In-situ measurements of the HDO/H2O Isotopic ratio in the Asian Summer Monsoon trace strong convective activity

2021 ◽  
Author(s):  
Benjamin Clouser ◽  
Clare Singer ◽  
Sergey Khaykin ◽  
Martina Krämer ◽  
Alexey Lykov ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Asian Summer Monsoon ◽  
Isotopic Ratio ◽  
Detailed Comparison ◽  
In Situ Measurements ◽  
Wide Range ◽  
Asian Summer ◽  
Asian Monsoons ◽  
Isotopic Measurements

<p>In-situ measurements of the HDO/H<sub>2</sub>O isotopic ratio from the Chicago Water Isotope Spectrometer (ChiWIS) during the 2017 StratoClim campaign help diagnose convective processes in the Asian Monsoon. Isotopic measurements show enormous diversity in isotopic composition, likely reflecting degree of recent convective influence. Eight flights in July—August sampled a wide range of convective influence at near-tropopause altitudes, with timescales of minutes to weeks, and mean isotopic compositions from -700 per mil in recent convective outflow to -350 per mil in more aged air that is at least several days from last convective influence. Above the tropopause, we use isotopic composition to understand the fate of convective remnants. Isotopic measurements suggest much in-situ cirrus measured during  StratoClim campaign is actually secondary cirrus which has reformed in an area of prior convective moistening. These flights allow detailed comparison between North American and Asian monsoons, and we compare StratoClim results to both satellite and in-situ measurements in other monsoon and tropical locations. Finally, we discuss prospects for detection and interpretation of convective remnants during the in the 2021/2022 ACCLIP campaign.</p>

scholarly journals Validation of modeled snow properties in Afghanistan, Pakistan, and Tajikistan

2019 ◽  
Author(s):  
Edward H. Bair ◽  
Karl Rittger ◽  
Jawairia A. Ahmad ◽  
Doug Chabot
Keyword(s):  
Snow Depth ◽  
Snow Water Equivalent ◽  
Median Number ◽  
In Situ Measurements ◽  
Snow Properties ◽  
Wide Range ◽  
Spatial Estimates ◽  
Snow Water ◽  
Critical Layers

Abstract. Ice and snowmelt feed the Indus and Amu Darya rivers, yet there are limited in situ measurements of these resources. Previous work in the region has shown promise using snow water equivalent (SWE) reconstruction, which requires no in situ measurements, but validation has been a problem until recently when we were provided with daily manual snow depth measurements from Afghanistan, Tajikistan, and Pakistan by the Aga Khan Agency for Habitat (AKAH). For each station, accumulated precipitation and SWE were derived from snow depth using the SNOWPACK model. High-resolution (500 m) reconstructed SWE estimates from the ParBal model were then compared to the modeled SWE at the stations. The Alpine3D model was then used to create spatial estimates at 25 km to compare with estimates from other snow models. Additionally, the coupled SNOWPACK and Alpine3D system has the advantage of simulating snow profiles, which provide stability information. Following previous work, the median number of critical layers and percentage of facets across all of the pixels containing the AKAH stations was computed. For SWE at the point scale, the reconstructed estimates showed a bias of −42 mm (−19 %) at the peak. For the coarser spatial SWE estimates, the various models showed a wide range, with reconstruction being on the lower end. For stratigraphy, a heavily faceted snowpack is observed in both years, but 2018, a dry year, according to most of the models, showed more critical layers that persisted for a longer period.

scholarly journals Calibration and field testing of cavity ring-down laser spectrometers measuring CH<sub>4</sub>, CO<sub>2</sub>, and <i>δ</i><sup>13</sup>CH<sub>4</sub> deployed on towers in the Marcellus Shale region

2018 ◽  
Vol 11 (3) ◽  
pp. 1273-1295 ◽  
Author(s):  
Natasha L. Miles ◽  
Douglas K. Martins ◽  
Scott J. Richardson ◽  
Christopher W. Rella ◽  
Caleb Arata ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Natural Gas ◽  
Mole Fraction ◽  
Isotopic Ratio ◽  
Marcellus Shale ◽  
Isotopic Ratios ◽  
Study Region ◽  
Wide Range ◽  
Cavity Ring Down

Abstract. Four in situ cavity ring-down spectrometers (G2132-i, Picarro, Inc.) measuring methane dry mole fraction (CH4), carbon dioxide dry mole fraction (CO2), and the isotopic ratio of methane (δ13CH4) were deployed at four towers in the Marcellus Shale natural gas extraction region of Pennsylvania. In this paper, we describe laboratory and field calibration of the analyzers for tower-based applications and characterize their performance in the field for the period January–December 2016. Prior to deployment, each analyzer was tested using bottles with various isotopic ratios, from biogenic to thermogenic source values, which were diluted to varying degrees in zero air, and an initial calibration was performed. Furthermore, at each tower location, three field tanks were employed, from ambient to high mole fractions, with various isotopic ratios. Two of these tanks were used to adjust the calibration of the analyzers on a daily basis. We also corrected for the cross-interference from ethane on the isotopic ratio of methane. Using an independent field tank for evaluation, the standard deviation of 4 h means of the isotopic ratio of methane difference from the known value was found to be 0.26 ‰ δ13CH4. Following improvements in the field tank testing scheme, the standard deviation of 4 h means was 0.11 ‰, well within the target compatibility of 0.2 ‰. Round-robin style testing using tanks with near-ambient isotopic ratios indicated mean errors of −0.14 to 0.03 ‰ for each of the analyzers. Flask to in situ comparisons showed mean differences over the year of 0.02 and 0.08 ‰, for the east and south towers, respectively. Regional sources in this region were difficult to differentiate from strong perturbations in the background. During the afternoon hours, the median differences of the isotopic ratio measured at three of the towers, compared to the background tower, were &amp;minus0.15 to 0.12 ‰ with standard deviations of the 10 min isotopic ratio differences of 0.8 ‰. In terms of source attribution, analyzer compatibility of 0.2 ‰ δ13CH4 affords the ability to distinguish a 50 ppb CH4 peak from a biogenic source (at −60 ‰, for example) from one originating from a thermogenic source (−35 ‰), with the exact value dependent upon the source isotopic ratios. Using a Keeling plot approach for the non-afternoon data at a tower in the center of the study region, we determined the source isotopic signature to be −31.2 ± 1.9 ‰, within the wide range of values consistent with a deep-layer Marcellus natural gas source.

scholarly journals Brief Communication: Evaluation and comparisons of permafrost map over Qinghai-Tibet Plateau based on inventory of in-situ evidence

2018 ◽  
Author(s):  
Bin Cao ◽  
Tingjun Zhang ◽  
Qinghai Wu ◽  
Yu Sheng ◽  
Lin Zhao ◽  
...  
Keyword(s):  
Controlling Factors ◽  
In Situ Measurements ◽  
Tibet Plateau ◽  
Permafrost Region ◽  
Improved Method ◽  
Limited Evidence ◽  
Wide Range ◽  
Communication Evaluation ◽  
Qinghai Tibet Plateau

Abstract. Many maps have been produced to estimate permafrost distribution over the Qinghai-Tibet Plateau, however, the evaluation and comparisons of them are poorly understood due to limited evidence. Using a large number data from various sources, we present the inventory of permafrost presence/absence with 1475 sites/plots over the QTP. Based on the in-situ measurements, our evaluation results showed a wide range of map performance with the overall accuracy of about 59–82 %, and the estimated permafrost region (1.42–1.84 × 106 km2) and area (0.76–1.25 × 106 km2) are extremely large. The low agreement in areas near permafrost boundary and fragile landscapes require improved method considering more controlling factors at both medium-large and local scales.

scholarly journals Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw

2010 ◽  
Vol 10 (12) ◽  
pp. 29683-29734 ◽  
Author(s):  
P. Zieger ◽  
E. Weingartner ◽  
J. Henzing ◽  
M. Moerman ◽  
G. de Leeuw ◽  
...  
Keyword(s):  
Optical Properties ◽  
Extinction Coefficient ◽  
In Situ Measurements ◽  
Optical Absorption Spectroscopy ◽  
Aerosol Composition ◽  
Large Variability ◽  
Extinction Coefficients ◽  
Ambient Aerosol ◽  
Wide Range

Abstract. In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30–40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, also their microphysical and optical properties – especially the aerosol light scattering – are strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol scattering coefficient σsp(λ) was measured dry and at various, predefined RH conditions between 20 and 95% with a humidified nephelometer. The scattering enhancement factor f(RH,λ) is the key parameter to describe the effect of RH on σsp(λ) and is defined as σsp(RH,λ) measured at a certain RH divided by the dry σsp(dry,λ). The measurement of f(RH,λ) together with the dry absorption measurement (assumed not to change with RH) allows the determination of the actual extinction coefficient σep(RH,λ) at ambient RH. In addition, a wide range of other aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of air mass origin (and thus aerosol composition) a simple parameterization of f(RH,λ) could not be established. If f(RH,λ) needs to be predicted, the chemical composition and size distribution needs to be known. Measurements of four MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments were used to retrieve vertical profiles of σep(λ). The values of the lowest layer were compared to the in-situ values after conversion of the latter to ambient RH. The comparison showed a good correlation of R2=0.62–0.78, but the extinction coefficients were a factor of 1.5–3.4 larger than the in-situ values. Best agreement is achieved for a few cases characterized by low aerosol optical depths and low planetary boundary layer heights. Differences showed to be dependent on the applied MAX-DOAS retrieval algorithm. The comparison of the in-situ data to a Raman lidar (light detection and ranging) showed a good correlation and higher values measured by the lidar (R2=0.79, slope of 1.81) if the Raman retrieved profile was used to extrapolate the directly measured extinction coefficient to the ground. The comparison improved if only nighttime measurements were used in the comparison (R2=0.93, slope of 1.19).

scholarly journals Comparison of modeled snow properties in Afghanistan, Pakistan, and Tajikistan

2020 ◽  
Vol 14 (1) ◽  
pp. 331-347
Author(s):  
Edward H. Bair ◽  
Karl Rittger ◽  
Jawairia A. Ahmad ◽  
Doug Chabot
Keyword(s):  
Snow Depth ◽  
Snow Water Equivalent ◽  
Median Number ◽  
In Situ Measurements ◽  
Balance Model ◽  
High Mountain ◽  
Wide Range ◽  
Spatial Estimates ◽  
Critical Layers

Abstract. Ice and snowmelt feed the Indus River and Amu Darya in western High Mountain Asia, yet there are limited in situ measurements of these resources. Previous work in the region has shown promise using snow water equivalent (SWE) reconstruction, which requires no in situ measurements, but validation has been a problem. However, recently we were provided with daily manual snow depth measurements from Afghanistan, Tajikistan, and Pakistan by the Aga Khan Agency for Habitat (AKAH). To validate SWE reconstruction, at each station, accumulated precipitation and SWE were derived from snow depth using the numerical snow cover model SNOWPACK. High-resolution (500 m) reconstructed SWE estimates from the Parallel Energy Balance Model (ParBal) were then compared to the modeled SWE at the stations. The Alpine3D model was then used to create spatial estimates at 25 km resolution to compare with estimates from other snow models. Additionally, the coupled SNOWPACK and Alpine3D system has the advantage of simulating snow profiles, which provides stability information. The median number of critical layers and percentage of faceted layers across all of the pixels containing the AKAH stations were computed. For SWE at the point scale, the reconstructed estimates showed a bias of −42 mm (−19 %) at peak SWE. For the coarser spatial SWE estimates, the various models showed a wide range, with reconstruction being on the lower end. A heavily faceted snowpack was observed in both years, but 2018, a dry year, according to most of the models, showed more critical layers that persisted for a longer period.

Vertical distribution of aerosol particles over the Russian Arctic derived from in-situ aircraft measurements: the September 2020 campaign

2021 ◽  
Author(s):  
Mikhail Yu. Arshinov ◽  
Boris Belan ◽  
Denis Davydov ◽  
Artem Kozlov ◽  
Alexandr Fofonov
Keyword(s):  
Vertical Distribution ◽  
Lower Troposphere ◽  
In Situ Measurements ◽  
The Arctic ◽  
Future Climate Change ◽  
Russian Arctic ◽  
Size Distributions ◽  
Cloudy Weather ◽  
Wide Range

&lt;p&gt;The Arctic is warming much faster than other regions of the globe. In 2020, temperature anomalies in the Russian Arctic reached unprecedented high levels. The atmospheric composition in this key region still remains insufficiently studied that makes difficult predicting future climate change.&lt;/p&gt;&lt;p&gt;In September 2020, an extensive aircraft campaign was conducted to document the tropospheric composition over the Russian Arctic. The Optik Tu-134 research aircraft was equipped with instruments to carry out in-situ measurements of trace gases and aerosols, as well as with a lidar for profiling of aerosol backscatter. The aircraft flew over a vast area from Arkhangelsk to Anadyr. Six measurement flights with changing altitudes from 0.2 to 9.0 m were conducted over the waters of the Barents, Kara, Laptev, East Siberian, Chukchi, and Bering Seas. The weather was unusually warm for this period of the year, surface air temperatures were above 0&amp;#176;C through the campaign.&lt;/p&gt;&lt;p&gt;Here, we present the results of in-situ measurements of the vertical distribution of aerosol number concentrations in a wide range of sizes. A modified diffusional particle sizer (DPS) consisted of the Novosibirsk-type eight-stage screen diffusion battery connected to the TSI condensation particle counter Model 3756 was used to determine the number size distribution of particles between 0.003 mm and 0.2 mm (20 size bins). Distribution of particles in the size range from 0.25 &amp;#181;m to 32 &amp;#181;m (31 size bins) was measured by means of the Grimm aerosol spectrometer Model 1.109.&lt;/p&gt;&lt;p&gt;The flights over Barents and Kara Seas were predominantly performed under clear sky or partly cloudy weather conditions. Number size distributions were wide representing particles of almost all aerosol fractions. When flying in the upper troposphere with a constant altitude over these seas, some cases of enhanced concentrations of nucleation and Aitken mode particles comparable to ones in the lower troposphere were recorded, suggesting in situ new particle formation was likely to be taking place via gas-to-particle conversion aloft.&lt;/p&gt;&lt;p&gt;East of the Kara Sea, flights were conducted under mostly cloudy conditions resulting in a lower median aerosol number concentration and narrower size distributions.&lt;/p&gt;&lt;p&gt;This work was supported by the Russian Foundation for Basic Research (Grant No. 19-05-50024).&lt;/p&gt;

Unique heliophysics science opportunities along the Interstellar Probe journey up to 1000 AU from the Sun

2021 ◽  
Author(s):  
Elena Provornikova ◽  
Pontus C. Brandt ◽  
Ralph L. McNutt, Jr. ◽  
Robert DeMajistre ◽  
Edmond C. Roelof ◽  
...  
Keyword(s):  
Space Mission ◽  
In Situ Measurements ◽  
Unique Determination ◽  
The Sun ◽  
Global Shape ◽  
Wide Range ◽  
First Time ◽  
Interstellar Probe ◽  
Probe Mission

&lt;p&gt;The Interstellar Probe is a space mission to discover physical interactions shaping globally the boundary of our Sun`s heliosphere and its dynamics and for the first time directly sample the properties of the local interstellar medium (LISM). Interstellar Probe will go through the boundary of the heliosphere to the LISM enabling for the first time to explore the boundary with a dedicated instrumentation, to take the image of the global heliosphere by looking back and explore in-situ the unknown LISM. The pragmatic concept study of such mission with a lifetime 50 years that can be implemented by 2030 was funded by NASA and has been led by the Johns Hopkins University Applied Physics Laboratory (APL). The study brought together a diverse community of more than 400 scientists and engineers spanning a wide range of science disciplines across the world.&lt;/p&gt;&lt;p&gt;Compelling science questions for the Interstellar Probe mission have been with us for many decades. Recent discoveries from a number of space missions exploring the heliosphere raised new questions strengthening the science case. The very shape of the heliosphere, a manifestation of complex global interactions between the solar wind and the LISM, remains the biggest mystery. Interpretations of imaging the heliosphere in energetic neutral atoms (ENAs) in different energy ranges on IBEX and Cassini/INCA from inside show contradictory pictures. Global physics-based models also do not agree on the global shape. Interstellar Probe on outbound trajectory will image the heliosphere from outside for the first time and will provide a unique determination of the global shape.&lt;/p&gt;&lt;p&gt;The LISM is a completely new area for exploration and discovery. We have a crude understanding of the LISM inferred from in-situ measurements inside the heliosphere of interstellar helium, pick-up-ions, ENAs, remote observations of solar backscattered Lyman-alpha emission and absorption line spectroscopy in the lines of sight of stars. We have no in-situ measurements of most LISM properties, e.g. ionization, plasma and neutral gas, magnetic field, composition, dust, and scales of possible inhomogeneities. Voyagers with limited capabilities have explored 30 AU beyond the heliosphere which appeared to be a region of significant heliospheric influence. The LISM properties are among the key unknowns to understand the Sun`s galactic neighborhood and how it shapes our heliosphere. Interstellar Probe will be the first NASA mission to discover the very nature of the LISM and shed light on whether the Sun enters a new region in the LISM in the near future.&lt;/p&gt;&lt;p&gt;In this presentation we give an overview of heliophysics science for the Interstellar Probe mission focusing on the critical science questions of the three objectives for the mission. We will discuss in more details a need for direct measurements in the LISM uniquely enabled by the Interstellar Probe.&lt;/p&gt;

scholarly journals Break of the Western North Pacific Summer Monsoon in Early August

2015 ◽  
Vol 28 (8) ◽  
pp. 3420-3434 ◽  
Author(s):  
Ke Xu ◽  
Riyu Lu
Keyword(s):  
Summer Monsoon ◽  
North Pacific ◽  
Western North Pacific ◽  
Asian Summer Monsoon ◽  
The Other ◽  
South Asian Summer Monsoon ◽  
Close Link ◽  
Rainfall Reduction ◽  
Asian Summer ◽  
Asian Monsoons

Abstract Although the monsoon break is a well-known phenomenon for the South Asian summer monsoon, it has not been well documented for the other monsoons, for instance, the western North Pacific (WNP) summer monsoon. This study identified a distinct monsoon break over the WNP by analyzing the subseasonal evolution of atmospheric convection and precipitation. This WNP monsoon break occurs climatologically in early August (3–8 August), but shows a strong variation, in either intensity or timing, from year to year. For about 30% of years, the rainfall amount reduces by more than 10 mm day−1 over the northeast WNP (10°–20°N, 140°–160°E) in early August, and is even less than that before the monsoon onset. However, for the other 30% of years, the subseasonal evolution of rainfall tends to be out of phase with the climatology, and rainfall reduction appears in mid-August. Furthermore, the 10–25-day oscillations, which originate at the equatorial western Pacific and propagate northwestward, are found to play a crucial role in forming the monsoon break. The 10–25-day oscillations exhibit a strong interannual variation, associated with the WNP monsoon trough during the period from late July to mid-August, and contribute greatly to the year-to-year variation in both the timing and intensity of the monsoon break. Considering the close link in subseasonal evolution between the WNP and East Asian monsoons, the present results indicate the necessity to investigate the possible role of the WNP monsoon break on the weather and climate over East Asia.

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