Trends In Water Vapor Research Articles

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.

Using the NAMA as a Natural Integrator to Quantify the Convective Contribution to Lower Stratospheric Water Vapor Over North America

AbstractThe dynamical environment of the stratosphere, during the summer over North America, provides a natural integrator of the impact of convection in the lower stratosphere, as air can be confined for periods of a few days to more than a week. In situ data obtained during the NASA Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) field campaign show increasing water vapor mixing ratios in background air as a function of time the air parcel spent within the North American Monsoon Anticyclone region. We find that water vapor added to the stratosphere by convection decreases with altitude and tends to drop below detectable limits by the 415 K isentrope in 2021 and the 430 K isentrope in 2022. Integrating between potential temperatures of 380 and 460 K we find that convection added between 20 and 32 Tg per summer to the stratosphere in 2021 and 2022. While the total amount is only 1%–4% of the amount ascending in the tropics across the tropical tropopause, small changes in the annual flux of water can have a significant effect on the radiation budget of the atmosphere. Locally, over North America we find that convection increased the water vapor mixing ratio at 380 K by as much as 40%. Tropopause‐penetrating convection is part of the yearly cycle of stratospheric water vapor and we suggest that it must be included in extratropical models to accurately predict future trends in stratospheric water vapor.

Assessing the Monthly Trends in Precipitable Water Vapor over the Indian Subcontinent

This study estimates the trends in precipitable water vapor (PWV), atmospheric moisture budget (AMB), and the factors influencing them: air temperature, evapotranspiration (ET), convective available potential energy (CAPE), and vertical velocity (Omega) over the Indian subcontinent using ERA5 reanalysis data sets between 1980 and 2020. PWV is examined across three atmospheric layers (1000–850 hPa: lower layer; 850–500 hPa: middle layer; 500–300 hPa: upper layer), and the entire atmospheric column (EAC; 1000–300 hPa). The observed PWV trends exhibit variability within the EAC, ranging from −0.53 to 1.25 mm/decade across the study area, with the middle layer showing the most pronounced variation (–0.44 to 0.83 mm/decade), followed by the lower layer (0.10 to 0.45 mm/decade), and the upper layer (–0.02 to 0.23 mm/decade). These fluctuations in PWV are attributed to changes in air temperature, ET, CAPE, and Omega. This investigation, however, underscores the necessity of delving into the impacts of these influencing factors on PWV using finer resolution data, to enhance our comprehension of its spatial and temporal dynamics in the region. Furthermore, the annual AMB analysis reveals a declining trend in the study region. These findings collectively contribute to the understanding of regional water-energy cycles and the recent shifts in atmospheric dynamics.

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.

Variation Trends of Asymmetrical Precipitable Water Vapor Outside the Tropical Cyclone Center Over the WNP and WSP Ocean

AbstractPrecipitable water vapor (PWV) is one of the crucial driving forces for tropical cyclone (TC) genesis. Under the impact of global warming, TCs have changed their way to concentrate PWV from the ambient atmosphere. This study starts with the asymmetric characteristics of PWV in the TC's north and south sides using altimetry‐satellite‐based PWV profiles paired with 367 TCs over the western Pacific Ocean between 2008 and 2020. The results suggest that the TC‐concentrated PWV has a north‐leaning and south‐leaning property over the western North Pacific (WNP) and western South Pacific (WSP), respectively. Moreover, it is observed that the radius of TC‐concentrated PWV has broadened by 5.44% (5.83%) over the WNP (WSP) from 2008 to 2020. In contrast, the PWV gradient has decreased by 23.5% (17.5%) over the WNP (WSP). Our findings highlight that the TC‐concentrated PWV can be used as an important indicator of TC responses to global warming.

Rising trends of global precipitable water vapor and its correlation with flood frequency

Using 4 global reanalysis data sets, significant upward trends of precipitable water vapor (PWV) were found in the 3 time periods of 1958–2020, 1979–2020, and 2000–2020. During 1958–2020, the global PWV trends obtained using the ERA5 and JRA55 data sets are 0.19 ± 0.01 mm per decade (1.15 ± 0.31%) and 0.23 ± 0.01 mm per decade (1.45 ± 0.32%), respectively. The PWV trends obtained using the ERA5, JRA55, NCEP-NCAR, and NCEP-DOE data sets are 0.22 ± 0.01 mm per decade (1.18 ± 0.54%), 0.21 ± 0.00 mm per decade (1.76 ± 0.56%), 0.27 ± 0.01 mm per decade (2.20 ± 0.70%) and 0.28 ± 0.01 mm per decade (2.19 ± 0.70%) for the period 1979–2020. During 2000–2020, the PWV trends obtained using ERA5, JRA55, NCEP-DOE, and NCEP-NCAR data sets are 0.40 ± 0.25 mm per decade (2.66 ± 1.51%), 0.37 ± 0.24 mm per decade (2.19 ± 1.54%), 0.40 ± 0.26 mm per decade (1.96 ± 1.53%) and 0.36 ± 0.25 mm per decade (2.47 ± 1.72%), respectively. Rising PWV has a positive impact on changes in precipitation, increasing the probability of extreme precipitation and then changing the frequency of flood disasters. Therefore, exploring the relationship between PWV (derived from ERA5 and JRA55) change and flood disaster frequency from 1958 to 2020 revealed a significant positive correlation between them, with correlation coefficients of 0.68 and 0.79, respectively, which explains the effect of climate change on the increase in flood disaster frequency to a certain extent. The study can provide a reference for assessing the evolution of flood disasters and predicting their frequency trends.

Increase in Tropospheric Water Vapor Amplifies Global Warming and Climate Change

Among the greenhouse gases (GHGs), atmospheric water vapor is the most abundant, has a large influence on the radiation budget of Earth, and plays a decisive role in regional weather processes. We investigate the long-term (1980–2020) changes in global tropospheric water vapor using satellite, radiosonde, and reanalysis data and assess the impact of changes in water vapor on regional and global climate with respect to its radiative feedback. The annual climatology of global tropospheric water vapor varies from 5 to 60 kg/m 2 across different regions. Except in the tropics, there is a strong seasonal cycle in both the southern and northern hemispheres, with the highest values in summer (25 to 65 kg/m 2 ) and smallest values in winter (5 to 20 kg/m 2 ). Most regions show positive trends in the annual mean tropospheric water vapor, at about 0.025 to 0.1 kg/m 2 /year, for the period of 1980–2020, with a notable increase in the Arctic because of the high rise in temperature there. Throughout the troposphere (except 200 hPa), the annual mean specific humidity shows significant positive trends over both land and oceans, with the highest values of approximately 0.015 g/kg/year at 1000 hPa in the tropics. The associated radiative effects on shortwaves at the surface vary from −5 to −70 W/m 2 , with the highest values at Manaus, Porto, and Hanty–Mawsijsk (tropical stations) and the smallest values of about −5 to −10 W/m 2 in the polar regions. The model projections for future high-emission scenarios show a large increase in atmospheric water vapor, approximately twice the current value in the polar latitudes by the end of the 21st century. This is a great concern for global and regional climate, as the rise in water vapor would further augment global warming and phenomena, such as the Arctic amplification. Therefore, this study cautions that there is a significant rise in tropospheric water vapor across latitudes and altitudes, which could further increase the global temperature and, thus, accelerate global climate change.

Measurements of Mesospheric Water Vapor From 1992 to 2021 at Three Stations From the Network for the Detection of Atmospheric Composition Change

AbstractWe present ground‐based microwave measurements of mesospheric water vapor made by the Water Vapor Millimeter‐wave Spectrometer (WVMS) instruments since the early 1990s from sites in California, Hawaii, and New Zealand. These measurements are compared with coincident measurements from the Halogen Occultation Experiment, the Aura Microwave Limb Sounder, and Sounding of the Atmosphere using Broadband Emission Radiometry; all of which combine to cover the entire time period of the ground‐based measurements. Comparisons are presented both on ∼weekly timescales in order to better identify discontinuities in the relative differences and on annual timescales in order to better study geophysical variations. The WVMS retrievals shown here are available on the Network for the Detection of Atmospheric Composition Change database. The range of WVMS trends and the differences from the satellite trends, with the latter varying over a range of ∼3%/decade, provide an estimate of how accurately it would be possible to determine multidecadal trends using ground‐based microwave instruments in a postsatellite era. This uncertainty is comparable to the trend in mesospheric water vapor that is expected to have occurred since the early 1990s.

The Spatiotemporal Patterns of the Upper-Tropospheric Water Vapor over the Tibetan Plateau in Summer Based on EOF Analysis

Abstract Using empirical orthogonal function (EOF) analysis, we investigate the spatial pattern and temporal variation of the upper-tropospheric water vapor (UTWV) over the Tibetan Plateau (TP) in summer based on the fifth-generation ECMWF atmospheric reanalysis (ERA5). The main factors affecting UTWV in different regions over the TP are also discussed. The results show that the spatial distribution of the UTWV over the TP mainly displays the so-called uniform, east–west dipole, and north–south dipole modes. The three modes show significant periods of 5, 8, and 4 years, respectively. The first mode exhibits a small but significant positive trend over the TP, which can be mainly attributed to the intensification of the South Asian summer monsoon and accounts for 31% of the UTWV variance, followed by the South Asian high and the Indian low with 17% and 16%, respectively. The second mode shows opposite variation of water vapor over the eastern and western TP, mainly resulting from the weakened westerly wind over the eastern TP and the enhanced westerly wind over the western TP, which accounts for 57% of the UTWV variance. The third mode exhibits a positive trend of water vapor over the northern TP, mainly attributed to the ascending motion associated with local anticyclonic circulation over the northeastern TP and the decrease of the static stability over the northern TP, which account for 45% and 11% of the UTWV variance, respectively. The tropopause folds also contribute to the positive trend of water vapor shown in the third mode.

The impact of aerosol fluorescence on long-term water vapor monitoring by Raman lidar and evaluation of a potential correction method

Abstract. The impact of aerosol fluorescence on the measurement of water vapor by UV (355 nm emission) Raman lidar in the upper troposphere and lower stratosphere (UTLS) is investigated using the long-term records of three high-performance Raman lidars contributing to the Network for the Detection of Atmospheric Composition Change (NDACC). Comparisons with co-located radiosondes and aerosol backscatter profiles indicate that laser-induced aerosol fluorescence in smoke layers injected into the stratosphere by pyrocumulus events can introduce very large and chronic wet biases above 15 km, thus impacting on the ability of these systems to accurately estimate long-term water vapor trends in the UTLS. In order to mitigate the fluorescence contamination, a correction method based on the addition of an aerosol fluorescence channel was developed and tested on the water vapor Raman lidar TMWAL located at the JPL Table Mountain Facility in California. The results of this experiment, conducted between 27 August and 4 November 2021 and involving 22 co-located lidar and radiosonde profiles, suggest that the proposed correction method is able to effectively reduce the fluorescence-induced wet bias. After correction, the average difference between the lidar and co-located radiosonde water vapor measurements was reduced to 5 %, consistent with the difference observed during periods of negligible aerosol fluorescence interference. The present results provide confidence that after a correction is applied, long-term water vapor trends can be reasonably well estimated in the upper troposphere, but they also call for further refinements or use of alternate Raman lidar approaches (e.g., 308 nm or 532 nm emission) to confidently detect long-term trends in the lower stratosphere. These findings may have important implications for NDACC's water vapor measurement strategy in the years to come.

Global Changes in Water Vapor 1979–2020

AbstractGlobal‐scale changes in water vapor and responses to surface temperature variability since 1979 are evaluated across a range of satellite and ground‐based observations, a reanalysis (ERA5) and coupled and atmosphere‐only CMIP6 climate model simulations. Global‐mean column integrated water vapor increased by 1%/decade during 1988–2014 in observations and atmosphere‐only simulations. However, coupled simulations overestimate water vapor trends and this is partly explained by past studies showing that internal climate variability suppressed observed warming in this period. Decreases in low‐altitude tropical water vapor in ERA5 and ground‐based observations before around 1993 are considered suspect based on inconsistency with simulations and increased column integrated water vapor in microwave satellite data since 1979. Atmospheric Infra‐red Sounder satellite data does not capture the increased tropospheric water vapor since 2002 shown by other satellite, reanalysis, and model products. However, global water vapor responses to interannual surface temperature variability are consistent across data sets with increases of ∼4%–5% near the surface and 10%–15% at 300 hPa for each 1°C increase in global surface temperature. Global water vapor responses are explained by thermodynamic amplification of upper tropospheric temperature changes and the Clausius Clapeyron temperature dependence of saturation vapor pressure that are dominated by the tropical ocean responses. Upper tropospheric moistening is larger in climate model simulations with greater upper tropospheric warming.

Long-term trend of water vapor over the Tibetan Plateau in boreal summer under global warming

Long-term trend of water vapor over the Tibetan Plateau in boreal summer under global warming

Drivers of Global Clear Sky Surface Downwelling Longwave Irradiance Trends From 1984 to 2017

AbstractRadiation changes at the Earth's surface alter climate, however, the causes of observed surface radiation changes are not precisely quantified globally. With complete global coverage by ERA‐Interim, the drivers of the clear sky surface downwelling longwave irradiance (SDLI) trends from 1984 to 2017 are quantifiable everywhere. Trends in atmospheric temperature and water vapor contributed significantly (∼90%) to clear sky SDLI trends, including trends consistent with Arctic warming and Southern Ocean cooling. CO2 contributed ∼10% and other greenhouse gases (CH4, N2O, CFC‐11, and CFC‐12) ∼1% to the SDLI trends. These observation‐based results are consistent with early CO2‐doubling climate model calculations wherein temperature and water vapor changes drove ∼90% of the SDLI change. The well‐mixed greenhouse gases drive location‐dependent SDLI trends that are strongest over regions with climatologically high temperatures and low water vapor amounts.

An Adaptive Non-Uniform Vertical Stratification Method for Troposphere Water Vapor Tomography

Global Navigation Satellite System (GNSS) water vapor tomography provides a four-dimensional (4-D) distribution of water vapor in the atmosphere for weather monitoring. It has developed into a widely used technique in numerical weather prediction (NWP). Vertical stratification is essential in discretizing the tomographic region. Traditional discretization methods divide the tomographic area into regular voxels with an equal height interval, which ignores the dynamic exponential distribution of water vapor. In recent years, non-uniform stratification methods have been widely validated by tomographic experiments. However, such experiments have not proposed a specific calculation method for stratification thickness. Therefore, in this paper, we introduced an adaptive non-uniform stratification method that follows the exponential distribution of water vapor in the tomographic region and presented the process of iterative calculation to acquire the optimal stratification interval. The proposed approach was applied based on the exponential decreasing trend in water vapor with increasing altitude. Moreover, it could adaptively calculate the interval of stratification height according to water vapor content. The tomographic experiments were performed using Global Positioning System (GPS) data from 19 ground-based stations in the Hong Kong Satellite Positioning Reference Station Network (SatRef) from 1 to 31 August 2019. The results indicated that, compared to the traditional stratification method, the root mean square error derived from the proposed approach was reduced by 0.26 g/m3. Additionally, severe weather can negatively affect the accuracy of the tomographic results. The results also showed that the accuracy of the tomographic results was reduced with increasing altitude. Moreover, the performance of the tomographic water vapor fields below 3000 m was improved by the proposed approach.

Using Climate Model Simulations to Constrain Observations

AbstractWe compare atmospheric temperature changes in satellite data and in model ensembles performed under phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP5 and CMIP6). In the lower stratosphere, multidecadal stratospheric cooling during the period of strong ozone depletion is smaller in newer CMIP6 simulations than in CMIP5 or satellite data. In the troposphere, however, despite forcing and climate sensitivity differences between the two CMIP ensembles, their ensemble-average global warming over 1979–2019 is very similar. We also examine four properties of tropical behavior governed by basic physical processes. The first three are ratios between trends in water vapor (WV) and trends in sea surface temperature (SST), lower-tropospheric temperature (TLT), and mid- to upper-tropospheric temperature (TMT). The fourth property is the ratio between TMT and SST trends. All four ratios are tightly constrained in CMIP simulations but diverge markedly in observations. Model trend ratios between WV and temperature are closest to observed ratios when the latter are calculated with datasets exhibiting larger tropical warming of the ocean surface and troposphere. For the TMT/SST ratio, model–data consistency depends on the combination of observations used to estimate TMT and SST trends. If model expectations of these four covariance relationships are realistic, our findings reflect either a systematic low bias in satellite tropospheric temperature trends or an overestimate of the observed atmospheric moistening signal. It is currently difficult to determine which interpretation is more credible. Nevertheless, our analysis reveals anomalous covariance behavior in several observational datasets and illustrates the diagnostic power of simultaneously considering multiple complementary variables.

Review on the Role of GNSS Meteorology in Monitoring Water Vapor for Atmospheric Physics

After 30 years since the beginning of the Global Positioning System (GPS), or, more generally, Global Navigation Satellite System (GNSS) meteorology, this technique has proven to be a reliable method for retrieving atmospheric water vapor; it is low-cost, weather independent, with high temporal resolution and is highly accurate and precise. GNSS ground-based networks are becoming denser, and the first stations installed have now quite long time-series that allow the study of the temporal features of water vapor and its relevant role inside the climate system. In this review, the different GNSS methodologies to retrieve atmospheric water vapor content re-examined, such as tomography, conversion of GNSS tropospheric delay to water vapor estimates, analyses of errors, and combinations of GNSS with other sources to enhance water vapor information. Moreover, the use of these data in different kinds of studies is discussed. For instance, the GNSS technique is commonly used as a reference tool for validating other water vapor products (e.g., radiosounding, radiometers onboard satellite platforms or ground-based instruments). Additionally, GNSS retrievals are largely used in order to determine the high spatio-temporal variability and long-term trends of atmospheric water vapor or in models with the goal of determining its notable influence on the climate system (e.g., assimilation in numerical prediction, as input to radiative transfer models, study of circulation patterns, etc.).

The Mechanism of Increasing Summer Water Vapor Over the Tibetan Plateau

AbstractRapid warming over the Tibetan Plateau (TP) has been associated with an increasing trend in atmospheric water vapor content, which is critical for recharging the Asian water tower. However, the mechanism associated with the wetting phenomenon remains unclear. Long‐term changes in moisture balance and precipitation (PRE) recycling processes are investigated using the ERA5 reanalysis from 1979 to 2019. The increasing trend over TP is mainly due to the summer water vapor trend with significantly increases over the western TP. Based on the moisture balance analysis, it is found that PRE, evaporation, and the convergence of moisture are all increasing over the western TP but decreasing over the eastern TP. Based on the dynamical PRE recycling model, the results suggest that both internal and external cycles contributes to the wetting over TP, with 63.87% and 36.13% contributions respectively. Further analysis found that the atmospheric heating source is also increasing over the western TP, which could shift the moisture transportation from east to west at the southern boundary of TP. The increasing moisture convergence could enhance PRE, and the enhanced latent heating in the mid‐atmosphere can further induced moisture convergence, which forms a positive feedback. However, an opposite situation occurred over the eastern TP. The internal and external cycle of the water cycle can stimulate (suppress) each other through PRE over the western (eastern) TP. This mechanism linked the changes in the PRE recycling and atmospheric circulation, and induced the increasing trend over TP in summer.

Differentiated Effects of Urbanization on Precipitation in South China

In this paper, precipitation data from the Tropical Rainfall Measuring Mission (TRMM), together with atmospheric reanalysis data, are employed to identify warm-season precipitation (1998–2014) changes and their association with rapid urbanization in south China. Three urban clusters (Chenyu, Yangtze Delta, and Fujian Guangdong coast) are focused. The results reveal that, for the inland Chengyu urban cluster, a lack of precipitation trend is likely due to insignificant trends in convective available potential energy (CAPE) and total column water vapor (TCWV). They are likely resulted from a reduced local moisture recycling in urban areas, balanced by an increased evapotranspiration of rural areas, together with a stable advection of water vapor input. For the Yangtze River Delta urban cluster, a negative trend in precipitation is associated with a slightly decreased CAPE and an increased TCWV, but is very likely related to urbanization induced an increased planetary boundary layer (PBL) and reduced land surface evaporation. For the Fujian Guangdong coast urban cluster, a marked positive precipitation trend is well explained by positive trends in CAPE and TCWV. The increased precipitation likely benefits from enhanced moisture recycling due to improved vegetation cover in rural areas, and enhanced advection moisture inputs due to urbanization along the coast. These results suggest urbanization effects on precipitation vary with regional conditions. In the coastal area, urbanization enhances sea breezes, which may benefit precipitation if sea breezes go along with the prevailing moisture. In inland area, urbanization likely leads to a warmer-dryer climate if large-scale land cover keeps stationary.

Feasibility of ERA5 integrated water vapor trends for climate change analysis in continental Europe: An evaluation with GPS (1994–2019) by considering statistical significance

Although the statistical significances for the trends of integrated water vapor (IWV) are essential for a correct interpretation of climate change signals, obtaining accurate IWV trend estimates with realistic uncertainties remains a challenge. This study evaluates the feasibility of the IWV trends derived from the newly released fifth generation European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis (ERA5) for climate change analysis in continental Europe. This is achieved by comparing the trends derived from in-situ ground-based Global Positioning System (GPS)’s daily IWV series from 1994 to 2019 at 109 stations. The realistic uncertainties and statistical significances of the IWV trends are evaluated with the time series analysis on their noise characteristics and proper noise models. Results show that autoregressive moving average ARMA(1,1) noise model is preferred rather than the commonly assumed white noise (WN) or first-order autoregressive AR(1) noise for about 68% of the ERA5 and GPS IWV series. An improper noise model would misevaluate the trend uncertainty of an IWV time series, compared with its specific preferred noise model. For example, ARMA(1,1) may misevaluate the standard deviations of their trend estimates (0.1–0.3 kg m−2 decade−1) by 10%. Nevertheless, ARMA(1,1) is recommended as the default noise model for the ERA5 and GPS IWV series. However, the preferred noise model for each ERA5 minus GPS (E-G) IWV series should be specifically determined, because the AR(1)-related models can result in an underestimation on its trend uncertainty by 90%. In contrast, power-law (PL) model can lead to an overestimation by up to nine times. The E-G IWV trends are within −0.2–0.4 kg m−2 decade−1, indicating that the ERA5 is a potential data source of IWV trends for climate change analysis in continental Europe. The ERA5 and GPS IWV trends are consistent in their magnitudes and geographical patterns, lower in Northwest Europe (0–0.4 kg m−2 decade−1) but higher around the Mediterranean Sea (0.6–1.4 kg m−2 decade−1).