Severe flooding occurred in Thailand during the 2011 summer season, which resulted in more than 800 deaths and affected 13.6 million people. The unprecedented nature of this flood in the Chao Phraya River basin (CPRB) was examined and compared with historical flood years. Climate diagnostics were conducted to understand the meteorological conditions and climate forcing that led to the magnitude and duration of this flood. Neither the monsoon rainfall nor the tropical cyclone frequency anomalies alone was sufficient to cause the 2011 flooding event. Instead, a series of abnormal conditions collectively contributed to the intensity of the 2011 flood: anomalously high rainfall in the premonsoon season, especially during March; record-high soil moisture content throughout the year; elevated sea level height in the Gulf of Thailand, which constrained drainage; and other water management factors. In the context of climate change, the substantially increased premonsoon rainfall in CPRB after 1980 and the continual sea level rise in the river outlet have both played a role. The rainfall increase is associated with a strengthening of the premonsoon northeasterly winds that come from East Asia. Attribution analysis using phase 5 of the Coupled Model Intercomparison Project historical experiments pointed to anthropogenic greenhouse gases as the main external climate forcing leading to the rainfall increase. Together, these findings suggest increasing odds for potential flooding of similar intensity to that of the 2011 flood.

During March and April, widespread burning occurs across farmlands in Indochina in preparation for planting at the monsoon onset. The resultant aerosols impact the air quality downwind. In this study, we investigate the climatic aspect of the interannual variation of springtime biomass burning in Indochina and its correlation with air quality at Mt. Lulin in Taiwan using long‐term (2005–2015) satellite and global reanalysis data. Based on empirical orthogonal function (EOF) analysis, we find that the biomass burning activities vary with two geographical regions: northern Indochina (the primary EOF mode) and southern Indochina (the secondary EOF mode). We determine that the variation of biomass burning over northern Indochina is significantly related with the change in aerosol concentrations at Mt. Lulin. This occurs following the change in the so‐called India‐Burma Trough in the lower and middle troposphere. When the India‐Burma Trough is intensified, a stronger northwesterly wind (to the west of the trough) transports the dryer air from higher latitude into northern Indochina, and this promotes local biomass burning activities. The increase in upward motion to the east of the intensified India‐Burma Trough lifts the aerosols, which are transported toward Taiwan by the increased low‐level westerly jet. Further diagnoses revealed the connection between the India‐Burma Trough and the South Asian jet's wave train pattern as well as the previous winter's El Niño–Southern Oscillation phase. This information highlights the role of the India‐Burma Trough in modulating northern Indochina biomass burning and possibly predicting aerosol transport to East Asia on the interannual time scale.

We present a statistically robust reconstruction of Thailand's Chao Phraya River peak season streamflow (CPRPF) that spans the 202 years from 1804 to 2005 CE. Our reconstruction is based on tree ring δ18O series derived from three Pinus merkusii sites from Laos and Thailand. The regional δ18O index accounts for 57% of the observed variance of CPRPF. Spatial correlation and 21‐year running correlation analyses reveal that CPRPF is greatly influenced by regional precipitation variations associated with the El Niño–Southern Oscillation (ENSO). Periods of enhanced and reduced ENSO activity are associated with strong and weak ENSO‐streamflow correlation, respectively. At the longer timescale, the Pacific Decadal Oscillation (PDO) appears to modulate the ENSO‐streamflow correlations, with the most extreme flood events along the Chao Phraya River occurring during periods of increased frequency of La Niña events that coincide with extended cold phases of the PDO. The CPRPF reconstruction could aid management planning for Thailand's water resources.

In India, a significant reduction of wheat yield would cause a widespread impact on food security for 1.35 billion people. The two highest wheat producing states, Punjab and Haryana in northern India, experienced a prolonged period of anomalously low wheat yield during 2002–2010. The extent of climate variability and change in influencing this prolonged reduction in wheat yield was examined. Daily air temperature (Tmax and Tave) was used to calculate the number of days above optimum temperature and growing degree days (GDD) anomaly. Two drought indices, the standard precipitation and evapotranspiration index and the radiation-based precipitation index, were used to describe the drought conditions. Groundwater variability was assessed via satellite-based approximation. The analysis results indicate that the wheat yield loss corresponds to the increase in the number of days with a temperature above 35 °C during the maturity stage (March). Reduction in monsoon rainfall led to a depletion of groundwater and reduced surface water for irrigation in the wheat growing season (November–March). Higher temperatures, coupled with water shortage and irregular irrigation, also appear to impact the yield reduction. In hindsight, improving the agronomic practices to minimize crop water usage could be an adaptation strategy to maintain the desired wheat yield in the face of climate-induced drought and precipitation anomaly.

Central Vietnam is particularly vulnerable to the impacts of climate change, with all of its incumbent socioeconomic and ecological consequences. This is due in part to the autumn timing of the peak rainfall season in Central Vietnam, at a time when tropical cyclones are most likely to make landfall. We conducted climate diagnostic analyses using meteorological and tropical cyclone data to understand the changing patterns of autumn rainfall and tropical cyclones, revealing an intensification of precipitation over Central Vietnam since the beginning of the 20 th century that is associated with increased tropical cyclones in the adjacent sea. A warming of the sea surface temperature (SST) and enhanced southerly low-level winds are coincident with the above noted increase in rainfall and tropical cyclones. The underlying regional SST and circulation patterns are part of a hemispheric-scale change in the general circulation, i.e. a La Nina-like SST anomaly and a strengthened Walker circulation with the ascending branch located near Vietnam and far-western Pacific. We make the case with this paper that increasing autumn rainfall and tropical cyclones should be taken into account any mitigation and adaptation plans anticipated for Central Vietnam.

Low temperature condition during December to January can limit seed emergence and seedling establishment for peanut production in Thailand. The objective of this study was to determine the effects of peanut seed priming on seed germination and vigor under optimal and low temperature conditions before and after 9 months of storage. Tainan 9 peanut seeds were primed with salicylic acid (SA), ascorbate (ASA), CaCl2, or chitosan and tested for germination at 25°C (optimal temperature) and 15°C (low temperature) before and after a 9-month storage period. Seed priming with 50 mg·L−1 SA and 50 mg·L−1 ASA for 12 hours before germinating improved germination at 15°C when compared to untreated seeds both before and after 9-month storage. The high seed quality, illustrated by high germination percentage, high seed vigor, and low mean germination time related to the low autoxidation substrates: lipoxygenase (LOX), malondialdehyde (MDA), and high antioxidants: superoxide dismutase (SOD) and catalase (CAT). It suggests that peanut seed priming with salicylic acid and/or ascorbate can improve seedling emergence and growth under low temperature conditions.

Winter crop losses from extreme weather in Taiwan have increased in the recent decade, with those losses associated with pronounced wet-and-cold events (temperature < 10 ∘ C and precipitation >5 mm day −1 ). The regional and global patterns of atmospheric circulation and the sea surface temperature (SST) related to the extreme cold that damages fruits, vegetables, and paddy rice in northwest Taiwan were investigated. Cool SST anomalies in the western North Pacific (WNP) and warm SST in the central-eastern Pacific associated with the Pacific meridional mode (PMM) shared a significant role in the occurrence of wet-and-cold events in northwest Taiwan. The interactions of the WNP/PMM with the North Pacific Oscillation (NPO) and the Central Pacific type of El Niño led to a pronounced lead-lag relationship with the occurrence of wet-and-cold events. An empirical model was subsequently developed to predict the wet-and-cold event frequency using observed values of WNP, Niño-3.4, and Arctic Oscillation from year-1 and predicted indices of WNP and PMM derived from the Climate Forecast System Version 2 (CFSv2) outputs. The predictive skill of this hybrid empirical-dynamical model was statistically significant throughout the 6 months leading up to the occurrence of wet-and-cold events.

Abstract