Individual Boxes Research Articles

Relationship between the conditions of lower airways in healthy horses, environmental factors and air quality in stables

In 6 healthy Haflinger horses stabled in individual boxes, different types of bedding (husk, straw and woodshavings) and hay (dry and soaked) were periodically changed. After each test period (45 days) bronchoalveolar lavage (BAL) was carried out for each horse, and the BAL fluid (BALF) withdrawn was submitted for citological and microbiological evaluation. The environmental dust burden was evaluated by means of an air filtration system and an optical counter with laser diode. Dust particles were sorted in eight size classes ranging from 0.3 to >20 μm. Qualitative evaluation of dust components was achieved by means of a Surface air system sampler (Sas). Total dust, which ranged from 0.03 mg/m3 to 0.40 mg/m3, prooved highly related with mast cell differential count (r = 0.61; P = 0.03). Besides, BALF mastcells differential count decreased significantly when hay was soaked. BALF alveolar macrophages showed a negative relationship with particles ranging from 1 to 2 μm (r = –0.55; P = 0.05) and from 2 to 5 μm (r = –0.61; P = 0.03), considered as respirable fraction (RF). It was concluded that even in healthy horses the investigated factors may play an important role in lower airways condition.

Implementing surface parameter aggregation rules in the CCM3 global climate model: regional responses at the land surface

Abstract. The land-surface parameters required as input to a GCM grid box (typically a few degrees) are often set to be those of the dominant vegetation type within the grid box. This paper discusses the use and effect of aggregation rules for specifying effective values of these land cover parameters by taking into account the relative proportion of each land-cover type within each individual grid box. Global land-cover classification data at 1 km resolution were used to define Biosphere Atmosphere Transfer Scheme (BATS) specific aggregate (using aggregation rules) land-cover parameters. Comparison of the values of the aggregate parameters and those defined using the single dominant vegetation type (default parameters) shows significant differences in some regions, particularly in the semi-desert and in forested regions, e.g. the Sahara Desert and the tropical forest of South America. These two different sets of parameters were used as input data for two 10-year simulations of the NCAR CCM3 model coupled to the BATS land-surface scheme. Statistical analyses comparing the results of the two model runs showed that the resulting effects on the land-surface diagnostics are significant only in specific regions. For example, the sensible heat flux in the Sahara Desert calculated for the aggregate parameter run increased due to the marked increase in the minimum stomatal resistance and the decrease in fractional vegetation cover in the aggregate parameters over the default parameters. The modelled global precipitation and surface air temperature fields were compared to observations: there is a general improvement in the performance of the aggregate parameter run over the default parameter run in areas where the differences between the aggregate and default parameter run are significant. However, most of the difference between the modelled and observed fields is attributable to other model deficiencies. It can be concluded that the use of aggregation rules to derive land-surface parameters results in significant changes in modelled climate and in some improvements in the land-surface diagnostics in selected regions. There is also some evidence that there is a response in the global circulation pattern, which is a focus of further work.

A comparison of downscaled and raw GCM output: implications for climate change scenarios in the San Juan River basin, Colorado

The fundamental rationale for statistical downscaling is that the raw outputs of climate change experiments from General Circulation Models (GCMs) are an inadequate basis for assessing the effects of climate change on land-surface processes at regional scales. This is because the spatial resolution of GCMs is too coarse to resolve important sub-grid scale processes (most notably those pertaining to the hydrological cycle) and because GCM output is often unreliable at individual and sub-grid box scales. By establishing empirical relationships between grid-box scale circulation indices (such as atmospheric vorticity and divergence) and sub-grid scale surface predictands (such as precipitation), statistical downscaling has been proposed as a practical means of bridging this spatial difference. This study compared three sets of current and future rainfall-runoff scenarios. The scenarios were constructed using: (1) statistically downscaled GCM output; (2) raw GCM output; and (3) raw GCM output corrected for elevational biases. Atmospheric circulation indices and humidity variables were extracted from the output of the UK Meteorological Office coupled ocean-atmosphere GCM (HadCM2) in order to downscale daily precipitation and temperature series for the Animas River in the San Juan River basin, Colorado. Significant differences arose between the modelled snowpack and flow regimes of the three future climate scenarios. Overall, the raw GCM output suggests larger reductions in winter/spring snowpack and summer runoff than the downscaling, relative to current conditions. Further research is required to determine the generality of the water resource implications for other regions, GCM outputs and downscaled scenarios.

The effect of lecithin supplementation on the biochemical profile and morphological changes in the liver of rats fed different animal fats.

Sixty-four Wistar rats were divided into 8 equal groups and kept for 36 days in individual boxes. Three of the groups were given full synthetic diets containing various animal fats: beef tallow, pork fat or fish oil. A control group was fed the diets without the fat. The other four groups were fed the same diets with lecithin supplementation. At the end of experiment, sections taken from the liver were stained with haematoxylin eosin and Sudan III to indicate fat infiltration. Liver enzyme levels, total bilirubin, albumin and two products of lipid metabolism were measured in serum from all the animals. The addition of lecithin to the diets did not influence the level of enzymes in the serum except in rats fed the diet containing beef tallow. A relationship between the type of diet, lecithin supplementation and the total cholesterol concentration in serum was observed. The concentration of HDL-cholesterol was only influenced by lecithin supplementation and that of triglycerides by the type of fat in the diet. The addition of lecithin to the diet was associated with proliferation of Kupffer cells, and an increased number of binuclear cells. Fatty degeneration of hepatocytes was less pronounced in all groups following lecithin supplementation. Lecithin supplementation of the diet did not elicit any pathological lesions and may be considered as a hepatocyte protector. This favourable effect of lecithin was most marked in the group of rats fed the fish oil.

Evaluation of HADCM2 and direct use of daily GCM data in impact assessment studies

This paper investigates two important aspects of methods used to explore possible effects of climatic changes on agricultural productivity on regional spatial scales. First, an evaluation of precipitation and near surface air temperature in two successive versions of the Hadley Centre General Circulation Model (GCM) has been performed to consider to what extent GCMs are capable of simulating the mean and variability of local climates. This is explored by comparing the output of an individual GCM grid box with three station observations. Several ancillary issues associated with the comparisons of observations of daily precipitation and model output that affect the statistical results are also discussed. Finally, daily data from the control and sulphate runs of the latest Hadley Centre GCM (HadCM2) have been used directly as input to the CERES-Wheat model, and the modelled yield distribution is compared to that produced with the historical data series. Our results imply that for this particular grid box covering the study region in central France, the daily raw data from HadCM2 experiment can be used directly to assess the potential impact of the greenhouse gas and sulphate aerosol radiative induced forcings and the associated climatic change on average regional winter wheat production. On the other hand, less confidence should be placed on their use regarding the estimation of future agricultural risk and variability assessment. Furthermore, a possibly more severe methodological problem that has arisen from our study is the inability of CERES-Wheat to simulate the waterlogging effects of excessive soil water on crop growth and development. Finally, we assess the potential impact of changing climate on regional winter wheat production by using the daily data from the sulphate integration up to the end of the 21st century.

Structural elements of the Streptomyces oriC region and their interactions with the DnaA protein.

Streptomycetes differ from other prokaryotic organisms in their mycelial life cycle and in possessing a large, linear, GC-rich chromosome. To deduce structural features of the Streptomyces origin of chromosomal replication, the oriC sequences of three Streptomyces species (S. antibioticus, S. chrysomallus and S. lividans) were compared. In Streptomyces, the oriC region contains 19 DnaA boxes whose location, orientation and spacing are conserved. The consensus sequence of the DnaA box identified within Streptomyces oriC is (T/C)(T/C)(G/A/C)TCCACA (preferred bases underlined). The interactions of DnaA with DNA fragments containing single, two or three DnaA boxes were studied using surface plasmon resonance. The dissociation constant (KD) for specific binding of individual DnaA boxes varied between 12 and 78 nM. Streptomyces oriC does not contain the three AT-rich 13-mer direct repeats present in the 5' part of the Escherichia coli oriC region. However, short AT-rich sequences are distributed among the DnaA boxes of Streptomyces oriC. Repeated attempts to unwind Streptomyces oriC have been unsuccessful. It remains to be elucidated whether DnaA interacts with putative accessory proteins which help in unwinding Streptomyces oriC.

Detailed analysis of the error associated with the rainfall retrieved by the NOAA/NESDIS SSM/I algorithm: 1. Tropical oceanic rainfall

A general formulation has been established for the total error associated with passive microwave retrieval of space‐time rainfall. The total error consists of two independent components: the sampling error and the algorithm error. The former arises from the discrete sampling scheme of a polar‐orbiting satellite, and the later is the result of the imperfect algorithm used to convert the measured radiation to instantaneous rain rate. Rainfall data over the Tropical Ocean and Global Atmosphere/Coupled Ocean and Atmosphere Response Experiment (TOGA/COARE) region has been used to represent oceanic rainfall conditions to evaluate the error of the National Oceanic and Atmospheric Administration/National Environmental Satellite, Data, and Information Service (NOAA/ NESDIS) Special Sensor Microwave/Imager (SSM/I) rainfall algorithm. Rainfall statistics that affect the sampling error have been obtained from radar data, which include mean, variance, and autocorrelation of areal rain. The magnitude of the variance and the strength of the autocorrelation are quantitatively related to the size of the averaging area. Instantaneous measurement errors on the FOV scale and the large scale (2.5° box) are obtained by analyzing simultaneous observations of SSM/I and radar. Based on these parameter values, the sampling error, the algorithm error, and the total error are computed as a function of sampling frequency, size of averaging area, and other factors. This study has demonstrated the feasibility of a procedure to quantify the total retrieval error of space‐time rainfall by focusing on TOGA/COARE area (equivalent in size to a 2.5° box). The same procedure can potentially be applied to other grid boxes to produce a global error field if rain statistics and measurement errors are estimated for those boxes. The accuracy of the global error field will depend on the accuracy of the rain statistics and the measurement error values used in the individual grid boxes.

Evaluation of the European daily precipitation characteristics from the atmospheric model intercomparison project

Evaluating the daily precipitation performance of general circulation models at a regional scale is beset with two (related) difficulties: (i) ensuring an adequate network of observed daily station data across a region; and (ii) establishing 'true' areal means of daily precipitation from these station data to ensure a like-with-like comparison. These two difficulties have generally restricted past evaluations of daily model precipitation to individual grid boxes and to comparisons of model grid-box data with observed sub-grid-box scale data. In this paper we exploit a dataset of several dozen daily station time series in western Europe using a recently published method for estimating 'true' areal mean daily precipitation to evaluate the daily precipitation performance in this region of 12 atmospheric general circulation model simulations undertaken as part of the Atmospheric Model Intercomparison Project. We examine four quantities derived from the simulated daily precipitation: seasonal mean precipitation, daily standard deviation, the frequency of raindays and the mean precipitation intensity of those raindays. We show that simulated winter precipitation tends to be too great, falls on too many-days, but is generally less intense than that observed. In summer, model results are more variable with some model simulations yielding statistics quite similar to those observed. Although there is some uncertainty in these evaluation statistics owing to the effect of inter-decadal climate variability, there is a weak suggestion of improved performance with increased spatial resolution. Any systematic effect in model performance due to different convective parameterisation schemes is obscured by other confounding factors.

Identification of cis-acting elements in the SUC2 promoter of Saccharomyces cerevisiae required for activation of transcription.

We analyzed the effects of site-directed mutations in the SUC2 promoter of Saccharomyces cerevisiae. Analyses were performed in wild-type as well as mig1 and tup1 mutant strains after the promoter mutants were reintroduced into the native SUC2 locus on the left arm of chromosome IX. Mutation of the two GC boxes revealed that these elements play two distinct roles: they are, as expected, required for Mig1-mediated repression but they are also necessary for activation of the SUC2 promoter in response to glucose limitation. The individual GC boxes are functionally redundant with regard to Mig1-mediated repression, however, only the upstream GC box is essential for high level expression of SUC2. Microccocal nuclease sensitivity of the SUC2 promoter in derepressed cells was reduced in the GC box mutant promoters, particularly in the vicinity of the TATA box. The difference in nuclease sensitivity between wild-type and GC box mutant promoters was not evident in tup1- cells. The formation of nuclease-resistant chromatin does not require the GC boxes, indicating that other cis-acting elements can serve to recruit the Ssn6-Tup1 co-repressor complex to the SUC2 promoter.

Cold Restraint-Induced Gastric Lesions in Individual-and Group-Stressed rats in an Experimental Model of Alzheimer's Disease

Ten days after bilateral electrolytic lesions of the nucleus basalis magnocellularis (NBM) (an experimental model of Alzheimer's disease), adult male Wistar rats were exposed to cold restraint stress in individual and social condition. Therefore, rats were placed into individual or group restraint boxes (composed of six single boxes) and exposed during 2 hr to the cold (4°C). The results showed that: 1) there were no differences in type and intensity of stress-induced gastric lesions between single-stressed intact control (IC), sham-operated (SO) and NBM-lesioned rats, 2) the incidence, number and length of gastric erosions were significantly higher in group-stressed NBM-lesioned rats than in IC and SO rats, 3) the individual-stressed IC and SO rats have significantly higher incidence, number and length of gastric erosions as well as ulcer index than IC and SO group-stressed rats, and 4) there were no significant differences in intensity and type of acute gastric lesions between single- and group-stressed NBM-lesioned rats. It could be concluded that NBM lesions induce significant changes in social behavior in rats.

Severe axial bending of RNA induced by the U1A binding element present in the 3′ untranslated region of the U1A mRNA

The 3′ untranslated region of the U1A mRNA contains a binding site for the U1A protein that consists of two asymmetric internal bulges. The bulges each comprise a loop of seven unpaired bases opposing a single base (termed a U1A box). The seven-base loops are located on opposite strands, distributed in a symmetrical manner about the intervening four-base duplex. We have investigated the global conformation of this binding element. Comparison of electrophoretic mobilities of RNA duplexes interrupted by a single U1A box with a series of duplexes of the same length containing oligoadenine bulges indicates that the individual boxes cause a substantial kinking of the helix axis, estimated to be 90 (±10)°. A series of RNA duplexes were constructed containing a U1A box separated from an A 5bulge by a duplex section of length between 3 and 21 bp. It was found that the electrophoretic mobilities of these species varied sinusoidally, indicating that the U1A box introduces a defined kink into the RNA helix, rather than a point of flexibility. Electrophoretic experiments with the complete U1A binding element suggest that the axial trajectories of the two U1A boxes combine to give an approximately in-line, 180° change in duplex direction.

A Hybrid Model for Chemical Process Modeling

Abstract This paper proposes a hybrid approach to chemical process modeling. The scheme combines empirical and theoretical models in various different configurations. Performance evaluations were carried out on two case studies, i.e. , a laboratory scaled liquid level apparatus and a simulation of the Tennessee Eastman Plant. Results obtained from these studies have shown that hybrid models are more superior compared to the individual theoretical or black box models. Among all structures considered, the structure with FPM preceding SIM in series was most promising. These investigations have proved the potentials of hybrid strategy in providing solution to complex modeling problem.

Adaptation of microphysical and chemical instrumentation to the airborne measuring platform Iljushin I1-18 ‘Cyclone’ and flight regime planning during the Arctic Haze investigation 1993–1995

In 1993 the joint Russian-German Research Project ‘Arctic Haze’ started (see the Introduction and editorial note of this issue, by Jaenicke, Khattatov, Jaeschke and Leiterer). Besides CAO, four German groups were involved. To the present three airborne measuring campaigns have been performed. In total 251 h of flight within altitudes up to 8.7 km were flown in the western and eastern part of the arctic leading to a comprehensive set of data of the northern arctic hemisphere. The measurements were conducted aboard the Russian research aircraft I1-18 ‘Cyclone’ which was used by CAO in numerous scientific projects mainly in the former USSR. This 4 engined turboprop aircraft is well equipped with sensitive thermodynamical, optical and radiometric instrumentation. In consideration of the estimated aspects of ‘Arctic Haze’ additional microphysical, optical, and chemical instrumentation was adapted to the research aircraft. For co-ordinated measurements a detailed flight regime was planned taking into account the special requirements of the groups involved in the project. Main parts of the measurements were performed in box flights designed to get representative information of the investigated area. This allows the comparison of results gained in individual boxes at different locations or at different seasons. This contribution describes the basic equipment of the Russian research aircraft IL-18 as well as the adaptation of the special instrumentation for the ‘Arctic Haze’ investigations.

Avaliação da digestibilidade aparente da matéria seca em sagüis de tufo preto (Callithrix penicilatta) e macacos-prego (Cebus apella)

Foi determinado o Coeficiente de Digestibilidade Aparente da Matéria Seca, em rações para animais silvestres. Foram utilizados 16 animais, oito (8) sagüis de tufo preto (Callithrix penicilatta) e oito (8) macacos-prego (Cebus apella). Os animais foram mantidos em gaiolas de digestibilidade e receberam a ração básica durante 10 dias. Após o período inicial, as amostras de fezes foram colhidas durante 5 dias para posterior análise. Os Coeficientes de Digestibilidade para o Callithrix estiveram entre 84,9 e 97,7%, enquanto para o Cebus oscilaram entre 75,4 e 86,2%. A pesquisa concluiu que as rações utilizadas foram muito bem aproveitadas pelos animais.

HOMOGENIZATION OF SWEDISH TEMPERATURE DATA. PART II: HOMOGENIZED GRIDDED AIR TEMPERATURE COMPARED WITH A SUBSET OF GLOBAL GRIDDED AIR TEMPERATURE SINCE 1861

Homogeneity tests of long seasonal temperature series from Sweden, Denmark, Finland, and Norway indicate that homogeneous series are rare and that an abrupt change of the relative mean level is a much more common type of nonhomogeneity than a gradual change. Furthermore, negative shifts were 20% more common than positive shifts. Homogenized temperature anomaly series that were constructed for six 5 degrees latitude x 5 degrees longitude grid boxes indicate that the temporal pattern of temperture changes has been similar in different parts of Sweden since 1861. The annual mean temperature over Sweden was found to have increased by 0.68 degrees C from the period 1861-1890 to 1965-1994. The corresponding changes for the seasons were: +0.18 degrees C (winter), +1.40 (spring), +0.42 (summer) and +0.60 (autumn). A direct comparson shows that non-homogeneities in the temperature series from individual grid boxes in a global data set can be as large as the total changes observed. We estimate that a 95 per cent confidence interval for the error, due to non-homogeneous long station records, in estimates of hemispheric temperature changes over land regions since the period 1861-1890 is +/-0.1 degrees C for the Northern Hemisphere and the globe and +/-0.25 degrees C for the Southern Hemisphere. For a region consisting of about five grid boxes, this error is +/-0.5 degrees C. The large non-homogeneities in individual grid-box series in the global data set is partly a consequence of the fact that homogeneous climate data are not always easily available for the open research community. We urge that efforts are made to improve this situation.

HOMOGENIZATION OF SWEDISH TEMPERATURE DATA. PART II: HOMOGENIZED GRIDDED AIR TEMPERATURE COMPARED WITH A SUBSET OF GLOBAL GRIDDED AIR TEMPERATURE SINCE 1861

Homogeneity tests of long seasonal temperature series from Sweden, Denmark, Finland, and Norway indicate that homogeneous series are rare and that an abrupt change of the relative mean level is a much more common type of non-homogeneity than a gradual change. Furthermore, negative shifts were 20% more common than positive shifts. Homogenized temperature anomaly series that were constructed for six 5° latitude×5° longitude grid boxes indicate that the temporal pattern of temperture changes has been similar in different parts of Sweden since 1861. The annual mean temperature over Sweden was found to have increased by 0ċ68°C from the period 1861–1890 to 1965–1994. The corresponding changes for the seasons were: +0ċ18°C (winter), +1ċ40 (spring), +0ċ42 (summer) and +0ċ60 (autumn). A direct comparson shows that non-homogeneities in the temperature series from individual grid boxes in a global data set can be as large as the total changes observed. We estimate that a 95 per cent confidence interval for the error, due to non-homogeneous long station records, in estimates of hemispheric temperature changes over land regions since the period 1861–1890 is ±0ċ1°C for the Northern Hemisphere and the globe and ±0ċ25°C for the Southern Hemisphere. For a region consisting of about five grid boxes, this error is ±0ċ5°C. The large non-homogeneities in individual grid-box series in the global data set is partly a consequence of the fact that homogeneous climate data are not always easily available for the open research community. We urge that efforts are made to improve this situation.

Cold Restraint-Induced Gastric Lesions in Individual- and Group-Stressed Rats

The aim of the present study was to 1) determine the intensity of cold restraint-induced gastric lesions and core body temperature in single- and group-stressed rats, and establish a correlation between them; and 2) determine the influence of visual contact among animals during cold restraint on development of gastric stress ulcer. Therefore, adult male Wistar rats were put into individual or group restraint boxes (composed of two, three, six or nine single boxes) with or without possibility of visual contact and then exposed 2 hr to the cold (4°C). Core body temperature was measured just before and after cold restraint using a digital rectal thermometar. The results showed that: 1) single stressed animals expressed significantly higher ulcer index than those stressed in group of three, six and nine rats; 2) there was no significant difference in degree of hypothermia among rats exposed to various group paradigms; and 3) there was no significant difference in ulcer index among animals stressed in conditions with or without visual contact. An absence of significant difference in ulcer index between single and paired stressed rats implies that three is the lowest number of animals per group at which an influence of group size on behavioral and adaptive mechanisms in rats exposed to cold restraint becomes manifest.

A comprehensive set of DnaA-box mutations in the replication origin, oriC, of Escherichia coli.

We probed the complex between the replication origin, oriC, and the initiator protein DnaA using different types of mutations in the five binding sites for DnaA, DnaA boxes R1-R4 and M: (i) point mutations in individual DnaA boxes and combinations of them; (ii) replacement of the DnaA boxes by a scrambled 9 bp non-box motif; (iii) positional exchange; and (iv) inversion of the DnaA boxes. For each of the five DnaA boxes we found at least one type of mutation that resulted in a phenotype. This demonstrates that all DnaA boxes in oriC have a function in the initiation process. Most mutants with point mutations retained some origin activity, and the in vitro DnaA-binding capacity of these origins correlated well with their replication proficiency. Inversion or scrambling of DnaA boxes R1 or M inactivated oriC-dependent replication of joint replicons or minichromosomes under all conditions, demonstrating the importance of these sites. In contrast, mutants with inverted or scrambled DnaA boxes R2 or R4 could not replicate in wild-type hosts but gave transformants in host strains with deleted or compromised chromosomal oriC at elevated DnaA concentrations. We conclude that these origins require more DnaA per origin for initiation than does wild-type oriC. Mutants in DnaA box R3 behaved essentially like wild-type oriC, except for those in which the low-affinity box R3 was replaced by the high-affinity box R1. Apparently, initiation is possible without DnaA binding to box R3, but high-affinity DnaA binding to DnaA box R3 upsets the regulation. Taken together, these results demonstrate that there are finely tuned DnaA binding requirements for each of the individual DnaA boxes for optimal build-up of the initiation complex and replication initiation in vivo.

Spatial memory in five-month-old infants

In this study, the effects of Garlicon (GLC) (vegetable oil from garlic and onion family) were evaluated in comparison to monensin (MON) on blood metabolites and performance of fattening lambs. Thirty-five four to five-month-old lambs in five groups (seven lambs in each group) were confined in individual boxes. The experimental diets were offered as: basal diet without additives (Control); basal diet supplemented with 33 mg MON/kg DM (positive control), and three other groups, including basal diet with 0.03 (GLC1), 0.06 (GLC2) and 0.09 (GLC3) ml of GLC/l of drinking water. Rumen pH increased and the rumen ammonia concentrations decreased significantly with both monensin and Garlicon supplementations. The MON and, to a lesser extent, GLC had similar effects on the molar ratio of volatile fatty acids. The observed changes in the concentrations of VFAs and ammonia in the rumen liquid could be considered as a favorable outcome of GLC supplementation. These findings were associated with significant reduction in blood NEFA and BHB concentrations. MON and GLC had no effects on feed intake (P>0.05). Values for average daily gain in lambs supplemented by MON and GLC indicated an improved energy intake efficiency. In conclusion, this study found that the most prominent effects of MON and GLC supplementations were increased ruminal propionate concentrations, propionate to acetate ratios, and decreased serum NEFA and BHB concentrations.

Climatological analysis of manually digitized radar data for the United States east of the Rocky Mountains

Climatological analyses of manually digitized radar (MDR) data are presented to illustrate geographic, seasonal, and diurnal heterogeneities of precipitation over the United States east of the Rocky Mountains. MDR data consist of hourly radar reflectivity data for the contiguous United States at a grid scale of approximately 40 km. Analyses of MDR data for the period 1978–1992 are presented. MDR data are especially useful for studying the geographic contrasts in precipitation over the continental domain and the contrasts between land and ocean along the Gulf of Mexico and the Atlantic Ocean. Climatological analyses of fractional coverage of rainfall on a continental scale are developed using MDR data. High‐resolution radar data from the RADAP II network are used to illustrate fractional coverage of rainfall within an individual MDR grid box. Intercomparison studies with rain gage data point to the potential for quantitative rainfall analyses based on MDR data. Analyses of MDR data illustrate the potential, and some of the difficulties, in using radar data for hydroclimatological studies.