scholarly journals On Turbulence and Mixing in the Free Atmosphere Inferred from High-Resolution Soundings

2008 ◽  
Vol 25 (6) ◽  
pp. 833-852 ◽  
Author(s):  
Carol Anne Clayson ◽  
Lakshmi Kantha
Keyword(s):  
High Resolution ◽  
Trace Gases ◽  
Free Atmosphere ◽  
Turbulent Dissipation ◽  
The Past ◽  
Direct Measurements ◽  
The World ◽  
Radar Measurements ◽  
Turbulence Scaling

Abstract Mixing in the free atmosphere above the planetary boundary layer is of great importance to the fate of trace gases and pollutants. However, direct measurements of the turbulent dissipation rate by in situ probes are very scarce and radar measurements are fraught with uncertainties. In this paper, turbulence scaling concepts, developed over the past decades for application to oceanic mixing, are used to suggest an alternative technique for retrieving turbulence properties in the free atmosphere from high-resolution soundings. This technique enables high-resolution radiosondes, which have become quite standard in the past few years, to be used not only to monitor turbulence in the free atmosphere in near–real time, but also to study its spatiotemporal characteristics from the abundant archives of high-resolution soundings from around the world. Examples from several locations are shown, as well as comparisons with radar-based estimations and a typical Richardson number–based parameterization.

The Vyredox and Nitredox Methods of in situ Treatment of Groundwater

1988 ◽  
Vol 20 (3) ◽  
pp. 149-163 ◽  
Author(s):  
Carol Braester ◽  
Rudolf Martinell
Keyword(s):  
Water Treatment ◽  
Surface Water ◽  
Traditional Method ◽  
Treatment Method ◽  
Nitrate Treatment ◽  
The Past ◽  
The World ◽  
Nitrate And Nitrite ◽  
Iron And Manganese

Nearly one fifth of all water used in the world is obtained from groundwater. The protection of water has become a high priority goal. During the last decades pollution of water has become more and more severe. Today groundwater is more and more used in comparison with surface water. Recently we have seen accidents, which can pollute nearly all surface water very quickly. Generally the groundwater is easier to protect, as well as cheaper to purify, and above all it is of better quality than the surface water. During the past two decades, alternatives to the traditional method of treating the water in filters have been developed, that is in situ water treatment i.e. the VYREDOX and NITREDOX methods. The most common problem regarding groundwater is too high content of iron and manganese, which can be reduced with the VYREDOX method. In some areas today there are severe problems with pollution by hydrocarbons and nitrate as well, and with modification of the VYREDOX treatment method it is used for hydrocarbon and nitrate treatment as well. The method to reduce the nitrate and nitrite is known as the NITREDOX method.

scholarly journals Integration of HF Radar Observations for an Enhanced Coastal Mean Dynamic Topography

2020 ◽  
Vol 7 ◽  
Author(s):  
Ainhoa Caballero ◽  
Sandrine Mulet ◽  
Nadia Ayoub ◽  
Ivan Manso-Narvarte ◽  
Xabier Davila ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Satellite Data ◽  
Coastal Areas ◽  
Hf Radar ◽  
Global Ocean ◽  
Dynamic Topography ◽  
Mean Dynamic Topography ◽  
Radar Measurements

Satellite altimeters provide continuous information of the sea level variability and mesoscale processes for the global ocean. For estimating the sea level above the geoid and monitoring the full ocean dynamics from altimeters measurements, a key reference surface is needed: The Mean Dynamic Topography (MDT). However, in coastal areas, where, in situ measurements are sparse and the typical scales of the motion are generally smaller than in the deep ocean, the global MDT solutions are less accurate than in the open ocean, even if significant improvement has been done in the past years. An opportunity to fill in this gap has arisen with the growing availability of long time-series of high-resolution HF radar surface velocity measurements in some areas, such as the south-eastern Bay of Biscay. The prerequisite for the computation of a coastal MDT, using the newly available data of surface velocities, was to obtain a robust methodology to remove the ageostrophic signal from the HF radar measurements, in coherence with the scales resolved by the altimetry. To that end, we first filtered out the tidal and inertial motions, and then, we developed and tested a method that removed the Ekman component and the remaining divergent part of the flow. A regional high-resolution hindcast simulation was used to assess the method. Then, the processed HF radar geostrophic velocities were used in synergy with additional in situ data, altimetry, and gravimetry to compute a new coastal MDT, which shows significant improvement compared with the global MDT. This study showcases the benefit of combining satellite data with continuous, high-frequency, and synoptic in situ velocity data from coastal radar measurements; taking advantage of the different scales resolved by each of the measuring systems. The integrated analysis of in situ observations, satellite data, and numerical simulations has provided a further step in the understanding of the local ocean processes, and the new MDT a basis for more reliable monitoring of the study area. Recommendations for the replicability of the methodology in other coastal areas are also provided. Finally, the methods developed in this study and the more accurate regional MDT could benefit present and future high-resolution altimetric missions.

scholarly journals Effect of Lockdown on Pollutant Levels in the Delhi Megacity: Role of Local Emission Sources and Chemical Lifetimes

2021 ◽  
Vol 9 ◽  
Author(s):  
Chinmay Mallik ◽  
Harish Gadhavi ◽  
Shyam Lal ◽  
Rahul Kant Yadav ◽  
R. Boopathy ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Trace Gases ◽  
Emission Sources ◽  
Air Masses ◽  
The World ◽  
Local Emission ◽  
Maximum Decrease ◽  
Emission Changes

The COVID-19 pandemic resulted in changed emission regimes all over the world. India also imposed complete lockdown on all modes of travel and industrial activities for about 2 months from 25-March-2020 and later unlocked these activities in a phased manner. Here, we study signatures of emissions changes on levels of atmospheric trace gases and aerosols contributing to air pollution over multiple sites in India’s capital Delhi covering various lockdown and unlock phases using satellite data and in-situ observations. The resulting changes in the levels of these species were compared with respect to their average of 2015–2019 to attribute for year to year and seasonal changes. A clear impact of lockdown was observed for AOD, PM, NO2, CO, and SO2 as a result of emission changes, while changed precursor levels led to a change in O3 chemical regimes impacting its concentrations. A detailed analysis of FLEXPART trajectories revealed increased PM levels over Delhi in north-westerly air masses sourced to Punjab region all the way up to Pakistan. Changes in aerosols and NO2 were not only restricted to the surface but transcended the total tropospheric column. The maximum decrease in PM, NO2, CO, and SO2 was observed during the month of total lockdown in April. The lockdown impact varied with species e.g., PM10 and PM2.5 as well as locations even within the periphery of Delhi. While surface level aerosols and NO2 showed significant and almost similar changes, AOD showed much lower decrease than tropospheric column NO2.

A high resolution reanalysis for the Mediterranean Sea

2021 ◽  
Author(s):  
Romain Escudier ◽  
Emanuela Clementi ◽  
Mohamed Omar ◽  
Andrea Cipollone ◽  
Jenny Pistoia ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Large Scale ◽  
Thermohaline Circulation ◽  
Deep Convection ◽  
Horizontal Resolution ◽  
Continuous Increase ◽  
The Past ◽  
The Mediterranean

<p>In order to be able to predict the future ocean climate and weather, it is crucial to understand what happened in the past and the mechanisms responsible for the ocean variability. This is particularly true in a complex area such as the Mediterranean Sea with diverse dynamics such as deep convection and thermohaline circulation or coastal hydrodynamics. To this end, effective tools are reanalyses or reconstructions of the past ocean state. </p><p>Here we present a new physical reanalysis of the Mediterranean Sea at high resolution, developed in the Copernicus Marine Environment Monitoring Service (CMEMS) framework. The hydrodynamic model is based on the Nucleus for European Modelling of the Ocean (NEMO) combined with a variational data assimilation scheme (OceanVar).</p><p>The model has a horizontal resolution of 1/24<strong>°</strong> and 141 vertical z* levels and provides daily and monthly 3D values of temperature, salinity, sea level and currents. Hourly ECMWF ERA-5 atmospheric fields force the model and daily boundary conditions in the Atlantic are taken from the global CMCC C-GLORS reanalysis. 39 rivers model the freshwater input to the basin plus the Dardanelles. The reanalysis covers 33-years, initialized from SeaDataNet climatology in January 1985, getting to a nominal state after a two-years spin-up and ending in 2019. In-situ data from CTD, ARGO floats and XBT are assimilated into the model in combination with satellite altimetry data.</p><p>This reanalysis has been validated and assessed through comparison to in-situ and satellite observations as well as literature climatologies. The results show an overall improvement of the skill and a better representation of the main dynamics of the region compared to the previous, lower resolution (1/16<strong>°</strong>) reanalysis. Temperature and salinity RMSE is decreased by respectively 12% and 20%. The deeper biases in salinity of the previous version are corrected and the new reanalysis present a better representation of the deep convection in the Gulf of Lion. Climate signals show continuous increase of the temperature due to climate change but also in salinity.</p><p>The new reanalysis will allow the study of physical processes at multi-scales, from the large scale to the transient small mesoscale structures.</p>

NOAA/AVHRR Satellite Data-Based Indices for Monitoring Agricultural Droughts

2005 ◽  
Author(s):  
Felix N. Kogan
Keyword(s):  
High Resolution ◽  
Satellite Data ◽  
Thermal Conditions ◽  
Early Years ◽  
Data Availability ◽  
Sources Of Information ◽  
In Situ Data ◽  
Marginal Areas ◽  
The World

Operational polar-orbiting environmental satellites launched in the early 1960s were designed for daily weather monitoring around the world. In the early years, they were mostly applied for cloud monitoring and for advancing skills in satellite data applications. The new era was opened with the series of TIROS-N launched in 1978, which has continued until present. These satellites have such instruments as the advanced very high resolution radiometer (AVHRR) and the TIROS operational vertical sounder (TOVS), which included a microwave sounding unit (MSU), a stratospheric sounding unit (SSU), and high-resolution infrared radiation sounder/2 (HIRS/2). These instruments helped weather forecasters improve their skills. AVHRR instruments were also useful for observing and monitoring earth surface. Specific advances were achieved in understanding vegetation distribution. Since the late 1980s, experience gained in interpreting vegetation conditions from satellite images has helped develop new applications for detecting phenomenon such as drought and its impacts on agriculture. The objective of this chapter is to introduce AVHRR indices that have been useful for detecting most unusual droughts in the world during 1990–2000, a decade identified by the United Nations as the International Decade for Natural Disasters Reduction. Radiances measured by the AVHRR instrument onboard National Oceanic Atmospheric Administration (NOAA) polar-orbiting satellites can be used to monitor drought conditions because of their sensitivity to changes in leaf chlorophyll, moisture content, and thermal conditions (Gates, 1970; Myers, 1970). Over the last 20 years, these radiances were converted into indices that were used as proxies for estimating various vegetation conditions (Kogan, 1997, 2001, 2002). The indices became indispensable sources of information in the absence of in situ data, whose measurements and delivery are affected by telecommunication problems, difficult access to environmentally marginal areas, economic disturbances, and political or military conflicts. In addition, indices have advantage over in situ data in terms of better spatial and temporal coverage and faster data availability. The AVHRR-based indices used for monitoring vegetation can be divided into two groups: two-channel indices, and three-channel indices.

scholarly journals Direct measurement of NO<sub>3</sub> reactivity in a boreal forest

2017 ◽  
Author(s):  
Jonathan Liebmann ◽  
Einar Karu ◽  
Nicolas Sobanski ◽  
Jan Schuladen ◽  
Mikael Ehn ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Dominant Role ◽  
Trace Gases ◽  
Vertical Mixing ◽  
Vertical Gradient ◽  
Mean Value ◽  
Diel Variation ◽  
Direct Measurements ◽  
Temperature Inversions

Abstract. We present the first direct measurements of NO3 reactivity (or inverse lifetime, s−1) in the Finnish boreal forest. The data were obtained during the IBAIRN campaign (Influence of Biosphere-Atmosphere Interactions on the Reactive Nitrogen budget) which took place in Hyytiälä, Finland during the summer/autumn transition in September 2016. The NO3 reactivity was generally very high with a maximum value of 0.94 s−1 and displayed a strong diel variation with a campaign-averaged nighttime mean value of 0.11 s−1 compared to a daytime value of 0.04 s−1. The highest nighttime NO3-reactivity was accompanied by major depletion of canopy level ozone and was associated with strong temperature inversions and high levels of monoterpenes. The daytime reactivity was sufficiently large that reactions of NO3 with organic trace gases could compete with photolysis and reaction with NO. There was no significant reduction in the measured NO3 reactivity between the beginning and end of the campaign indicating that any seasonal reduction in canopy emissions of reactive biogenic trace gases was offset by emissions from the forest floor. Observations of biogenic hydrocarbons (BVOC) suggested a dominant role for monoterpenes in determining the NO3 reactivity. Reactivity not accounted for by in-situ measurement of NO and BVOCs was variable across the diel cycle with, on average, circa 30 % “missing” during nighttime and circa 60 % missing during the day. Measurement of the NO3 reactivity at various heights (8.5 to 25 m) both above and below the canopy, revealed a strong nighttime, vertical gradient with maximum values closest to the ground. The gradient disappeared during daytime due to efficient vertical mixing.

The Global Ocean Observing Component of IOOS: Implementation of the Initial Global Ocean Observing System for Climate and the Path Forward

2011 ◽  
Vol 45 (1) ◽  
pp. 9-18 ◽  
Author(s):  
Joel M. Levy ◽  
Derrick Snowden ◽  
Candyce Clark ◽  
Kathleen Crane ◽  
Howard J. Diamond ◽  
...  
Keyword(s):  
Global Climate ◽  
Global Ocean ◽  
Generation System ◽  
World Community ◽  
Design Goal ◽  
The Past ◽  
The World ◽  
Ocean Observing ◽  
The U.S

AbstractThe global ocean observing system for climate, which comprises the global in situ component of the U.S. Integrated Ocean Observing System, has now achieved about 61% of its initial design goal. Although this observing system, implemented cooperatively by over 70 countries worldwide, serves multiple applications, it is designed primarily to address climate requirements defined by the international Global Climate Observing System. The U.S. contribution to the system, described here, is implemented as an interdependent set of observational subsystems that constitute about half of the over 8,000 observing platforms deployed by the world community. Although much work remains to complete the initial global observing system, scientific advances of the past decade have identified the need to deploy a second-generation system that integrates biogeochemical and ecological observations with the primarily physical and carbon-related oceanographic observations that form the backbone of the initial observing system.

scholarly journals A High Resolution Reanalysis for the Mediterranean Sea

2021 ◽  
Vol 9 ◽  
Author(s):  
Romain Escudier ◽  
Emanuela Clementi ◽  
Andrea Cipollone ◽  
Jenny Pistoia ◽  
Massimiliano Drudi ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Large Scale ◽  
Mixed Layer Depth ◽  
Horizontal Resolution ◽  
Continuous Increase ◽  
The Past ◽  
The Mediterranean

In order to be able to forecast the weather and estimate future climate changes in the ocean, it is crucial to understand the past and the mechanisms responsible for the ocean variability. This is particularly true in a complex area such as the Mediterranean Sea with diverse dynamics like deep convection and overturning circulation. To this end, effective tools are ocean reanalyses or reconstructions of the past ocean state. Here we present a new physical reanalysis of the Mediterranean Sea at high resolution, developed in the Copernicus Marine Environment Monitoring Service (CMEMS) framework. The hydrodynamic model is based on the Nucleus for European Modelling of the Ocean (NEMO) combined with a variational data assimilation scheme (OceanVar). The model has a horizontal resolution of 1/24° and 141 unevenly distributed vertical z* levels. It provides daily and monthly temperature, salinity, current, sea level and mixed layer depth as well as hourly fields for surface velocities and sea level. ECMWF ERA-5 atmospheric fields force the model and daily boundary conditions in the Atlantic are taken from a global reanalysis. The reanalysis covers the 33 years from 1987 to 2019. Initialized from SeaDataNet climatology in January 1985, it reaches a nominal state after a 2-years spin-up. In-situ data from CTD, ARGO floats and XBT are assimilated into the model in combination with satellite altimetry observations. This reanalysis has been validated and assessed through comparison to in-situ and satellite observations as well as literature climatologies. The results show an overall improvement of the comparison with observations and a better representation of the main dynamics of the region compared to a previous, lower resolution (1/16°), reanalysis. Temperature and salinity RMSD are decreased by respectively 14 and 18%. The salinity biases at depth of the previous version are corrected. Climate signals show continuous increase of the temperature and salinity, confirming estimates from observations and other reanalysis. The new reanalysis will allow the study of physical processes at multi-scales, from the large scale to the transient small mesoscale structures and the selection of climate indicators for the basin.

scholarly journals Fast SARS-CoV-2 Variant Detection Using Snapback Primer High-Resolution Melting

Diagnostics ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1788
Author(s):  
Joseph C. Lownik ◽  
Jared S. Farrar ◽  
Grayson W. Way ◽  
Angela McKay ◽  
Pavitra Roychoudhury ◽  
...  
Keyword(s):  
High Resolution ◽  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
High Resolution Melting ◽  
Whole Genome ◽  
Current Standard ◽  
The Past ◽  
The World ◽  
Variant Detection ◽  
Sensitive Testing

SARS-CoV-2, the virus responsible for COVID-19, emerged in late 2019 and has since spread throughout the world, infecting over 200 million people. The fast spread of SARS-CoV-2 showcased the need for rapid and sensitive testing methodologies to help track the disease. Over the past 18 months, numerous SARS-CoV-2 variants have emerged. Many of these variants are suggested to be more transmissible as well as less responsive to neutralization by vaccine-induced antibodies. Viral whole-genome sequencing is the current standard for tracking these variants. However, whole-genome sequencing is costly and the technology and expertise are limited to larger reference laboratories. Here, we present the feasibility of a fast, inexpensive methodology using snapback primer-based high-resolution melting to test for >20 high-consequence SARS-CoV-2 spike mutations. This assay can distinguish between multiple variant lineages and be completed in roughly 2 h for less than $10 per sample.

scholarly journals Multi-decadal mass balance series of three Kyrgyz glaciers inferred from transient snowline observations

2017 ◽  
Author(s):  
Martina Barandun ◽  
Matthias Huss ◽  
Etienne Berthier ◽  
Andreas Kääb ◽  
Erlan Azisov ◽  
...  
Keyword(s):  
Mass Balance ◽  
Tien Shan ◽  
High Mountain ◽  
Glacier Mass Balance ◽  
The Past ◽  
Digital Elevation ◽  
Direct Measurements ◽  
Pamir Mountains ◽  
Continuous Mass

Abstract. Glacier mass balance observations in the Tien Shan and Pamir mountains are sparse and often discontinuous. Nevertheless, glaciers are one of the most important components of the high-mountain cryosphere in the region; they strongly influence water availability in the arid, continental and intensely populated downstream areas. This study provides reliable and continuous mass balance series for selected glaciers located in the Tien Shan and Pamir-Alay. A combination of three independent methods was used to reconstruct for the past two decades the mass balance of the three benchmark glaciers, Abramov, Golubin and No. 354. By applying different approaches, it was possible to compensate for the limitations and shortcomings of each individual method. This study proposes the use of transient snowline observations throughout the melting season obtained from satellite imagery and terrestrial automatic cameras. By combining modelling with remotely acquired information on summer snow depletion, it was possible to infer glacier mass changes for unmeasured years. Multi-annual mass changes based on high accuracy digital elevation models and in situ glaciological surveys were used to validate the results for the investigated glaciers. Substantial mass loss was confirmed for the three studied glaciers by all three methods, ranging from −0.30 ± 0.19 m w. e. a−1 to −0.41 ± 0.33 m w. e. a−1 over the 2004–2016 period. Our results indicate that integration of snowline observations into mass balance modelling significantly narrows the uncertainty ranges of the estimates, and hence highlights the potential of the methodology for application to inaccessible glaciers at larger scales for which no direct measurements are available.

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