Melting Layer Research Articles

Experiment and modeling of static layer melt crystallization in a crystallizer with an inner cooling tube

Layer melt crystallization has attracted much attention for its excellent purification effects and low consumption of energy. This study focused on the static layer melt crystallization process of phosphoric acid. The crystallizer with an inner cooling tube was utilized to provide a cooled surface for the crystal layer growth. The crystal layer thickness was measured by processing images captured during the crystallization. Effects of various process parameters such as cooling rate of the coolant, initial coolant temperature, jacket temperature, etc. on the crystal layer growth were studied. Distribution coefficients of three types of ions were measured to evaluate the feasibility of purification for phosphoric acid. An efficient driving force relating to the heat transfer process was defined. And an empirical layer growth kinetic was achieved by fitting the experimental data. Modeled results illustrate that slowly decreasing the jacket temperature with rapidly decreasing the coolant temperature helps improve the crystal layer growth rate. The model with full consideration of process conditions might provide prospective guidance for optimizing the production in static layer melt crystallization.

Sensitivity of energy performance to the selection of PCM melting temperature for the building located in Cfb climate zone

In the present study, optimization of PCM layer thickness and melting temperature to increase the energy-saving potential of the office building located in eight cities in the Cfb climate zone was conducted using the Fanger model. The sensitivity of the energy savings to the selection of PCM melting temperature was quantitatively analyzed using a novel indicator of average savings drop. Additionally, the investigation of the effect of real PCMs on the energy performance of the building located in Cfb climate as well as the economic and environmental analyses were accomplished. The results showed that the PCM layer with a thickness of 2 cm reached the highest values of energy savings per unit thickness. The optimization of the PCM melting temperature revealed that PCM 22–25 were optimum for the whole Cfb climate zone and resulted in energy consumption reduction values of up to 37.6%. The sensitivity analysis showed that the steadiness of the outdoor climate conditions affects the sensitivity of the energy savings to the selection of PCM melting temperature. The analysis of real PCMs revealed that PCM 25-r demonstrated more efficient performance in all cities. Overall, it was concluded that the integration of PCM can be considered an economically and environmentally feasible solution.

Experimental and numerical studies of titanium foil/steel explosively welded clad plate

Ti/Fe clad plate had attracted extensive attention because of its important application. In order to reduce the titanium layer thickness, the explosive welding of TA1 titanium foil to Q235 steel plate was carried out. The interfacial bonding performance was analyzed by micromorphology analysis and mechanical property test, and the formation process of interfacial wave and molten block in the vortex was simulated by smoothed particle hydrodynamics (SPH) method. The results showed that salt as pressure transfer layer used in explosive welding could play a good buffer effect on the collision between flyer and base layers. Regular waveforms were formed on the bonding interface, and the titanium foil/steel clad plate exhibited good welding quality and bonding property. The crest of the observed interfacial wave moved 200 μm from the beginning to the final formation, and it was important of jet on the formation of interfacial waveform. The interface was mainly bonded in the form of molten layer, and the grains near the interface were streamlined. Molten block containing intermetallic compounds and metal oxides appeared in the vortex of wave crest.

Orientation impact on structural integrity of a shell and tube latent heat thermal energy storage system

Latent heat thermal energy storage systems can regulate the intermittency of electricity generation in a grid powered by renewable energy sources. Such systems could be used in conjunction with Brayton power generation cycles operating at high temperatures (520 °C–750 °C) delivering higher efficiency. However, a trade-off of higher thermal efficiency can be higher thermal stresses. The isothermal latent heat thermal energy storage and release can reduce the thermal stresses for a specific design. This study investigates the impact of the orientation on the melting process and the consequent thermal stresses in a lab-scale latent heat shell and tube system using a combination of transient computational fluid dynamics and finite element analyses. With a high temperature phase change material melting at 705.8°C, two initial temperatures of 700°C and 650°C were considered in transient analyses, leading to a 50 K and 100 K initial temperature difference across the tubes, respectively. For the structural analysis, an elastic method was employed for the condition of 50 K temperature difference, and an elastic-plastic analysis for the condition of 100 K to account for plastic deformation. The results of the elastic analysis presented the maximum thermal stresses of 63.5 MPa and 106.7 MPa in tubes in the horizontal and vertical orientations, respectively. The stress in the tube sheet was slightly higher (94.5 MPa) for the horizontal system compared with 90.4 MPa in the vertical position. For the condition of 100 K, the results of the elastic-plastic analysis identified the highest stresses of 172.5 MPa and 147.4 MPa in the tube sheets of the horizontal and vertical systems, respectively. For both initial temperature conditions, the stress level in tubes is lower in the horizontal orientation, which is where most cost occurs in a shell and tube system. Particularly important for the 100 K condition, the results show a lower stress of 100 MPa in tubes for a horizontal system compared with 140 MPa in a vertical orientation. In general, the lowest thermal stress occurs where a melt layer forms around tubes during the early stages of a melting process. A higher stress occurred in parts in contact with argon. The highest level of stress occurred in parts in contact with solid PCM, which has direct implications for larger vessel designs. This study provides insights into hydrothermal and mechanical design of a PCM system to prevent and/or manage localised maximum thermal stresses for a cost-effective thermal energy storage system.

Physicochemical properties of teas sold in Abuja, Nigeria, and evaluation of their caffeine content using HPLC

Tea is commonly consumed in Nigeria. Caffeine, a major constituent in tea, has some beneficial pharmacological properties, but can negatively affect human health if consumed excessively. The objective of the study was to evaluate some physicochemical properties and caffeine content of teas marketed in FCT, Abuja, Nigeria. Ten commercial brands of teas (8 black teas and 2 green teas) were assessed for weight variation, moisture content and pH tests using standard methods. Extraction of caffeine was carried out and the identity determined by thin layer chromatography and melting points, respectively. High performance liquid chromatography (HPLC) method for analysis of caffeine was developed, validated, and applied to determine caffeine content in the tea brands. Results of the weight, moisture content and pH tests of the samples ranged from 2.07–2.33 g, 5.65–11.0 % and 4.9–5.5, respectively. Caffeine was isolated from all the samples and showed same Rf value (0.46) with that of the reference standard. Melting points ranged from 236.0–238.5 °C. Caffeine content ranged from 12.25–21.76 mg/g for black teas and 13.35–15.05 mg/g for green teas. The study provides information on the stability, acidity and caffeine content in some commercially available tea brands.

Melt in the Greenland EastGRIP ice core reveals Holocene warm events

Abstract. We present a record of melt events obtained from the East Greenland Ice Core Project (EastGRIP) ice core in central northeastern Greenland, covering the largest part of the Holocene. The data were acquired visually using an optical dark-field line scanner. We detect and describe melt layers and lenses, seen as bubble-free layers and lenses, throughout the ice above the bubble–clathrate transition. This transition is located at 1150 m depth in the EastGRIP ice core, corresponding to an age of 9720 years b2k. We define the brittle zone in the EastGRIP ice core as that from 650 to 950 m depth, where we count on average more than three core breaks per meter. We analyze melt layer thicknesses, correct for ice thinning, and account for missing layers due to core breaks. Our record of melt events shows a large, distinct peak around 1014 years b2k (986 CE) and a broad peak around 7000 years b2k, corresponding to the Holocene Climatic Optimum. In total, we can identify approximately 831 mm of melt (corrected for thinning) over the past 10 000 years. We find that the melt event from 986 CE is most likely a large rain event similar to that from 2012 CE, and that these two events are unprecedented throughout the Holocene. We also compare the most recent 2500 years to a tree ring composite and find an overlap between melt events and tree ring anomalies indicating warm summers. Considering the ice dynamics of the EastGRIP site resulting from the flow of the Northeast Greenland Ice Stream (NEGIS), we find that summer temperatures must have been at least 3 ± 0.6 ∘C warmer during the Early Holocene compared to today.

Analysis of Two Convective Storms Using Polarimetric X-Band Radar and Satellite Data

We analyzed two convective storms that passed over or near the Milešovka meteorological observatory. The observatory is located at the top of a hill and has been recently equipped with a Doppler polarimetric X-band radar FURUNO WR2120 for cloud investigations. Our analysis was based mainly on Doppler polarimetric radar data measured in vertical cross-sections (RHI-Range-Height Indicator). Radar data was also used for classifying hydrometeors by a newly developed XCLASS (X-band radar CLASSification) algorithm. We also used rapid scan data measured by the geostationary satellite Meteosat Second Generation to validate radar measurements at the upper parts of storms. Although an attenuation correction was applied to the reflectivity and differential reflectivity measurements, the attenuation typical of X-band radars was noticeable. It was mainly manifested in the differential reflectivity, co-polar correlation coefficient and specific differential phase. Nevertheless, radar measurements can be used to analyze the internal cloud structure of severe convective storms. The XCLASS classification was developed by major innovation of a previously published algorithm. The XCLASS algorithm identifies seven types of hydrometeors: light rain, rain, wet snow, dry snow, ice, graupel, and hail. It uses measured horizontal and vertical radar reflectivity, specific differential phase, co-polar correlation coefficient, and temperature, and applies fuzzy logic to determine the type of hydrometeor. The new algorithm practically eliminates unrealistic results around and below the melting layer provided by the original algorithm. It identifies wet snow in more cases, and areas with individual hydrometeors have more realistic shapes compared to the original algorithm. The XCLASS algorithm shows reasonable results for the classification of hydrometeors and can be used to study the structure of convective storms.

Melting Behavior of Rimed and Unrimed Snowflakes Investigated With Statistics of Triple‐Frequency Doppler Radar Observations

AbstractComparing the reflectivity flux at the top and bottom of the melting layer (ML) reveals the overall effect of the microphysical processes occurring within the ML on the particle population. If melting is the only process taking place and all particles scatter in the Rayleigh regime, the reflectivity flux increases in the ML by a constant factor given by the ratio of the dielectric factors. Deviations from this constant factor can indicate that either growth or shrinking processes (breakup, sublimation, and evaporation) dominate. However, inference of growth or shrinking dominance from the increase in reflectivity flux is only possible if other influences (e.g., vertical wind speed) are negligible or corrected. By analyzing radar Doppler spectra and multi‐frequency observations, we correct the reflectivity fluxes for vertical wind and categorize the height profiles by the riming degree at the ML top. We apply this reflectivity flux ratio (ZFR) approach to a multi‐month mid‐latitude winter data set that contains mostly stratiform clouds. The profiles of radar variables in the ML are found to be surprisingly similar for both unrimed and rimed profiles with slight differences, for example, in the absolute values of the reflectivity flux. Statistical analysis of the ZFR suggests that either microphysical processes other than melting are not important or strongly compensate for each other. The results seem to confirm that at least for moderately precipitating stratiform clouds, the melting‐only assumption applied in several retrievals and microphysical schemes is reasonable.

New Polarimetric Radar Algorithm for Melting-Layer Detection and Determination of Its Height

Abstract A novel polarimetric radar algorithm for melting-layer (ML) detection and determination of its height has been developed and tested for a large number of cold-season weather events. The algorithm uses radial profiles of the cross-correlation coefficient (ρhv or CC) at the lowest elevation angles (<5°–6°). The effects of beam broadening on the spatial distribution of CC have been taken into account via theoretical simulations of the radial profiles of CC assuming intrinsic vertical profiles of polarimetric radar variables within the ML with varying heights and depths of the ML. The model radial profiles of CC and their key parameters are stored in lookup tables and compared with the measured CC profiles. The matching of the model and measured CC radial profiles allows the algorithm to determine the “true” heights of the top and bottom of the ML, Ht and Hb, at distances up to 150 km from the radar. Integrating the CC information from all available antenna elevations makes it possible to produce accurate maps of Ht and Hb over large areas of radar coverage as opposed to the previous ML detection methods including the existing algorithm implemented on the U.S. network of the WSR-88Ds. The initial version of the algorithm has been implemented in C++ and tested for a multitude of cold-season weather events characterized by a low ML with different degrees of spatial nonuniformity including cases with sharp frontal boundaries and rain–snow transitions. The new ML detection algorithm (MLDA) exhibits robust performance, demonstrating spatial and temporal continuity, and showing general consistency of the ML designations matching those obtained from the regional model and the quasi-vertical profiles (QVP) methodology output.

Characteristics of Precipitation Particles and Microphysical Processes during the 11–12 January 2020 Ice Pellet Storm in the Montréal Area, Québec, Canada

Abstract Freezing rain and ice pellets are particularly difficult to forecast when solid precipitation is completely melted aloft. This study addresses this issue by investigating the processes that led to a long-duration ice pellet event in Montreal, Québec, Canada, on 11–12 January 2020. To do so, a benchmark model initialized with ERA5 data is used to show that solid precipitation was completely melted below the melting layer, which discards partial melting from the possible ice pellet formation processes. Macro photography of precipitation reveals that small columnar crystals (∼200 μm) and ice pellets occurred simultaneously for more than 10 h. The estimation of ice crystal number concentration using macro photographs and laser-optical disdrometer data suggests that all supercooled drops could have refrozen by contact freezing with ice crystals. Rimed ice pellets also indicate ice supersaturation in the subfreezing layer. Given these observations, the formation of ice pellets and ice crystals was probably promoted by secondary ice production and the horizontal advection of ice crystals below the melting layer, as we illustrate using a conceptual model. Overall, these findings demonstrate how ice nucleation processes at temperatures near 0°C can drastically change the precipitation phase and the impact of a storm. Significance Statement Ice pellets are generally formed when snow particles partially melt while falling through a warm layer aloft before completely refreezing in a cold layer closer to the surface. Ice pellets can also be formed when snow particles completely melt aloft, but freezing rain is often produced in such conditions. On 11–12 January 2020, ice pellets were produced during more than 10 h in Montreal, Quebec, Canada. Macro photographs of the precipitation particles show that ice pellets occurred simultaneously with small ice crystals. Most of the ice pellets were produced while snow particles were completely melted aloft. The supercooled drops probably refroze due to collisions with the ice crystals that could have been advected by the northeasterly winds near the surface.

Experimental investigation of hot-wire laser deposition for the additive manufacturing of titanium parts

Hot-wire laser welding is additive manufacturing (AM) technique that allows for the direct creation of complicated objects by melting layers of wire. This process is characterized by the use of hot-wire process, unification with the laser welding (LW) process in AM process. The empirical investigation of AM employing a hot-wire laser welding on a titanium alloy (grade 2) workpiece is presented in this research. There are three parameters in the hot-wire laser process namely wire current, welding speed, and wire feeding speed; this research examined porosities, microhardness, tensile stress, and residual stress. The filler metal used titanium AMS (American welding society) 4951F welding wire of grade 2 and measures 1.6 mm in diameter. Finally, the suitable hot wire laser welding parameters should be 0.183 cm s−1 for the welding speed, the wire current of 40 A, and the wire feeding speed of 1.00 m min−1 are 0.183 cm s−1 for welding speed, 40 A for wire current, and 1.00 m min−1 for wire feeding speed, which will give the average Vicker microhardness of 321.00–345.80 HV, the average tensile strength of 432.02 MPa (substrate); 670.30 MPa (horizontal direction), 497.39 MPa (vertical direction).

Melting of Titanium by a Shock Wave Generated by an Intense Femtosecond Laser Pulse

Laser shock peening with ultrashort laser pulses has been studied by hydrodynamic and atomistic simulations, as well as experimentally. It has been shown that, in contrast to traditional nanosecond pulses, ultrashort laser pulses allow one to increase the produced pressures by two or three orders of magnitude from 1–10 GPa to 1000 GPa (1 TPa). The physics of phenomena changes fundamentally because shock waves generating pressures exceeding the bulk modulus of a metal melt it. It has been shown for the first time that the shock melting depth at pressures about 1 TPa is an order of magnitude larger than the thickness of the melt layer caused by heat conduction. The appearance, propagation, and damping of a melting shock wave in titanium have been studied. The damping of the shock wave makes it possible to modify the surface layer, where the melting regime changes from a fast one in the shock jump to a slow propagation of the melting front in the unloading tail behind the shock wave. It has been shown experimentally that the ultrafast crystallization of the melt forms a solid layer with a structure strongly different from that before the action. The measured depth of this layer is in good agreement with the calculation.

Microstructure and Wear of W-Particle-Reinforced Al Alloys Prepared by Laser Melt Injection

W-particle-reinforced Al alloys were prepared on a 7075 aluminum alloy surface via laser melt injection to improve their wear resistance, and the microstructure, microhardness, and wear resistance of the W/Al layers were studied. Scanning electron microscopy (SEM) results confirmed that a W/Al laser melting layer of about 1.5 mm thickness contained W particles, and Al4W was formed on the surface of the Al alloys. Due to the reinforcement of the W particles and good bonding of the W and Al matrix, the melting layer showed excellent wear resistance compared to that of Al alloys.

Microphysical Characteristics of the Phase‐Locking VRW‐Induced Asymmetric Convection in the Outer Eyewall of Super Typhoon Lekima (2019)

AbstractMicrophysical signatures relevant to the asymmetric convection in the outer eyewall of Super Typhoon Lekima (2019) before its landfall in China were analyzed from ground‐based radar observations. The results indicate that the microphysical characteristics varied in quadrants. In the upshear‐left outer eyewall, the convection was deepened on the inner edge due to the phase locking between vortex Rossby waves (VRWs), and warm rain was the predominant process contributing to the enhancement of rainfall. In contrast, the strongest precipitation occurred on the outer edge of the upshear‐right outer eyewall. In this region, exuberant riming processes and graupel formation prevailed above the melting layer due to the strongest and more outward tilted updrafts induced by the phase locking between the VRWs. A good deal of graupel melted into raindrops, along with significant accretion processes, produced intense rainfall with larger drop sizes.

Influence of the wrinkle surface structures on the vapor flow and keyhole stability in 20 kW high power laser welding

The stability of the extremely narrow keyhole is still the biggest challenge for the 20 kW or higher-level laser welding. The underlying causes of keyhole instability, including the wrinkle structures-induced thermal instability and vapor-induced dynamic instability, are studied in this work. A multiphase flow model integrated with a high-efficient free surface reconstruction algorithm and a high-accuracy wrinkle surface structures observation platform are built to study the morphology evolution and thermodynamic behaviors on the extremely narrow keyhole. It is found that the wrinkle structures (humps) that exist on the front keyhole wall could significantly regulate the energy distribution, and change the pressure condition in keyhole civility. The excessive energy accumulation, which is aroused by the abnormal hump distribution, is the reason for the unstable keyhole wall fluctuation. By increasing the welding speed, the intermittent-contact behavior between the laser beam and the keyhole opening is suppressed, which helps reduce the hump generation. By increasing the laser power, the drilling effect on the solid-liquid interface could be avoided, which helps to improve the downward flow efficiency of the melting layer on the front keyhole wall. An optimizing strategy based on the welding speed and laser power adjusting is offered to regulate wrinkle morphology. The experiment results show that keyhole stability is significantly improved under the optimized wrinkle surface structures.

Determination of the inner forms of hollow blocks containing phase-changing material for different climate regions

Hollow blocks are used widely in buildings for their lightweight construction and high thermal resistance characteristics. When used with a phase change material (PCM), these blocks can reduce the heating and cooling loads of buildings compared to conventional hollow blocks. However, it is essential that the block inner forms and PCMs should be selected based on climate conditions. In this study, hollow blocks containing PCM in different climate types are thermally analysed. In the first step, ten different formed blocks are thermally analysed. In these blocks, the effects of hollow ratio (HR), inner form, and the number of cavities on heat flux and temperature distribution are investigated. The inner form of the hollow block with the least heat flux is determined in this step. The second step consists of optimization for the PCM melting temperature and layer thickness for the different provinces. The optimization results are evaluated on a building in terms of primary energy consumption and global costs. The best performing locations of the PCMs within the block are defined for all provinces in the last step. The results of the study are discussed in terms of the block surface temperatures and liquid fraction. The best PCM locations are found close to the block’s centerline in hot and warm climates and close to the indoor side in cold climates.

Effect of lamination layer thickness and abutment preparation on the fit of Co-Cr multi-unit prostheses fabricated by additive manufacturing: An in vitro study

Statement of problemSelective laser melting has been increasingly used in the fabrication of metal-ceramic prostheses. The lamination layer thickness may influence the fit of the restoration. However, data regarding its impact remain scarce. PurposeThe purpose of this in vitro study was to evaluate the marginal and internal fit of cobalt-chromium (Co-Cr) 3-unit frameworks fabricated by additive manufacturing with different melting layer thicknesses on different abutments. Material and methodsThe first right maxillary premolar and molar from a typodont were prepared with a circumferential 1.2-mm chamfer, 2-mm occlusal reduction, and total taper of 8 degrees to receive 3-unit fixed partial dentures. After framework design, the data were sent to a laser machine, and 30 specimens were fabricated from Co-Cr metal powder (Mediloy S-Co) by selective laser melting. Specimens were assigned to 3 groups (n=10) with different lamination layer thicknesses of 25 (L25), 50 (L50), and 100 (L100) μm. Marginal fit and internal fit were evaluated. Results were compared among layer thickness groups and abutments. Data were compared by using the Levene test, t test, and ANOVA (α=.05). ResultsA statistical difference was found between different layer thickness groups (P=.016), but not between abutments (P=.429). On the abutment level, significant difference was found in the gap values for the molars (P=.049) between layer thickness groups, but not for the premolars (P=.126). Group L25 reported the smallest mean discrepancy values, and group L100 reported the highest, with statistical difference found between group L100 and groups L25 (P<.001) and L50 (P<.025), but not between groups L25 and L50 (P=.094). ConclusionsThe lamination layer thickness affected the adaptation of the metal frameworks. Framework fit did not significantly differ between abutments.

Plasma-induced atom migration manufacturing of fused silica

In this study, we report an ultra-precision nonsubtractive surface polishing technique named plasma-induced atom migration manufacturing (PAMM). In PAMM, the molten layer of the fused silica surface can be formed owing to the energy transmitted by inductively coupled plasma (ICP) which has a high gas temperature and radical density. The smoothing of surface is attributed to the rearrangement of surface atoms or clusters driven by surface tension. Unlike conventional subtractive smoothing processes, PAMM removes no material and can achieve damage-free surface with high efficiency and low cost, which makes it a promising technique to obtain large optical components with excellent optical performance and long operation life. The static and scanning smoothing characteristics of PAMM were presented and the surface smoothing mechanism was discussed. By this method, an ultrasmooth surface with Sa roughness of 0.15 nm was achieved. Furthermore, the validity of PAMM of spherical surface polishing and damaged surface recovering of fused silica was experimentally verified.

New Equipment and Method for Refining the Solidified Grain Structure

The mechanical properties of solidified alloys strongly depend on the grain size. In many practical cases at the given solidification parameters (temperature gradient and solid/liquid interface velocity), the solidified microstructure is columnar, meaning that the mechanical properties differ depending on the direction, which results in the material being unsuitable for application. The microstructure can be changed from columnar to equiaxed through the inclusion of grain refinement material. This strategy is well known in the literature as the columnar/equiaxed transition (CET). In some cases, it is beneficial if the CET can be produced without using grain refinement material; for example, it may detrimentally affect the mechanical properties (such as when the Al alloy ingot is used in pressing). The stirring of the melt as an alternative for the use of grain refinement material could solve this problem as intensive melt flow can break some particles from growing dendrites. This paper demonstrates a new type of traveling magnetic field inductor that is used to produce strong shearing stress in the flow perpendicular to the solidification front by causing part of the metallic melt layers touching each other to flow in an opposite direction. Through some examples, we demonstrate the effect of stirring by the new inductor on the solidified grain structure.

The GPM-DPR Blind Zone Effect on Satellite-Based Radar Estimation of Precipitation over the Andes from a Ground-Based Ka-band Profiler Perspective

Abstract A vertically pointing Ka-band radar (Metek MIRA-35C) installed at the Instituto Geofísico del Perú, Atmospheric Microphysics and Radiation Laboratory (LAMAR) Huancayo Observatory, which is located at an elevation of 3.3 km MSL in the Andes Mountains of Peru, is used to investigate the effects of terrain on satellite-based precipitation measurement in the Andes. We compare the vertical structure of precipitation observed by the MIRA-35C with Ka-band radar measurements from the Dual-Frequency Precipitation Radar (DPR) on board the Global Precipitation Measurement (GPM) mission core satellite using an approach based on Taylor’s hypothesis of frozen turbulence that attempts to reduce the impact of spatiotemporal offsets between these two radar measurements. From 3 April 2014 to 20 May 2018, the DPR measured precipitation near LAMAR during 15 of its 157 coincident overpasses. There were six simultaneous observations with MIRA-35C. We found that the average of the DPR’s lowest clutter-free bin is 1.62 km AGL, but the presence of precipitation worsens the situation, causing a 0.4-km-deeper algorithm-detected blind zone for the DPR at the Huancayo Observatory. In the study area, the depth of the clutter layer observed with DPR often extends above the melting layer but can be highly variable, extending even as high as 5 km AGL. These results suggest that DPR estimates of stratiform precipitation over the Andes Mountains are likely underestimated because of the terrain effects on the satellite measurements and problems in its blind zone detection algorithms, highlighting the difficulty in estimating precipitation in mountainous terrain from spaceborne radar.