Atmospheric variations in summertime column integrated CO2 on synoptic and seasonal time scale over the U.S.

2021 ◽  
Author(s):  
Qingyu Wang ◽  
Sean Crowell ◽  
Sandip Pal
Keyword(s):  
Time Scale ◽  
Seasonal Time Scale ◽  
Atmospheric Variations ◽  
The U.S

scholarly journals An Analysis of Moisture Fluxes into the Gulf of California

2009 ◽  
Vol 22 (8) ◽  
pp. 2216-2239 ◽  
Author(s):  
Man-Li C. Wu ◽  
Siegfried D. Schubert ◽  
Max J. Suarez ◽  
Norden E. Huang
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Gulf Of California ◽  
Large Scale ◽  
Moisture Flux ◽  
Easterly Waves ◽  
Low Level ◽  
Moisture Fluxes ◽  
The Caribbean ◽  
The U.S

Abstract This study examines the nature of episodes of enhanced warm-season moisture flux into the Gulf of California. Both spatial structure and primary time scales of the fluxes are examined using the 40-yr ECMWF Re-Analysis data for the period 1980–2001. The analysis approach consists of a compositing technique that is keyed on the low-level moisture fluxes into the Gulf of California. The results show that the fluxes have a rich spectrum of temporal variability, with periods of enhanced transport over the gulf linked to African easterly waves on subweekly (3–8 day) time scales, the Madden–Julian oscillation (MJO) at intraseasonal time scales (20–90 day), and intermediate (10–15 day) time-scale disturbances that appear to originate primarily in the Caribbean Sea–western Atlantic Ocean. In the case of the MJO, enhanced low-level westerlies and large-scale rising motion provide an environment that favors large-scale cyclonic development near the west coast of Central America that, over the course of about 2 weeks, expands northward along the coast eventually reaching the mouth of the Gulf of California where it acts to enhance the southerly moisture flux in that region. On a larger scale, the development includes a northward shift in the eastern Pacific ITCZ, enhanced precipitation over much of Mexico and the southwestern United States, and enhanced southerly/southeasterly fluxes from the Gulf of Mexico into Mexico and the southwestern and central United States. In the case of the easterly waves, the systems that reach Mexico appear to redevelop/reorganize on the Pacific coast and then move rapidly to the northwest to contribute to the moisture flux into the Gulf of California. The most intense fluxes into the gulf on these time scales appear to be synchronized with a midlatitude short-wave trough over the U.S. West Coast and enhanced low-level southerly fluxes over the U.S. Great Plains. The intermediate (10–15 day) time-scale systems have zonal wavelengths roughly twice that of the easterly waves, and their initiation appears to be linked to an extratropical U.S. East Coast ridge and associated northeasterly winds that extend well into the Caribbean Sea during their development phase. The short (3–8 day) and, to a lesser extent, the intermediate (10–15 day) time-scale fluxes tend to be enhanced when the convectively active phase of the MJO is situated over the Americas.

scholarly journals Prediction of Seasonal Meteorological Drought Onset and Termination over the Southern Great Plains in the North American Multimodel Ensemble

2020 ◽  
Vol 21 (10) ◽  
pp. 2237-2255
Author(s):  
Richard Seager ◽  
Jennifer Nakamura ◽  
Mingfang Ting
Keyword(s):  
Great Plains ◽  
North American ◽  
Time Scale ◽  
Meteorological Drought ◽  
Atmospheric Variability ◽  
Multimodel Ensemble ◽  
Southern Great Plains ◽  
The North ◽  
Seasonal Time Scale ◽  
North American Multimodel Ensemble

AbstractThe predictability on the seasonal time scale of meteorological drought onsets and terminations over the southern Great Plains is examined within the North American Multimodel Ensemble. The drought onsets and terminations were those identified based on soil moisture transitions in land data assimilation systems and shown to be driven by precipitation anomalies. Sea surface temperature (SST) forcing explains about a quarter of variance of seasonal mean precipitation in the region. However, at lead times of a season, forecast SSTs only explain about 10% of seasonal mean precipitation variance. For the three identified drought onsets, fall 2010 is confidently predicted and spring 2012 is predicted with some skill, and fall 2005 was not predicted at all. None of the drought terminations were predicted on the seasonal time scale. Predictability of drought onset arises from La Niña–like conditions, but there is no indication that El Niño conditions lead to drought terminations in the southern Great Plains. Spring 2012 and fall 2000 are further examined. The limited predictability of onset in spring 2012 arises from cool tropical Pacific SSTs, but internal atmospheric variability played a very important role. Drought termination in fall 2000 was predicted at the 1-month time scale but not at the seasonal time scale, likely because of failure to predict warm SST anomalies directly east of subtropical Asia. The work suggests that improved SST prediction offers some potential for improved prediction of both drought onsets and terminations in the southern Great Plains, but that many onsets and terminations will not be predictable even a season in advance.

scholarly journals Decennal geomorphic transport from archived time series digital elevation models: a cookbook for tropical and alpine environments.

2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer
Keyword(s):  
Time Series ◽  
Time Scale ◽  
Aerial Images ◽  
Sensor Calibration ◽  
Dense Matching ◽  
Time Period ◽  
Digital Elevation ◽  
Seasonal Time Scale ◽  
Areas Of Interest ◽  
Alpine Environments

<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>

scholarly journals Asynchronism in leaf and wood production in tropical forests: a study combining satellite and ground-based measurements

2013 ◽  
Vol 10 (5) ◽  
pp. 8247-8281 ◽  
Author(s):  
F. Wagner ◽  
V. Rossi ◽  
C. Stahl ◽  
D. Bonal ◽  
B. Hérault
Keyword(s):  
Carbon Cycle ◽  
Tropical Forests ◽  
Time Scale ◽  
Carbon Allocation ◽  
Net Primary Production ◽  
Time Lag ◽  
Production Model ◽  
Wood Production ◽  
Modis Evi ◽  
Seasonal Time Scale

Abstract. The fixation of carbon in tropical forests mainly occurs through the production of wood and leaves, both being the principal components of net primary production. Currently field and satellite observations are independently used to describe the forest carbon cycle, but the link between satellite-derived forest phenology and field-derived forest productivity remains opaque. We used a unique combination of a MODIS EVI dataset, a climate-explicit wood production model and direct litterfall observations at an intra-annual time scale in order to question the synchronism of leaf and wood production in tropical forests. Even though leaf and wood biomass fluxes had the same range (respectively 2.4 ± 1.4 Mg C ha−1yr−1 and 2.2 ± 0.4 Mg C ha−1yr−1), they occured separately in time. EVI increased with the magnitude of leaf renewal at the beginning of the dry season when solar irradiance was at its maximum. At this time, wood production stopped. At the onset of the rainy season when new leaves were fully mature and water available again, wood production quickly increased to reach its maximum in less than a month, reflecting a change in carbon allocation from short lived pools (leaves) to long lived pools (wood). The time lag between peaks of EVI and wood production (109 days) revealed a substantial decoupling between the irradiance-driven leaf renewal and the water-driven wood production. Our work is a first attempt to link EVI data, wood production and leaf phenology at a seasonal time scale in a tropical evergreen rainforest and pave the way to develop more sophisticated global carbon cycle models in tropical forests.

Testing the influence of snow and meteorological conditions on snow avalanche deposit volumes

2021 ◽  
Author(s):  
Hippolyte Kern ◽  
Vincent Jomelli ◽  
Nicolas Eckert ◽  
Delphine Grancher
Keyword(s):  
Time Scale ◽  
Snow Depth ◽  
Snow Avalanche ◽  
Wet Snow ◽  
The Mean ◽  
Seasonal Time Scale ◽  
Snow Conditions ◽  
Complex Relationships ◽  
The Relationship ◽  
Annual Time

&lt;p&gt;Snow avalanche deposit volume is an important characteristic that determines vulnerability to snow avalanche. However, there is insufficient knowledge about snow and meteorological variables controlling deposit volumes. Our study focuses on the analysis of 1986 deposit volumes from 182 paths located in different regions of the French Alps including Queyras, and Maurienne valleys, between 2003 and 2017. This work uses data from the Permanent Avalanche Survey (EPA) database, an inventory of avalanche events occurring at well-known, delineated and mapped paths in France. We investigated relationships between snow deposit volumes and meteorological quantities, such as precipitation and temperature determined from SAFRAN reanalyses and snow-depth and wet snow-depth estimated from CROCUS reanalyses at a daily time scale at 2100m a.s.l. Analysis was conducted at an annual and seasonal time scale considering winter (November-February) and spring (March-May) between the mean deposit volumes and the mean meteorological and snow conditions.&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;&lt;p&gt;Results do not show any significant relationship between deposit volumes and meteorological or snow conditions at an annual time scale or for spring season. However, correlations between deposit volumes and meteorological and snow variables are high in winter (R&lt;sup&gt;2&lt;/sup&gt;=0.78). The best model includes two snow variables: mean snow-depth and maximal wet snow-depth. We suggest that these two important snow variables reflect variations in the snow cover characteristics later influencing the nature of the flow and the deposit volumes. Dividing the studied paths sample into several classes according to their morphology (i.e: surface area or mean slope) increases the significance of the relationship for both seasons and highlights more complex relationships with meteorological and snow variables.&lt;/p&gt;

scholarly journals Microbial dormancy improves predictability of soil respiration at the seasonal time scale

2019 ◽  
Vol 144 (1) ◽  
pp. 103-116 ◽  
Author(s):  
Alejandro Salazar ◽  
J. T. Lennon ◽  
J. S. Dukes
Keyword(s):  
Soil Respiration ◽  
Time Scale ◽  
Seasonal Time Scale

scholarly journals Decennal geomorphic transport from archived time series digital elevation models: a cookbook for tropical and alpine environments.

2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer
Keyword(s):  
Time Series ◽  
Time Scale ◽  
Aerial Images ◽  
Sensor Calibration ◽  
Dense Matching ◽  
Time Period ◽  
Digital Elevation ◽  
Seasonal Time Scale ◽  
Areas Of Interest ◽  
Alpine Environments

<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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