Characteristics Of Precipitation Events Research Articles

Assessing precipitation event characteristics throughout North Carolina derived from GPM IMERG data products

The Global Precipitation Measurement (GPM) mission provides near-real time precipitation estimates that can be used for monitoring water supply infrastructure. To better understand the potential use of GPM data products for use in relevant applications, this study examines the performance of the Integrated Multi-satellitE Retrievals for GPM (IMERG) precipitation products throughout North Carolina to capture rainfall events. Event characteristics derived from IMERG precipitation products: early (4 h latency), late (14 h latency), and final (3.5 month latency) are compared to characteristics derived from gauges (N = 282) for the period 2000–2021. Results show that the IMERG data products identify events reasonably well (mean event errors of 6.0, 6.8, and 1.7 mm for early, late, and final products; probability of detection: 0.83, 0.83, 0.86; false alarm ratio: 0.20, 0.18, 0.18, respectively). While the final product performs best, the early and late products perform similarly. While additional research is needed to better understand factors leading to under- and over-estimates of event magnitudes, the findings from this study support the potential use of early/late IMERG data products in water supply monitoring or flood warning systems, where rapid estimates of event precipitation characteristics are needed.

Spatiotemporally contiguous precipitation events across China: Role of atmospheric rivers and tropical cyclones in heavy precipitation

Precipitation events exhibit a spatiotemporal continuity since they move across both space and time, however, the joint spatiotemporal characteristics of precipitation events are often neglected, and the role of Atmospheric rivers (ARs) and tropical cyclones (TCs) in the events has not been systematically explored. To solve these problems, this study seeks to detect and characterize the three-dimensional (latitude + longitude + time) structures of spatiotemporally contiguous precipitation events, distinguish the heavy events associated with ARs or TCs, and systematically explore the different roles of these events. We do so by combining Forward-in-Time algorithm, an object-based physical event detecting algorithm, with TMPA precipitation estimates to detect spatiotemporally contiguous precipitation events over China, and an AR detection technique considering a combination of fixed lower limit and Integrated Water Vapor Transport percentile threshold is adopted to identify ARs. The heavy events are defined to analyze the differences of the events associated with TCs and ARs as a function of precipitation total, duration, and intensity. Results show that approximately half or more of precipitation events are shorter than 6-hour, and the precipitation total of each event is strongly correlated with maximum intensity and average intensity across China. The heavy events normally occur in southern, center, northern, and southwestern regions, where have approximately 10 to 40 heavy events at each grid. The fraction of heavy events associated with TCs generally increase for events with larger precipitation totals and for events with higher maximum intensity, until all of events are associated with TCs. The percentages of events associated with ARs as well normally increase as precipitation totals and maximum intensity increase up to around 150 mm and 30 mm/h, respectively. Our findings show that the events associated with TCs or ARs exhibit distinct different characteristics, and suggest that the different spatiotemporal dynamics should be sufficient considered in contiguous events analyses in different regions.

Effects of interaction between forest structure and precipitation event characteristics on fuel moisture conditions

Estimating forest fire danger is of primary concern for the Austrian forest fire management. The fine fuel moisture code (FFMC) of the Canadian Fire Weather Index (CFWI) is used for determining ignition danger. The FFMC is calculated by using the Integrated Nowcasting through Comprehensive Analysis (INCA) system, which provides interpolated weather parameters, available at 1 km2 spatial resolution. Automated fuel sticks were used for measuring microclimate-defined moisture content from 2018 to 2020 in two differently structured sites: closed forest and forest gap. A remotely automated weather station (RAWS) measured the meteorological parameters of the research area. First, the capability of an interpolated large-scale FFMC to capture local moisture conditions was studied. Second, the effects of an interaction between forest structure and precipitation event characteristics on moisture content behaviour were investigated. Bayesian-based techniques in dependence of the three consecutive years were applied. Our results show that the correlations between INCA FFMC and RAWS FFMC are high (0.80–0.95) and INCA FFMC is capable of capturing the local microclimatic variations (0.68–0.78). Correlations ranging from 0.74 to 0.86 were evidenced between the fuel stick FFMC values of the forest and the gap, revealing that INCA FFMC cannot capture the microclimate induced differences between the two forest conditions. We found that: (i) the buffering capability of forest structure slows the absorption rate by 1.8 to 3.4%/h, (ii) absorption rate difference between the forest and the gap was lowest (1.8%/h) in the case of short and heavy rain, (iii) during the desorption phase the moisture content remained similar for both the closed forest and the gap. Overall, the structure induced buffering capability was strongest in the case of short and light rain. Longer and more intensive precipitation events, especially after canopy saturation during throughfall, are likely to lessen the buffering capability of the forest.

The Effects of Precipitation Event Characteristics and Afforestation on the Greening in Arid Grasslands, China

Global greening and its relationship with climate change remain the hot topics in recent years, and are of critical importance for understanding the interactions between the terrestrial ecosystem carbon cycle and the climate system. China, especially north China, has contributed a lot to global greening during the past few decades. As a water-limited ecosystem, human activities, not precipitation amount, were thought as the main contributor to the greening of north China. Considering the importance of precipitation event characteristics (PEC) in the altered precipitation regimes, we integrated long-term normalized difference vegetation index (NDVI) and meteorological datasets to reveal the role of precipitation regimes, especially PECs, on vegetation growth across temperate grasslands in north China. Accompanied with a significantly decreased growing season precipitation (GSP), NDVI increased significantly in the largest area of the temperate grasslands during 1982–2015, i.e., greening. We found that 28.44% of the area was explained by PECs, including more heavy or extreme precipitation events, alleviated extreme drought, and fewer light events, while only 0.92% of the area was associated with GSP. NDVI did not always increase over the 30 years and there was a decrease during 1996–2005. Taking afforestation projects in desertified lands into account, we found that precipitation, mainly PECs, explained more the increase and decline of NDVI during 1982–1995 and 1996–2005, respectively, while an equivalent explanatory power of precipitation and afforestation projects to the increase in NDVI after 2005. Our study indicates a possible higher productivity under future precipitation regime scenario (e.g., fewer but larger precipitation events) or intensive afforestation activity, implying more carbon sequestration or livestock production of temperate steppe in the future.

Analysis of extreme precipitation event characteristics and typical events based on the intensity–area–duration method in Liaoning Province

Analysis of extreme precipitation event characteristics and typical events based on the intensity–area–duration method in Liaoning Province

Stormflow concentration–discharge dynamics of suspended sediment and dissolved phosphorus in an agricultural watershed

AbstractConcentration–discharge (C‐Q) relationships are an effective tool for identifying watershed biogeochemical source and transport dynamics over short and long timescales. We examined stormflow C‐Q, hysteresis, and flushing patterns of total suspended sediment (TSS) and soluble reactive phosphorus (SRP) in two stream reaches of a severely impaired agricultural watershed in northeastern Wisconsin, USA. The upper watershed reach—draining a relatively flat, row crop‐dominated contributing area—showed predominantly anti‐clockwise TSS hysteresis during storms, suggesting that particulate materials were mobilized more from distal upland sources than near‐ and in‐channel areas. In contrast, the incised lower watershed reach produced strong TSS flushing responses on the rising limb of storm hydrographs and clockwise hysteresis, signalling rapid mobilization of near‐ and in‐channel materials with increasing event flows. C‐Q relationships for SRP showed complex patterns in both the upper and lower reaches, demonstrating largely non‐linear chemodynamic C‐Q behaviour during events. As with TSS, anti‐clockwise SRP hysteresis in the upper reach suggested a delay in the hydrologic connectivity between SRP sources and the stream, with highly variable SRP concentrations during some events. A broad range of clockwise, anti‐clockwise, and complex SRP hysteresis patterns occurred in the lower watershed, possibly influenced by in‐channel legacy P stores and connection to tile drainage networks in the lower watershed area. Total suspended sediment and SRP responses were also strongly related to precipitation event characteristics including antecedent precipitation, recovery period, and precipitation intensity, highlighting the complexity of stormflow sediment and phosphorus responses in this severely impaired agricultural stream.

Connectivity of Ephemeral and Intermittent Streams in a Subtropical Atlantic Forest Headwater Catchment

Stream network extension and contraction depend on landscape features and the characteristics of precipitation events. Although this dependency is widely recognized, the interaction among overland-flow generation processes, drainage active length, and frequency in temporary streams remains less understood. We studied a forest headwater catchment with wide variation in soil depth to investigate the runoff generation processes that lead to the occurrence of ephemeral and intermittent flow and connectivity between hillslope and outlet. We used low-cost equipment to monitor the variation in the length of the active drainage network and to measure the water table development. The flow in the channels can develop even under light rainfall conditions, while the connectivity is controlled by antecedent wetness, total precipitation, and active contribution area thresholds. Runoff permanence and fragmentation were related to soil depth variation; flow being usually more disconnected due to deeper water tables in deeper soil locations. Our findings emphasized the impact of soil structure on runoff generation in hillslopes and can be useful in the management of the most active areas and their impact on the quality of available water.

Responses of grassland ecosystem productivity to altered precipitation regime: A review.

Under global change scenario, precipitation pattern has significantly changed, mainly in the aspects of annual precipitation amount, precipitation seasonal distribution and precipitation event characteristics (size of individual precipitation event, periods length between two precipitation events, and number of precipitation events in a year), which combined to affect various processes of terrestrial ecosystems, especially productivity. Grassland ecosystem is one of the most sensitive ecosystems to the changes of precipitation regime. Therefore, it is necessary to clarify the responses of productivity to altered precipitation regime in grasslands. In this study, I firstly reviewed the responses of grassland productivity to each characteristic of the altered precipitation regime. Then, I summarized the methods that employed in the study of productivity-precipitation relationship, including long-term observations, manipulative field experiments, and modelling. Finally, I came up with several theoretical and methodological problems that needed to be solved in the future. This work would facilitate the understanding of how grasslands response to the global climate change, with implications for grassland management in the context of climate change.

Diagnosing added value of convection-permitting regional models using precipitation event identification and tracking

Dynamical downscaling with high-resolution regional climate models may offer the possibility of realistically reproducing precipitation and weather events in climate simulations. As resolutions fall to order kilometers, the use of explicit rather than parametrized convection may offer even greater fidelity. However, these increased model resolutions both allow and require increasingly complex diagnostics for evaluating model fidelity. In this study we use a suite of dynamically downscaled simulations of the summertime U.S. (WRF driven by NCEP) with systematic variations in parameters and treatment of convection as a test case for evaluation of model precipitation. In particular, we use a novel rainstorm identification and tracking algorithm that allocates essentially all rainfall to individual precipitation events (Chang et al. 2016). This approach allows multiple insights, including that, at least in these runs, model wet bias is driven by excessive areal extent of precipitating events. Biases are time-dependent, producing excessive diurnal cycle amplitude. We show that this effect is produced not by new production of events but by excessive enlargement of long-lived precipitation events during daytime, and that in the domain average, precipitation biases appear best represented as additive offsets. Of all model configurations evaluated, convection-permitting simulations most consistently reduced biases in precipitation event characteristics.

Hourly station‐based precipitation characteristics over the Tibetan Plateau

ABSTRACTBased on precipitation data collected from 100 surface stations on the Tibetan Plateau, the summer climatology of the hourly characteristics of precipitation events, including hourly frequency and intensity, frequency–intensity structure, diurnal circle, and duration, was comprehensively analysed. Both hourly frequency and intensity are high (low) over the southeastern (western and northern) plateau. In the Yurlung Zangbo River valley, which is located on the central southern plateau, the precipitation frequency is low and the intensity is high. The proportion of strong (weak) precipitation, in terms of frequency, is relatively large (small) in this valley, and similar features with respect to the frequency–intensity structure were also found for the northeastern plateau. In contrast, precipitation over the southern edge of the plateau is characterized by high frequency and low intensity, and the percentage of weak precipitation hours is higher than in other regions. Most stations over the plateau exhibit precipitation peaks either in late afternoon or around midnight. The late afternoon (midnight) peak is mainly contributed to by precipitation events that are short (long) in duration. These ‘short‐afternoon’ and long‐nighttime' types constitute the two major modes of precipitation over the plateau. Extreme events tend to begin in late afternoon, reach a maximum around midnight, and stop in the morning. The possible mechanisms are discussed. The quantity of available water vapour determines the geographical distribution of precipitation frequency through modulating the duration of precipitation events. High‐intensity events are related to well‐organized convective systems. The ratio of short‐afternoon and long‐nighttime precipitation is significantly influenced by local topography.

Evaluation of cool season precipitation event characteristics over the Northeast US in a suite of downscaled climate model hindcasts

Cool season precipitation event characteristics are evaluated across a suite of downscaled climate models over the northeastern US. Downscaled hindcast simulations are produced by dynamically downscaling the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA2) using the National Aeronautics and Space Administration (NASA)-Unified Weather Research and Forecasting (WRF) regional climate model (RCM) and the Goddard Earth Observing System Model, Version 5 (GEOS-5) global climate model. NU-WRF RCM simulations are produced at 24, 12, and 4-km horizontal resolutions using a range of spectral nudging schemes while the MERRA2 global downscaled run is provided at 12.5-km. All model runs are evaluated using four metrics designed to capture key features of precipitation events: event frequency, event intensity, even total, and event duration. Overall, the downscaling approaches result in a reasonable representation of many of the key features of precipitation events over the region, however considerable biases exist in the magnitude of each metric. Based on this evaluation there is no clear indication that higher resolution simulations result in more realistic results in general, however many small-scale features such as orographic enhancement of precipitation are only captured at higher resolutions suggesting some added value over coarser resolution. While the differences between simulations produced using nudging and no nudging are small, there is some improvement in model fidelity when nudging is introduced, especially at a cutoff wavelength of 600 km compared to 2000 km. Based on the results of this evaluation, dynamical regional downscaling using NU-WRF results in a more realistic representation of precipitation event climatology than the global downscaling of MERRA2 using GEOS-5.

Hydrologic Response of Four Ecological Sites to Natural Rainfall Events Within a Semiarid Watershed

Understanding the capture and redistribution of water within ecological sites should improve our understanding of the function of rangeland watersheds. We compare ecological site physical properties, runoff events, and precipitation event characteristics to assess the variability in hydrologic response of four ecological sites to natural rainfall events in a semiarid watershed in southeast Wyoming, United States. Ecological sites were selected on the basis of their extent of areal coverage in the watershed and their perceived importance in watershed scale hydrologic response. At each study site, four 12-m2 runoff plots were installed with collection troughs to capture and quantify the rate and amount of runoff. A tension infiltrometer was used to measure effective saturated hydraulic conductivity at the point scale, and a data-logging rain gauge was installed at each site to measure rainfall. One-way analysis of variance (α = 0.05) was used to compare the hydrologic characteristics of ecological sties. Amounts and intensities of rainfall required to generate runoff, timing of overland flow, and peak runoff rates differed (P < 0.05) among sites in their current state. We found differences in effective hydraulic conductivity, 20.30 mm hr−1 on shallow loamy site up to 50.40 mm hr−1 on the coarse upland, and plot water storage potential, which varied from 101.8 mm on the shallow loamy site to 472.0 mm on the loamy upland site, due to differences in soil depth and porosity among sites. After normalizing runoff according to rainfall depth, we found no statistical difference (P > 0.05) in the volumes of runoff produced by different sites. The amount of runoff generated on all sites was very small, indicating high infiltration and limited ponding and overland flow. Ecological sites were shown to have different hydrologic response characteristics (i.e., timing of runoff), suggesting that they can be used to better quantify and understand the variability in hydrology in rangeland watersheds.

解析雨量を用いた降雨の地域特性－松山平野を対象とした事例研究－

Though the radar-raingauge analyzed precipitation data is useful to analyze the temporal and spatial characteristics of precipitation, less attention has been paid on the impact of land-use on precipitation in study of the urban climate. This study focuses on the availability and the potential of the radar-raingauge analyzed precipitation data for the evaluation of local and regional rainfall. Thus, for this purpose two indices, “Rainfall intensity index“ and “Rainfall skewed index” has been introduced. We observed that the 7- year total precipitation shows the urban effect especially in warm season. These indices are promising for understanding the characteristics of precipitation events, though they hardly detect the urban effect on precipitation.

Contrasting responses of gross primary productivity to precipitation events in a water-limited and a temperature-limited grassland ecosystem

The impact of global climate change on precipitation regimes may bring about significant consequences to the productivity of grassland ecosystems. This study reports the effects of the characteristics of precipitation events (PEC, e.g., size, frequency, interval, and seasonal distribution of precipitation events) on gross primary productivity (GPP) based on long-term measurements of net ecosystem CO2 exchange and evapotranspiration by the eddy covariance technique in a water-limited temperate steppe in Inner Mongolia and a humid but temperature-limited alpine meadow in Tibet, China. We determined that the predominant characteristics of precipitation events that affected GPP differed remarkably between these two ecosystems. The number of heavy precipitation events (>10mmday−1) was the most important PEC to impact GPP in the temperate steppe. Years with more frequent heavy precipitation events favored higher GPP. However, in contrast with the case in the temperate steppe, precipitation interval was the factor that affected GPP most in the alpine meadow. GPP was higher as the precipitation intervals lengthened or their distribution shifted to fewer but longer intervals (concentrated distribution). Additionally, the mechanisms for the effects of PEC on GPP also differed between these two ecosystems. Compared with small events, heavy precipitation events recharged deeper soil layers in the temperate steppe, which was biologically more meaningful for plant transpiration (i.e., an increase in the ratio of transpiration to evapotranspiration), relief from drought stress (an increase in the duration of high soil water content), and thereby higher GPP. In contrast, mean air temperature was higher in the alpine meadow when the precipitation intervals increased or their distribution was more concentrated, leading to a longer period of higher temperature that was favorable to higher GPP. Our results imply that soil water is not the exclusive means of revealing the mechanism of precipitation affecting productivity; the corresponding changes in temperature along with precipitation events may also play a substantial role in temperature-limited grasslands.

Analysis of potential impacts of climate change on intensity–duration–frequency (IDF) relationships for six regions in the United States

Potential changes in climate are expected to lead to future changes in the characteristics of precipitation events, including extreme rainfall intensity in most regions. In order for government agencies and design engineers to incorporate these trends and future changes into assessment and design processes, tools for planning and design should be capable of considering nonstationary climate conditions. In this work, potential changes are investigated in intensity–duration–frequency (IDF) curves, which are often used for assessment of extreme rainfall events, using historic data and future climate projections. An approach is proposed for calculating IDF curves that incorporates projected changes in rainfall intensity at a range of locations in the United States. The results elucidate strong regional patterns in projected changes in rainfall intensity, which are influenced by the rainfall characteristics of the region. Therefore, impacts of climate change on extreme hydrologic events will be highly regional and thus such assessments should be performed for specific project locations.

Hydro-NEXRAD: metadata computation and use

To enable the efficient use of the Hydro-NEXRAD system in hydrologic research, the authors are developing and computing a set of metadata. Vast archives of radar-centric NEXRAD data, the highly variable spatial and temporal characteristics of precipitation events, and the existence of anomalous data complicate the process of selecting subsets of the data for specific investigation. Well-defined, pre-computed, radar-centric, basin-centric and point (for a selected set of rain gauge locations) metadata offer the possibility of efficiently selecting data subsets that meet user-specified criteria. Metadata have to be computed quickly so that they do not slow down the data ingest process, but they do not have to be highly accurate. Separating rainfall from clear air conditions and heavy rainfall from light precipitation is often sufficient. In this paper, the authors discuss the technical challenges of computing metadata for the vast archives of NEXRAD data and basic data quality control incorporated into that process. Users of Hydro-NEXRAD will be able to query the database using different criteria based on the metadata or visually inspect the time series of the metadata.

PRECIPITATION CHANGES FROM 1956 TO 1996 ON THE WALNUT GULCH EXPERIMENTAL WATERSHED1

ABSTRACT: The climate of Southern Arizona is dominated by summer precipitation, which accounts for over 60 percent of the annual total. Summer and non‐summer precipitation data from the USDA‐ARS Walnut Gulch Experimental Watershed are analyzed to identify trends in precipitation characteristics from 1956 to 1996. During this period, annual precipitation increased. The annual precipitation increase can be attributed to an increase in precipitation during non‐summer months, and is paralleled by an increase in the proportion of annual precipitation contributed during non‐summer months. This finding is consistent with previously reported increases in non‐summer precipitation in the southwestern United States. Detailed event data were analyzed to provide insight into the characteristics of precipitation events during this time period. Precipitation event data were characterized based on the number of events, event precipitation amount, 30‐minute event intensity, and event duration. The trend in non‐summer precipitation appears to be a result of increased event frequency since the number of events increased during nonsummer months, although the average amount per event, average event intensity, and average event duration did not. During the summer “monsoon” season, the frequency of recorded precipitation events increased but the average precipitation amount per event decreased. Knowledge of precipitation trends and the characteristics of events that make up a precipitation time series is a critical first step in understanding and managing water resources in semiarid ecosystems.

Meteorologic and isotopic characteristics of precipitation events with implications for groundwater recharge, Southern High Plains

Recharge estimates for the Ogallala aquifer in the Southern High Plains vary by two orders of magnitude (0.01 to 1.6 inches/yr or 0.25 to 41 mm/yr) because of differing interpretations of the contribution of the area's numerous playa lakes to the recharge of the aquifer. Higher rates are suggested by studies in which the playa lakes are assumed to be a major source of recharge. To reevaluate the recharge potential of precipitation, we measured meteorologic and isotopic properties of single precipitation events at five stations for one year. Values of precipitation for δ 18O (−22.7‰ to −4.7‰) and δD (−162% to +35%) plot along the world meteoric water line. Mean annual weighted values of δ 18O and δD are −7.5‰ and −48‰, respectively. Air masses from the Gulf of Mexico account for most summer precipitation, which is more isotopically enriched than winter precipitation, mainly derived from air masses from the eastern Pacific Ocean. Precipitation is more depleted in δ 18O and δD toward the northwestern part of the Southern High Plains, becoming isotopically enriched toward the southeast. These isotopic differences reflect temperature, continental, and altitude effects. Isotopic composition of Ogalla ground water has a spatial distribution similar to that of precipitation. Ground water, however, is consistently more enriched than precipitation sampled in the same area, suggesting evaporation during recharge. Evaporation can occur either in playa lakes prior to infiltration or in the vadose zone. Tritium in precipitation ranges from 1.1 to 14.7 TU, and in groundwater it ranges from zero where the vadose zone is thick, to 73 TU, where the zone is thin. The calculated recharge rate (using tritium as a tracer) ranges from 0.5 to 3.24 inches/yr, or 12.7 to 82 mm/yr. Such high recharge rates were only measured below playa lakes. Because of the fast recharge rates and the slightly enriched values of δ 18O and δD in ground water, the Ogalla a aquifer is most likely recharged by focused percolation of partly evaporated playa lake water, rather than by slow regional diffusive percolation of precipitation.