Rainfall Record Research Articles

SMAP observes flooding from land to sea: The Texas event of 2015

AbstractFloods can have damaging impacts on both land and sea, yet studies of flooding events tend to focus on only one side of the land/sea continuum. Here we present the first two‐sided analysis, focusing on the May 2015 severe flooding in Texas. Our investigation benefits from simultaneous measurements of land surface soil moisture and sea surface salinity from NASA's recent Soil Moisture Active Passive (SMAP) mission as well as ancillary data. We report the comprehensive chronology of the flooding: above average rainfall preceding the flood caused soils to saturate; record rainfall then generated record river discharge; and subsequently, an unusual freshwater plume associated with anomalous ocean currents formed in the north central Gulf of Mexico. Together with the Mississippi River plume, a rare “horseshoe” pattern was created that may have significant biogeochemical implications. Such integrated land/sea analysis of flood evolution can improve impact assessments of future extreme flooding events.

Ocurrencia de eventos de sequías en la ciudad de Santiago de Chile desde mediados del siglo XIX

High quality instrumental precipitation records are useful in evaluating extreme events suchs as droughts and their recurrence rate at different time scales. The city of Santiago de Chile has a historical rainfall record that started in 1867, making it one of the most complete and extensive in South America. In this work, April through October precipitation have been analyzed over the 1867 - 2015 period in order to evaluate moderate, severe and extreme of droughts occurrence rate based on precipitation reductions. Main results expose an increase of all types of droughts since 1930 and an increase of consecutive drought episodes unprecedented over the instrumental period. In addition, there has been an increase in extreme droughts occurring from May to June since 1950 indicanting very dry winter conditions for the city of Santiago, Chile.

Squeezing a rainfall record out of desert sand dunes

Squeezing a rainfall record out of desert sand dunes

The North Antrim Flood of October 1990

The frontal depression of the 27-28 October 1990 was responsible for remarkable rainfall intensities and record floods in northeast Ireland. The synoptic event is described, and the dynamic and orographic influences responsible for the highly localized nature of the mesoscale precipitation signatures outlined. Intense precipitation had its most dramatic impact in Ballycastle and Cushendall, where flooding was widespread. Extreme precipitation was the causal factor, but the event draws attention to perceived changes of flow regimes and landuse in the upper catchments of rivers in North Antrim. A need exists to closely monitor the hydrological characteristics of these catchments in order to calibrate more precisely the flood hazard in this part of northeast Ireland.

Quantification of southwest China rainfall during the 8.2 ka BP event with response to North Atlantic cooling

Abstract. The 8.2 ka BP event could provide important information for predicting abrupt climate change in the future. Although published records show that the East Asian monsoon area responded to the 8.2 ka BP event, there is no high-resolution quantitative reconstructed climate record in this area. In this study, a reconstructed 10-year moving average annual rainfall record in southwest China during the 8.2 ka BP event is presented by comparing two high-resolution stalagmite δ18O records from Dongge cave and Heshang cave. This decade-scale rainfall reconstruction is based on a central-scale model and is confirmed by inter-annual monitoring records, which show a significant positive correlation between the regional mean annual rainfall and the drip water annual average δ18O difference from two caves along the same monsoon moisture transport pathway from May 2011 to April 2014. Similar trends between the reconstructed rainfall and the stalagmite Mg ∕ Ca record, another proxy of rainfall, during the 8.2 ka BP period further increase the confidence of the quantification of the rainfall record. The reconstructed record shows that the mean annual rainfall in southwest China during the central 8.2 ka BP event is less than that of present (1950–1990) by ∼ 200 mm and decreased by ∼ 350 mm in ∼ 70 years experiencing an extreme drying period lasting for ∼ 50 years. Comparison of the reconstructed rainfall record in southwest China with Greenland ice core δ18O and δ15N records suggests that the reduced rainfall in southwest China during the 8.2 ka BP period was coupled with Greenland cooling with a possible response rate of 110 ± 30 mm °C−1.

Coastal evacuations by fish during extreme weather events

An increase in the intensity and frequency of extreme events is predicted to occur as a result of climate change. In coastal ecosystems, hurricanes and flooding can cause dramatic changes in water quality resulting in large mortality events in estuarine fauna. Facultative migration behaviors represent a key adaptation by which animals can evacuate ecological catastrophes, but remain poorly studied in marine systems. Here we identify coastal evacuations by otherwise resident riverine striped bass in the Hudson River Estuary, New York, USA, caused by an intense period of tropical storms in autumn 2011. These storms produced record rainfall and high water discharges into the Hudson River Estuary that increased the water level and reduced the water temperature, salinity and dissolved oxygen levels. Striped bass moved out of the estuary, exhibiting novel migration behaviours, that may have been in response to the strong flow and unsuitable conditions. In the months following the storms, some fish demonstrated exploratory trips back to the estuary, which may have been to assess the conditions before returning for the remainder of the winter. Behavioural adaptions to weather events by striped bass and other coastal fishes will depend on maintenance of key population segments and unimpeded evacuation routes.

A Regional Stable Carbon Isotope Dendro-Climatology from the South African Summer Rainfall Area.

Carbon isotope analysis of four baobab (Adansonia digitata L.) trees from the Pafuri region of South Africa yielded a 1000-year proxy rainfall record. The Pafuri record age model was based on 17 radiocarbon dates, cross correlation of the climate record, and ring structures that were presumed to be annual for two of the trees. Here we present the analysis of five additional baobabs from the Mapungubwe region, approximately 200km west of Pafuri. The Mapungubwe chronology demonstrates that ring structures are not necessarily annually formed, and accordingly the Pafuri chronology is revised. Changes in intrinsic water-use efficiency indicate an active response by the trees to elevated atmospheric CO2, but this has little effect on the environmental signal. The revised Pafuri record, and the new Mapungubwe record correlate significantly with local rainfall. Both records confirm that the Medieval Warm Period was substantially wetter than present, and the Little Ice Age was the driest period in the last 1000 years. Although Mapungubwe is generally drier than Pafuri, both regions experience elevated rainfall peaking between AD 1570 and AD 1620 after which dry conditions persist in the Mapungubwe area until about AD 1840. Differences between the two records correlate with Agulhas Current sea-surface temperature variations suggesting east/west displacement of the temperate tropical trough system as an underlying mechanism. The Pafuri and Mapungubwe records are combined to provide a regional climate proxy record for the northern summer rainfall area of southern Africa.

Лізиметр - унікальний інструмент для контролю взаємодії між компонентами середовища

Сучасні лізиметричні об'єкти у зв'язку з метеорологічними станціями дозволяють здійснювати контроль та оцінку екосистемно пов'язаних основних компонентів довкілля, таких як вода, повітря, ґрунт і рослинність. Вода є найбільш важливим компонентом екосистеми та елементом, який поєднує всі інші компоненти. Тому необхідне знання щодо основного розподілу і водного балансу у різних компонентах довкілля, щоб інтерпретувати процеси в природі. Кількість опадів, що є основним джерелом життєво важливих процесів у ґрунті, формується в повітрі. Кількість опадів, що потрапляє в ґрунт і ґрунтові води, залежить від погодних умов. Первинний розподіл дощової води ділиться між інфільтрацією, поверхневим стоком, транспірацією та евапотранспірацією. Кількість води, що проникає в ґрунт, а потім випаровується за рахунок сонячної активності або діяльності рослин, можна визначити, у першу чергу, шляхом моніторингу змін у вазі. Для цього моніторингу ми використовуємо вагомий лізиметр. Це обладнання розміром з моноліт, площа поверхні якого 1 м2 і глибина 1,5 м, здатне стежити в онлайн режимі за оновленням ваги маси в 2 тони з точністю до 100 г. Коли ми додаємо до кількісної оцінки фільтрат нижнього шару, ми отримуємо повноцінний облік опадів в довкіллі щодо окремих компонентів. Отримані дані можна інтерпретувати з точки зору потреб гідрології, сільського господарства, довкілля та відповідно до цілей і завдань, для яких ми хочемо їх використовувати.

Investigating the Homogeneity of Monthly Rainfall Records in Kenya

Investigating the Homogeneity of Monthly Rainfall Records in Kenya

The Historic South Carolina Rainfall and Major Floods of October 1-5, 2015

A record setting and historic rainfall event occurred October 1-5, 2015, producing widespread and significant flooding across much of South Carolina. The rainfall resulted from several atmospheric and hydrometeorological factors. The record rainfall triggered flash floods and riverine flooding that resulted in emergency evacuations, travel disruptions, personal property damage, business losses, bridge collapses, dam failures and tragic loss of life. Precipitation records were broken from the midlands to the coast, with totals ranging from 10 to over 26 inches of rain. Sixteen National Weather Service Cooperative Weather Stations set new 24-hour rainfall records for October. The amount of rainfall during the event at various locations and for various durations (6-, 24-, 48-, 72-, 96- hours) had a statistical probability of occurrence of 0.1% or 1 in 1,000 chance of happening in any given year, according to the National Oceanic and Atmospheric Administration (NOAA) Atlas 14. Streams and creeks swelled out of their banks with at least 17 U.S. Geological Survey (USGS) stream gages reaching record peaks. The event was the worst flooding most residents had ever experienced. This report will provide a synoptic and chronological overview of how the historic rain and flooding unfolded with documentation of the meteorological and hydrological records. A comprehensive interactive journal of the event is available on-line at http://www.dnr.sc.gov/flood2015.

A high resolution proxy rainfall record from isotopic analysis of trees from southern Africa

A high resolution proxy rainfall record from isotopic analysis of trees from southern Africa

An ice core derived 1013-year catchment-scale annual rainfall reconstruction in subtropical eastern Australia

Abstract. Paleoclimate research indicates that the Australian instrumental climate record (∼ 100 years) does not cover the full range of hydroclimatic variability that is possible. To better understand the implications of this on catchment-scale water resources management, a 1013-year (1000–2012 common era (CE)) annual rainfall reconstruction was produced for the Williams River catchment in coastal eastern Australia. No high-resolution paleoclimate proxies are located in the region and so a teleconnection between summer sea salt deposition recorded in ice cores from East Antarctica and rainfall variability in eastern Australia was exploited to reconstruct the catchment-scale rainfall record. The reconstruction shows that significantly longer and more frequent wet and dry periods were experienced in the preinstrumental compared to the instrumental period. This suggests that existing drought and flood risk assessments underestimate the true risks due to the reliance on data and statistics obtained from only the instrumental record. This raises questions about the robustness of existing water security and flood protection measures and has serious implications for water resources management, infrastructure design and catchment planning. The method used in this proof of concept study is transferable and enables similar insights into the true risk of flood/drought to be gained for other paleoclimate proxy poor regions for which suitable remote teleconnected proxies exist. This will lead to improved understanding and ability to deal with the impacts of multi-decadal to centennial hydroclimatic variability.

A comparison of two optical precipitation sensors with different operating principles: The PWS100 and the OAP-2DP

Precipitation measurements can be performed with a variety of techniques and instruments. Optical devices allow for rain measurements in terms of the number and size of individual drops and have been helpful to improve the knowledge of the processes involved in the development and variability of precipitation. A comparative study was conducted during natural rain events in Mexico City using two classes of optical instruments: a light beam occlusion type (OAP-2DP) and a light scatter sensor (PWS100). The sensors were collocated a few metres from each other, along with a tipping bucket rain gauge to simultaneously record rainfall intensity. The results show that both optical instruments measured larger amounts of accumulated rain compared to the rain gauge. Bias and percent bias outcomes suggest that the PWS100 records the largest rain amounts among the devices used, but statistical analyses and the study of instrumental uncertainties did not provide enough evidence to prove significant differences in rain estimation. Although the PWS100 detects larger drops than the OAP-2DP, no significant differences were found between the liquid water content estimates obtained with them. Drop size spectra and velocity distributions also showed good agreement. In particular, both instruments showed similar characteristics for drop fall speed distributions that may be attributed to effects in the hydrometeor fall behaviour produced by horizontal wind. It is concluded that the performance of these two optical instruments is very similar, and that the PWS100 provides reliable data for rain measurements.

Co-evolution of monsoonal precipitation in East Asia and the tropical Pacific ENSO system since 2.36 Ma: New insights from high-resolution clay mineral records in the West Philippine Sea

Clay mineralogical analysis and scanning electron microscope (SEM) analysis were performed on deep-sea sediments cored on the Benham Rise (core MD06-3050) in order to reconstruct long-term evolution of East Asian Summer Monsoon (EASM) rainfall in the period since 2.36 Ma. Clay mineralogical variations are due to changes in the ratios of smectite, which derive from weathering of volcanic rocks in Luzon Island during intervals of intensive monsoon rainfall, and illite- and chlorite-rich dusts, which are transported from East Asia by winds associated with the East Asian Winter Monsoon (EAWM). Since Luzon is the main source of smectite to the Benham Rise, long-term consistent variations in the smectite/(illite + chlorite) ratio in core MD06-3050 as well as ODP site 1146 in the Northern South China Sea suggest that minor contributions of eolian dust played a role in the variability of this mineralogical ratio and indicate strengthening EASM precipitation in SE Asia during time intervals from 2360 to 1900 kyr, 1200 to 600 kyr, and after 200 kyr. The EASM rainfall record displays a 30 kyr periodicity suggesting the influence of El Nino–Southern Oscillation (ENSO). These intervals of rainfall intensification on Luzon Island are coeval with a reduction in precipitation over central China and an increase in zonal SST gradient in the equatorial Pacific Ocean, implying a reinforcement of La Nina-like conditions. In contrast, periods of reduced rainfall on Luzon Island are associated with higher precipitation in central China and a weakening zonal SST gradient in the equatorial Pacific Ocean, thereby suggesting the development of dominant El Nino-like conditions. Our study, therefore, highlights for the first time a long-term temporal and spatial co-evolution of monsoonal precipitation in East Asia and of the tropical Pacific ENSO system over the past 2.36 Ma.

Flood Frequency Analysis (FFA) in Spanish catchments

Summary A frequency analysis of rainfall and flow from the available data and applications in Spain takes place. In the case of streamflow, various methods that can be grouped into two categories are used, (1) the gauged method which consist in the analysis of maximum flow rate annual series, and (2) the hydro-meteorological method which take into account processes with rainfall–runoff transformation models. The results are compared with observed data in historical series. Finally, six episodes with actual rainfall and flow record are analyzed. These episodes are also classified according to their frequency domain and results obtained from models are contrasted. To make this work we have used two applications launched in the University of Zaragoza: the SHEE program, which provides a simple and flexible working environment which allows the simultaneous management of the most actual and important databases from a hydrological point of view, highlighting the digital terrain models, the rainfall coverage and the curve number coverage, and that is suitable for the application of hydro-meteorological models; and the EHVE software, which is a hydrological statistical program for analysis of time series of extreme values, suitable for application in models of gauged data.

Inconsistency in rainfall characteristics estimated from records of different rain gauges

The goal of this work is to assess the effect of utilizing different types of tipping bucket rain gauges in investigating rainfall characteristics. A dual tipping bucket (TB) rain gauge station is installed in the upper catchment of Numan basin in Saudi Arabia. The main difference between the two gauges is that the Hydrological Services (HS) gauge is equipped with a siphon tube which reduces undercatchment particularly during heavy rainfall. Records of both gauges for the period 2006 to 2013 are collected, analyzed, and compared, focusing on the characteristics of rainfall events as well as rainfall temporal variability. The HS gauge recorded higher values of total rainfall depth compared to the Texas Electronics (TEMM) gauge. For the individual storms as well as the 5-min rainfall, HS gauge also reported higher mean rainfall depths. Regarding temporal characteristics of reported rainfall, no significant variations are observed between the values of storm duration of the two gauges. The TEMM gauge has the advantage of recoding more storms with depth less than 1 mm. The current study suggests the use of a corrective factor for rainfall record of the TEMM gauge.

Quantification of the effect of forest harvesting versus climate on streamflow cycles and trends in an evergreen broadleaf catchment

ABSTRACTA new method known as Unobserved Components–Dynamic Harmonic Regression (UC-DHR) was applied to a 39-year record of rainfall and streamflow for three sub-catchments of the Sarukawa Experimental Watershed in southwestern Japan. Some 25% of the timber was harvested from one of the sub-catchments in May–July 1982 and the objective was to quantify the magnitude of this effect relative to the effects of climate cycles (e.g. Southern Oscillation Index). The observed effects of inter-annual climate cycles (i.e. 0.89–1.36 mm/d) were seen to be comparable (i.e. 0.70–1.17 mm/d) to the effects of harvesting 25% of the standing timber. This result underlines the importance of always quantifying the effect of climate on streamflow response when harvesting impacts are studied.Editor D. Koutsoyiannis; Associate editor T. Okruszko

WRF simulation of the heavy rainfall over Metropolitan Manila, Philippines during tropical cyclone Ketsana: a sensitivity study

In September 2009, tropical cyclone Ketsana brought record rainfall over Metropolitan Manila, Philippines, resulting in widespread flooding and incapacitated the city for days. The extensive damage caused by heavy rainfall events such as this highlights the need to have an effective weather prediction model to forecast these extreme events for the Philippines. As an initial step towards this goal, this study aims to examine the sensitivity of the rainfall simulation of the Weather Research and Forecasting (WRF) model to the physical parameterization schemes related to the planetary boundary layer (PBL) and microphysics processes. Comparison with observation data shows that the PBL scheme influences the spatial distribution of rainfall, whereas the microphysics scheme can affect rainfall magnitudes. The PBL scheme can also affect the intensity and track of the tropical cyclone as indicated in the surface latent heat flux and vertical velocity, as well as the magnitude of the mixing ratio of the different hydrometeors, which consequently affects the simulated rainfall. On the other hand, microphysics schemes can also influence the vertical distribution of each hydrometeor, likely due to differences in the treatment of ice phase processes and its interaction with the PBL scheme. Among the schemes tested, the model simulation using the ACM2 PBL and the WSM6 microphysics schemes captures this particular heavy rainfall event, in terms of spatial distribution, amount and timing. The results of this study show the importance of the PBL and microphysics schemes in simulating heavy rainfall, as well as the high potential of using WRF for future forecasts, especially for extreme weather events in the Philippines.

The stable hydrogen isotopic composition of sedimentary plant waxes as quantitative proxy for rainfall in the West African Sahel

Various studies have demonstrated that the stable hydrogen isotopic composition (δD) of terrestrial leaf waxes tracks that of precipitation (δDprecip) both spatially across climate gradients and over a range of different timescales. Yet, reconstructed estimates of δDprecip and corresponding rainfall typically remain largely qualitative, due mainly to uncertainties in plant ecosystem net fractionation, relative humidity, and the stability of the amount effect through time. Here we present δD values of the C31n-alkane (δDwax) from a marine sediment core offshore the Northwest (NW) African Sahel covering the past 100years and overlapping with the instrumental record of rainfall. We use this record to investigate whether accurate, quantitative estimates of past rainfall can be derived from our δDwax time series. We infer the composition of vegetation (C3/C4) within the continental catchment area by analysis of the stable carbon isotopic composition of the same compounds (δ13Cwax), calculated a net ecosystem fractionation factor, and corrected the δDwax time series accordingly to derive δDprecip. Using the present-day relationship between δDprecip and the amount of precipitation in the tropics, we derive quantitative estimates of past precipitation amounts. Our data show that (a) vegetation composition can be inferred from δ13Cwax, (b) the calculated net ecosystem fractionation represents a reasonable estimate, and (c) estimated total amounts of rainfall based on δDwax correspond to instrumental records of rainfall. Our study has important implications for future studies aiming to reconstruct rainfall based on δDwax; the combined data presented here demonstrate that it is feasible to infer absolute rainfall amounts from sedimentary δDwax in tandem with δ13Cwax in specific depositional settings.

Activity of Slow-Moving Landslides Recorded in Eccentric Tree Rings of Norway Spruce Trees (<i>Picea Abies</i> Karst.) — An Example from the Kamienne MTS. (Sudetes MTS., Central Europe)

We found ubiquitous evidence of ongoing slope instability by analysing the variability of tree-ring eccentricity index in trees growing on three apparently relict landslide slopes in the Sudetes (Poland, Central Europe). Slow movement of these landslide bodies occurs in the present-day conditions and is recorded almost every year, although with variable intensity. Correlation of dendrochronological record with the rainfall record from a nearby station in Mieroszów for the 1977–2007 period is very poor for two deep-seated rotational slides at Mt Suchawa and Mt Turzyna but considerably better for a shallow flowslide at Mt Garbatka. While this may reflect higher permeability of heavily jointed rocks involved in deep-seated sliding this could be linked with imperfections in the rainfall record. Dendrochronology proved capable of detecting minor displacements within landslides which otherwise show no geomorphic evidence of recent activity. Therefore, claims for the entirely relict nature of the landslides are not substantiated.