Monsoon Area Research Articles

Is survival of Himalayan Cedar (Cedrus deodara) threatened? An evaluation based on predicted scenarios of its growth trend under future climate change

Global warming is likely to become one of the significant drivers of forest losses in the Hindu-Kush Himalaya (HKH) during the 21st century. Better understanding of how forest ecosystem will respond to global warming requires a precise knowledge of site and species specific responses to climate change. We applied dendrochronological technique to quantify and predict future growth trend of Himalayan cedar (Cedrus deodara), a tree of high commercial importance, and explored its spatial growth variability under two different climatic regimes from 17 deodar sites in the HKH. Of the two climate regimes, one is dominated by the monsoon rainfall and the other by the westerly disturbances. Analysis of tree ring width and climate (monthly temperature and precipitation) data reveals that the spring (March–May) temperature and precipitation affect the growth of deodar negatively and positively, respectively. We used Generalized Least Squares (GLS) regression model to forecast future growth of deodar by taking an ensemble of 40 General Circulation Models (GCMs) for emission scenarios RCP 4.5 and RCP 8.5. Predicted growth trends indicate the decline between 34 % and 38 % under RCP 4.5, and between 29 % and 32 % under RCP 8.5 scenarios, for the low and mid latitude sites. In contrast, a moderate increase in growth was observed in high latitude sites under the both climate scenarios. The study shows more drought stress to deodar trees growing in monsoon areas in mid-and low-latitude sites where less snow melt and low precipitation during the spring season are predicted to increase evapotranspiration. In comparison, in the higher latitude sites where there is a high snowfall due to western disturbances, the growth of deodar is predicted to increase. These findings may be used to take suitable migratory steps for the conservation of deodar in the HKH region.

Austral and Subtropical Gyre Radiolaria – latest Jurassic to Early Cretaceous Leg 123, Site 765, Argo Abyssal Plain revisited: Southern Hemisphere paleobiogeography and global climate change

The aim of this report is to 1) to formally describe Austral and Subtropical Gyre Radiolaria recovered from ODP Hole 123-765C), 2) to compare them with published records of Southern Hemisphere “non-Tethyan” assemblages and 3) to discuss radiolarian paleobiogeography of the Southern Hemisphere and its implications for global climate change during the Jurassic–Cretaceous transition. The Tithonian to Aptian/early Albian radiolarian record recovered from Hole 765C, Cores -62R to -36R in the Argo Abyssal Plain (AAP) is unique in its density of well-preserved samples and in its faunal contents. Radiolaria recovered from claystones yielded the low diversity, ecologically tolerant “Crypto-Archaeo” Assemblage, (chiefly cryptocephalic and cryptothoracic nassellarians and Archeodictyomitra spp.) interpreted herein as originated in the Subtropical Gyre (STG). In contrast, assemblages extracted from radiolarite layers, interpreted as pelagic turbidites derived from the deeper Australian margin, are dominated by Austral taxa. Neotethyan taxa are very rare to absent before the late Hauterivian/Barremian, when they gradually gain in diversity and abundance. Described Austral and STG taxa include 10 families, of which Fusitanellidae n. fam. and Windaliinae n. subfam. are new. Of 18 genera 7 are new (Nodosphaera, Praewindalia, Pachycingula, Archaeotanella, Morchella, Fusitanella, Argofusus) and of 55 species 30 new ones are formally described and 14 new ones are left in open nomenclature. The southern hemisphere Late Jurassic to Early Cretaceous radiolarian biogeography is defined from low- to high latitude: 1. the Neotethyan (NT) and 2. the Central Panthalassan (CP) realms, 3. Eastern Boundary Current (EBC) realm, 4. the Subtropical Gyre (STG) and the Austral (A) circum south-polar realm. Radiolarian biogeography and plate tectonic models support a scenario of palaeoceanographic and global climatic change during the Jurassic–Cretaceous transition related to progressive Pangea break-up with the following consequences: 1. an increased heat transfer to the Southern hemisphere which caused cooling of Neotethyan regions during the Late Tithonian dry event. 2. A northward shift of the southern summer Intertropical Conve nience Zone reduced the Neotethyan monsoon area and allowed the establishment of a southern Neotethyan subtropical gyre documented by the “Crypo-Archaeo” Assemblage. 3. The south-polar West Wind Drift may have forced a circum Antarctic-Australian cold current through the epicontinental rift between India and Antarctica-Australia since the Berriasian (140 my), transporting Austral Radiolaria into the AAP where they accumulated in radiolarite layers.

Bias of automatic weather parameter measurement in monsoon area, a case study in Makassar Coast

<abstract><p>The shift from manual weather measurements to automation is almost inevitable. When switching to AWS (Automatic Weather Station), WMO requires parallel data testing between automatic and manual measurements to be performed. The purpose of this paper is to conduct a parallel test of AWS data using a simple statistical test that has been applied to three main weather parameters, namely temperature, pressure, humidity, rainfall, and wind direction and speed. The months of January and June were used as samples to represent the character of the wet and dry seasons in the Makassar monsoon area. The results of the analysis show that during the rainy season, only pressure and temperature are identical and homogeneous. Meanwhile, in the dry season, apart from these two parameters, humidity and wind speed are also homogeneous and rainfall is a non-homogeneous parameter in January and June. Both AWS and manual observations show that the influence of land-sea winds in Makassar is very strong. Considering that there are inhomogeneous parameters, it is highly recommended to test for a longer time, taking into account the season, the influence of other global phenomena, the effect of missing data and incorrect data testing various methods of homogeneity and characteristics in each place and their effect on forecasts.</p></abstract>

Investigating and optimizing a method to determine atmospheric mercury for application in Ho Chi Minh City, Viet Nam

Mercury (Hg) is a toxic of global concern due to its bioaccumulation in the environment and the atmosphere which is an important environment in the biogeochemical cycle of Hg. IO-5 method (US-EPA) is the most common analysis method to measure the concentration of atmospheric Hg. However, few studies have been done in tropical monsoonal areas such as Ho Chi Minh City (HCMC). This paper reported the investigation and optimization of the IO-5 method for WA-5F, NIC with the purpose of measuring the atmospheric Hg in Ho Chi Minh City as well as other tropical monsoon regions. The sampling temperature of gold trap, sampling flow rate and time, use of soda lime, passive Hg infection over time, and concentration repeatability were investigated. The results showed that the NIC gold trap was in good stability with recoveries (H%) always higher than 95% for temperatures of 30‒150oC. Because of the tropical climatology in HCM City, a heater for the gold trap was not necessary. The recoveries were > 95% for sampling rates of 0,3‒2,5 L/min. A sampling rate of 0,5 L/min for 12‒24 hours sampling periods as well as a soda lime trap to protect the gold trap during sampling were recommended. Testing the gold traps blank showed a negligible passive contamination after 30 days of storage, demonstrating the suitability of the procedure for long-term sampling campaigns. In addition, the average difference in the Hg concentration between two parallel samples was less than 10%, consistent with standards from the professional monitoring networks worldwide. In general, applying the IO-5 method in monitoring the atmospheric Hg in HCM City was suitable. Moreover, the obtained result offered a suitable method to collect the atmospheric Hg data in Vietnam as well as in Southeast Asia where the anthropogenic Hg monitoring data were limited.

The Effect of El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on Rainfall and Its Correlation with Consecutive Dry Days (CDD) of South Sumatra Province from 1981-2020

El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD)` are events where the phenomenon of rising and falling sea surface temperatures becomes unnatural. Stronger events where the sea surface temperature anomaly becomes large, then this disrupts local fish and bird populations. The ENSO and IOD phenomena also affect rainfall in several parts of Indonesia. This study analyzed the effect of ENSO and IOD phenomena on rainfall in South Sumatra Province from 1981 to 2020 and the correlation between Consecutive Dry Days (CDD) and Rainfall in South Sumatra Province for the last 40 years. ENSO data and IOD data were analyzed against rainfall data analyzed using a simple linear regression method and associated with CDD in South Sumatra Province with the correlation method. In addition, a correlation analysis was also carried out between the Niño 3.4 index and the Dipole Mode Index (DMI) with rainfall at two stations, namely the Palembang Climatology Station and the Sultan Mahmud Badaruddin II Meteorological Station to determine how much influence the ENSO and IOD phenomena had on rainfall in the Sumatra Province. South. The results of the analysis show that the effect of ENSO and IOD on rainfall at each station is generally not significant. The state of rainfall in the Province of South Sumatra for the last 40 years is almost not influenced by El Nio and La Nia. This is presumably due to the location of the South Sumatra Region which is in the Munsonal area. Monsoon areas are characterized by a unimodial type of rainfall (one peak of the rainy season) where in June, July and August the dry season occurs, while December, January and February are the wet months. The remaining six months is a transitional or transitional period (three months of transition from dry season to rainy season and three months of transition from rainy season to dry season).

Comparison of the Causes of Erosion-Deposition between Yellow River, Yangtze River and Mekong River Subaqueous Deltas II: Comparative Analysis

The estuary delta is an area where human economic activities are active and natural ecological environment is fragile. With global change and the intensification of human activities, coastal and seabed erosion around the world is becoming more and more serious. In this paper, we used the Delft 3D numerical simulation to compare the hydrodynamic effects of sediment transport paths in the Yellow River delta (river-controlled type), Yangtze River delta (tidal type) and Mekong River delta (tidal wave type) in the East Asian monsoon area, and analyzed the causes of accumulation erosion landform distribution in three different types of subaqueous deltas. This study finds the Yellow River Delta has experienced varying degrees of erosion at the estuary, but its subaqueous delta is still dominated by deposition; the Yangtze River Delta has ensured the stability of its shoreline under the influence of artificial shoreline reinforcement, but the subaqueous delta (water depth: 0–15 m) is in a state of erosion all year round; and in the Mekong River Delta the erosion occurs in both its shoreline and subaqueous delta. Additionally, only by analyzing the erosion and deposition within the transport range of resuspended sediment, the changes in the properties of the entire subaqueous delta could be recognized. The research results can not only be helpful to analyze whether the change of river sediment will lead to the change of delta type under human influence, but also provide more powerful scientific support for the protection of delta ecological environment, geological environment safety and geological disaster prevention.

Seasonal Cycles of High Mountain Asia Glacier Surface Elevation Detected by ICESat‐2

AbstractHigh Mountain Asia (HMA) glaciers are a key component of mountain hydrology and their seasonal ablation contributes significantly to the annual runoff of several large river systems that protect large populations from water stress. However, the seasonal cycle of glacial change remains unclear. Recent NASA's Ice, Cloud, and Land Elevation Satellite (ICESat‐2) provides an opportunity to survey changes in the glacier surface elevation in unprecedented detail. Here, we used a new approach—which is based on a developed elevation bin cluster with a sliding filter and an iterative recovery method—to obtain the complete seasonal cycle of glacier thickness changes in HMA. We generally identified three types of glaciers: (a) glaciers in the westerly dominant area (WDA) (b) glaciers in the Indian monsoon area (IMA), and (c) glaciers in the transition area (TA). The peak thickness values for the IMA, WDA, and TA glaciers occur in February, May, and June, respectively. Most glaciers in WDA and IMA show a strong seasonal cycle with variations of more than 2 m, while the TA glaciers are mainly characterized by weak changes of up to 1 m. Overall, our results show that the glaciers can provide 67–138 Gt of meltwater per year to downstream. These results provide crucial information for the calibration of models that project glacier response to climate change and simulate the downstream water availability. Our methodology facilitates the application of ICESat‐2 to seasonal tracking of glacier variability in global alpine areas.

Vegetation succession, climate change and cold events during 9.2–8.0 cal kyr BP in eastern China: High-resolution pollen evidence from the Yangtze delta plain area

High resolution pollen records in the northern edge of subtropical China are crucial to understand the pattern of postglacial vegetation change and climate transition. Here we present vegetation succession and climate change during 9.2–8.0 cal kyr BP based on sub-decennial scale pollen data. Pollen spectra show that Quercus (evergreen) &Cyclobalanopsis were relatively stable during the whole period, while Quercus (deciduous) were gradually decreased. Pollen-based climate change shows gradual warming during this period, and noticeably, the rapid warming during 8610–8545 cal yr BP can be detected according to the sharp decrease of Quercus (deciduous). Our results show two cold and dry events at 8.5 ka and 8.2 ka. The 8.5 ka event is rarely reported in the East Asian Monsoon area, while the 8.2 ka event is frequently mentioned. In this study, the 8.2 ka event has two peaks, similar to the previous reports from the Yangtze delta area and Dongge Dong Cave. In the Yangtze delta area, the vegetation and climate change show a strong relationship with the high latitude area, indicating that they are not only related to solar activity, but also impacted by the high latitude climate events. However, the impacts of these events on the Asian monsoon area still need further studies to verify.

Prediksi Perubahan Iklim Ekstrem di Kota Palembang dan Kaitannya dengan Fenomena El Niño-Southern Oscillation (ENSO) Berbasis Machine Learning

The purpose of this study is to provide predictions of climate conditions and trend of temperature rise in the city of Palembang in the 21st century. The BMKG station data used, namely SK Palembang and SM SMB II from the 2000-2020 period were analyzed based on the agreement of the Expert Team for Climate Change Detection and Indices (ETCCDI). ). Analysis using google colab shows that rainfall in the city of Palembang has a fairly high variability and a decrease in the number of rainy days that occur in the city of Palembang with the trend of air temperature, namely TMAXmean and TMINmean, has increased significantly by 2.40C for 50 years. Based on the correlation analysis between rainfall and El Niño-Southern Oscillation (ENSO) with Google Colab, a negative relationship was found. The El Niño-Southern Oscillation (ENSO) index used is the Niño 3.4 index. The study concluded that although the geographical location of Palembang city is located in the Asian Monsoon area, the ENSO phenomenon does not significantly affect rainfall variability in Palembang city.

Contributions of Multiple Water Vapor Sources to the Precipitation in Middle and Lower Reaches of Yangtze River Based on Precipitation Recycle Ratio

Global warming weakened the summer monsoon and increased the evaporation, leading to more contribution of local evaporation moisture to the local precipitation for the monsoon areas. However, the descriptions of the contribution of the local moisture to the total precipitation and its characteristics have not been known very well. In this paper, taking the middle and lower Reaches of the Yangtze River (MLRYR) as a case and using the precipitation recycling process model, we analyzed the characteristics of the contribution of the local moisture to the total precipitation and the possible reasons. The results show that: the seasonal difference in precipitation recycling rates is obvious, the precipitation recycling rates in spring and summer are small (18.30% and 19.30%), the maximum in autumn is 30.50%, and the precipitation recycling rates in all seasons except summer show a significant upward trend (about 1.70%/10a). Additionally, the water vapor input into MLRYR from four boundaries significantly reduced except for the eastern boundary, and the water vapor contribution from the South and East borders is in summer, and the water vapor contribution from the North and West borders is in autumn, winter and spring. We suggest that the model of the precipitation recycling rate is important to evaluate the contribution of different water vapor sources, and help to further improve the ability of river water prediction in flood season.

Reversals in Temperature‐Precipitation Correlations in the Northern Hemisphere Extratropics During the Holocene

AbstractFuture precipitation levels remain uncertain because climate models have struggled to reproduce observed variations in temperature‐precipitation correlations. Our analyses of Holocene proxy‐based temperature‐precipitation correlations and hydrological sensitivities from 2,237 Northern Hemisphere extratropical pollen records reveal a significant latitudinal dependence and temporal variations among the early, middle, and late Holocene. These proxy‐based variations are largely consistent with patterns obtained from transient climate simulations (TraCE21k). While high latitudes and subtropical monsoon areas show mainly stable positive correlations throughout the Holocene, the mid‐latitude pattern is temporally and spatially more variable. In particular, we identified a reversal from positive to negative temperature‐precipitation correlations in the eastern North American and European mid‐latitudes from the early to mid‐Holocene that mainly related to slowed down westerlies and a switch to moisture‐limited convection under a warm climate. Our palaeoevidence of past temperature‐precipitation correlation shifts identifies those regions where simulating past and future precipitation levels might be particularly challenging.

Comparison of the Causes of Erosion–Deposition between Yellow River, Yangtze River, and Mekong River Subaqueous Delta l: Model Building

An estuary delta is an area with active human economic activities and a fragile natural ecological environment. With the intensification of global changes and human activities, coastal and seabed erosion around the world is becoming more and more serious. This study compared the hydrodynamic effect and sediment diffusion path at the Yellow River subaqueous delta (river control type) and the Yangtze River subaqueous delta (tide-river type) in the East Asian monsoon area using a Delft 3D numerical simulation to analyse the causes of the distribution of accumulation and erosion landform in the different types of subaqueous deltas. This study found that the river deltas were dominated by the river when the accumulation landforms concentrated in the direction of the Coriolis forces, which was due to hydrodynamic erosion driven by wind, and the sediment diffusion range was mainly concentrated in shallow water areas (water depth < 6 m), resulting the Yellow River subaqueous delta presenting the pattern of “northern erosion and south accumulation”. The Yangtze River subaqueous delta was controlled by tidal effects, making the southern part of the estuary more susceptible to erosion. The research results can not only further deepen the understanding of the physical process and mechanism of erosion and deposition in the subaqueous delta but also provide stronger scientific support for the deltas’ ecological environment protection, geological environment safety, and disaster geology prevention.

Spatial Representativeness of Eddy Covariance Measurements in a Coniferous Plantation Mixed with Cropland in Southeastern China

The eddy covariance (EC) technique has been widely used as a micrometeorological tool to measure carbon, water and energy exchanges. When utilizing the EC measurements, it is critical to be aware of the long-term information on source areas. In China, large-scale forest plantations have become a dominant driver of greening and carbon sinks on the planet. However, the spatial representativeness of EC measurements on forest plantations is still not well understood. Here, an EC flux site of a coniferous plantation mixed with cropland in a subtropical monsoon climate was selected to evaluate the spatial representativeness of the two approaches. One is the fraction of target vegetation type (FTVT), which was used to detect to what degree the flux is related to the target vegetation. The other is the sensor location bias calculated from the enhanced vegetation index (EVI), which was used to detect to what spatial extent the flux can be upscaled. The results showed that the monthly footprint climatologies changed intensely throughout the year. The source area is biased toward the southeast in summer and northwest in winter. The study area was mainly a composite of coniferous plantations (70.08%) and double-cropped rice (27.83%). The double-cropped rice, with a higher seasonal variation of EVI than the coniferous plantation, was mainly distributed in the eastern areas of the study site. As a result of spatial heterogeneity and footprint variation, the FTVT was 0.89 when the wind direction was southwest; however, this reduced to 0.65 when the wind direction changed to the northeast and exhibited a single-peak seasonal variation during a year. The sensor location bias of the EVI also showed a significant monthly variation and ranged from −14.21% to 19.04% in a circular window with an increasing size from 250 to 3000 m. The overlap index between daytime and nighttime (Oday_night) can potentially be a quality flag for the GPP derived from the EC flux data. These findings demonstrate the joint effects of the monsoon climate and underlying surface heterogeneity on the spatial representativeness of the EC measurements. Our study highlights the importance of having footprint awareness in utilizing EC measurements for calibration and validation in monsoon areas.

Analysis of Microtopography Atmospheric Precipitable Water Vapour over the Northeastern Margin of the Qinghai–Tibet Plateau

The Liupan Mountain (LPM) area is located on the northeast margin of the Qinghai–Tibet Plateau, which is the western part of the second ladder of China’s terrain. It is also an intersection area of two air currents, which are caused by the combined action of the Qinghai–Tibet Plateau, the middle and lower levels of the westerly belt and the edge of the monsoon area. LPM is one of the main air water vapour transport pathways in Northwest China as well as a main water conservation area for nearly ten million people. Research on atmospheric precipitable water vapour (PWV) variation characteristics in LPM is beneficial for understanding the mechanisms of orographic precipitation and improving the effects of weather modification. Based on the data from 10 Global Navigation Satellite System Meteorology (GNSS/MET) stations for 6 years and the data of automatic weather stations in the LPM, the temporal and spatial variation characteristics of PWV in the LPM were analysed, and the differences in PWV in the 24 h before and after precipitation were compared in this study. The results showed that the hourly, monthly and seasonal variations in PWV displayed obvious patterns. PWV increased rapidly 10 h ahead of precipitation, while it decreased rapidly within 10 h after precipitation, which was slower than that before precipitation. In terms of spatial distribution, PWV was larger in the south than in the north and larger in the east than in the west. Although the precipitation on the LPM peak was the highest in the whole LPM area, its PWV was always the lowest, indicating that the PWV was obviously affected by the air temperature. This showed that under the same water vapour condition, precipitation was more likely to form in the area with low temperature, and the precipitation was larger, which also provided a train of thought for improving the method of artificial precipitation enhancement by using the condensation catalyst.

Early onset of summer monsoon during the Mystery Interval (17.5–14.5 ka BP) in the East Asian Summer Monsoon area: Evidence from leaf alkane δ2H

Exploring the seasonal atmospheric processes involved with hydroclimate changes of the East Asian Summer Monsoon (EASM) during the Mystery Interval (MI, 17.5–14.5 ka BP) will enhance understanding of the EASM climate system. Here we report on the δ2H values of leaf wax n-alkanes (δ2Halk) in a wetland core retrieved from southern China. These values are relatively negative during the MI, contrasting to positive excursion recorded by stalagmite δ18O in nearby caves during the same period. Considering the overlap of the primary synthesis time of leaf waxes in deciduous woody plants and periods of precipitation δ2H alteration in the EASM (late spring to early summer), we interpret the relatively negative signal of δ2Halk in the wetland core as the early onset of summer rainfall during the MI. The early onset of summer rainfall was likely due to the early northeastward shifting of the Western Pacific subtropical high due to the low land-sea thermogradient between the Qinghai-Tibet Plateau and the West Pacific Ocean.

Meteorological Factors Affecting Infectious Diarrhea in Different Climate Zones of China.

Meteorological factors and the increase in extreme weather events are closely related to the incidence rate of infectious diarrhea. However, few studies have explored whether the impact of the same meteorological factors on the incidence rate of infectious diarrhea in different climate regions has changed and quantified these changes. In this study, the time series fixed-effect Poisson regression model guided by climate was used to quantify the relationships between the incidence rate of various types of infectious diarrhea and meteorological factors in different climate regions of China from 2004 to 2018, with a lag of 0–2 months. In addition, six social factors, including per capita Gross Domestic Product (GDP), population density, number of doctors per 1000 people, proportion of urbanized population, proportion of children aged 0–14 years old, and proportion of elderly over 65 years old, were included in the model for confounding control. Additionally, the intercept of each province in each model was analyzed by a meta-analysis. Four climate regions were considered in this study: tropical monsoon areas, subtropical monsoon areas, temperate areas and alpine plateau areas. The results indicate that the influence of meteorological factors and extreme weather in different climate regions on diverse infectious diarrhea types is distinct. In general, temperature was positively correlated with all infectious diarrhea cases (0.2 ≤ r ≤ 0.6, p < 0.05). After extreme rainfall, the incidence rate of dysentery in alpine plateau area in one month would be reduced by 18.7% (95% confidence interval (CI): −27.8–−9.6%). Two months after the period of extreme sunshine duration happened, the incidence of dysentery in the alpine plateau area would increase by 21.9% (95% CI: 15.4–28.4%) in that month, and the incidence rate of typhoid and paratyphoid in the temperate region would increase by 17.2% (95% CI: 15.5–18.9%) in that month. The meta-analysis showed that there is no consistency between different provinces in the same climate region. Our study indicated that meteorological factors and extreme weather in different climate areas had different effects on various types of infectious diarrhea, particularly extreme rainfall and extreme sunshine duration, which will help the government develop disease-specific and location-specific interventions, especially after the occurrence of extreme weather.

COVID-19 incidence and local average rainfall: An analysis from a tropical monsoon area.

Sir, COVID-19 pandemic is an important global problem that has affected more than 30,000,000 people worldwide. The disease is a viral respiratory infection. The effect of climate on the incidence of COVID-19 is interesting. There are a few reports on the climate–geographical pathology of COVID-19. It is mentioned that there might be an association between COVID-19 incidence and environmental background.[1] Here, the authors analyze the data to assess the relationship between COVID-19 incidence and local average rainfall in a tropical monsoon area in Indochina where the second area of the world affected by COVID-19 after China is. The official data from the local Public Health Ministry on the incidence of COVID-19 and the data from the local Metrological Department are collected as primary data for further analysis. The focus area is on 20 provinces in the northeastern region of the country, which is not an international tourist destination and is not affected by the importation of disease by foreign tourists. The incidence is the case with local transmission and the imported case from aboard are excluded. The period of the analysis is from March to September 2020. The relationship between COVID-19 incidence and local average rainfall is shown in Figure 1. There was no statistically significant correlation (r = −0.227, P = 0.336) between COVID-19 incidence and local average rainfall in the studied tropical area. This is in contrast to other local endemic diseases such as malaria and dengue that have a significant correlation between disease incidence and local average rainfall in the study setting.[23] Because this study was on a limited area in the tropical zone, a further comparative study between tropical and non-tropical countries should be done for further conclusion on the interrelationship between COVID-19 epidemiology and background rainfall.Figure 1: Figure showing the relationship between COVID-19 incidence and local average rainfallFinancial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Evaluation of the Technical Efficiency of Taiwan’s Milkfish Polyculture in Consideration of Differences in Culturing Models and Environments

Taiwan has cultured milkfish for longer than hundreds of years. Given its long and narrow terrain surrounded by sea and location in a subtropical monsoon area, it has developed a unique culture bounded by the Erren River in the south. The Yunjianan area in the north is cold in winter and thus follows the “current year harvest” culturing model. In contrast, the Gaoping area in the south is warmer in winter and follows the “overwinter harvest” culturing model. This paper evaluated the production efficiency by using the stochastic metafrontier production model and the multi-input-multi-output distance function using input from in-person interviews with 100 current year harvest farmers and 70 overwinter harvest farmers from 2017 to 2019. In the first stage, the environmental variables of various regions were internalized into the model to obtain the group technical efficiency (GTE) of different farming models. In the second stage, the common environmental variables were re-internalized to evaluate the metafrontier technical efficiency (MTE) of both culturing modes. In this way, the technical efficiency and production technology of the two different culturing model are reasonably evaluated by taking into account not only the difference between their input and output, but also their environmental difference during their farming periods. The results show that in spite of the environmental difference between th two culturing models, shallower pond, smaller size of fish fry and lower shrimp density should make culturing more technically efficient. When cultured in a common environment, the lower the temperature, the worse the culture efficiency is. It indicated that milkfish are highly sensitive to low temperature. Therefore, the MTE and technical gap rate (TGR) of current year harvest farming are significantly higher than those of overwinter harvest farming. Finally, the regression analysis showed that the younger the farmers were, the lower the average pond age was, the larger the freshwater culture area was, and the greater the experience in fish farming was. Thus, the relatively better the MTE is; the younger the farmers, the higher the education level is and the more years of experience in fish farming they have, thus the relatively better the production technology level is.

The ExtremeX global climate model experiment: investigating thermodynamic and dynamic processes contributing to weather and climate extremes

Abstract. The mechanisms leading to the occurrence of extreme weather and climate events are varied and complex. They generally encompass a combination of dynamic and thermodynamic processes, as well as drivers external to the climate system, such as anthropogenic greenhouse gas emissions and land use change. Here we present the ExtremeX multi-model intercomparison experiment, which was designed to investigate the contribution of dynamic and thermodynamic processes to recent weather and climate extremes. The numerical experiments are performed with three Earth system models: CESM, MIROC, and EC-Earth. They include control experiments with interactive atmosphere and land surface conditions, as well as experiments wherein the atmospheric circulation, soil moisture, or both are constrained using observation-based data. The temporal evolution and magnitude of temperature anomalies during heatwaves are well represented in the experiments with a constrained atmosphere. However, the magnitude of mean climatological biases in temperature and precipitation are not greatly reduced in any of the constrained experiments due to persistent or newly introduced biases. This highlights the importance of error compensations and tuning in the standard model versions. To show one possible application, ExtremeX is used to identify the main drivers of heatwaves and warm spells. The results reveal that both atmospheric circulation patterns and soil moisture conditions substantially contribute to the occurrence of these events. Soil moisture effects are particularly important in the tropics, the monsoon areas, and the Great Plains of the United States, whereas atmospheric circulation effects are major drivers in other midlatitude and high-latitude regions.

Effects of Tillage System, Sowing Date, and Weather Course on Yield of Double-Crop Soybeans Cultivated in Drained Paddy Fields

In temperate monsoon areas, major constraints of soybean production in drained paddy fields are excess soil water during monsoon seasons. To further understand how agronomic practices and weather course affect the yield of soybeans, we conducted field experiments at Gwangju, Korea (35°10′ N, 126°53′ E) over three years (2018–2020). Double-crop soybeans were grown at two tillage systems (TS) [rotary tillage (RT), deep plowing followed by rotary tillage (DPRT)] and three sowing dates (SD) (June 10–15, June 25–30, and July 10–15) in drained paddy fields. Flowering phenology (R2) was accelerated by 5 days with each 15-day delay in SD. This resulted in a significant reduction in vegetative growth up to R2, with subsequent reductions in CGR and NAR through R2–R5 (beginning of grain filling). With a 30-day delay in SD, yield was significantly reduced by 27.0%. The better performance of RT over DPRT was demonstrated by greater yields (13.7%). In addition, yield was greatly varied with weather volatility among years, ranging from 123.8 to 552.0 g m−2. Weather volatility was the greatest contributor to yield variability (30.4%), followed by SD (17.0%) and TS (10.3%). Our results suggest that the yield might be mainly determined by how much growth has already been achieved before flowering and through R2–R5.