Flat Areas Research Articles

PREDIKSI CURAH HUJAN DI KABUPATEN BADUNG, BALI MENGGUNAKAN METODE LONG SHORT-TERM MEMORY

Rainfall is the height of rainwater that falls on a flat area, assuming it doesn't evaporate, doesn't seep, and doesn't flow. Rain levels are measured in mm (millimeters). The target of the research being conducted is in Badung Regency, Bali because Bali is a tourist area that is often visited by tourists and from Indonesian itself, so predictions of meteorology, such as rainfall will greatly impact tourism. In this test, predictions use the Long Short Term Memory (LSTM) method, using daily weather data from the BMKG from 2010 to 2020 as training data and daily weather data for 2021 as prediction data. Based on the test results above, the results show that the two LSTM tests with LSTM Model 128.64 and LSTM Model 64.32 have low MAE and MAPE error values. From First Scenario, the Mean Absolute Error (MAE) value is 8.97246598930908 and Mean Absolute Percentage Error (MAPE) value is 1.7657206683278308%. From Second Scenario, the Mean Absolute Error is 9.706669940783014 and Mean Absolute Percentage Error is 1.9028466692362323%. From the MAE and MAPE values obtained in these two scenarios, it can be proven that from the evaluation results of Rainfall predictions in Badung Regency, Bali, the predictions can be said to be very accurate because they have an error value of less than 10.

Validation of Satellite Rainfall Product (GPM-IMERG) an Bali and Nusa Tenggara: A Comparison of Normal Seasons, El Nino and La Nina Events

Bali and Nusa Tenggara are regions where monsoonal wind changes and strange interactions between the ocean and atmosphere influence rainfall. The purpose of this research is to evaluate Integrated Multi-Satellite Retrievals for GPM (IMERG) rainfall data using in-situ observations from Bali and Nusa Tenggara, Indonesia, while considering seasonal variations and the El Nino-Southern Oscillation (ENSO) phenomenon. The study combines rainfall data from synoptic stations with rain gauge measurements over ten years, from January 2012 to December 2021, to obtain more accurate verification results. The study's findings indicate that, apart from the transitional seasons, IMERG data provides substantial estimates of monthly rainfall accumulation with low error values for both light and heavy rainfall. The study also reveals that the islands' complexity and topography can impact each province's validation values. The verification results show excellent accuracy in flat terrain areas and moderate elevations, while performance decreases in regions with high altitudes. These findings are significant because IMERG data can estimate rainfall for regions lacking monitoring stations during specific seasons and active ENSO conditions. Thus, this information can serve as a valuable tool to address the issue of data unavailability in hard-to-access areas and contribute to optimizing water resource management and weather-related disaster mitigation. Keywords: Validation, Rainfall, IMERG, ENSO

UAV Monitoring Topsoil Moisture in an Alpine Meadow on the Qinghai–Tibet Plateau

Soil moisture is one of the most critical soil components for sustained plant growth and grassland management. Unmanned aerial vehicles (UAVs) are gradually replacing manual labor in various aspects of grassland management. However, their potential for monitoring soil moisture in grasslands remains largely unexplored. High vegetation coverage and frequent rainfall in the Tibetan Plateau pose a challenge for personnel working in alpine meadows. To explore the potential of UAV technology for soil moisture detection in these areas, we conducted a rainfall reduction experiment in Maqu County, China to understand the relationships among soil moisture, vegetation coverage, and visible-light images captured using UAVs. The findings indicated a significant correlation between topsoil moisture and the brightness values in visible-light images acquired by UAVs (p < 0.0001). These results demonstrated that visible-light brightness, vegetation coverage, rainfall reduction, and aboveground biomass can be utilized for estimating the topsoil moisture using these images (y = −0.2676 × Brightness + 0.2808 × Vegetation coverage −0.1862 × Rainfall reduction + 0.1357 × Aboveground biomass + 37.77). The model validation worked well (E = 0.8291, RS = −3.58%, RMA = 10.38%, RMSE = 3.5878, Pearson’s r = 0.9631, PSI = 0.0125). This study further addresses the problem of topsoil moisture measurement in flat areas of mesoscale moist alpine meadows and is expected to facilitate the widespread adoption of UAV use in grassland ecology research.

Comparative study of bubble forming sites at the laser-induced microstructure on a Ni electrode during hydrogen and oxygen evolution reactions

We study the formation of hydrogen and oxygen bubbles on the identical Ni electrode with a single laser-induced microstructure to understand the role of local surface morphology on bubble formation. All the forming sites of hydrogen bubbles are found at the microstructure, while those of oxygen bubbles are found not only at the microstructure but also on the flat area. Interestingly, not all but only a few of the sites at the microstructure produce both hydrogen and oxygen bubbles, and we find that these sites have partially confined structures. In contrast, the presence of oxygen bubble forming sites on the flat area implies that the local surface morphology is not the only decisive factor to be a bubble forming site. Through the elemental analysis of the electrode surface, we find the tendency that the sites with more nickel oxides show the less bubble forming activities.

THE WIND ENERGY POTENTIAL IN COASTAL AREAS OF MERAUKE CITY

Energy transformation to new and renewable energy starts from the green economy, green technology, and green products. The electricity demand in 2060 reached 1942 TWh which was dominated by the industrial and transportation sectors. Electricity demand is supplied by 96% renewable energy and 4% new energy with a total capacity of 708 GW. Merauke city with a geographical location between 137-141 degrees and 5-9 degrees of 46,791.63 km2 is a flat area and has several coastal areas, namely : Lampu Satu beach, Payum beach, and Domande beach with a beach length of 846.36 km. The method used is Topographical analysis, Google map and ESDM one map. Merauke city has two potential areas for wind energy, namely plains with a green spectrum having wind speeds of 4-6 m/s while beaches coastal with a red spectrum wind speed exceeding 6 m/s. For an altitude of 50 meters from the ground at coordinates 141.59621 - 8.04586 degrees, green area with wind speed of 4.27 m/s, area of 0.99 km2 and Musamus University at coordinates 140.47110 - 8.103640 degrees, wind speed 4.97 m/s for an area of 0.99 km2. The point 141.563250 - 8.040420 degrees is placed on the . Lampu satu beach wind speed 8.04 m/s, Domande beach 6.56 m/s, Payum beach wind speed 6.75 m/s

Geological characterization and controlling factors of small-scale variations in the cobalt-rich ferromanganese crust deposits

Cobalt-rich ferromanganese crusts (CRC) are potential resources for Co, Ni, Pt, and other strategic metals. The CRC thickness varies from a few mm to more than 100 mm at various distance scales over the rock outcrops in the seamounts. However, their variation patterns and controlling factors are not well understood. We conducted a comprehensive small-scale survey, including shipboard acoustic measurements, seafloor observations, and rock drilling over the Xufu Guyot of the Marcus-Wake seamounts in the Northwestern Pacific to characterize the thickness variations on a scale of several kilometers with the topography and geological evolution of the guyot. Rock drilling revealed that thicker CRC (>100 mm) tend to occur on the margins and flat areas on the guyot, while thinner CRC are associated with carbonate reef mounds over the volcanic pinnacles and seamount slopes. The microstratigraphic description indicated that the CRC thickness is strongly related to the geological evolution of the guyot, mainly the stability of the substrate rocks and coverage with calcareous pelagic sedimentation.

Land surface diversity: A geomorphodiversity index of Italy

AbstractGeomorphodiversity refers to the variety of landforms and morphological processes characterizing the landscape. The definition of an index to quantify geomorphodiversity is a relevant step for multiple fields of Earth sciences, since it is widely accepted that the variability of the geosphere deeply influences the diversity of the biosphere. Such an index should describe the number and type of landforms and geomorphological processes. We propose a quantitative land surface diversity index valid for Italy, considering multiple input quantities to describe geological constraints and geomorphological processes. Critical issues were the selection of moving window size for focal statistics operations, to calculate local diversity of slope, lithology, drainage density and terrain forms in individual raster maps. We compared the index with traditional geomorphological maps, in selected locations, in which information was available. Results show that a minimal set of heterogeneous data is a satisfactory approach to investigate the landscape diversity. Relating processing parameters and terrain spatial characteristics to the dataset resolution is a good choice to assess a reproducible land surface diversity index. Inclusion of drainage density allows the improvement of results in flat areas, in which other factors show trivial results. We argue that the index is relevant for land use management, assessment of ecodiversity, and it may help describing the interaction between abiotic and biotic compartments.

Conduction mechanism of Schottky contacts fabricated on etch pits originating from single threading dislocation in a highly Si-doped HVPE GaN substrate

This paper reports the relationship between a single dislocation structure and current leakage mechanism observed in a Pt/n+-GaN Schottky contacts with the combined use of transmission electron microscopy (TEM) and conductive atomic force microscopy (C-AFM). The contacts were fabricated on a substrate grown by hydride vapor phase epitaxy. TEM analysis clarified that large- and small-size etch pits are attributed to mixed/screw and edge dislocations, respectively. Schottky contacts formed on the surfaces of large and small etch pits (L-EPC, S-EPC), a dislocation-free flat area (FLAT), and a Schottky barrier diode with a diameter of 50 μm (SBD) were prepared and their temperature-dependent current-voltage characteristics were measured using C-AFM. Analysis of the forward bias characteristics revealed that the Schottky barrier height increased and the ideality factor approached unity with increasing temperature. Such temperature dependence of the barrier height was well explained by barrier inhomogeneity at the metal/semiconductor interface. From the analysis of the reverse bias characteristics, we found that field emission (FE) currents caused by the high donor concentration of the sample were the dominant conduction mechanism for S-EPC and FLAT. On the other hand, for L-EPC, the FE currents were overlapped by Poole-Frenkel emission (PFE) currents. For SBD, the leakage currents were successfully explained by the FE and thermionic field emission (TFE) mechanisms by assuming dislocation regions with a lowered barrier height. These findings suggest that mixed dislocations are associated with PFE and lower the Schottky barrier.

Epilithic biofilms of the Eastern Caspian (Aktau region, Kazakhstan) under conditions of falling sea level

Communities of microorganisms that form biofilms on the rocky shores of the Middle Caspian are capable of maintaining the integrity of the coastal landscape in the conditions of sea retreat associated with the ongoing drop in sea level since 1995. Algal-bacterial biofilms developing on rocky substrates of the East Caspian coast within the City of Aktau were studied in autumn (October 2022) and spring (April 2023) seasons. Communities in biotopes with different structure were investigated. It has been established that the most stable and diverse communities with a pronounced vertical structure live in the areas with high sheer cliffs on capes. On flat areas of the coast, which have undergone recent shallowing and are protected from surfing waves by ridges of large stones, less diverse cenoses, demonstrating clear spatial organization. In the shallow open areas of the shore, which are subject to intense wave action, live communities of two types were observed. Both cenoses contained a relatively small number of species, but differed in structure and potential for protecting the coast from erosion. The first of them live in biotopes outside the impact of urban domestic sewage, and are able to protect coastal marl from destruction due to the development of stable, rapidly regenerating complex structural elements. The latter were noted in the conditions of along-shore spreading of untreated domestic wastewater from new city developments located close to the coast. Such biofilms were no longer able to protect marls from being destroyed by waves, and took the form of constantly renewed patches with minimum diversity of components and unstable spatial organization.

Geospatial Characterisation of Gravitational and Erosion Risks to Establish Conservation Practices in Vineyards in the Arribes del Duero Natural Park (Spain)

Landslide movements and soil loss due to erosion have increased dramatically, causing numerous human and economic losses. Therefore, it is necessary to delimit these risks in order to prevent and mitigate the effects in natural parks of great value, as is the case of the Arribes del Duero Natural Park. As for landslide movements, they are evaluated by estimating the susceptibility to their occurrence, taking into account the different thematic layers: lithology, geomorphology (slopes, curvature, orientations), hydrogeology and vegetation, weighting each of them using the analytical hierarchy method. Then, by means of map algebra, the cartography of susceptibility to landslides is obtained. On the other hand, the RUSLE equation was used to calculate erosive losses. The results of the gravitational susceptibility are grouped into five classes: very high, high, medium, low and very low, so that the first corresponds to areas of high slope, without vegetation, south facing, with a lithology of quartzites, metapelites and gneisses (canyons, sloping valleys) and, on the contrary, the sectors of lower susceptibility coincide with flat areas, more density of vegetation, north facing, with conglomerates, cobbles, sands and clays, corresponding to erosion surfaces or valley bottoms. In terms of erosion results, the greatest losses are found in areas of steep slopes, with little or no vegetation and with poorly developed soils. Finally, taking into account the cartography of landslide risk, the cartography of potential water erosion and land use, it is possible to determine which conservation practices should be carried out, as well as the land uses that are less susceptible to these movements, highlighting in our study the importance of vineyards in their control.

South European mountain butterflies at a high risk from land abandonment and amplified effects of climate change

Abstract Data from existing monitoring schemes point to a global crisis of butterflies across Europe, with habitat loss/degradation, climate change and chemical pollution as the main drivers of decline. The existing butterfly time series from Western Europe come from densely populated, relatively flat areas. However, population trends from less populated areas, such as mountain ranges in the south of Europe, have been less studied, despite these areas harbouring one of the highest butterfly biodiversity of the continent. Here, we analyse trends for butterfly populations in a Southwestern Europe mountain range (Picos de Europa, Northwest Spain), for the last 9 years (2013–2021), across an altitudinal gradient (80–2000 m). We show that this region, protected as National Park more than 100 years ago, is nonetheless under a great threat, with a decline in butterfly abundance of, on average, 5.7% per year (45.7% cumulative decline in the last 9 years). Species at higher elevations are faring worse than those at low elevations and communities at mid‐elevations (below the tree line) are changing towards higher abundance of species with a preference from closed habitats. Combined effects of amplified climate change in mountains and habitat loss, due to abandonment of traditional management, appear to be affecting both individual species and community composition of butterflies in our study area.

Pemodelan Rain-On-Grid Untuk Kasus Banjir pada Polder Pluit, Jakarta

Jakarta flood occurs almost every year, one of the reasons is the rapid development of its urban areas. Generally, Jakarta is categorized as a flat area, of which some locations are lower than the mean sea level, for example Pluit Polder area, thus being prone to flood. In this study, the rain-on-grid modeling with HEC-RAS software is carried out to determine the parts of the Pluit Polder that are still inundated so that better mitigation strategies can be achieved. The modeling results show that there are still inundated areas around the Pluit Polder ranging from 0.25 m to 2.75 m.

Characterisation of the Susceptibility to Slope Movements in the Arribes Del Duero Natural Park (Spain)

In recent decades, natural disasters have increased drastically, with slope movements being the most damaging geological hazard, causing thousands of deaths and considerable economic losses. To reduce these losses, it is necessary to carry out cartographies that spatially delimit these risks, preventing and mitigating the effects through the analysis of susceptibility in areas of great environmental value, as is the case of the Arribes del Duero Natural Park. For this purpose, different statistical methods combined with Geographic Information Systems have been developed. The susceptibility assessment methodology is carried out by integrating different thematic layers: lithology, geomorphology (slopes, curvature, aspect), hydrogeology and vegetation, performing map algebra and taking into consideration their weighting using deterministic methods (analytical hierarchy method). The susceptibility results are grouped into Very High, High, Medium, Low and Very Low so that the areas of Very High susceptibility correspond to areas of the high slope, without vegetation, south facing, with a lithology of quartzites, metapelites, and gneisses (canyons, steep valleys) and, in the case of very low susceptibility, with a lithology of quartzites, metapelites, and gneisses, On the contrary, the sectors of lower susceptibility coincide with flat areas, denser vegetation, north facing, with a lithology of conglomerates, pebbles, sands and clays, such as erosion surfaces or valley bottoms. The analysis carried out in this current investigation will allow the territorial delimitation of problem areas and the establishment of risk mitigation and management measures.

Characteristics and Controlling Factors of Crystalline Dolostone Reservoirs of the Sanshanzi Formation, Central-Eastern Ordos Basin, Northwestern China

In recent years, Ordos Basin has been the largest petroleum field in China and represents significant potential for gas exploration in the Lower Paleozoic carbonate reservoirs. Taking the central-eastern Ordos Basin as an example, this work studies the reservoir characteristics, origin, and controlling factors of the crystalline dolomites of the Sanshanzi Formation by means of petrological and geochemical studies. The Sanshanzi Formation dolostones comprise three kinds: crystalline dolostone with grain-shadow (Rd1), very fine–fine crystalline dolostone (Rd2), and medium-coarse crystalline dolostone (Rd3). The pore spaces include intercrystalline pores and intercrystalline solution pores, residual intergranular pores, vugs, and fractures. The medium-coarse crystalline dolostone is the best reservoir. The average porosity is 4.61%, and the average permeability is 0.91 mD. The sedimentary environment in the upper Cambrian was a large area of tidal flats. Under the influence of penecontemporaneous meteoric water leaching, dissolution developed at the top of the dolomite flat–lagoon depositional cycle, with vugs developing in the very fine–fine crystalline dolostone. Penecontemporaneous dolomitization enhanced the compaction resistance and effectively preserved the pore space of the reservoir. In addition, recrystallization improved the crystalline texture, turning the intergranular pores into residual intergranular pores and intercrystalline micropores into intercrystalline pores. In this case, the very fine–fine crystalline dolostone was transformed into medium-coarse crystalline dolostone. The results of this study provide a case for the in-depth understanding of the development and preservation mechanism of ancient dolomite reservoirs and also point to the research pathways for oil and gas exploration in the Cambrian in the Ordos Basin in the future.

Multiple wind turbines shielding model of lightning attractiveness for mountain wind farms

In this study, a lightning attractiveness assessment method was proposed for mountain wind farms (WFs). A full-size wind turbine (WT) model accounting for terrain topography was established. Then, the lightning collection area (LCA) of WTs was calculated using the self-consistent leader inception and propagation model (SLIM). Finally, a quantitative relationship between terrain structure and the LCA of a WT was obtained, and a shielding model was incorporated to realize differentiated lightning attractiveness assessment of WFs. Results showed that higher terrain height and steeper ground slope angle both increase the size and the height of the LCA, meaning that lightning attractiveness can vary because of terrain differences, even for WTs with the same elevation. The influence of ground slope angle on the LCA showed a saturation trend. The variation of the LCA was analyzed based on the distortion effect of the terrain structure on the electric field. By comparison, the simulation results of lightning attractiveness for mountain WFs in this paper are in good agreement with the actual observation results in flat and mountainous areas. The proposed model could be used to identify weaknesses in the lightning protection of mountain WFs.

Adaptive Total-Variation and Nonconvex Low-Rank Model for Image Denoising

In recent years, image denoising methods based on total variational regularization have attracted extensive attention. However, the traditional total variational regularization method is an approximate solution based on convex method, and does not consider the particularity of the region with rich details. In this paper, the adaptive total-variation and nonconvex low-rank model for image denoising is proposed, which is a hybrid regularization model. First, the image is decomposed into sparse terms and low rank terms, and then the total variational regularization is used to denoise. At the same time, an adaptive coefficient based on gradient is constructed to adaptively judge the flat area and detail texture area, slow down the denoising intensity of detail area, and then play the role of preserving detail information. Finally, by constructing a nonconvex function, the optimal solution of the function is obtained by using the alternating minimization method. This method not only effectively removes the image noise, but also retains the detailed information of the image. The experimental results show the effectiveness of the proposed model, and SNR and SSIM of the denoised image are improved.

Distribution, sources and influencing factors of organic carbon in the surface sediments of the coastal tidal flats in Jiangsu Province

Coastal tidal flats are situated in the interaction zone between the ocean and land and are vulnerable to natural changes, human activities, and global changes; these areas serve as an important mixing zone and burial area for carbon and nitrogen storage. Coastal tidal flats contribute significantly to the global carbon cycle due to their high biological productivity, high sedimentation rate, and low decomposition rate. However, there is a lack of research on the sources and influencing factors of organic carbon in surface sediments in the coastal tidal flat area of Jiangsu Province. In this study, fourteen surface sediment samples were collected from the Jiangsu coastal tidal flats, and the distribution of organic carbon was analyzed. The sources and influencing factors of sediment organic carbon were also investigated by analyzing the contents, ratios and stable isotopes of carbon and nitrogen in the sediments. The results indicated that the total organic carbon (TOC) and total nitrogen (TN) contents in the surface sediments of Jiangsu coastal tidal flats ranged from 0.09% to 0.82% and from 0.01% to 0.1%, with mean values of 0.36% and 0.04%, respectively, and that there was a significant positive correlation between TOC and TN. Moreover, the high-value areas were located mostly along the borders or in sections covered in vegetation, whereas the mudflat areas without vegetation had lower values. Considering the status of the Jiangsu coastal zone, the abandoned Yellow River estuary, Yangtze River inlet, marine benthic microalgae, C3 plants and C4 plants were selected as end members of organic carbon concentrations. The contributions of different sources were quantified using a Bayesian mixture model (MixSIAR). Among them, the abandoned Yellow River estuary and Yangtze River inlet contributed 28.1% and 19.3%, respectively, followed by marine benthic microalgae with a contribution of 26%, whereas C3 and C4 plants made limited contributions of 9% and 8.8%, respectively. Additionally, the sediment particle size, hydrodynamics, and tidal flat vegetation such as Spartina alterniflora were the key factors influencing the organic carbon distribution. In general, this study contributes to a better understanding of the biogeochemical processes and sources of organic carbon in coastal tidal flats. It also provides a solid foundation for the creation of carbon sink measures in nearshore tidal flats.

Saltmarsh vegetation alters tidal hydrodynamics of small estuaries

Saltmarshes in most estuaries in the UK and elsewhere are heavily exploited for numerous purposes including farming, fishing, and recreation. In this study, a computational model was used to investigate the impact of saltmarsh vegetation on tidal dynamics and residual currents in three distinctly different estuaries in Wales, UK, in order to understand the impacts of marsh vegetation on wider estuarine hydrodynamics. The three estuaries, Mawddach, Taf and Loughor, vary in size, tidal range, exposure, and saltmarsh coverage. Tidal constituents and residual currents were calculated using a year-long simulation of tidal dynamics. Tidal dynamics are discussed in terms of five important primary tidal constituents (M2, S2, N2, K1, O1) and two shallow water constituents (M4, MS4). The results reveal that saltmarsh vegetation reduces the amplitude of both primary and shallow water tidal constituents not only on and at the proximity of marsh platforms but also in the wider estuary, mostly confined to tidal channels and surrounding intertidal areas. Most notable changes were observed in the middle and upper estuary. Notable changes to residual current velocities were observed on marsh flat areas and in tidal channels and saltmarsh creeks which indicates that changes to marsh vegetation have the potential to alter sediment transport and hence wider estuary hydrodynamics. Our results will be useful when making decisions to restore, reclaim and realign existing saltmarshes for environmental, conservation and socioeconomic purposes, or integrate them in nature-based solutions for estuarine flood and erosion management.

A Spiral-Propulsion Amphibious Intelligent Robot for Land Garbage Cleaning and Sea Garbage Cleaning

To address the issue of current garbage cleanup vessels being limited to performing garbage cleaning operations in the ocean, without the capability of transferring the garbage from the ocean to the land, this paper presents a spiral-propulsion amphibious intelligent robot for land garbage cleaning and sea garbage cleaning. The design solution is as follows. A mechanical structure based on a spiral drum is proposed. The interior of the spiral drum is hollow, providing buoyancy, allowing the robot to travel both on marshy, tidal flats and on the water surface, in conjunction with underwater thrusters. Additionally, a mechanical-arm shovel is designed, which achieves two-degrees-of-freedom movement through a spiral spline guide and servo, facilitating garbage collection. Our experimental results demonstrated that the robot exhibits excellent maneuverability in marine environments and on beach, marsh, and tidal flat areas, and that it collects garbage effectively.

Deep convective clouds observed by ground-based radar over Naqu, Qinghai–Tibet Plateau

The deep convective clouds (DCCs, 20 dBZ echo top exceeding 14 km) and intense DCCs (IDCCs, 40 dBZ echo top exceeding 10 km) over Naqu, a city featuring the most active convection in the central Qinghai–Tibet Plateau, were analyzed on the basis of data derived from the Naqu C-band radar within a radius of 100 km. The most frequent DCCs occur in July and at 15:00 LT (local time), in terms of monthly and diurnal variations, respectively. The geographic distribution of the DCCs seems to be related to the topography. The centers featuring the most frequent DCCs correspond to some certain hilly areas, while the ratio of IDCC to DCC is greater in some specific flat areas, which may be because the hilly topography is conducive to triggering convection but is unfavorable to the full accumulation of unstable energy. The DCCs (IDCCs) have average 20, 30 and 40 dBZ echo tops of approximately 15.8 (16.5), 12.3 (14.1) and 9.9 (11.3) km, and average areas of the regions with a composite reflectivity >20, 30 and 40 dBZ of approximately 120.3 (196.1), 37.4 (75.3) km2 and 9.2 (14.6) km2, respectively. The maximum reflectivity and horizontal extents of 20 and 30 dBZ radar echoes tend to occur at the level around −20 °C. The average horizontal extent of DCCs is much smaller than that suggested by the satellite-based radar data. In the diurnal variations in the vertical and horizontal extents of DCCs, the parameters related to 30 dBZ always increase more slowly and decrease more rapidly than those related to 20 dBZ in the afternoon, which is attributed to the generally weak convection characteristics of DCCs. The strongest convection may be around 16:00 LT in Naqu.