scholarly journals The role of DYNAMO in situ observations in improving NASA CERES-like daily surface and atmospheric radiative flux estimates

2017 ◽  
Vol 4 (4) ◽  
pp. 164-183 ◽  
Author(s):  
Hailan Wang ◽  
Wenying Su ◽  
Norman G. Loeb ◽  
Deepthi Achuthavarier ◽  
Siegfried D. Schubert
Keyword(s):  
Radiative Flux ◽  
In Situ Observations

scholarly journals Role of Convective Precipitation in the Relationship between Subdaily Extreme Precipitation and Temperature

2017 ◽  
Vol 30 (23) ◽  
pp. 9527-9537 ◽  
Author(s):  
In-Hong Park ◽  
Seung-Ki Min
Keyword(s):  
South Korea ◽  
Extreme Precipitation ◽  
Physical Effect ◽  
Convective Precipitation ◽  
Statistical Effect ◽  
Convective Process ◽  
In Situ Observations ◽  
The Relationship

On a subdaily time scale, the intensities of extreme precipitation are observed to increase with temperature at a rate exceeding water vapor constraints determined by the Clausius–Clapeyron (C-C) relationship. This so-called super C-C scaling has been suggested to occur as a result of 1) the statistical effect that involves the transition of precipitation types from stratiform to convective events and 2) the physical effect by which the convective process itself can overcome the thermodynamic limitation. This study examines these two mechanisms for the super C-C relationship using in situ observations in South Korea for a recent 35-yr period, focusing on the role of convective rainfall. Scaling results show that hourly extreme precipitation undergoes a transition from a C-C rate to a super C-C rate at around 20°C, supporting the statistical effect. The transition temperature observed in South Korea is, however, much higher than in European regions (12°C), which seems to be due to the climatologically lower frequency of convective events in South Korea than in Europe. Nevertheless, the threshold fraction of convective precipitation when the scaling transition starts to occur is found to very similar between two regions, around 0.2, indicating the important role of convective events in shaping the scaling. On the other hand, convective extreme precipitation alone exhibits a super C-C scaling, suggesting that the physical effect is also at work in South Korea. Also, the scaling shows a robust peaklike shape with maximum precipitation intensity near 24°C, which is closely linked with moisture limitation at high temperature, supporting the previous findings.

scholarly journals Fingerprints of a riming event on cloud radar Doppler spectra: observations and modeling

2015 ◽  
Vol 15 (20) ◽  
pp. 28619-28658 ◽  
Author(s):  
H. Kalesse ◽  
W. Szyrmer ◽  
S. Kneifel ◽  
P. Kollias ◽  
E. Luke
Keyword(s):  
Supercooled Liquid ◽  
Relative Role ◽  
Traditional Use ◽  
Radar Observations ◽  
Atmospheric Radiation Measurement ◽  
In Situ Observations ◽  
Air Motion ◽  
Biogenic Aerosols

Abstract. Radar Doppler spectra measurements are exploited to study a riming event when precipitating ice from a seeder cloud sediments through a supercooled liquid water (SLW) layer. The observations were collected during the deployment of the Atmospheric Radiation Measurement Program's (ARM) mobile facility AMF2 at Hyytiälä, Finland during the BAECC (Biogenic Aerosols – Effects on Clouds and Climate Snowfall Experiment) field campaign. The presented analysis of the height evolution of the radar Doppler spectra is a state-of-the-art retrieval with profiling cloud radars in SLW layers beyond the traditional use of spectral moments. Dynamical effects are taken into account by following the particle population evolution along slanted tracks that are caused by horizontal advection of the cloud under wind shear conditions. In the SLW layer, the identified liquid peak is used as an air motion tracer to correct the Doppler spectra for vertical air motion and the ice peak is used to study the radar profiles of rimed particles. A 1-D steady-state bin microphysical model is constrained using the SLW and air motion profiles and cloud top radar observations. The observed radar moment profiles of the rimed snow can be simulated reasonably well by the model, but not without making several assumptions about the ice particle concentration and the relative role of deposition and aggregation. This suggests that in-situ observations of key ice properties are needed to complement the profiling radar observations before process-oriented studies can effectively evaluate ice microphysical parameterizations.

scholarly journals Analysis of the Khmer Walled Defensive System of Vimayapura (Phimai City, Thailand): Symbolism or Military Effectiveness?

MANUSYA ◽  
2020 ◽  
Vol 23 (2) ◽  
pp. 253-285
Author(s):  
Víctor Lluís Pérez Garcia
Keyword(s):  
City Centre ◽  
Military Effectiveness ◽  
Archaeological Remains ◽  
Theoretical Level ◽  
In Situ Observations ◽  
The City

This article analyses the walled defensive system of the Khmer city centre of Vimayapura (modern Phimai, Thailand) to evaluate the theoretical level of military effectivity of both the walls and the moats against potential attackers, considering their technical characteristics and the enemy’s weapons. We also study the layout of the urban enceinte, the constructive material, the gateways as well as weakness and strengths of the stronghold and the symbolic, monumental and ornamental functions in the overall role of the walls. Based on comparisons with similar cases, as well as in situ observations of the archaeological remains and a bibliographical research, our study reveals that the stonewalls were not designed primarily to resist military attacks. Instead, the army, the moat, and possibly the embankments and/or palisades would have been the first lines of defence of the city.

scholarly journals The changing role of organic nitrates in the removal and transport of NO<sub><i>x</i></sub>

2020 ◽  
Vol 20 (1) ◽  
pp. 267-279 ◽  
Author(s):  
Paul S. Romer Present ◽  
Azimeh Zare ◽  
Ronald C. Cohen
Keyword(s):  
Air Pollution ◽  
The United States ◽  
Ozone Production ◽  
Organic Nitrates ◽  
Nox Emissions ◽  
Direct Formation ◽  
In Situ Observations ◽  
Changing Role

Abstract. A better understanding of the chemistry of nitrogen oxides (NOx) is crucial to effectively reducing air pollution and predicting future air quality. The response of NOx lifetime to perturbations in emissions or in the climate system is set in large part by whether NOx loss occurs primarily by the direct formation of HNO3 or through the formation of alkyl and multifunctional nitrates (RONO2). Using 15 years of detailed in situ observations, we show that in the summer daytime continental boundary layer the relative importance of these two pathways can be well approximated by the relative likelihood that OH will react with NO2 or instead with a volatile organic compound (VOC). Over the past decades, changes in anthropogenic emissions of both NOx and VOCs have led to a significant increase in the overall importance of RONO2 chemistry to NOx loss. We find that this shift is associated with a decreased effectiveness of NOx emissions reductions on ozone production in polluted areas and increased transport of NOx from source to receptor regions. This change in chemistry, combined with changes in the spatial pattern of NOx emissions, is observed to be leading to a flatter distribution of NO2 across the United States, potentially transforming ozone air pollution from a local issue into a regional one.

Role of the Interfaces on the Activation of Slip Systems in The PST TiAl Alloy

1998 ◽  
Vol 552 ◽  
Author(s):  
Slim Zghal ◽  
Haruyuki Inui ◽  
Masaharu Yamaguchi ◽  
Alain Couret
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tial Alloy ◽  
Slip Systems ◽  
Post Mortem ◽  
Transmission Electron ◽  
In Situ Observations ◽  
Deformation Modes

ABSTRACTThe operative slip systems in the so-called PST alloy are determined by transmission electron microscopy. Both post-mortem analyses and in situ observations are presented. It is shown that glide of ordinary dislocations and twinning are the most easily deformation modes activated at yield. The role of the interfaces on the activation of these operative slip systems is then examined and discussed.

scholarly journals Acquisition and Transmission of Peanut clump virus by Polymyxa graminis on Cereal Species

2011 ◽  
Vol 101 (10) ◽  
pp. 1149-1158 ◽  
Author(s):  
Benjamin Dieryck ◽  
Jeannine Weyns ◽  
Diane Doucet ◽  
Claude Bragard ◽  
Anne Legrève
Keyword(s):  
Host Plants ◽  
Chain Reaction ◽  
Polymyxa Graminis ◽  
Cereal Species ◽  
New Strategy ◽  
In Situ Observations ◽  
The Common ◽  
Polymerase Chain

The objective of this study was to investigate the specificity of the interactions between Polymyxa graminis, Peanut clump virus (PCV), and cereals, particularly the acquisition and the transmission of the virus by three P. graminis formae speciales. A new strategy has been developed: it involves using sugarcane as the common host for both the virus and its vector in order to produce the viruliferous zoospores of P. graminis f. sp. subtropicalis, temperata, and tropicalis that were then inoculated on cereal species. This experiment enabled the role of P. graminis f. sp. tropicalis and subtropicalis zoospores in PCV transmission to be demonstrated. The efficiency of this transmission was shown to vary, depending on the P. graminis special forms. Interestingly, the high transmission of the PCV isolate from Burkina Faso by an isolate of P. graminis f. sp. tropicalis from Niger on pearl millet suggests that there is a coevolution mechanism in this pathosystem. The study also provides evidence that the host plant species in which Polymyxa zoospores are produced could affect the infectivity of the vector. Finally, using Polymyxa quantitation by quantitative reverse-transcription polymerase chain reaction and in situ observations of the virus, the study demonstrates the independence of the development of PCV and its vector in the host plants.

scholarly journals Snow Cover and Spring Flood Flow in the Northern Part of Western Siberia (the Poluy, Nadym, Pur, and Taz Rivers)

2011 ◽  
Vol 12 (6) ◽  
pp. 1498-1511 ◽  
Author(s):  
E. A. Zakharova ◽  
A. V. Kouraev ◽  
S. Biancamaria ◽  
M. V. Kolmakova ◽  
N. M. Mognard ◽  
...  
Keyword(s):  
Snow Depth ◽  
Meteorological Station ◽  
Spring Flood ◽  
Study Region ◽  
Snow Water ◽  
In Situ Observations ◽  
Microwave Imager ◽  
Flood Flow

Abstract The paper aims to quantitatively estimate the role of snowmelt in the spring flood flow and the redistribution of river runoff for the northern (Arctic) part of the western Siberian Plain (the rivers Poluy, Nadym, Pur, and Taz). In this region, the presence of wetlands and thermokarst lakes significantly influences the seasonal redistribution of river discharge. First the study region is described, and the snow regime from in situ observations at the Tarko-Sale meteorological station is analyzed. As Special Sensor Microwave Imager (SSM/I) estimates of snow depth for this region are lower than in situ observations, a correction of the SSM/I snow depth estimates is done using snow parameters measured on the snow transect near the meteorological station Tarko-Sale for 1991–96. This reestimated snow depth is then used to assess the volume of water stored every winter on the watersheds for 1989–2006. This snow product is compared with the spring flood streamflow estimated from in situ observations, and the regional relationship between the snow water storage and flood flow is constructed. The proportion of meltwater that does not reach the main rivers and is thus evaporated or stored by the wetlands is estimated to be on average 30% (varying from 0% to 74%). We observe an increasing trend of this value from 20%–30% in the early 1990s to 50%–60% in the mid-2000s. This increase could be attributed to several factors such as increased air temperature (leading to increased evaporation, changes in vegetation cover, and active layer depth) and also to human activity.

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