seasonal time scale
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2022 ◽  
Vol 314 ◽  
pp. 108786
Author(s):  
Dipankar Sarma ◽  
Pramit Kumar Deb Burman ◽  
S. Chakraborty ◽  
Nirmali Gogoi ◽  
Abhijit Bora ◽  
...  

2021 ◽  
Author(s):  
Meseret Bekele Toma ◽  
Mulugeta Dadi Belete ◽  
Mihret Dananto Ulsido

Abstract BackgroundIdentifying hydro-meteorological trends is basic for assessing change in climate and river discharge at watershed level. This study examined the long-term trends of rainfall, temperature, and discharge in the annual, monthly and seasonal time scale of Ajora-Woybo watershed in Ethiopia. The data span of rainfall and temperature is between 1990 and 2020 and that of discharge is between 1990 and 2015. Homogeneity test was performed by using Pettit and SNHT tests. Then Mann-Kendall and Sen's slope test for trend analysis and different variability measures were used. ResultsResults indicate that inhomogeneity was detected in annual rainfall data of Angacha and Areka stations. On annual basis, rainfall and discharge exhibited insignificant trends over time while showing a general decreasing pattern. On monthly basis, February and March were found to have significantly decreasing trend for rainfall. During the Kiremt season, rainfall increases and discharge decreases insignificantly. In contrast, maximum, minimum and mean annual temperatures exhibited significant trends with annual increment of 0.04oC, 0.01oC, and 0.025 oC per year respectively. Correlations of discharge with both temperature and rainfall have found to be weak in this study.ConclusionsThis trend, combined with population growth and increasing demand of water for agricultural activities exacerbates competing demands for water resources. Caution is therefore required when it comes to developing appropriate measures for the planning and sustainable development of the water resources in the watershed.


2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>


2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>


Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1311
Author(s):  
Suryun Ham ◽  
Yeomin Jeong

In this study, the characteristics of systematic errors in subseasonal prediction for East Asia are investigated using an ensemble hindcast (1991–2010) produced by the Global Seasonal Forecasting System version 5 (GloSea5). GloSea5 is a global prediction system for the subseasonal-to-seasonal time scale, based on a fully coupled atmosphere, land, ocean, and sea ice model. To examine the fidelity of the system with respect to reproducing and forecasting phenomena, this study assesses the systematic biases in the global prediction model focusing on the prediction skill for the East Asian winter monsoon (EAWM), which is a major driver of weather and climate variability in East Asia. To investigate the error characteristics of GloSea5, the hindcast period is analyzed by dividing it into two periods: 1991–2000 and 2001–2010. The main results show that the prediction skill for the EAWM with a lead time of 3 weeks is significantly decreased in the 2000s compared to the 1990s. To investigate the reason for the reduced EAWM prediction performance in the 2000s, the characteristics of the teleconnections relating to the polar and equatorial regions are examined. It is found that the simulated excessive weakening of the East Asian jet relating to the tropics and a failure in representing the Siberian high pressure relating to the Arctic are mainly responsible for the decreased EAWM prediction skill.


2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>


2021 ◽  
Vol 13 (30) ◽  
pp. 64-73
Author(s):  
Ilian Gospodinov ◽  
◽  
Valentin Kazandjiev ◽  
Veska Georgieva ◽  
◽  
...  

Seasonal forecasting gained ground in the last decades by building up knowledge on the processes staying behind the climate variability at the seasonal time scale, constructing ever more sophisticated general circulation models and ensemble prediction systems and thus enhancing forecast skill. The seasonal forecast is a climate forecast and is therefore probabilistic in nature. The predictability of the atmospheric circulation at the seasonal scale is limited in the middle latitudes, where Europe and Bulgaria are situated, by its chaotic nature. The current standard is to give forecast of the potential anomalies of the mean seasonal temperature and the seasonal amount of precipitation. The National Institute of Meteorology and Hydrology of Bulgaria has been issuing operationally seasonal forecast for the country since 2005. The goal of this work is to discuss the seasonal forecast for the last agricultural year 2019-2020. The year was characterized by its drought conditions especially in Eastern Bulgaria. This work would show the extent to which it was successfully predicted and how the seasonal forecast could have been used for decision making. The use of agrometeorological indices for the analysis of the skill of the seasonal forecast has been shown.


2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>


2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>


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