This Special Issue of Remote Sensing, which is the third in a series entitled “Remote Sensing of Precipitation”, comprises a collection of ten papers devoted to remote sensing applications for ...measuring precipitation; these include new satellite technologies for the remote sensing of precipitation, the validation of satellite-based precipitation estimates using rain gauge measurements and surface radar estimates, and comparisons between gridded precipitation data ...
In this study, the focus is on investigating how different climate scenarios, as they have been adopted in Phase 6 of the Coupled Model Intercomparison Project (CMIP6), can lead to different regimes ...in the energetics components in Lorenz’s energy cycle, hence impacting the “working rate” of the climate system, which is considered as a “heat engine.” The four energy forms on which this investigation is based on are the zonal and eddy components of the available potential and kinetic energies. The permissible correspondingly considered transformations between these forms of energy are also studied. Generation of available potential energy and dissipation of kinetic energy complete the Lorenz energy cycle that is adopted here. In the CMIP6 approach, the results of different climate change analyses were collected in a matrix defined by two dimensions: climate exposure as characterized by a radiative forcing or temperature level and socioeconomic development as classified by the pathways, known as Shared Socioeconomic Pathways (SSPs). The basis of the calculations in this study is the climatic projection produced by the HadGEM3-GC3.1-LL climatic model in the period from 2015 to 2100. In this respect, the results are presented in terms of time projections of the energetics components under different SSPs. The results have shown that the different SSPs yield diverse energetics regimes, consequently impacting on Lorenz energy cycle and, hence, a “working rate” of the climate system based on the components of this cycle. In this respect, Lorenz energy cycle projections are presented, under different SSPs. The results are also contrasted to the calculations for the historical period 1929 to 2014 as this is simulated by the same climatic model.
The ongoing and intensive consideration by the scientific community of the many facets of precipitation science constitutes a broad recognition of the significance of this indispensable component of ...the hydrologic cycle ...
This Special Issue hosts papers on all aspects of remote sensing of precipitation, including applications that embrace the use of remote-sensing techniques of precipitation in tackling issues, such ...as precipitation estimations and retrievals, along with their methodologies and corresponding error assessment; precipitation modelling including validation, instrument comparison, and calibration; understanding of cloud and precipitation microphysical properties; precipitation downscaling; precipitation droplet size distribution; assimilation of remotely sensed precipitation into numerical weather prediction models; and measurement of precipitable water vapor.
The aim of this study is to investigate whether different Representative Concentration Pathways (RCPs), as they are determined in the Fifth Assessment Report (AR5) of the Intergovernmental Panel on ...Climate Change (IPCC), lead to different regimes in the energetics components of the Lorenz energy cycle. The four energy forms on which this investigation is based are the zonal and eddy components of the available potential and kinetic energies. The corresponding transformations between these forms of energy are also studied. RCPs are time-dependent, consistent scenarios of concentrations of radiatively active gases and particles. In the present study, four RCPs are explored, namely, rcp26, rcp45, rcp60, rcp85; these represent projections (for the future period 2006–2100) that result in radiative forcing of approximately 2.6, 4.5, 6.0 and 8.5 Wm−2 at year 2100, respectively, relative to pre-industrial conditions. The results are presented in terms of time projections of the energetics components from 2020 to 2100 and show that the different RCPs yield diverse energetics regimes, consequently impacting the Lorenz energy cycle. In this respect, projections under different RCPs of the Lorenz energy cycle are presented.
Plastic litter floating in the ocean is a significant problem on a global scale. This study examines whether Sentinel-2 satellite images can be used to identify plastic litter on the sea surface for ...monitoring, collection and disposal. A pilot study was conducted to determine if plastic targets on the sea surface can be detected using remote sensing techniques with Sentinel-2 data. A target made up of plastic water bottles with a surface measuring 3 m × 10 m was created, which was subsequently placed in the sea near the Old Port in Limassol, Cyprus. An unmanned aerial vehicle (UAV) was used to acquire multispectral aerial images of the area of interest during the same time as the Sentinel-2 satellite overpass. Spectral signatures of the water and the plastic litter after it was placed in the water were taken with an SVC HR1024 spectroradiometer. The study found that the plastic litter target was easiest to detect in the NIR wavelengths. Seven established indices for satellite image processing were examined to determine whether they can identify plastic litter in the water. Further, the authors examined two new indices, the Plastics Index (PI) and the Reversed Normalized Difference Vegetation Index (RNDVI) to be used in the processing of the satellite image. The newly developed Plastic Index (PI) was able to identify plastic objects floating on the water surface and was the most effective index in identifying the plastic litter target in the sea.
In this research, one aspect of the climate that is not commonly referred to, namely, the long-term changes in the components of the atmospheric energy, is investigated. In this respect, the changes ...in four energy forms are considered, namely, Kinetic Energy (KE), Thermal Energy (TE), Internal Energy (IE), Potential Energy (PE) and Latent Energy (LE); the Energy Conversion (EC) between Kinetic Energy and Potential plus Internal Energy (PIE) is also considered. The area considered in this long-term energetics analysis covers the entire Mediterranean basin, the Middle East and a large part of North Africa. This broad geographical area has been identified by many researchers as a hot spot of climate change. Analyses of climatic data have indeed shown that this region has been experiencing marked changes regarding several climatic variables. The present energetics analysis makes use of the ERA-Interim database for the period from 1979 to 2018. In this 40-year period, the long-term changes in the above energetics components are studied. The monthly means of daily means for all the above energy forms and Energy Conversion comprise the basis for the present research. The results are presented in the form of monthly means, annual means and spatial distributions of the energetics components. They show the dominant role of the subtropical jet-stream in the KE regime. During the study period, the tendency is for KE to decrease with time, with this decrease found to be more coherent in the last decade. The tendency for TE is to increase with time, with this increase being more pronounced in the most recent years, with the maximum in the annual mean in KE noted in 2015. The sum of Potential and Internal energies (PIE) and the sum of Potential, Internal and Latent energies (PILE) follow closely the patterns established for TE. In particular, the strong seasonal influence on the monthly means is evident with minima of PIE and PILE noted in winters, whereas, maxima are registered during summers. In addition, both PIE and PILE exhibit a tendency to increase with time in the 40-year period, with this increase being more firmly noted in the more recent years. Although local conversion from KE into PIE is notable, the area averaging of EC shows that the overall conversion is in the direction of increasing the PIE content of the area at the expense of the KE content. EC behaves rather erratically during the study period, with values ranging from 0.5 to 3.7 × 102 W m−2. Averaged over the study area, the Energy Conversion term operates in the direction of converting KE into PIE; it also lacks a seasonal behavior.
Global Precipitation Measurement (GPM) Integrated Multi-satellitE Retrievals for GPM (IMERG) high-resolution product and Tropical Rainfall Measuring Mission (TRMM) 3B43 product are validated against ...rain gauges over the island of Cyprus for the period from April 2014 to June 2018. The comparison performed is twofold: firstly, the Satellite Precipitation (SP) estimates are compared with the gauge stations’ records on a monthly basis and, secondly, on an annual basis. The validation is based on ground data from a dense and well-maintained network of rain gauges, available in high temporal (hourly) resolution. The results show high correlation coefficient values, on average reaching 0.92 and 0.91 for monthly 3B43 and IMERG estimates, respectively, although both IMERG and TRMM tend to underestimate precipitation (Bias values of −1.6 and −3.0, respectively), especially during the rainy season. On an annual basis, both SP estimates are underestimating precipitation, although IMERG estimates records (R = 0.82) are slightly closer to that of the corresponding gauge station records than those of 3B43 (R = 0.81). Finally, the influence of elevation of both SP estimates was considered by grouping rain gauge stations in three categories, with respect to their elevation. Results indicated that both SP estimates underestimate precipitation with increasing elevation and overestimate it at lower elevations.
Frequent water table measurements are crucial for sustainable groundwater management in arid regions. Such monitoring is more important in areas that are already facing an acute problem with ...excessive groundwater withdrawal. In the majority of these locations, continuous readings of groundwater levels are lacking. Therefore, an approximate estimate of the rate of increase or decrease in water consumption over time may serve as a proxy for the missing data. This could be achieved by tracking the changes in vegetated areas that generally correlate with changes in the rate of water use. The technique proposed in this paper is based on two remote sensing datasets: Landsat 7 and 8 from 2001 to 2021, and Sentinel 2A from 2015 to 2021, as well as five vegetation indices: Normalized Difference Vegetation Index (NDVI), Renormalized Difference Vegetation Index (RDVI), Soil Adjusted Vegetation Index (SAVI), Enhanced Vegetation Index (EVI), and Transformed Vegetation Index (TVI). The findings have shown that the datasets chosen performed best for small-scale land farms at the research location, which was chosen to be the El-Qaa plain, in the southwestern corner of the Sinai Peninsula in Egypt. Landsat 7 data with a resolution of 30 m revealed a substantial increase in land farms from 2.9 km2 in 2001 to 23.3 km2 in 2021. By using the five indices based on Sentinel 2A data, vegetated areas were categorized as heavy, moderate, or light. In addition, the expansion of each class area from 2015 to 2021 was tracked. Additionally, the NDVI index was modified to better reflect the arid environment (subsequently naming this new index as the Arid Vegetation Index: AVI). Rough scenarios of the increase in water consumption rate at the research site were generated by observing the increase in vegetated areas and collecting rough information from the farmers regarding the crop types.
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