scholarly journals Meridional Changes in Satellite Chlorophyll and Fluorescence in Optically-Complex Coastal Waters of Northern Patagonia

2021 ◽  
Vol 13 (5) ◽  
pp. 1026
Author(s):  
Sebastián I. Vásquez ◽  
María Belén de la Torre ◽  
Gonzalo S. Saldías ◽  
Aldo Montecinos
Keyword(s):  
Estuarine System ◽  
A Algorithm ◽  
Annual Cycles ◽  
Chl A ◽  
Northern Patagonia ◽  
In Situ Data ◽  
Time Space ◽  
Meridional Winds

Northern Patagonia is one of the largest estuarine systems worldwide. It is characterized by complex geography, including islands, peninsulas, channels, and fjords. Here, the Inner Sea of Chiloé (ISC) is the largest estuarine system extending about 230 km in the meridional direction. Phytoplankton’s long-term dynamics and the main physical drivers of their variability are not well understood yet. Time-space fluctuations of Chlorophyll-a (Chl-a) and Chlorophyll fluorescence (nFLH) within the ISC and their association with meteorological and oceanographic processes were analyzed using high resolution (1000 m) satellite data (2003–2019). Our results revealed a meridional Chl-a and nFLH gradient along the ISC, with higher concentrations north of the Desertores islands where the topography promotes a semi-closed system with estuarine characteristics yearlong. Satellite Chl-a and nFLH were characterized by asynchronous seasonal cycles (nFLH peaks in fall) that differed from the southern ISC where the maximum Chl-a and nFLH occurs in spring-summer. The adjacent coastal ocean influences the southern ISC, and thus, the Chl-a and nFLH variability correlated well with the seasonal variation of meridional winds. The northern ISC was clearly influenced by river discharges, which can bias the Chl-a retrievals, decoupling the annual cycles of Chl-a and nFLH. In situ data from a buoy in Seno Reloncaví reaffirmed this bias in satellite Chl-a and a higher correlation with nFLH, by which the construction of a local Chl-a algorithm for northern Patagonia is essential.

scholarly journals Phytoplankton Phenology in the Coastal Zone of Cyprus, Based on Remote Sensing and In Situ Observations

2021 ◽  
Vol 14 (1) ◽  
pp. 12
Author(s):  
Monica Demetriou ◽  
Dionysios E. Raitsos ◽  
Antonia Kournopoulou ◽  
Manolis Mandalakis ◽  
Spyros Sfenthourakis ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Time Series ◽  
Phytoplankton Biomass ◽  
Trophic Levels ◽  
Data Availability ◽  
Ocean Colour ◽  
Chl A ◽  
In Situ Data

Alterations in phytoplankton biomass, community structure and timing of their growth (phenology), are directly implicated in the carbon cycle and energy transfer to higher trophic levels of the marine food web. Due to the lack of long-term in situ datasets, there is very little information on phytoplankton seasonal succession in Cyprus (eastern Mediterranean Sea). On the other hand, satellite-derived measurements of ocean colour can only provide long-term time series of chlorophyll (an index of phytoplankton biomass) up to the first optical depth (surface waters). The coupling of both means of observations is essential for understanding phytoplankton dynamics and their response to environmental change. Here, we use 23 years of remotely sensed, regionally tuned ocean-colour observations, along with a unique time series of in situ phytoplankton pigment composition data, collected in coastal waters of Cyprus during 2016. The satellite observations show an initiation of phytoplankton growth period in November, a peak in February and termination in April, with an overall mean duration of ~4 months. An in-depth exploration of in situ total Chl-a concentration and phytoplankton pigments revealed that pico- and nano-plankton cells dominated the phytoplankton community. The growth peak in February was dominated by nanophytoplankton and potentially larger diatoms (pigments of 19’ hexanoyloxyfucoxanthin and fucoxanthin, respectively), in the 0–20 m layer. The highest total Chl-a concentration was recorded at a station off Akrotiri peninsula in the south, where strong coastal upwelling has been reported. Another station in the southern part, located next to a fish farm, showed a higher contribution of picophytoplankton during the most oligotrophic period (summer). Our results highlight the importance of using available in situ data coupled to ocean-colour remote sensing, for monitoring marine ecosystems in areas with limited in situ data availability.

scholarly journals Rainfall Estimates on a Gridded Network (REGEN) – a global land-based gridded dataset of daily precipitation from 1950 to 2016

2020 ◽  
Vol 24 (2) ◽  
pp. 919-943 ◽  
Author(s):  
Steefan Contractor ◽  
Markus G. Donat ◽  
Lisa V. Alexander ◽  
Markus Ziese ◽  
Anja Meyer-Christoffer ◽  
...  
Keyword(s):  
Daily Precipitation ◽  
In Situ Data ◽  
Global Precipitation Climatology Centre ◽  
Historical Climatology ◽  
Global Land ◽  
Global Historical Climatology Network ◽  
Global Precipitation ◽  
Rainfall Estimates

Abstract. We present a new global land-based daily precipitation dataset from 1950 using an interpolated network of in situ data called Rainfall Estimates on a Gridded Network – REGEN. We merged multiple archives of in situ data including two of the largest archives, the Global Historical Climatology Network – Daily (GHCN-Daily) hosted by National Centres of Environmental Information (NCEI), USA, and one hosted by the Global Precipitation Climatology Centre (GPCC) operated by Deutscher Wetterdienst (DWD). This resulted in an unprecedented station density compared to existing datasets. The station time series were quality-controlled using strict criteria and flagged values were removed. Remaining values were interpolated to create area-average estimates of daily precipitation for global land areas on a 1∘ × 1∘ latitude–longitude resolution. Besides the daily precipitation amounts, fields of standard deviation, kriging error and number of stations are also provided. We also provide a quality mask based on these uncertainty measures. For those interested in a dataset with lower station network variability we also provide a related dataset based on a network of long-term stations which interpolates stations with a record length of at least 40 years. The REGEN datasets are expected to contribute to the advancement of hydrological science and practice by facilitating studies aiming to understand changes and variability in several aspects of daily precipitation distributions, extremes and measures of hydrological intensity. Here we document the development of the dataset and guidelines for best practices for users with regards to the two datasets.

scholarly journals Mass balance of Trambau Glacier, Rolwaling region, Nepal Himalaya: in-situ observations, long-term reconstruction and mass-balance sensitivity

2019 ◽  
Vol 65 (252) ◽  
pp. 605-616 ◽  
Author(s):  
SOJIRO SUNAKO ◽  
KOJI FUJITA ◽  
AKIKO SAKAI ◽  
RIJAN B. KAYASTHA
Keyword(s):  
Mass Balance ◽  
High Elevation ◽  
Climatic Conditions ◽  
Balance Model ◽  
Glacier Mass Balance ◽  
Balance Study ◽  
Nepal Himalaya ◽  
In Situ Data

ABSTRACTWe conducted a mass-balance study of debris-free Trambau Glacier in the Rolwaling region, Nepal Himalaya, which is accessible to 6000 m a.s.l., to better understand mass-balance processes and the effect of precipitation on these processes on high-elevation Himalayan glaciers. Continuous in situ meteorological and mass-balance observations that spanned the three melt seasons from May 2016 are reported. An energy- and mass-balance model is also applied to evaluate its performance and sensitivity to various climatic conditions. Glacier-wide mass balances ranging from −0.34 ± 0.38 m w.e. in 2016 to −0.82 ± 0.53 m w.e. in 2017/18 are obtained by combining the observations with model results for the areas above the highest stake. The estimated long-term glacier mass balance, which is reconstructed using the ERA-Interim data calibrated with in situ data, is −0.65 ± 0.39 m w.e. a−1for the 1980–2018 period. A significant correlation with annual precipitation (r= 0.77,p< 0.001) is observed, whereas there is no discernible correlation with summer mean air temperature. The results indicate the continuous mass loss of Trambau Glacier over the last four decades, which contrasts with the neighbouring Mera Glacier in balance.

scholarly journals West African Summer Monsoon Precipitation Variability as Represented by Reanalysis Datasets

Climate ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 111
Author(s):  
Kwesi Akumenyi Quagraine ◽  
Francis Nkrumah ◽  
Cornelia Klein ◽  
Nana Ama Browne Klutse ◽  
Kwesi Twentwewa Quagraine
Keyword(s):  
Summer Monsoon ◽  
Southern Oscillation ◽  
West African Monsoon ◽  
West African ◽  
Positive Trend ◽  
In Situ Data ◽  
Dry Conditions ◽  
Long Term Trends

Focusing on West Africa, a region riddled with in situ data scarcity, we evaluate the summer monsoon monthly rainfall characteristics of five global reanalysis datasets: ERA5, ERA-Interim, JRA-55, MERRA2, and NCEP-R2. Their performance in reproducing the West African monsoon (WAM) climatology, interannual variability, and long-term trends for the main monsoon months are compared to gauge-only and satellite products. We further examine their ability to reproduce teleconnections between sea surface temperatures and monsoon rainfall. All reanalyses are able to represent the average rainfall patterns and seasonal cycle; however, regional biases can be marked. ERA5, ERA-Interim, and NCEP-R2 underestimate rainfall over areas of peak rainfall, with ERA5 showing the strongest underestimation, particularly over the Guinea Highlands. The meridional northward extent of the monsoon rainband is well captured by JRA-55 and MERRA2 but is too narrow in ERA-Interim, for which rainfall stays close to the Guinea Coast. Differences in rainband displacement become particularly evident when comparing strong El Niño Southern Oscillation (ENSO) years, where all reanalyses except ERA-Interim reproduce wetter Sahelian conditions for La Niña, while overestimating dry conditions at the coast except for NCEP-R2. Precipitation trends are not coherent across reanalyses and magnitudes are generally overestimated compared to observations, with only JRA-55 and NCEP-R2 displaying the expected positive trend in the Sahel. ERA5 generally outperforms ERA-Interim, highlighting clear improvements over its predecessor. Ultimately, we find the strengths of reanalyses to strongly vary across the region.

scholarly journals A comparison of empirical and physically based glacier surface melt models for long-term simulations of glacier response

2014 ◽  
Vol 60 (224) ◽  
pp. 1140-1154 ◽  
Author(s):  
Jeannette Gabbi ◽  
Marco Carenzo ◽  
Francesca Pellicciotti ◽  
Andreas Bauder ◽  
Martin Funk
Keyword(s):  
Shortwave Radiation ◽  
Radiation Balance ◽  
Volume Changes ◽  
Glacier Surface ◽  
Surface Evolution ◽  
Ice Volume ◽  
In Situ Data ◽  
Physically Based

AbstractWe investigate the performance of five glacier melt models over a multi-decadal period in order to assess their ability to model future glacier response. The models range from a simple degree-day model, based solely on air temperature, to more-sophisticated models, including the full shortwave radiation balance. In addition to the empirical models, the performance of a physically based energy-balance (EB) model is examined. The melt models are coupled to an accumulation and a surface evolution model and applied in a distributed manner to Rhonegletscher, Switzerland, over the period 1929–2012 at hourly resolution. For calibration, seasonal mass-balance measurements (2006–12) are used. Decadal ice volume changes for six periods in the years 1929–2012 serve for model validation. Over the period 2006–12, there are almost no differences in performance between the models, except for EB, which is less consistent with observations, likely due to lack of meteorological in situ data. However, simulations over the long term (1929–2012) reveal that models which include a separate term for shortwave radiation agree best with the observed ice volume changes, indicating that their melt relationships are robust in time and thus suitable for long-term modelling, in contrast to more empirical approaches that are oversensitive to temperature fluctuations.

scholarly journals MODIS STANDARD (OC3) CHLOROPHYLL-A ALGORITHM EVALUATION IN INDONESIAN SEAS

2017 ◽  
Vol 11 (1) ◽  
pp. 11
Author(s):  
Gathot Winarso ◽  
Yennie Marini
Keyword(s):  
Pacific Ocean ◽  
Research And Development ◽  
Chlorophyll A ◽  
A Algorithm ◽  
Concentration Data ◽  
Indonesian Seas ◽  
In Situ Data ◽  
The North ◽  
Level 2

The MODIS-estimated chlorophyll-a information was widely used in some operational application in Indonesia. However, there is no information about the performance of MODIS chlorophyll-a in Indonesian seas and there is no data used in development of algorithm was taken in Indonesian seas. Even the algorithm was validated in other area, it is important to know the performance of the algorithm work in Indonesian seas. Performance of MODIS Standard (OC3) algorithm at Indonesian seas was analyzed in this paper. The in-situ chlorophyll-a concentration data was collected during MOMSEI (Monsoon Offset Monitoring and Its Social and Ecosystem Impact) 2012 Cruise 25th April – 12th   May 2012 and also from archived data of the Research and Development Center for Marine Coastal Resources, Agency of Marine and Fisheries Research and Development, Indonesian Ministry of  Marine Affairs and Fisheries. The in-situ data used in this research is located in Indian Ocean the west of Sumatera part and Pacific Ocean the north of Papua Province part. Satellite data which is used is Ocean Color MODIS Level-2 Product that downloaded from NASA and MODIS L-0 from LAPAN Ground Station. MODIS Level 0 from LAPAN then processed to Level-2  using latest SeaDAS Software. The match-up resulted the MNB(%) is -4.8% that means satellite-estimated was underestimate in 4.8 % and RMSE is 0.058. When the data was separated following to the data source, the correlation and trend line equation became better. From MOMSEI Cruise data, the MNB(%) was -18.8% and RMSE 0.05. From Pacific Ocean Data, MNB (%) was -27 % and RMSE 0.049. From SONNE Cruise 2005, MNB (%) was -27 % and RMSE 0.049. MODIS standard algorithm is work well in Indonesia case-1 seawaters, which contain chlorophyll-a only, and derived that influence to the electromagnetic wave.

Estimation of Salt Rocks’ Long-Term Strength in Natural Conditions

2015 ◽  
Vol 243 ◽  
pp. 11-16
Author(s):  
Alexander A. Baryakh ◽  
Sergey Yu. Lobanov ◽  
Ivan S. Lomakin
Keyword(s):  
Underground Mining ◽  
Term Strength ◽  
New Approach ◽  
In Situ Data ◽  
The Earth ◽  
Deformation And Fracture ◽  
Strength Based ◽  
Fracture Processes

New approach to construction curve of salt rock’s long-term strength based on the diagram’s analysis of the earth surface subsidence growth under the influence of underground mining has been proposed. Performed verification of received estimation showed acceptable fit of mathematical modeling results of interchamber pillars’ deformation and fracture processes with in-situ data.

Post-storm recuperation as a stepping-stone towards long-term integrated modelling in steep beaches

2020 ◽  
Author(s):  
Katerina Kombiadou ◽  
Susana Costas ◽  
Dano Roelvink ◽  
Robert McCall
Keyword(s):  
Methodological Approach ◽  
Integrated Approach ◽  
Integrated Modelling ◽  
Dune System ◽  
Critical System ◽  
Event Scale ◽  
Nearshore Processes ◽  
In Situ Data

&lt;p&gt;Integrated modelling approaches for the evolution of the entire dune-beach system have become increasingly sought-after, not only for management purposes, but also to allow better understanding of the feedbacks between processes and scales and a closer approximation of where critical system thresholds may lie. The effective reproduction of both destructive and constructive processes over a broad spectrum of temporal scales is crucial to any, such, integrated approach. Recent improvements of the XBeach-Duna model regarding approximation of nearshore processes were tested using in-situ data from the Emma storm impacts on a reflective beach (Praia de Faro, in S. Portugal). The model results compare well with measured post-storm and recovered profiles, showing high model skill under both erosive and constructive regimes. Building from this event-scale analysis, a gradual increase of temporal windows in simulated forcing conditions, through wave schematisation, is presented and discussed in terms of optimisation between gains in simulation time and losses in geomorphic change information. This methodological approach and findings are the basis that will allow passing on to dependable, long-term simulations of the beach-dune system evolution.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;em&gt;Acknowledgements: The work was implemented in the framework of the ENLACE project (ref. 28949 FEDER), funded by FCT (Funda&amp;#231;&amp;#227;o para a Ci&amp;#234;ncia e a Tecnologia)&lt;/em&gt;&lt;/p&gt;

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