Increase In Precipitation Research Articles

Bayesian spatio-temporal modelling of environmental, climatic, and socio-economic influences on malaria in Central Vietnam

BackgroundDespite the successful efforts in controlling malaria in Vietnam, the disease remains a significant health concern, particularly in Central Vietnam. This study aimed to assess correlations between environmental, climatic, and socio-economic factors in the district with malaria cases.MethodsThe study was conducted in 15 provinces in Central Vietnam from January 2018 to December 2022. Monthly malaria cases were obtained from the Institute of Malariology, Parasitology, and Entomology Quy Nhon, Vietnam. Environmental, climatic, and socio-economic data were retrieved using a Google Earth Engine script. A multivariable Zero-inflated Poisson regression was undertaken using a Bayesian framework with spatial and spatiotemporal random effects with a conditional autoregressive prior structure. The posterior random effects were estimated using Bayesian Markov Chain Monte Carlo simulation with Gibbs sampling.ResultsThere was a total of 5,985 Plasmodium falciparum and 2,623 Plasmodium vivax cases during the study period. Plasmodium falciparum risk increased by five times (95% credible interval [CrI] 4.37, 6.74) for each 1-unit increase of normalized difference vegetation index (NDVI) without lag and by 8% (95% CrI 7%, 9%) for every 1ºC increase in maximum temperature (TMAX) at a 6-month lag. While a decrease in risk of 1% (95% CrI 0%, 1%) for a 1 mm increase in precipitation with a 6-month lag was observed. A 1-unit increase in NDVI at a 1-month lag was associated with a four-fold increase (95% CrI 2.95, 4.90) in risk of P. vivax. In addition, the risk increased by 6% (95% CrI 5%, 7%) and 3% (95% CrI 1%, 5%) for each 1ºC increase in land surface temperature during daytime with a 6-month lag and TMAX at a 4-month lag, respectively. Spatial analysis showed a higher mean malaria risk of both species in the Central Highlands and southeast parts of Central Vietnam and a lower risk in the northern and north-western areas.ConclusionIdentification of environmental, climatic, and socio-economic risk factors and spatial malaria clusters are crucial for designing adaptive strategies to maximize the impact of limited public health resources toward eliminating malaria in Vietnam.

Assessing teleconnection influences on the spatial and temporal patterns of meteorological drought in Northwest China

ABSTRACT This study delves into the complex relationship between teleconnection patterns and meteorological drought in Northwest China, highlighting the crucial influence of global circulation indices on regional drought dynamics. By analyzing precipitation and temperature data from 1962 to 2022 using the CN05.1 datasets and incorporating various global circulation indices, the study employs the Standardized Precipitation Evapotranspiration Index (SPEI) to delineate drought conditions. Utilizing the Modified Mann-Kendall test and segmented models for trend and change point detection, along with cross wavelet transforms (XWT) and wavelet coherence (WTC) analysis to examine the impact of 15 global circulation indices, the study uncovers significant spatial and temporal climatic variations. Findings indicate a significant increase in temperature and precipitation, with March-April-May (MAM) season showing pronounced drought severity mainly due to a significant temperature rise with a value of 0.0420 °C/year. Change point analysis reveals pivotal shifts in climate, highlighting the region’s susceptibility to climate change. The study identified strong correlations between drought occurrences and global circulation indices like the Artic Oscillation (AO), Atlantic Multidecadal Oscillation (AMO), Pacific Decadal Oscillation (PDO) and the Southern Oscillation Index (SOI), especially within a 4–8 year timeframe, pointing to the significant role of teleconnections in affecting local drought conditions. These insights are vital for formulating effective drought management and climate adaptation strategies in arid and semi-arid regions, offering valuable guidance for policymakers and researchers focused on improving water resource management and enhancing climate resilience in such vulnerable environments.

Impacts of Climate Change on Streamflow on Dawa Sub-watershed, Genale-Dawa River Basin, Southern Ethiopia

<i>Climate change is statistical variations over an extended period in the features of the climate system, such as variations in global temperatures and precipitation, caused by human and natural sources.</i> In this study aimed to measure and examine how streamflow in the Dawa sub-basin, Genale Dawa River basin was affected by climate change. It used the average of five regional climate models from the Coordinated Regional Climate Downscaling Experiment (CORDEX) Africa, under two different scenarios of Representative Concentration Pathways: RCP4.5 and RCP8.5. The baseline scenario was based on the data from 1975 to 2005, while the future scenarios were based on the data from 2020s (2025–2054) and 2050s (2055–2084). The HBV hydrological model used to assess the impact on streamflow. The HBV model showed good statistical performance in simulating the impact of climate change on streamflow, with a coefficient of determination (R<sup>2</sup>) of 0.88 and Nash-Sutcliffe Efficiency (NSE) of 0.77 for monthly calibration, and R<sup>2</sup> of 0.86 and NSE of 0.83 for monthly validation. The impacts quantified using the mean monthly changes in precipitation, maximum and minimum temperatures. The bias-corrected precipitation and temperature showed a reasonable increase in both future periods for both RCP 4.5 and RCP 8.5 scenarios. These changes in climate variables resulted in a decrease in mean annual streamflow by 1.6 and 3.5% for RCP 4.5 and by 4.6 and 4.9% for RCP 8.5 scenarios of the 2020s and 2050s, respectively. Based on the analysis that predicted a drop in precipitation during the months, and seasons and an increase in precipitation during the <i>Belg</i> season, with a corresponding decrease and rise in stream flow throughout the watershed. So to offset the variation in the watershed, community should adopt various; Soil and water conservation technologies, Using drought tolerant crops, Implementing various trees and appropriate design and applying a water harvesting structure like in-situ, internal or micro catchment, external or macro catchment water harvesting and Surface runoff harvesting. This result offers useful information for current and future water resource management in the basin and similar other watershed in the country.

Aerosol effects during heat waves in summer 2022 and responses to emission change over China

This study explores aerosol direct, indirect, and feedback effects on meteorology and fine particulate matter during heat waves of August 2022 over eastern China by using an online coupled regional climate–chemistry–aerosol model. In this period, aerosols exerted mean direct (DRE) and indirect (IRE) radiative effects of −3.9 Wm−2 and −2.4 Wm−2 at TOA, which totally caused a decrease in average surface air temperature by 0.3 °C over east China, accompanied by decreases in PBLH (planetary boundary layer height) and precipitation and an increase in PM2.5 concentration. With the anthropogenic emission reduction from 2013 to 2022, DRE apparently decreased while IRE changed little, leading to a decrease in total aerosol radiative effect (TRE) by 27% at TOA. The weakened TRE resulted in increases in surface air temperature and precipitation by 0.14 °C and 2.7 mm, respectively, on average over east China, with the maximum warming exceeding 0.5 °C in BTH (Beijing–Tianjin–Hebei province). This study highlights a warming trend due to weakened TRE, which may exacerbate heat wave, and an increasing importance of aerosol IRE relative to DRE due to weak sensitivity of cloud properties to aerosol change during the emission reduction.

Long‐term snowfall trends and variability in the Alps

AbstractSnow is particularly impacted by climate change and therefore there is an urgent need to understand the temporal and spatial variability of depth of snowfall (HN) trends. However, the analysis of historical HN observations on large‐scale areas is often impeded by lack of continuous long‐term time series availability. This study investigates HN trends using observed time series spanning the period 1920–2020 from 46 sites in the Alps at different elevations. To discern patterns and variations in HN over the years, our analysis focuses also on key parameters such as precipitation (P), mean air temperature (TMEAN), and large‐scale synoptic descriptors, that is, the North Atlantic Oscillation (NAO), Arctic Oscillation (AO) and Atlantic Multidecadal Oscillation (AMO) indices. Our findings reveal that in the last 100 years and below 2000 m a.s.l., despite a slight increase in winter precipitation, there was a decrease in HN over the Alps, especially for southern and low‐elevation sites. The South‐West and South‐East regions experienced an average loss of 4.9 and 3.8%/decade, respectively. A smaller relative loss was found in the Northern region (2.3%/decade). The negative HN trends can be mainly explained by an increase of TMEAN by 0.15°C/decade. Most of the decrease in HN occurred mainly between 1980 and 2020, as a result of a more pronounced increase in TMEAN. This is also confirmed by the change of the running correlation between HN and TMEAN, NAO, AO over time, which until 1980 were not correlated at all, while the correlation increased in later years. This suggests that in more recent years favourable combinations of temperature, precipitation, and atmospheric pattern have become more crucial for snowfall to occur. On the other hand, no correlation was found with the AMO index.

The White Hills Gravel of central Victoria: an anomalous Paleogene very coarse-grained fluvial deposit

The White Hills Gravel is the coarsest fluvial gravel within Victoria, southeastern Australia, and outcrops discontinuously across a substantial part (>35 000 km2) of this region. It overlies a major regional unconformity representing >300 Ma, and is dominated by conglomerate (61% of beds), with less abundant sandy lithofacies (36% of beds) and rare mudstones (3% of beds). The sedimentary characteristics of the basal conglomerates (e.g. thick bedding, common boulders, very poor sorting and in places chaotic appearance) indicate deposition by significant paleofloods, including debris floods, within braided streams that had similar flow directions to the modern drainage. Paleohydraulic calculations estimate that the paleofloods had discharges exceeding >7200 m3 s−1, over 25 times the largest recorded floods in the same valleys. These paleofloods were probably caused by exceptionally severe storm systems, consisting of many individual thunderstorms. Deposition of the White Hills Gravel has previously been attributed to the mid-Cretaceous uplift that affected southeastern Australia, but the maximum possible age of the formation (early Paleocene) is too young for this to be a viable explanation. Instead, the White Hills Gravel may have been deposited during a period of increased precipitation at the Paleocene–Eocene Thermal Maximum (ca 56 Ma), when an intensification of the hydrological system generated significant sediment responses within fluvial systems around the world. Modelling indicates that this climatic event had a substantial impact in Victoria, where increases in mean annual precipitation (50–60%) and the most extreme rainfall rates achieved by the strongest storms (60–70%) were some of the largest globally, and frequent and intense Atmospheric Rivers were an important part of the hydrological system. These factors, together with a period of disturbed vegetation cover, resulted in major paleofloods that could have deposited the coarse-grained conglomerates of the White Hills Gravel.

Wildfire-smoke-precipitation interactions in Siberia: Insights from a regional model study

Powerful wildfires occurring in Siberia each summer emit large amounts of smoke aerosol that, according to studies of the environmental impacts of biomass burning (BB) aerosol in different regions of the world, can affect precipitation and other weather parameters and induce feedback on fires. However, the knowledge of smoke-weather interactions and fire-weather feedback in Siberia is presently limited. To advance this knowledge, we performed coupled-meteorology-chemistry simulations of aerosols and weather in a Siberian region covering taiga and tundra using the CHIMERE chemistry-transport model and the WRF meteorological model. We addressed a monthly period of July 2016 and considered several modeling scenarios in which aerosol-radiation interaction (ARI) and aerosol-cloud interaction (ACI) were taken into account jointly or separately. The simulation results were combined with emission and precipitation data retrieved from satellite observations. The joint analysis of the simulated precipitation fields and satellite-observation-based data revealed that in the taiga, the inhibiting effect of Siberian smoke on precipitation induced a significant positive feedback on BB aerosol emissions that, according to our estimates, enhanced by 27 (±7) % respective to a hypothetical situation in which smoke-weather interactions were absent. At the same time, an increase of precipitation over active fire spots due to ACI and ARI in tundra led to the formation of a negative feedback loop between fire emissions and BB smoke, resulting in a reduction of BB aerosol emissions there by 14 (±6) %. Hence, this study revealed evidence for significant feedback of smoke-induced precipitation changes on fire emissions in Siberia. Given the global importance of Siberia as a major carbon sink, this feedback needs to be studied further and accurately taken into account in projections of climate change both on regional and global scales.

Development of Polar Lows in Future Climate Scenarios over the Barents Sea

Abstract Polar lows (PLs) are intense mesoscale cyclones that form over polar oceans during colder months. Characterized by high wind speeds and heavy precipitation, they profoundly impact coastal communities, shipping, and offshore activities. Amid the substantial environmental changes in polar regions due to global warming, PLs are expected to undergo noteworthy transformations. In this study, we investigate the response of PL development in the Barents Sea to climate warming based on two representative PLs. Sensitivity experiments were conducted including the PLs in the present climate and the PLs in a pseudo–global warming scenario projected by the late twenty-first century for Shared Socioeconomic Pathway (SSP) 2-4.5 and SSP 3-7.0 scenarios from phase 6 of the Coupled Model Intercomparison Project (CMIP6). In both warming climate scenarios, there is an anticipated decrease in PL intensity, in terms of the maximum surface wind speed and minimum sea level pressure. Despite the foreseen increase in latent heat release in the future climate, contributing to the enhancement of PL intensity, other primary factors such as decreased baroclinic instability, heightened atmospheric static stability, and reduced overall surface heat fluxes play pivotal roles in the overall decrease in PL intensity in the Barents Sea under warming conditions. The augmentation of surface latent heat flux, however, results in increased precipitation associated with PLs by enhancing the latent heat release. Furthermore, the regional steering flow shifts in the warming climate can influence the trajectory of PLs during their development. Significance Statement Global warming is anticipated to impact cyclone systems worldwide. Polar lows (PLs), intense mesocyclones in polar regions with potential socioeconomic and human life implications, pose uncertainties regarding intensity changes in a warming climate. In this study, we aimed to better understand how PLs over the Barents Sea will respond to the environmental changes in future climate conditions [Shared Socioeconomic Pathway (SSP) 2-4.5 and SSP 3-7.0] by the end of the twenty-first century. Our results find that the intensity of PLs is expected to decrease in the future while there is an expected increase in precipitation associated with PLs in the warming climate. These findings aim to contribute valuable insights for disaster management strategies in the face of evolving climate scenarios.

Patterns and Trends in Northern Hemisphere River Ice Phenology from 2000 to 2021

River ice plays a crucial role in hydrology, ecosystems, and socio-economic systems in mid-to-high latitude regions. However, there is a notable gap in the analysis of patterns and trends in river ice phenologies and their influence factors at the river level. In this study, we developed a practical method to identify river ice phenologies by leveraging Landsat observations from 2000 to 2021, and established a comprehensive dataset encompassing 7970 river segments across the entire Northern Hemisphere. Our results revealed that the mean freeze-up date, break-up date, and ice duration for these river segments were October 24, May 4, and 192.1 days, respectively. Notably, 56% of the river segments exhibited a warming trend, with the average freeze-up date delayed by 2.7 days per decade, break-up date advanced by 2.5 days per decade, and ice duration shortened by 5.5 days per decade—nearly five times the documented decrease rate over the past 150 years. Furthermore, high-latitude polar regions and the Qinghai-Tibet Plateau demonstrated the most pronounced decreases in ice duration, exceeding 7.0 days per decade on average. We observed a substantial relative contribution, reaching up to 70%, of surface air temperature (SAT) in middle and low latitude regions characterized by relatively high winter temperatures. However, as winter temperatures decrease, the relative influence of SAT diminishes, while the contributions of precipitation, solar radiation, and residuals increase. Our dataset provided essential baseline for further understanding the fundamental physical processes within river systems, offering crucial insights for river management, hydrological disaster risk control, climate change research, and ecosystem conservation efforts.

Spatiotemporal variations of precipitation patterns in the middle and lower reaches of Yangtze River Basin

Context With escalating global climate change, regional flood disasters have become increasingly prevalent. Precipitation, as a primary influencing factor, has garnered significant attention. Aims This study is based on precipitation data to investigate the spatiotemporal characteristics of precipitation in the middle and lower reaches of Yangtze River Basin (MLYB), trying to explore more concise methods for precipitation forecasting. Methods Statistical methods were employed to analyse historical precipitation patterns, followed by forecasting future trends using statistical time series models. Key results Precipitation in the MLYB exhibited a decreasing trend during 1961–2010, which shifted to an increasing trend after 2011, becoming more pronounced since 2017. Precipitation patterns in the MLYB were clearly increasing in the east and decreasing in the west, with the Taihu Basin showing the greatest rise. The ARIMA model predicted a significant increase in precipitation after 2022. Conclusions In recent years, precipitation in the MLYB has significantly increased, especially in downstream areas. Although the ARIMA model offers an effective and reasonably simple method for short-term forecast, it struggles with complex terrain influences. Implications These findings provide a theoretical basis for flood prevention in the MLYB, as well as a reference for precipitation prediction simulations in data-limited regions.

The East China Sea Kuroshio Current Intensifies Deep Convective Precipitation: A Case Study

AbstractDeep atmospheric convection is often observed over the Kuroshio in the East China Sea (ECSK). However, the mechanisms by which warm oceanic currents fuel transient deep convection are not fully understood. This study investigates an atmospheric cold front that brought heavy precipitation as it traversed the ECSK in April 2004. The southwesterlies ahead of the cold front advected moist and warm air, creating a zone with high convective available potential energy (CAPE) values. As the cold front approached the ECSK, the pre‐frontal high CAPE values coalesced with those over the warm current that substantially strengthened the deep convection, with precipitation rate increasing from 3 mm hr−1 to 10 mm hr−1. A numerical model well simulated the marked increase in precipitation over the ECSK, permitting the isolation of the ECSK's influence by contrasting the control (CTRL) run with an experiment with smoothed sea surface temperatures (SMTH run). Results show the ECSK contributed to 46% of the precipitation over the warm current. The ECSK was found to amplify ascending motion and elevate neutral buoyancy levels, extending its effect up to the tropopause. Furthermore, the strengthened deep convection significantly lowered the sea level pressure (SLP) over the ECSK and impressed upon the time‐mean SLP field. An additional experiment with lowered SST underscored the high SST's critical role in deep convection. This case study suggests a novel pathway by which the effects of warm oceanic currents influence the upper troposphere under extreme conditions with strong baroclinic instability.

Holocene insolation and sea surface temperature influences on the polar front jet stream and precipitation in the midcontinental United States

Variability in the source and seasonality of precipitation in the midcontinental United States during the Holocene was investigated using isotopic and sedimentological data from Martin Lake, northeastern Indiana, USA. Between 7100 and 4000 years before present (yr BP; present = 1950 CE), high δ18Ocal and δ13Ccal values with low variability indicate that moisture was predominantly derived from subtropical, southerly sources and delivered primarily during the warm season. Mean state shifts toward lower δ18Ocal and δ13Ccal occurred at ca. 4000 and 2550 yr BP, respectively, indicating an increase in northerly-sourced cold-season precipitation during the Late Holocene (i.e., the past 4200 years) and a subsequent reduction in warm season duration after 2550 yr BP. Record low %lithics from ca. 5000 to 4000 yr BP indicates major reductions in warm-season rain storms, consistent with regional evidence of drought at this time. An increase in the amplitude of centennial-scale variability in δ18Ocal, δ13Ccal, and %lithics after 1900 yr BP indicates greater precipitation source variability during the Common Era. During this interval, precipitation fluctuated between southerly-sourced, convective rainstorms when the Northern Hemisphere (NH) was warm (e.g., during the Medieval Climate Anomaly; 700–1000 yr BP) and northerly-sourced rain and snow when the NH was cool (e.g., during the Little Ice Age; 150–550 yr BP). These trends, especially the change at ca. 4000 yr BP, are consistent with other North American paleoclimate records that collectively suggest a continental-scale shift in precipitation seasonality during the Middle to Late Holocene transition as the tropical Pacific Ocean transitioned from La Niña-like conditions to a more El Niño-like mean state. Concurrent NH cooling and persistent El Niño-like conditions during the Late Holocene would have favored a southerly polar front jet stream with enhanced ridge and trough atmospheric circulation over North America – conditions resembling the positive mode of the Pacific-North American teleconnection (PNA). This would have increased interactions between high-latitude and subtropical airmasses over the midcontinent, increasing the proportion of northerly precipitation with low δ18O delivered during the cold season (i.e., snowfall) and during extended periods with +PNA-like atmospheric circulation (e.g., the Little Ice Age).

Towards understanding climate change impacts: monitoring the vegetation dynamics of terrestrial national parks in Indonesia

Monitoring vegetation dynamics in terrestrial national parks (TNPs) is crucial for ensuring sustainable environmental management and mitigating the potential negative impacts of short- and long-term disturbances understanding the effect of climate change within natural and protected areas. This study aims to monitor the vegetation dynamics of TNPs in Indonesia by first categorizing them into the regions of Sumatra, Jawa, Kalimantan, Sulawesi, and Eastern Indonesia and then applying ready-to-use MODIS EVI time-series imageries (MOD13Q1) taken from 2000 to 2022 on the GEE cloud-computing platform. Specifically, this research investigates the greening and browning fraction trends using Sen's slope, considers seasonality by analyzing the maximum and minimum EVI values, and assesses anomalous years by comparing the annual time series and long-term median EVI value. The findings reveal significantly increasing greening trends in most TNPs, except Danau Sentarum, from 2000 to 2022. The seasonality analysis shows that most TNPs exhibit peak and trough greenness at the end of the rainy and dry seasons, respectively, as the vegetation response to precipitation increases and decreases. Anomalies in seasonality that is affected by climate change was detected in all of the regions. To increase TNPs resilience, suggested measures include active reforestation and implementation of Assisted Natural Regeneration, strengthen the enforcement of fundamental managerial task, and forest fire management.

Trends in atmospheric water vapour over the Thar Desert during Indian Summer Monsoon period of 2003-2020.

The Thar is the most densely populated desert in the world, which supports diverse ecosystems and human endeavours such as agriculture and socioeconomic activities. Water demand and supply in the Thar play an essential role in regulating the socioeconomic activities of the region. Inland water and precipitation aid the movement of water in the Thar Desert. Precipitation in the Thar is governed by the Indian Summer Monsoon (ISM), during which the winds distribute water vapour to regulate precipitation across the region. Therefore, we analyse the water vapour, its sources and its relation with precipitation using satellite measurements and reanalysis data in the Thar during ISM. Like other regions, a clear seasonal cycle of water vapour is observed in the Thar, with very high values (> 45 kg/m2) during ISM and low in winter (< 15 kg/m2). Evapotranspiration and moisture transport have significant effects on the amount of water vapour during ISM. There is a significant increase in water vapour in the troposphere, with high trends at the surface (0.032 g/kg/year) and small at the tropopause (0.00002 g/kg/year). A significant increase in column water vapour is also estimated in the Thar during ISM, with high trends in the eastern and southern areas, at about 0.15-0.35 kg/m2/year. The rise in water vapour in the Thar can be attributed to the increase in evapotranspiration (0.03-0.07 mm/day/year) and water vapour transport (> 0.5 kg/m/s/year) from the Arabian Sea and Indian Ocean. The rise in water vapour can lead to an increase in precipitation in the Thar, as it shows significant positive trends (0.05-0.1 mm/day/year) in the eastern areas during ISM. The increase in precipitation and water vapour in the arid Thar Desert can have significant implications for the regional environment and agriculture.

Diagnosing drivers of tropical precipitation biases in coupled climate model simulations

In this study, we analyse the large-scale biases in tropical precipitation climatology of two different types of coupled ocean–atmosphere general circulation models (GCMs): the coupled model intercomparison project (CMIP) models and ICON-Sapphire, a global storm-resolving model. We employ the simple globally resolved energy balance (GREB) diagnostic precipitation model to evaluate four drivers of the precipitation biases in the simulations: surface specific humidity, surface relative humidity, tropospheric mean and variability in the vertical motion. The tropical precipitation biases in the CMIP and ICON-Sapphire simulations are surprisingly similar in their patterns and also in the elements forcing them. The results of our analysis using the GREB model show that the precipitation biases result from both biases in the sensitivity to the four forcing fields and biases in the simulated forcing fields themselves. The most significant bias for both, the CMIP and ICON-Sapphire simulations, is a too high sensitivity to the mean vertical circulation (ωmean\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\omega }_{\ ext{mean}}$$\\end{document}) and bias in the ωmean\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\omega }_{\ ext{mean}}$$\\end{document} climatology itself. This also holds for specific long-standing biases, such as the double intertropical convergence zone problem. Meanwhile, biases in the climatology of specific and relative humidity play only a minor role but contribute to an overall small increase in precipitation in CMIP models that may be related to the “drizzling” bias. These results can give insights to the modelling community regarding model development, and illustrate that the GREB diagnostic precipitation model applied is a good tool for evaluating the drivers of large-scale tropical precipitation.

Underestimates of Orographic Precipitation in Idealized Simulations. Part I: Evidence from Unidirectional Warm-Sector Environments

Abstract Heavy precipitation in midlatitude mountain ranges is largely driven by the episodic passage of weather systems. Previous studies have shown a high correlation between the integrated vapor transport (IVT) in the airstream striking a mountain and the precipitation rate. Using data collected during the Olympic Mountain Experiment (OLYMPEX) project from a pair of sounding stations and a dense precipitation network, we further document the tight relation between IVT and precipitation rate and obtain results consistent with earlier work. We also survey previous studies that simulated orographic precipitation forced by unidirectional shear flows. Some of these simulations were performed using models that produce reasonably accurate rainfall totals in nested simulations of actual events driven by large-scale flows. Nevertheless, the increase in precipitation with IVT in all the simulations with unidirectional upstream flows is far lower than what would be expected based on the observationally derived correlation between IVT and precipitation rate. As a first step toward explaining this discrepancy, we conduct idealized simulations of a midlatitude cyclone striking a north–south ridge. The relationship between IVT and rainfall rate in this “Cyc+Mtn” simulation matches that which would be expected from observations. In contrast, when the conditions upstream of the ridge in the Cyc+Mtn case were used as upstream forcing in a horizontally uniform unidirectional flow with the same IVT over the same mountain ridge, far less precipitation was produced. These idealized simulations will, therefore, be used to study the discrepancy in rainfall between simulations driven by unidirectional shear flows and observations in a companion paper. Significance Statement Idealized simulations of orographic precipitation using horizontally uniform environmental forcing fail to capture the observed relationship between integrated water vapor flux impinging on the mountain and the precipitation rate. This suggests we need to improve the design of such idealized simulations.

Quantile Delta-Mapped Spatial Disaggregation Analysis for Climate Variations over the Yangtze River Basin

Abstract Significant increases in temperature and precipitation due to global warming affect socioeconomics. Accurate analysis is needed for future temperature and precipitation variations across the Yangtze River basin (YRB). A novel quantile delta-mapped spatial disaggregation (QDMSD) approach was developed in this study to analyze temperature and precipitation changes for the first time. The evaluation results show that the QDMSD has a similar performance in simulating temperature with the bias correction and spatial disaggregation (BCSD) model, while it shows improvement in reproducing precipitation. Projections indicate the annual-mean temperature will increase from 2020 to 2080 under shared socioeconomic pathway (SSP) scenarios SSP2-4.5 and SSP5-8.5. The projected temperature obtained from five downscaled GCMs has the smallest range of differences in summer. Conversely, annual-mean temperatures significantly decrease from 2081 to 2100 under SSP2-4.5. In terms of spatial distribution characteristics, most of the positive changes tend to expand across the YRB. The annual-mean precipitation will increase from 2020 to 2080 but decrease from 2081 to 2100 under SSP2-4.5 over the YRB. In terms of spatial distribution, precipitation in the southeast region of the YRB will increase, and the maximum variations in precipitation will occur downstream of the YRB. The QDMSD method reproduces observed precipitation trends well and enhances simulation accuracy in the YRB. For projected temperature, there will be a widespread increase across the YRB; for projected precipitation, significant increases will occur in the eastern YRB. These findings support policymaking to address potential risks from temperature and precipitation changes across multiple sectors (e.g., agriculture and industry).

Impact of interplanetary shock on nitric oxide cooling emission: A superposed epoch study

The impact of interplanetary (IP) shock on Nitric Oxide (NO) 5.3 µm cooling emission is studied during geomagnetic quiet periods. The Active Magnetosphere and Planetary Electrodynamics Response Experiment measurements of field-aligned-currents intensify during IP shock with a relatively higher magnitude in southern hemisphere as compared to the northern hemispheric counterpart. The Defense Meteorological Satellite Program spacecraft observations displayed an early and strong enhancement in the precipitating particle flux of energy less than 1 keV. The particle flux of higher energy responds at later time. The NO density exhibited a significant, pre-event increase by an order of magnitude due to low-energy particle precipitation. The thermospheric temperature increased by about 100 K at 400 km. The superposed epoch analysis study revealed a linear enhancement in SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) measurements of NO cooling emission onboard the TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics) satellite due to the prompt increase in particle precipitations and thermospheric temperature triggered by IP shock.

Anticipating how rain-on-snow events will change through the 21st century: lessons from the 1997 new year’s flood event

The California-Nevada 1997 New Year’s flood was an atmospheric river (AR)-driven rain-on-snow (RoS) event and remains the costliest in their history. The joint occurrence of saturated soils, rainfall, and snowmelt generated inundation throughout northern California-Nevada. Although AR RoS events are projected to occur more frequently with climate change, the warming sensitivity of their flood drivers across scales remains understudied. We leverage the regionally refined mesh capabilities of the Energy Exascale Earth System Model (RRM-E3SM) to recreate the 1997 New Year’s flood with horizontal grid spacings of 3.5 km across California, with forecast lead times of up to 4 days, and across six warming levels ranging from pre-industrial conditions to +3.5∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$+3.5\\,^\\circ$$\\end{document}C. We describe the sensitivity of the flood drivers to warming including AR duration and intensity, precipitation phase, intensity and efficiency, snowpack mass and energy changes, and runoff efficiency. Our findings indicate current levels of climate change negligibly influence the flood drivers. At warming levels ≥1.7∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ge 1.7\\,^\\circ$$\\end{document}C, AR hazard potential increases, snowpack nonlinearly decreases, antecedent soil moisture decreases (except where the snowline retreats), and runoff decreases (except in the southern Sierra Nevada where antecedent snowpack persists). Storm total precipitation increases, but at rates below warming-induced increases in saturation-specific humidity. Warming intensifies short-duration, high-intensity rainfall, particularly where snowfall-to-rainfall transitions occur. This study highlights the nonlinear tradeoffs in 21st-century RoS flood hazards with warming and provides water management and infrastructure investment adaptation considerations.

An increase in global daily precipitation records in response to global warming based on reanalysis and observations

Understanding trends in extreme precipitation events in the context of global warming is critical for assessing climate change impacts. This study employs a novel methodology developed by Giorgi and Ciarlo (2022) to analyze record-breaking daily precipitation events from 1980 to 2020, utilizing three reanalysis products (ERA5, MERRA-2, and JRA-55) and one global observation dataset (MSWEP). Our results indicate a consistent and statistically significant increase in record-breaking precipitation events globally, with variations across different latitude bands and between land and ocean areas. This trend is evident in all datasets, with the most substantial increases observed over oceans in ERA5 and over land in JRA and MERRA. Notably, the Southern Hemisphere shows mixed results, with some regions displaying negative trends. This study highlights the increasing frequency of extreme precipitation events, supporting the hypothesis of intensified hydrological cycles under a warming climate. Our findings enhance understanding of precipitation extremes and underscore the importance of regional analyses in climate impact studies. Future work could extend these findings to formal attribution studies linking observed trends directly to anthropogenic climate change.