scholarly journals Comparison of Phenology Models for Predicting the Onset of Growing Season over the Northern Hemisphere

PLoS ONE ◽  
2014 ◽  
Vol 9 (10) ◽  
pp. e109544 ◽  
Author(s):  
Yang Fu ◽  
Haicheng Zhang ◽  
Wenjie Dong ◽  
Wenping Yuan
Keyword(s):  
Northern Hemisphere ◽  
Growing Season

scholarly journals Seasonal biological carryover dominates northern vegetation growth

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xu Lian ◽  
Shilong Piao ◽  
Anping Chen ◽  
Kai Wang ◽  
Xiangyi Li ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Growing Season ◽  
Ecosystem Dynamics ◽  
Environmental Drivers ◽  
Subsequent Growth ◽  
Ecosystem Models ◽  
Carryover Effect ◽  
Vegetation Growth ◽  
Sequestration Potential ◽  
Future Warming

AbstractThe state of ecosystems is influenced strongly by their past, and describing this carryover effect is important to accurately forecast their future behaviors. However, the strength and persistence of this carryover effect on ecosystem dynamics in comparison to that of simultaneous environmental drivers are still poorly understood. Here, we show that vegetation growth carryover (VGC), defined as the effect of present states of vegetation on subsequent growth, exerts strong positive impacts on seasonal vegetation growth over the Northern Hemisphere. In particular, this VGC of early growing-season vegetation growth is even stronger than past and co-occurring climate on determining peak-to-late season vegetation growth, and is the primary contributor to the recently observed annual greening trend. The effect of seasonal VGC persists into the subsequent year but not further. Current process-based ecosystem models greatly underestimate the VGC effect, and may therefore underestimate the CO2 sequestration potential of northern vegetation under future warming.

The use of multi-tracer flask-measurements to understand changes in the land-surface processes.

2021 ◽  
Author(s):  
Theertha Kariyathan ◽  
Wouter Peters ◽  
Julia Marshall ◽  
Ana Bastos ◽  
Markus Reichstein
Keyword(s):  
Northern Hemisphere ◽  
Land Surface ◽  
Seasonal Cycle ◽  
Growing Season ◽  
Plant Productivity ◽  
Surface Processes ◽  
Terrestrial Biosphere ◽  
Land Surface Processes ◽  
Species Analysis

<p>Carbon dioxide (CO<sub>2</sub>) is an important greenhouse gas, and it accounts for about 20% of the present-day anthropogenic greenhouse effect. Atmospheric CO<sub>2</sub> is cycled between the terrestrial biosphere and the atmosphere through various land-surface processes and thus links the atmosphere and terrestrial biosphere through positive and negative feedback. Since multiple trace gas elements are linked by common biogeochemical processes, multi-species analysis is useful for reinforcing our understanding and can help in partitioning CO<sub>2</sub> fluxes. For example, in the northern hemisphere, CO<sub>2</sub> has a distinct seasonal cycle mainly regulated by plant photosynthesis and respiration and it has a distinct negative correlation with the seasonal cycle of the δ<sup>13</sup>C isotope of CO<sub>2</sub>, due to a stronger isotopic fractionation associated with terrestrial photosynthesis. Therefore, multi-species flask-data measurements are useful for the long-term analysis of various green-house gases. Here we try to infer the complex interaction between the atmosphere and the terrestrial biosphere by multi-species analysis using atmospheric flask measurement data from different NOAA flask measurement sites across the northern hemisphere.</p><p>This study focuses on the long-term changes in the seasonal cycle of CO<sub>2</sub> over the northern hemisphere and tries to attribute the observed changes to driving land-surface processes through a combined analysis of the δ<sup>13</sup>C seasonal cycle. For this we generate metrics of different parameters of the CO<sub>2</sub> and δ<sup>13</sup>C seasonal cycle like the seasonal cycle amplitude given by the peak-to-peak difference of the cycle (indicative of the amount of CO<sub>2</sub> taken up by terrestrial uptake),  the intensity of plant productivity inferred from the slope of the seasonal cycle during the growing season , length of growing season and the start of the growing season. We analyze the inter-relation between these metrics and how they change across latitude and over time. We hypothesize that the CO<sub>2 </sub>seasonal cycle amplitude is controlled both by the intensity of plant productivity and period of the active growing season and that the timing of the growing season can affect the intensity of plant productivity. We then quantify these relationships, including their variation over time and latitudes and describe the effects of an earlier start of the growing season on the intensity of plant productivity and the CO<sub>2</sub> uptake by plants.</p>

scholarly journals Spatio-Temporal Variation of Drought within the Vegetation Growing Season in North Hemisphere (1982–2015)

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2146 ◽  
Author(s):  
Zhaoqi Zeng ◽  
Yamei Li ◽  
Wenxiang Wu ◽  
Yang Zhou ◽  
Xiaoyue Wang ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Gross Primary Production ◽  
Coniferous Forest ◽  
Critical Time ◽  
Growing Season ◽  
Well Being ◽  
Estimation Methods ◽  
Drought Risk ◽  
Drought Characteristics ◽  
The Impact

Drought disasters jeopardize the production of vegetation and are expected to exert impacts on human well-being in the context of global climate change. However, spatiotemporal variations in drought characteristics (including the drought duration, intensity, and frequency), specifically for vegetation areas within a growing season, remain largely unknown. Here, we first constructed a normalized difference vegetation index to estimate the length of the growing season for each pixel (8 km) by four widely used phenology estimation methods; second, we analyzed the temporal and spatial patterns of climate factors and drought characteristics (in terms of the Standardized Precipitation Evapotranspiration Index (SPEI)), within a growing season over vegetation areas of the northern hemisphere before and after the critical time point of 1998, which was marked by the onset of a global warming hiatus. Finally, we extracted the highly drought-vulnerable areas of vegetation by examining the sensitivity of the gross primary production to the SPEI to explore the underlying effects of drought variation on vegetation. The results revealed, first, that significant (p < 0.05) increases in precipitation, temperature, and the SPEI (a wetting trend) occurred from 1982 to 2015. The growing season temperature increased even more statistically significant after 1998 than before. Second, the duration and frequency of droughts changed abruptly and decreased considerably from 1998 to 2015; and this wetting trend was located mainly in high-latitude areas. Third, at the biome level, the wetting areas occurred mainly in the tundra, boreal forest or taiga, and temperate coniferous forest biomes, whereas the highly drought-vulnerable areas were mainly located in the desert and xeric shrubland (43.5%) biomes. Our results highlight the fact that although the drought events within a growing season decreased significantly in the northern hemisphere from 1998 to 2015, the very existence of a mismatch between a reduction in drought areas and an increase in highly drought-vulnerable areas makes the impact of drought on vegetation nonnegligible. This work provides valuable information for designing coping measures to reduce the vegetative drought risk in the Northern Hemisphere.

scholarly journals The imprint of surface fluxes and transport on variations in total column carbon dioxide

2011 ◽  
Vol 8 (4) ◽  
pp. 7475-7524 ◽  
Author(s):  
G. Keppel-Aleks ◽  
P. O. Wennberg ◽  
R. A. Washenfelder ◽  
D. Wunch ◽  
T. Schneider ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Large Scale ◽  
Carbon Sink ◽  
Potential Temperature ◽  
Surface Flux ◽  
Growing Season ◽  
Temporal Variations ◽  
Surface Fluxes ◽  
Synoptic Scale ◽  
Meridional Gradient

Abstract. New observations of the vertically integrated CO2 mixing ratio, ⟨CO2⟩, from ground-based remote sensing show that variations in ⟨CO2⟩ are primarily determined by large-scale flux patterns. They therefore provide fundamentally different information than observations made within the boundary layer, which reflect the combined influence of large scale and local fluxes. Observations of both ⟨CO2⟩ and CO2 concentrations in the free troposphere show that large-scale spatial gradients induce synoptic-scale temporal variations in ⟨CO2⟩ in the Northern Hemisphere midlatitudes through horizontal advection. Rather than obscure the signature of surface fluxes on atmospheric CO2, these synoptic-scale variations provide useful information that can be used to reveal the meridional flux distribution. We estimate the meridional gradient in ⟨CO2⟩ from covariations in ⟨CO2⟩ and potential temperature, θ, a dynamical tracer, on synoptic timescales to evaluate surface flux estimates commonly used in carbon cycle models. We find that Carnegie Ames Stanford Approach (CASA) biospheric fluxes underestimate both the ⟨CO2⟩ seasonal cycle amplitude throughout the Northern Hemisphere midlatitudes as well as the meridional gradient during the growing season. Simulations using CASA net ecosystem exchange (NEE) with increased and phase-shifted boreal fluxes better reflect the observations. Our simulations suggest that boreal growing season NEE (between 45–65° N) is underestimated by ~40 % in CASA. We describe the implications for this large seasonal exchange on inference of the net Northern Hemisphere terrestrial carbon sink.

scholarly journals Global upper-tropospheric formaldehyde: seasonal cycles observed by the ACE-FTS satellite instrument

2009 ◽  
Vol 9 (1) ◽  
pp. 1051-1095 ◽  
Author(s):  
G. Dufour ◽  
S. Szopa ◽  
M. P. Barkley ◽  
C. D. Boone ◽  
A. Perrin ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Biomass Burning ◽  
Growing Season ◽  
Global Scale ◽  
Tropospheric Chemistry ◽  
Data Set ◽  
Mixing Ratios ◽  
Good Reproduction ◽  
Summer Maximum

Abstract. Seasonally-resolved upper tropospheric profiles of formaldehyde (HCHO) observed by the ACE Fourier transform spectrometer (ACE-FTS) on a near-global scale are presented for the time period from March 2004 to November 2006. Large upper tropospheric HCHO mixing ratios (>150 pptv) are observed during the growing season of the terrestrial biosphere in the Northern Hemisphere and during the biomass burning season in the Southern Hemisphere. The total errors estimated for the retrieved mixing ratios range from 30 to 40% in the upper troposphere and increase in the lower stratosphere. The sampled HCHO concentrations are in satisfactory agreement with previous aircraft and satellite observations with a negative bias (<25%) within observation errors. An overview of the seasonal cycle of the upper tropospheric HCHO is given for different latitudes. A maximum is observed during summer, i.e. during the growing season, in the northern mid- and high latitudes. The influence of biomass burning is visible in HCHO upper tropospheric concentrations during the September-to-October period in the southern tropics and subtropics. Comparisons with two state-of-the-art models (GEOS-Chem and LMDz-INCA) show that the models fail to reproduce the seasonal variations observed in the southern tropics and subtropics but they capture well the variations observed in the Northern Hemisphere (correlation >0.9). Both models underestimate the summer maximum over Europe and Russia and differences in the emissions used for North America result in a good reproduction of the summer maximum by GEOS-Chem but in an underestimate by LMDz-INCA. Globally, GEOS-Chem reproduces well the observations on average over one year but has some difficulties in reproducing the spatial variability of the observations. LMDz-INCA shows significant bias in the Southern Hemisphere, likely related to an underestimation of methane, but better reproduces the temporal and spatial variations. The differences between the models underline the large uncertainties that remain in the emissions of HCHO precursors. Observations of the HCHO upper tropospheric profile provided by the ACE-FTS represent a unique data set for investigating and improving our current understanding of the formaldehyde budget and upper tropospheric chemistry.

Phenology shifts at start vs. end of growing season in temperate vegetation over the Northern Hemisphere for the period 1982-2008

2011 ◽  
Vol 17 (7) ◽  
pp. 2385-2399 ◽  
Author(s):  
SU-JONG JEONG ◽  
CHANG-HOI HO ◽  
HYEON-JU GIM ◽  
MOLLY E. BROWN
Keyword(s):  
Northern Hemisphere ◽  
Growing Season

Trends toward an earlier peak of the growing season in Northern Hemisphere mid-latitudes

2016 ◽  
Vol 22 (8) ◽  
pp. 2852-2860 ◽  
Author(s):  
Chongyang Xu ◽  
Hongyan Liu ◽  
A. Park Williams ◽  
Yi Yin ◽  
Xiuchen Wu
Keyword(s):  
Northern Hemisphere ◽  
Growing Season

Photosynthetic climate in selected regions during the northern hemisphere growing season

1994 ◽  
Vol 8 (2) ◽  
pp. 117-125 ◽  
Author(s):  
R. T. Pinker ◽  
I. Laszlo ◽  
F. Miskolczi
Keyword(s):  
Northern Hemisphere ◽  
Growing Season

Diverse effects of climate at different times on grassland phenology in mid-latitude of the Northern Hemisphere

2020 ◽  
Author(s):  
Shilong Ren ◽  
Yating Li ◽  
Matthias Peichl
Keyword(s):  
Northern Hemisphere ◽  
Air Temperature ◽  
Time Window ◽  
Climatic Factors ◽  
Growing Season ◽  
Study Region ◽  
Growing Season Length ◽  
Continental Scale ◽  
Significant Prolongation ◽  
Window Opening

&lt;p&gt;Studying grassland phenology and its relationships to climate would deepen our understanding of vegetation-air interactions under global climate change. To date, however, our knowledge of the responses of grassland phenology to climatic factors is still limited at the continental scale. In this study, we retrieved the start (SOS) and end (EOS) of the growing season for mid-latitude (30&amp;#176;N~55&amp;#176;N) grasslands of the Northern Hemisphere during 1981-2014, and investigated their relations with previous temperature, rainfall, and snowfall (only for SOS) through trends analysis and time window analysis. Results illustrated a predominant significant advancing/delaying trend of SOS/EOS in 23.2%/20.5% of the study region. They jointly resulted in a primarily significant prolongation trend of growing season length in 22.7% of the study region. Next, a dominated negative correlation between air temperature/rainfall and SOS was found in 62.4%/57.6% of areas. Snowfall showed converse effects (positive/negative) among different grasslands. The time window opening date for air temperature to start to affect SOS was identified as the day 1-90 before the multi-year average SOS in 76.1% of areas, while the time window opening date for the effect of rainfall/snowfall on SOS was relatively evenly distributed between the 1st and 180th day before the multi-year average SOS. EOS was found to be significantly negatively/positively correlated with air temperature/precipitation in 74.8%/83.7% of areas. The time window opening date for the effect of air temperature on EOS was identified as the 90-180th day before the multi-year average EOS in 66.9% of areas, while the time window opening date for the effect of precipitation on EOS was mainly concentrated on the 60-120th day before the multi-year average EOS in 51.5% of areas. Overall, this study highlights the distinctly different time windows for the thermal-moisture effects on grassland vegetation phenology and this should be considered when establishing process-based phenological models.&lt;/p&gt;

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