarios. Our results show that the balance of the basin is already upset due to glacier mass loss and that groundwater processes play a significant role in generating discharge. Climate projections for the next 40 years (2020–2060) show no significant trend in precipitation under scenario ssp2–4.5 but an 8.9 % decrease in precipitation under scenario ssp5–8.5. at the same time, air temperature will increase by 0.4 °C under scenario ssp2–4.5, and by 1.8 °C under scenario ssp5–8.5. Under the “business as usual” scenario (ssp2–4.5), the annual river flow of the headwater basins should increase by 13 %, or under the “pessimistic” ssp5–8.5 scenario, by 28 %, mainly due to the increase in glacier runoff. These results make it possible to envisage realistic modeling at the scale of the lake at a daily time step.

Moisture sources for precipitation variability over the Arabian Peninsula

We apply the Lagrangian-based moisture back trajectory method to two reanalysis datasets to determine the moisture sources for wet season precipitation over the Arabian Peninsula, defined as land on the Asian continent to the south of the Turkish border and west of Iran. To accomplish this, we make use of the evaporative source region between 65°W–120°E and 30°S–60°N, which is divided into twelve sub-regions. Our comparison of reanalyses and multiple observations allows us to validate datasets and highlight broad-scale similarities in characteristics, notwithstanding some inconsistencies in the southwest AP. The results indicate north-to-south spatiotemporal heterogeneity in the characteristics of dominant moisture sources. In the north, moisture for precipitation is mainly sourced from midlatitude land and water bodies, such as the Mediterranean and Caspian Seas. Areas further south are dependent on moisture transport from the Western Indian Ocean and parts of the African continent. The El Niño-Southern Oscillation (ENSO) exhibits an overall positive but sub-seasonally varying influence on the precipitation variability over the region, with noticeable moisture anomalies from all major source regions. A significant drying trend exists over parts of the Peninsula, which both reanalyses partially attribute to anomalies in the moisture advection from the Congo Basin and South Atlantic Ocean. However, considerable uncertainty in evaporation trends over the terrestrial evaporative sources in observations warrants additional modeling studies to further our understanding of key processes contributing to the negative trends.

Deriving a high-quality daily dataset of large-pan evaporation over China using a hybrid model

Global warming is expected to increase the atmospheric evaporative demand and make more surface water for evapotranspiration, aggerating water sources' social and ecological shortage. Pan evaporation, as a routine observation worldwide, is an excellent metric to indicate the response of terrestrial evaporation to global warming. However, several non-climatic effects, such as instrument upgrades, have destroyed the homogenization of pan evaporation and limited its applications. In China, 2400s meteorological stations have observed daily pan evaporation since 1951. The observed records became discontinuous and inconsistent due to the instrument upgrade from micro-pan D20 to large-pan E601. Here, combining the Penpan model (PM) and random forest model (RFM), we developed a hybrid model to assimilate different types of pan evaporation into a consistent dataset. Based on the cross-validation test, on a daily scale, the hybrid model has a lower bias (RMSE=0.41 mm day−1) and better stability (NSE=0.94) than the two sub-models and the conversion coefficient method. Finally, we produced a homogenized daily dataset of E601 across China from 1961 to 2018. Based on this dataset, we analyzed the long-term trend of pan evaporation. Pan evaporation showed a -1.23±0.57 mm a−2 downward trend from 1961-1993, primarily caused by decreased pan evaporation in warm seasons over North China. After 1993, the pan evaporation in South China increased significantly, resulting in a 1.83±0.87 mm a−2 upward trend across China. With better homogeneity and higher temporal resolution, the new dataset is expected to promote drought monitoring, hydrological modeling, and water resources management. Free access to the dataset can be found at https://figshare.com/s/0cdbd6b1dbf1e22d757e.