Average Rainfall Rate Research Articles

Estimating methane emissions from landfills based on rainfall, ambient temperature, and waste composition: The CLEEN model

Accurately estimating landfill methane emissions is important for quantifying a landfill’s greenhouse gas emissions and power generation potential. Current models, including LandGEM and IPCC, often greatly simplify treatment of factors like rainfall and ambient temperature, which can substantially impact gas production. The newly developed Capturing Landfill Emissions for Energy Needs (CLEEN) model aims to improve landfill methane generation estimates, but still require inputs that are fairly easy to obtain: waste composition, annual rainfall, and ambient temperature. To develop the model, methane generation was measured from 27 laboratory scale landfill reactors, with varying waste compositions (ranging from 0% to 100%); average rainfall rates of 2, 6, and 12mm/day; and temperatures of 20, 30, and 37°C, according to a statistical experimental design. Refuse components considered were the major biodegradable wastes, food, paper, yard/wood, and textile, as well as inert inorganic waste. Based on the data collected, a multiple linear regression equation (R2=0.75) was developed to predict first-order methane generation rate constant values k as functions of waste composition, annual rainfall, and temperature. Because, laboratory methane generation rates exceed field rates, a second scale-up regression equation for k was developed using actual gas-recovery data from 11 landfills in high-income countries with conventional operation.The Capturing Landfill Emissions for Energy Needs (CLEEN) model was developed by incorporating both regression equations into the first-order decay based model for estimating methane generation rates from landfills. CLEEN model values were compared to actual field data from 6 US landfills, and to estimates from LandGEM and IPCC. For 4 of the 6 cases, CLEEN model estimates were the closest to actual.

Dissolution on Titan and on Earth: Toward the age of Titan's karstic landscapes

AbstractTitan's polar surface is dotted with hundreds of lacustrine depressions. Based on the hypothesis that they are karstic in origin, we aim at determining the efficiency of surface dissolution as a landshaping process on Titan, in a comparative planetology perspective with the Earth as reference. Our approach is based on the calculation of solutional denudation rates and allow inference of formation timescales for topographic depressions developed by chemical erosion on both planetary bodies. The model depends on the solubility of solids in liquids, the density of solids and liquids, and the average annual net rainfall rates. We compute and compare the denudation rates of pure solid organics in liquid hydrocarbons and of minerals in liquid water over Titan and Earth timescales. We then investigate the denudation rates of a superficial organic layer in liquid methane over one Titan year. At this timescale, such a layer on Titan would behave like salts or carbonates on Earth depending on its composition, which means that dissolution processes would likely occur but would be 30 times slower on Titan compared to the Earth due to the seasonality of precipitation. Assuming an average depth of 100 m for Titan's lacustrine depressions, these could have developed in a few tens of millions of years at polar latitudes higher than 70°N and S, and a few hundreds of million years at lower polar latitudes. The ages determined are consistent with the youth of the surface (<1 Gyr) and the repartition of dissolution‐related landforms on Titan.

Rapid appraisal of rainfall threshold and selected landslides in Baguio, Philippines

Among the most landslide prone in the Philippines is the Baguio district, a center of trade, commerce, education and governance. It also has the highest recorded rainfall in the country. Rainfall-induced landslides (RILs) occur yearly and are triggered by rainfall due to southwest monsoon, tropical cyclones and their interactions; and orographic lifting by the Cordillera mountain range. Both natural and human factors contribute to the region’s susceptibility to RIL. Fatalities can reach hundreds, and economic damages may reach billions of dollars per event. The rainfall and reported RIL occurrence were compiled for the period 2000–2013. The characteristics and impact of major RIL such as those instigated by Typhoon Parma in October 2009 are highlighted. Most landslides were associated with tropical cyclones, enhanced monsoon flow and 24-h rainfall that ranged from 73 to 1086 mm, corresponding to average rainfall rates of 3–45 mm per hour. The number of daily-reported landslide incidents ranged from 1 to 41. Slides, debris flows and earth flows were observed as the predominant types. As the observed landslide-triggering rainfall is below or within the range of the observed yearly maximum 24-h rainfall, which is 164–1086 mm, RIL will likely continue to occur annually and pose a major challenge for Baguio. The minimum of 70-mm daily rainfall may serve as a threshold for early landslide advisory. Given the limited number of landslides and analysis of landslide occurrence in relation to other controlling/predisposing factors undertaken, the threshold identified can only be regarded as indicative.

Climate change and tectonic uplift triggered the formation of the Atacama Desert’s giant nitrate deposits

The giant nitrate deposits of the hyperarid Atacama Desert (Chile) are one of the most extraordinary, yet enigmatic, mineral occurrences on Earth. These deposits are complex assemblages of highly soluble nitrates, chlorides, sulfates, perchlorates, iodates, and chromates, and their preservation is the result of prevalent hyperarid climate conditions in the Atacama Desert since the late Miocene, with average rainfall rates of <10 mm/yr in the past ~3 m.y. Although several hypotheses have been proposed since the mid-1800s, the formation of these extensive deposits still remains highly controversial despite the fact that recent studies have argued toward an atmospheric source for the nitrate, sulfate, and perchlorate components. In this report, we focus on the often overlooked and poorly studied iodine and chromium components of Atacama’s nitrates. We present the fi rst cosmogenic iodine ( 129 I) and stable chromium (δ 53/52 Cr) isotope data of nitrates showing that groundwater has played an unforeseen role in the formation of these massive deposits. The isotopic signature of I in the nitrates ( 129 I/I ~150–600 × 10 –15 ) share similarities with deep sedimentary (marine) pore waters and shales, deviating signifi cantly from atmospheric iodine ( 129 I/I ~1500 × 10 –15 ), while the positive and highly fractionated δ 53/52 Cr SRM979 values (+0.7‰ to +3‰) are indicative of intense Cr redox cycling due to groundwater transport. Our evidence points toward a multi-source genetic model for the Atacama Desert nitrate deposits, where these extensive accumulations were the result of long-lived, near-surface mineral precipitation driven by groundwater (i.e., chromates, iodates) coupled with dry atmospheric deposition (i.e., nitrates, perchlorates) and sea spray inputs (i.e., sulfates, chlorides), triggered by increasing aridity and tectonic uplift.

Incidence of lettuce downy mildew (Bremia lactucae) and powdery mildew (Golovinomyces cichoracearum) in natural populations of prickly lettuce (Lactuca serriola)

The study was focused on the wild pathosystem Lactuca serriola&amp;ndash;lettuce downy mildew (Bremia lactucae) and lettuce powdery mildew (Golovinomyces cichoracearum). Observations were focused mainly on recording natural infection of prickly lettuce (Lactuca serriola) by downy and powdery mildews in the East Bohemia and Moravia (the Czech Republic) in the May&amp;ndash;September period of 2007&amp;ndash;2011, and on the influence of environmental conditions on disease incidence. Only data for July and August were used for the detailed comparisons of occurrence of both pathogens, because intensity of disease in this period was the highest. Data were linked with the average monthly temperature and rainfall rate in the Czech Republic. G. cichoracearum prefers rather low levels of precipitation and temperatures around 20&amp;deg;C, therefore significantly higher incidence of this pathogen was recorded in August 2007. On the other hand in July 2009 and 2010, when the intensities of precipitation were higher, incidence of Bremia lactucae prevailed. In August 2010 and 2011 incidence of both pathogens were more or less similar at all locations. Our observations showed that climatic conditions influence the incidence and prevalence of both pathogens in weedy growing populations of Lactuca serriola.

Above-treeline Linanthus pungens shrub-chronologies on the eastern Sierra Nevada crest, Mono county, California contain records of precipitation and temperature

It is hotly debated whether and how climate changes are recorded by terrestrial stratigraphy. Basin sediments produced by catchment-alluvial fan systems may record past climate over a variety of timescales, and could offer unique information about how climate controls sedimentation. Unfortunately, there are fundamental uncertainties about how climatic variables such as rainfall and temperature translate into sedimentological signals. Here, we examine 35 debris flow fan surfaces in Owens Valley, California, that record deposition throughout the past 125,000 years, during which climate has varied significantly. We show that the last full glacial-interglacial cycle is recorded with high fidelity by the grain size distributions of the debris flow deposits. These flows transported finer sediment during the cooler glacial climate, and became systematically coarser-grained as the climate warmed and dried. We explore the physical mechanisms that might explain this signal, and rule out changes in sediment supply through time. Instead, we propose that grain size records past changes in storm intensity, which is responsible for debris flow initiation in this area and is decoupled from average rainfall rates. This is supported by an exponential Clausius-Clapeyron-style scaling between grain size and temperature, and also reconciles with climate dynamics and the initiation of debris flows. The fact that these alluvial fans exhibit a strong, sustained sensitivity to orbital climate changes sheds new light on how eroding landscapes and their sedimentary products respond to climatic forcing. Finally, our findings highlight the importance of threshold-controlled events, such as storms and debris flows, in driving erosion and sedimentation at the Earth's surface in response to climate change.

Evaluation of forest interception estimation in the continental scale Australian Water Resources Assessment – Landscape (AWRA-L) model

summary The AWRA-L model is a core component of the joint Bureau of Meteorology (BOM) and CSIRO Australian Water Resources Assessment (AWRA) system which integrates hydrological models and a variety of observations and satellite products to produce a National Water Accounting system for Australia. AWRA-L is a continental scale sub-model which provides surface water balance component estimates for all landscape types, including forests ranging from sparse woody vegetation in dry climates to dense tropical rainforest in wet climates. This paper describes the AWRA-L interception sub-routine, which is based on the widely used Gash model, and considers how its predictions compare with measurements of interception in tropical rainforests in north Queensland and sparse jarrah forests in Western Australia. The results demonstrate the importance of having accurate estimates of the three parameters which dominate the interception loss (as a fraction of rainfall), i.e. canopy water holding capacity, S, the average wet canopy evaporation rate, E, and the average rainfall rate, R. The current ‘default’ values of these parameters used in AWRA-L lead to significant errors in interception, which will also be reflected in the AWRA stream flow estimates. Analysis of how E and R values vary across the Australian continent have led to recommendations for how the interception calculations made by the AWRA-L model can be improved using values of E and R calculated from forest height and latitude. Revisions of the canopy storage parameters based on regressions derived from measured values at the rainforest and jarrah sites are also evaluated. Overall, the adoption of both updated canopy storage and E/R ratios outlined in this paper does provide a measurable improvement to the performance of the AWRA-L interception model. The approach developed in this study also has direct relevance to other applications of interception models for water balance modelling at large spatial scales.

Sub-daily rainfall events in an arid environment with marked climate variability: Variation among wet and dry years at Fowlers Gap, New South Wales, Australia

The nature of rainfall events is explored through six years of below average rainfall, associated with negative Southern Oscillation Index (SOI), and three years of above average rainfall, associated with positive SOI (and strong La Niña conditions), at arid Fowlers Gap, Australia. There is a greater probability of rainfall in wet years, but the events themselves also change significantly. Rainfall depth per event was 116% larger on average in wet years than dry, and average event rainfall rate was 85% higher. However, these results are influenced by a small number of very large events in the wet years, and events of <2 mm occur at about the same rate in dry and wet years. Rainfall event profiles in dry years showed more Huff first quartile events likely to promote partitioning of rain into infiltration. In contrast, larger events in wet years showed a preponderance of Huff third quartile profiles likely to be associated with greater partitioning of rainfall into overland flow. This co-variation in rainfall event profile with annual rainfall, not previously described, is reasoned to increase the amplitude of ecological impacts of the SOI-related rainfall variability at this site.

As amenidades naturais influenciam a escolha locacional dos trabalhadores? evidências para as regiões metropolitanas brasileiras

O artigo apresenta evidências da importância das características naturais das regiões metropolitanas brasileiras para as escolhas locacionais dos trabalhadores. A análise baseia-se no modelo de escolha locacional de Roback (1982), a partir do qual é derivado o valor que os trabalhadores atribuem para morar em localidades que lhe ofertem um bom consumo de amenidades naturais. Os principais resultados da pesquisa indicam que os trabalhadores estão dispostos a pagar para morar nas RMs mais próximas à costa, com os maiores índices médios anuais de precipitação, nas RMs mais úmidas, e com as maiores temperaturas médias no mês de janeiro. Por outro lado, os trabalhadores devem ser compensados monetariamente para morar nas RMs com os maiores índices médios de precipitação em setembro e com as maiores temperaturas médias em julho.

Ecological characteristics of Sahastradhara stream at Dehradun (Uttarakhand)

Sahastradhara sulphur stream is a natural perennial hill stream which originates from the upper mountainous terrains of Mussoorie in Garhwal region. The climate of Garhwal region depends on the temperature variability. on monthly and seasonally changing patterns. Sahastradhara stream had a cool and pleasant climate but at current stage it has changed at a great extent due to natural and anthropogenic factors. In the present study, the changes were recorded as annual average temperature (3.4 °C – 38.3 °C), wind velocity (0.9 km - 2.5 km), rainfall (225 mm – 371 mm), precipitation and sedimentation rate just double from two decay periods. Twenty tree genera of macrobenthic organisms in sediments and other existed native species of macrophytic vegetation in littoral zones of stream. The physico-chemical characteristics of Sahastradhara hill-stream showed seasonal variations and influenced the distributional patterns of macrobenthic communities. Presently, eco-biological characteristics of Sahastradhara stream exhibited continuous degradation nature in and around stream ecosystem in terms of biological productivity and macro-benthic diversity.

Evaluation of mesoscale convective systems in South America using multiple satellite products and an object-based approach

[1] In this study, an object-based verification method was used to reveal the existence of systematic errors in three satellite precipitation products: Tropical Rainfall Measurement Mission (TRMM), Climate Prediction Center Morphing Technique (CMORPH), and Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks (PERSIANN). Mesoscale convective systems (MCSs) for the austral summer 2002–2003 in the La Plata river basin, southeastern South America, were analyzed with the Contiguous Rain Area (CRA) method. Errors in storms intensity, volume, and spatial location were evaluated. A macroscale hydrological model was used to assess the impact of spatially shifted precipitation on streamflows simulations. PERSIANN underestimated the observed average rainfall rate and maximum rainfall consistent with the detection of storm areas systematically larger than observed. CMORPH overestimated the average rainfall rate while the maximum rainfall was slightly underestimated. TRMM average rainfall rate and rainfall volume correlated extremely well with ground observations whereas the maximum rainfall was systematically overestimated suggesting deficiencies in the bias correction procedure to filter noisy measurements. The preferential direction of error displacement in satellite-estimated MCSs was in the east-west direction for CMORPH and TRMM. Discrepancies in the fine structure of the storms dominated the error decomposition of all satellite products. Errors in the spatial location of the systems influenced the magnitude of simulated peaks but did not have a significant impact on the timing indicating that the system's response to precipitation was mitigating the effect of the errors.

The Linear Relationship Between Attenuation and Average Rainfall Rate for Terrestrial Links

Attenuation measured on terrestrial links can be used to estimate surface rainfall rates along a link path. There is current interest in the use of inverse methods to estimate rainfall over areas inferred from terrestrial links. A power-law relationship can be used to estimate rainfall rate from attenuation measured by a terrestrial link. However, the inverse method is simplified with a linear relationship between attenuation and rainfall rate when determining path averaged rainfall rates. This paper investigates power-law and linear relationships between rainfall rate and attenuation. It examines their goodness of fit for a range of frequencies and rainfall rates. Six years of disdrometer data from Chilbolton in the U.K. has been used to study both linear and power-law fits to attenuation and quantify the associated errors.

Scale Interaction of the Diurnal Cycle of Rainfall over the Maritime Continent and Australia: Influence of the MJO

Abstract The influence of the MJO on the phase and amplitude of the diurnal cycle of rainfall during Australian summer [December–February (DJF)] over the Maritime Continent (MC) and northern Australia is investigated using the Tropical Rainfall Measuring Mission (TRMM) 3B42 and 3G68 datasets. The gridded rainfall was partitioned into MJO categories (active, suppressed, and weak) based on their longitudinal position and by utilizing the real-time multivariate MJO (RMM) index of Wheeler and Hendon. The diurnal cycles were composited and an empirical orthogonal function (EOF) analysis was applied to extract the spatial and temporal variability. Distinct variations in the rainfall distribution pattern among categories of the MJO over land and ocean are seen. The result of the composite-mean rainfall distribution shows that the average daily rainfall rate over islands is higher during suppressed MJO days, while for surrounding oceans and northern regions of Australia, more rainfall occurs during MJO active days. The normalized relative amplitude (NRA) of the diurnal cycle of rainfall shows that morning rainfall near coastal areas during active days of the MJO is 1.5 times greater than the climatological-mean rainfall but is less than or equal to the climatological mean during other phases of the MJO. Similarly, during the suppressed phase of the MJO evening rainfall is greater over the islands than in other MJO phases. The first two modes of the EOF alone explain more than 88% (65%) of the variance for the 3B42 (3G68) rainfall, and the corresponding principal component time series show a marked diurnal cycle. The results show that both the amplitude and phase of the diurnal cycle of rainfall are modulated by the categories of the MJO. In general, the peak in the diurnal cycle for active (suppressed/weak) days of the MJO lags (leads) the peak in the diurnal cycle for total rainfall by 2 h. Over Darwin and its adjacent regions, the active phase of the MJO is responsible for the occurrence of maximum rainfall after midnight, which is unusual in this region.

RAINFALL RATE PROBABILITY DENSITY EVALUATION AND MAPPING FOR THE ESTIMATION OF RAIN ATTENUATION IN SOUTH AFRICA AND SURROUNDING ISLANDS

The paper describes the modelling of the average rainfall rate distribution measured at difierent locations in South Africa. There are three major aspects this paper addresses: to develop a rainfall rate model based on the maximum likelihood method (ML); to develop contour maps based on rainfall rate at 0:01% percentage of exceedence; and re-classiflcation of the ITU-R and Crane rain zones for the Southern Africa region. The work presented is based on flve- minute rainfall data converted to one-minute equivalent using a newly proposed hybrid method. The results are mapped and compared with conventional models such as the ITU-R model, Rice-Holmberg, Moupfouma and Crane models. The proposed rainfall rate models are compared and evaluated using root mean square and chi-square (´ 2 ) statistics. Then re-classiflcation of the rain zone using ITU-R and Crane designations is suggested for easy integration with existing radio planning tools. The rainfall rate contour maps at 0:01% percentage of exceedence are then developed for South Africa and its surrounding islands.

Precipitation Characteristics of Trade Wind Clouds during RICO Derived from Radar, Satellite, and Aircraft Measurements

Abstract Precipitation characteristics of trade wind clouds over the Atlantic Ocean near Barbuda are derived from radar and aircraft data and are compared with satellite-observed cloud fields collected during the Rain in Cumulus over the Ocean (RICO) field campaign. S-band reflectivity measurements Z were converted to rainfall rates R using a Z–R relationship derived from aircraft measurements. Daily rainfall rates varied from 0 to 22 mm day−1. The area-averaged rainfall rate for the 62-day period was 2.37 mm day−1. If corrected for evaporation below cloud base, this value is reduced to 2.23 mm day−1, which translates to a latent heat flux to the atmosphere of 63 W m−2. When compared with the wintertime ocean-surface latent heat flux from this region, the average return of water to the ocean through precipitation processes within the trade wind layer during RICO was 31%–39%. A weak diurnal cycle was observed in the area-averaged rainfall rate. The magnitude of the rainfall and the frequency of its occurrence had a maximum in the predawn hours and a minimum in the midmorning to early afternoon on 64% of the days. Radar data were collocated with data from the Multiangle Imaging Spectroradiometer (MISR) to develop relationships between cloud-top height, cloud fraction, 866-nm bidirectional reflectance factor (BRF), and radar-derived precipitation. The collocation took place at the overpass time of ∼1045 local time. These relationships revealed that between 5.5% and 10.5% of the cloudy area had rainfall rates that were &amp;gt; 0.1 mm h−1, and between 1.5% and 3.5% of the cloudy area had rainfall rates that were &amp;gt;1 mm h−1. Cloud-top heights between ∼3 and 4 km and BRFs between 0.4 and 1.0 contributed ∼50% of the total rainfall. For cloudy pixels having detectable rain, average rainfall rates increased from ∼1 to 4 mm h−1 as cloud-top heights increased from ∼1 to 4 km. Rainfall rates were closely tied to the type of mesoscale organization, with much of the rainfall originating from shallow (&amp;lt;5 km) cumulus clusters shaped as arcs associated with cold-pool outflows.

Seasonal variability of interception evaporation from the canopy of a mixed deciduous forest

Gross rainfall, net rainfall and stemflow were measured in a mixed deciduous woodland in southern England over a period of 14 months. Continuous measurements of standard weather data and momentum and sensible heat fluxes between the forest canopy and the atmosphere accompanied the investigation. The gross rainfall was corrected for catch losses due to high turbulence. Reliable net rainfall data were obtained from a combined application of simple storage gauges and troughs connected to automatic tipping bucket gauges. The evaporation rates from the wet canopy were calculated with the Penman–Monteith equation using the measured aerodynamic conductance to the momentum flux and, additionally, with the eddy covariance energy balance approach. Both methods agreed in the observation that the average wet canopy evaporation rate was slightly higher in the leafless period, due to higher wind speeds and the different aerodynamic properties of the canopy. Together with the lower average rainfall rate this counterbalanced the reduced storage capacity of the leafless canopy and maintained a relatively high interception loss throughout the year being 29% of the gross rainfall in the leafed period and 20% in the leafless period. The analytical sparse canopy rainfall interception model of Gash et al. [Gash, J.H.C., Lloyd, C.R., Lachaud, G., 1995. Estimating sparse forest rainfall interception with an analytical model. J. Hydrol. 170, 79–86] was parameterised, for the first time, for a mixed deciduous woodland. Separate parameters were derived for the leafed and the leafless canopy. The model explained the seasonal variability in the interception loss very well and is a suitable tool to analyse and predict this important component of the annual water balance of deciduous forests.

Radar Observations of Rainfall Variability Using Non-Rayleigh Signal Fluctuations

Abstract The spatial variability and temporal variability of precipitation are widely recognized. In particular, rainfall rates can fluctuate widely in regions where the raindrops are clustered and where mean conditions are changing (statistical heterogeneity). Indeed, at times, the ambiguity associated with an estimated average rainfall rate may become very large. Therefore, in quantitative measurements of precipitation, it would be useful to identify where this occurs. In this work a technique is proposed and applied to quantify the variability in rainfall rates introduced by statistical heterogeneity and raindrop clustering using deviations from Rayleigh statistics of intensity fluctuations. This technique separates the Rayleigh contributions to the observed relative dispersion from those arising from clustering and statistical heterogeneities. Applications to conventional meteorological radar measurements are illustrated using two scans. Often, but not always, the greatest ambiguities in estimates of the average rainfall rate occur just where the rainfall rates are the largest and presumably where accurate estimates are most important. This ambiguity is not statistical; rather, it indicates the presence of important sub-beam-scale fluctuations. As a consequence, no single average value can be applied uniformly to the entire domain. The examples provided here also demonstrate that the appropriate observations are feasible using current conventional meteorological radars with adequate processing capabilities. However, changes in radar technology that improve and increase pulse-to-pulse statistical independence will permit such observations to be gathered more routinely at finer spatial resolution and with enhanced precision.

Effects of Radar Beam Shielding on Rainfall Estimation for the Polarimetric C-Band Radar

Abstract Radar reflectivity (Zh), differential reflectivity (Zdr), and specific differential phase (Kdp) measured from the operational, polarimetric weather radar located in Trappes, France, were used to examine the effects of radar beam shielding on rainfall estimation. The objective of this study is to investigate the degree of immunity of Kdp-based rainfall estimates to beam shielding for C-band radar data during four typical rain events encountered in Europe. The rain events include two cold frontal rainbands with average rainfall rates of 7 and 17 mm h−1, respectively, and two summertime convective rain events with average rainfall rates of 11 and 22 mm h−1. The large effects of beam shielding on rainfall accumulation were observed for algorithms using Zh and Zdr with differences of up to ∼2 dB (40%) compared to a Kdp-based algorithm over a power loss range of 0–8 dB. This analysis reveals that Zdr and Kdp are not affected by partial beam shielding. Standard reflectivity corrections based on the degree of beam shielding would have overestimated rainfall rates by up to 1.5 dB for less than 40% beam shielding and up to 3 dB for beam shielding less than 75%. The investigation also examined the sensitivity of beam shielding effects on rainfall rate estimation to (i) axis–ratio parameterization and drop size distribution, (ii) methods used to smooth profiles of differential propagation phase (ϕdp) and estimate Kdp, and (iii) event-to-event variability. Although rainfall estimates were sensitive to drop size distribution and axis–ratio parameterization, differences between Zh- and Kdp-based rainfall rates increased independently from those parameters with amount of shielding. Different approaches to smoothing ϕdp profiles and estimating Kdp were examined and showed little impact on results.

Simulation of sampling error of average rainfall rates in space and time by five satellites using radar‐AMeDAS composites

Sampling error has long been an important issue in satellite‐based rainfall measuring mission planning such as for TRMM and GPM (Global Precipitation Measurement), and in evaluating global maps of space‐time average rain rate from multi‐satellite rainfall data. Sampling errors due to sparse space‐time rainfall observations from five currently operated low‐earth‐orbiting satellites (Aqua, DMSP‐F13, F14, F15, TRMM (Tropical Rainfall Measuring Mission)) were evaluated using 3‐year radar‐AMeDAS composite data around Japan. We simulate realistic observational patterns for the satellite‐borne microwave radiometers. Root‐mean‐square sampling error is expressed as a fraction of true average rain rate. We formulate sampling error as a function of space scale ranging from 0.1° to 5.0°, time scale from 1 to 30 (day), and true average rain rate from 0.001 to 15 (mm/h) for five different combinations of these five satellites.

호우이동을 고려한 DAD 분석방법

수문학 교과서를 통해 널리 알려진 기존의 유역중심 DAD 분석방법은 유역면적이 작거나 호우이동이 거의 없는 경우에 매우 유용한 방법으로 계산이 비교적 간단하다. 그러나, 태풍과 같이 호우이동이 뚜렷한 경우에는 DAD 관계를 명확히 표현하기 어려우며, 특히 유역면적이 증가함에 따라 평균면적강우량의 오차도 증가하므로, 분석자의 혼란을 야기시킬 수 있다. 이에 본 연구에서는 기존의 유역중심 DAD 분석방법의 단점을 보완코저 호우중실 DAD 분석방법을 개발하였고, 객관적인 DAD 분석결과를 얻기 위해 이를 프로그램화하였다. 관측강우량을 이용하여 기존의 방법과 비교ㆍ검토를 수행한 결과 제안된 방법이 평균면적강우량을 보다 적절하게 표현함을 알 수 있었다. 따라서 개발된 프로그램을 이용하여 우리나라의 전국단위 호우분석(1969년부터 1999년까지 약 130여개 호우)을 수행하였으며, 그 결과를 유역중심 DAD 분석결과와 비교ㆍ검토하였다. The traditional fixed areal DAD(rainfall Depth-Area-Duration) method, generally quoted in most hydrology texts, is a simple and useful procedure when watersheds are small and storm movement is not an important factor of consideration. However, it is difficult to obtain satisfactory results for the more apparent forms of storm movement such as typhoons, or for large watershed. In the latter case, especially the margin of error for the areal average rainfall increases proportionally to the area of study, causing biased result. To overcome these limitations, this study focuses on the storm-centered DAD analysis(moving area DAD method) developed and programmed by the isohyetal concept to obtain accurate and objective results. By comparing and analyzing the observed rainfall rates through both method, it was proved that the currently Proposed method more accurately reflected the average rainfall rate. In short, through this new method, approximately 130 storm events nationwide from 1969 to 1999 was analyzed and compared with the fixed areal method results.