Effect of frost on plants, leaves, and forecast of frost events using convolutional neural networks

Climate change brings many changes in a physical environment like plants and leaves. The flowers and plants get affected by natural climate and local weather extremes. However, the projected increase in the frost event causes sensitivity in plant reproduction and plant structure vegetation. The timing of growing and reproduction might be an essential tactic by which plant life can avoid frost. Flowers are more sensitive to hoarfrost than leaves but more sensitive to frost in most cases. In most cases, frost affects the size of the plant, its growth, and the production of seeds. In this article, we examined that how frost affects plants and flowers? How it affects the roots and prevents the growth of plants, vegetables, and fruits? Furthermore, we predicted how the frost will grow and how we should take early precautions to protect our crops? We presented the convolutional neural network model framework and used the conv1d algorithm to evaluate one-dimensional data for frost event prediction. Then, as part of our model contribution, we preprocessed the data set. The results were comparable to four weather stations in the United States. The results showed that our convolutional neural network model configuration is reliable.

Analysis of Extreme Meteorological Events in the Central Andes of Peru Using a Set of Specialized Instruments

A set of instruments to measure several physical, microphysical, and radiative properties of the atmosphere and clouds are essential to identify, understand and, subsequently, forecast and prevent the effects of extreme meteorological events, such as severe rainfall, hailstorms, frost events and high pollution events, that can occur with some regularity in the central Andes of Peru. However, like many other Latin American countries, Peru lacks an adequate network of meteorological stations to identify and analyze extreme meteorological events. To partially remedy this deficiency, the Geophysical Institute of Peru has installed a set of specialized sensors (LAMAR) on the Huancayo observatory (12.04° S, 75.32° W, 3350 m ASL), located in the Mantaro river basin, which is a part of the central Andes of Peru, especially in agricultural areas. LAMAR consists of a set of sensors that are used to measure the main atmosphere and soil variables located in a 30-meter-high tower. It also has a set of high-quality radiation sensors (BSRN station) that helps measure the components of short-wave (SW) (global, diffuse, direct and reflected) and long-wave (LW) (emitted and incident) irradiance mounted in a 6-meter-high tower. Moreover, to analyze the microphysics properties of clouds and rainfall, LAMAR includes a set of profiler radars: A Ka-band cloud profiler (MIRA-35c), a UHF wind profiler (CLAIRE), and a VHF wind profiler (BLTR), along with two disdrometers (PARSIVEL2) and two rain gauges pluviometers. The present study performs a detailed dynamic and energetic analysis of two extreme rainfall events, two intense frost events, and three high-pollution events occurring on the Huancayo observatory between 2018 and 2019. The results show that the rainfall events are similar to the 1965–2019 climatological 90th percentile of the daily accumulated rainfall. The results also highlighted the patterns of reflectivity in function of height for both events, which is measured by highlighting the presence of convective and stratiform rainfall types for both events. The first intense rainfall event was associated with strong easterly circulations at high levels of the atmosphere, and the second one was associated with the presence of strong westerly circulations and the absence of BH-NL system around the central Andes. The first frost event was mainly associated with continuous clear sky conditions in the few previous days, corresponding to a radiative frost event. The second one was mainly associated with the intrusion of cold surges from extra-tropical South America. For both events, the energy budget components were strong-lower in comparison to the mean monthly values during early morning hours. Finally, for the high pollution events, the study identified that the main source of aerosols were the forest fires that took place in Peru with certain contributions from the fires in the northern area of Bolivia.

Medium-Resolution Multispectral Data from Sentinel-2 to Assess the Damage and the Recovery Time of Late Frost on Vineyards

In a climate-change context, the advancement of phenological stages may endanger viticultural areas in the event of a late frost. This study evaluated the potential of satellite-based remote sensing to assess the damage and the recovery time after a late frost event in 2017 in northern Italian vineyards. Several vegetation indices (VIs) normalized on a two-year dataset (2018–2019) were compared over a frost-affected area (F) and a control area (NF) using unpaired two-sample t-test. Furthermore, the must quality data (total acidity, sugar content and pH) of F and NF were analyzed. The VIs most sensitive in the detection of frost damage were Chlorophyll Absorption Ratio Index (CARI), Enhanced Vegetation Index (EVI), and Modified Triangular Vegetation Index 1 (MTVI1) (−5.26%, −16.59%, and −5.77% compared to NF, respectively). The spectral bands Near-Infrared (NIR) and Red Edge 7 were able to identify the frost damage (−16.55 and −16.67% compared to NF, respectively). Moreover, CARI, EVI, MTVI1, NIR, Red Edge 7, the Normalized Difference Vegetation Index (NDVI) and the Modified Simple Ratio (MSR) provided precise information on the full recovery time (+17.7%, +22.42%, +29.67%, +5.89%, +5.91%, +16.48%, and +8.73% compared to NF, respectively) approximately 40 days after the frost event. The must analysis showed that total acidity was higher (+5.98%), and pH was lower (−2.47%) in F compared to NF. These results suggest that medium-resolution multispectral data from Sentinel-2 constellation may represent a cost-effective tool for frost damage assessment and recovery management.

Synoptic and Large-Scale Determinants of Extreme Austral Frost Events

We define and examine extreme frost events at three station locations across southern Australia. A synoptic assessment of the events shows that they are generally characterized by passage of a front or trough followed by a developing blocking high. Frost typically occurs at the leading edge of the block. The very cold air pool leading to the frost event is the result of descent of cold, dry midtropospheric air parcels from regions poleward of the station. The air is exceptionally cold because it is advected across the strong meridional temperature gradients in the storm track. The air is dry because this equatorward meridional pathway requires descent and so must have origins well above the surface in the dryer midtroposphere. The position of the block and location of the dry descent are dynamically determined by large-scale waveguide modes in the polar jet waveguide. The role of the waveguide modes is deduced from composites of midtropospheric flow anomalies over the days preceding and after the frost events. These show organized wavenumber 3 or 4 wave trains, with the block associated with the frost formed as a node of the wave train. The wave trains resemble known waveguide modes such as the Pacific–South America mode, and the frost event projects clearly onto these modes during their life cycle. The strong interannual and decadal variability of extreme frost events at a location can be understood in light of event dependence on organized waveguide modes.

Effect of late spring frost event on nutrition aspects of a sour cherry orchard in East Hungary

Similarly to 2007, 2011 was also critical year for fruit growers in Eastern-Hungary. Serious frost damage was observed at late blooming period (6 May (T=-1.6°C)) in this region, which caused approximately 60-65% of fruit loss. The aim of this study is to investigate the effects of a spring frost event on nutrient uptake and status of the trees of a sour cherry plantation at Újfehértó. The symptoms of frost were observed visually. This visual observation was confirmed by SPAD readings. The frost affected the macroand micronutrient contents of leaves. It was found that the frost affected the nutrient uptake negatively, but the effect of it was not significantly sometimes. It can be stated that the nutrient demand of trees can be supplied only under even worse conditions.

Effects of pine shelterwoods on microclimate and frost damage to Norway spruce seedlings

Cuttings of Norway spruce, Picea abies (L.) Karst., were planted under two Scots pine, Pinus sylvestris L., shelterwoods with a density gradient varying from fully stocked forest to clearcuts. This provided a range of near-ground temperature and radiation regimes. The microclimate was monitored near each cutting, using an automated mobile system. The factors monitored were air temperature, global radiation, and net radiation. Frost damage to the spruce cuttings was assessed by two methods. First, the percentage of actively growing shoots with visible damage was determined. Second, the maximum photochemical efficiency of photosystem II (Fv /Fm) in 1-year-old and current-year needles was estimated from measurements of chlorophyll a fluorescence. A frost event in May 1990 was analysed using the partial least squares in latent variables (PLS) method of multivariate statistical analysis. Different microclimatic variables were used as predictors. Visible damage to actively growing shoots and the Fv /Fm ratio in 1-year-old needles were used as response variables. The predictors were used to produce a separate PLS model for each response variable. Nocturnal net radiation during the frost event, and both the net and global radiation the day after, were found to be important for explaining the visible damage and the Fv /Fm ratios. In both the PLS analyses, the modelling power of these three variables was ranked among the highest of all microclimatic factors tested. The accumulated air temperature below 0°C, the duration of the frost, and the minimum air temperature near the ground (at 0.4 m) also had high predictive power. Thus, both higher nocturnal air temperature near the ground and shading the day after the frost event were important factors explaining the reduction of visible damage and low-temperature induced photoinhibition. Leaving a dense shelterwood moderates both the nocturnal air temperature and the radiation regime and, therefore, is recommended on sites where early summer frosts are expected.