Sujong Jeong 교수

Changes in vegetative growing seasons are dominant indicators of the dynamic response of ecosystems to climate change. Therefore, knowledge of growing seasons over the past decades is essential to predict ecosystem changes. In this study, the long-term changes in the growing seasons of temperate vegetation over the Northern Hemisphere were examined by analyzing satellite-measured normalized difference vegetation index and reanalysis temperature during 1982–2008. Results showed that the length of

In temperate regions, the budburst date of deciduous trees is mainly regulated by temperature variation, but the exact nature of the temperature dependence has been a matter of debate. One hypothesis is that budburst date depends purely on the accumulation of warm temperature; a competing hypothesis states that exposure to cold temperatures is also important for budburst. In this study, variability in budburst is evaluated using 15 years of budburst data for 17 tree species at Harvard Forest. We

Abstract Aim Previous studies have shown that warming temperatures can affect the phenology of cold deciduous forests, delaying the timing of leaf coloration. However, these works have principally been based on observations from a small number of sites. Consequently it has been challenging to infer continental‐scale variations in the phenology of individual deciduous forest species and the extent to which there may be underlying climate drivers for these variations. To address that problem, this

This study investigates the impact of increased vegetation greening on the springtime temperature over east Asia for 1982–2000. An analysis of station‐based temperature records and satellite‐measure normalized difference vegetation index (NDVI) indicates that slight warming (<0.4°C 10‐yr −1 ) occurred over regions that experienced large increase in NDVI (≥0.08 10‐yr −1 ). On the contrary, strong warming (≥0.8°C 10‐yr −1 ) occurred over regions that exhibited minor changes in NDVI (<0.04 10

The contemporary Arctic carbon balance is uncertain, and the potential for a permafrost carbon feedback of anywhere from 50 to 200 petagrams of carbon (Schuur <i>et al</i>., 2015) compromises accurate 21st-century global climate system projections. The 42-year record of atmospheric CO₂ measurements at Barrow, Alaska (71.29 N, 156.79 W), reveals significant trends in regional land-surface CO₂ anomalies (ΔCO₂), indicating long-term changes in seasonal carbon uptake

Understanding the variations in spring vegetation phenology associated with preseason climate conditions can significantly improve our knowledge on ecosystem dynamics and biosphere-atmosphere interactions. Recent studies have shown that wet winters can delay the start date of the vegetation growing season (SOS) in the high latitudes. However, associated underlying mechanisms remain unclear due to the lack of observation sites as well as complex interactions between various climate and ecosystem

The seasonal greening of Northern Hemisphere (NH) ecosystems, due to extended growing periods and enhanced photosynthetic activity, could modify near-surface warming by perturbing land-atmosphere energy exchanges, yet this biophysical control on warming seasonality is underexplored. By performing experiments with a coupled land-atmosphere model, here we show that summer greening effectively dampens NH warming by -0.15 ± 0.03 °C for 1982-2014 due to enhanced evapotranspiration. However, greening

Mid- to high-latitude vegetation are experiencing changes in their seasonal cycles as a result of climate change. Although the rates of seasonal growth from winter dormancy to summer maturity have accelerated because of changes in environmental conditions, less attention has been paid to the rate of vegetation green-up (RVG) and its dynamics, which could advance vegetation maturity. We analyzed the long-term changes in RVG and the drivers at high northern latitudes for 35 years (1982-2016) using

Abstract. In this study, an extension on the previously reported status of the COllaborative Carbon Column Observing Network's (COCCON) calibration procedures incorporating refined methods is presented. COCCON is a global network of portable Bruker EM27/SUN FTIR spectrometers for deriving column-averaged atmospheric abundances of greenhouse gases. The original laboratory open-path lamp measurements for deriving the instrumental line shape (ILS) of the spectrometer from water vapour lines have be

Over East Asia, surface air temperature displays a significant increasing trend particularly in early months of the year for the period of 1982–2000. Warming per decade is strongest in late winter, 1.5°C in February and 1.1°C in March, but is significantly reduced in spring, 0.4°C in April and 0.1°C in May. During the analysis period, the reduced temperature increase from late winter to spring is found to be in contrast with the increased vegetation greenness derived from the satellite‐measured

[1] In this study, the changes in desert boundaries in Asia (Gobi, Karakum, Lut, Taklimakan, and Thar deserts) during the growing season (April–October) in the years 1982–2008 were investigated by analyzing the normalized difference vegetation index (NDVI), precipitation, and temperature. In the desert boundary regions, the domain mean NDVI values increased by 7.2% per decade in 1982–1998 but decreased by 6.8% per decade thereafter. Accordingly, the bare soil areas (or nonvegetated areas) of the

This study examines the potential impact of vegetation feedback on the changes in the diurnal temperature range (DTR) due to the doubling of atmospheric CO2 concentrations during summer over the Northern Hemisphere using a global climate model equipped with a dynamic vegetation model. Results show that CO2 doubling induces significant increases in the daily mean temperature and decreases in DTR regardless of the presence of the vegetation feedback effect. In the presence of vegetation feedback,

A new framework for understanding the macro‐scale variations in spring phenology is developed by using new data from the USA National Phenology Network. Changes in spring budburst for the United States are predicted by using Coupled Model Intercomparison Project phase 5 outputs. Macro‐scale budburst simulations for the coming century indicate that projected warming leads to earlier budburst by up to 17 days. The latitudinal gradient of budburst becomes less pronounced due to spatially varying se