The cloud drop effective radius (R.sub.e) of the drop size distribution derived from passive satellite sensors is a key variable used in climate research. Validation of these satellite products has ...often taken place under stratiform cloud conditions that favor the assumption of cloud horizontal homogeneity used by the retrieval techniques. However, many studies have noted concerns with respect to significant biases in retrieved R.sub.e arising from cloud heterogeneity, for example, in cumulus cloud fields. Here, we examine data collected during the 2019 "Cloud, Aerosol and Monsoon Processes Philippines Experiment" (CAMP.sup.2 Ex), which, in part, targeted the objective of providing the first detailed evaluation of R.sub.e retrieved across multiple platforms and techniques in a cumulus and congestus cloud region. Our evaluation consists of cross-comparisons of R.sub.e between the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra satellite, the Research Scanning Polarimeter (RSP) onboard the NASA P-3 aircraft, and in situ measurements from both the NASA P-3 and Learjet aircraft that are all taken in close spatiotemporal proximity to the same cloud fields. A particular advantage of our approach lies in the capability of the RSP to retrieve R.sub.e using a bi-spectral MODIS approach and a polarimetric approach, which allows for the evaluation of bi-spectral and polarimetric R.sub.e retrievals from an airborne perspective using the same samples.
The cloud drop effective radius (Re) of the drop size distribution derived from passive satellite sensors is a key variable used in climate research. Validation of these satellite products has often ...taken place under stratiform cloud conditions that favor the assumption of cloud horizontal homogeneity used by the retrieval techniques. However, many studies have noted concerns with respect to significant biases in retrieved Re arising from cloud heterogeneity, for example, in cumulus cloud fields. Here, we examine data collected during the 2019 “Cloud, Aerosol and Monsoon Processes Philippines Experiment” (CAMP2Ex), which, in part, targeted the objective of providing the first detailed evaluation of Re retrieved across multiple platforms and techniques in a cumulus and congestus cloud region. Our evaluation consists of cross-comparisons of Re between the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra satellite, the Research Scanning Polarimeter (RSP) onboard the NASA P-3 aircraft, and in situ measurements from both the NASA P-3 and Learjet aircraft that are all taken in close spatiotemporal proximity to the same cloud fields. A particular advantage of our approach lies in the capability of the RSP to retrieve Re using a bi-spectral MODIS approach and a polarimetric approach, which allows for the evaluation of bi-spectral and polarimetric Re retrievals from an airborne perspective using the same samples.
Averaged over all P-3 flight segments examined here for warm clouds, the RSP polarimetric method, the in situ method, and the bias-adjusted MODIS method of Fu et al. (2019) show a comparable median (mean ± standard deviation) for the Re samples of 9.6 (10.2 ± 4.0) µm, 11.0 (13.6 ± 11.3) µm, and 10.4 (10.8 ± 3.8) µm, respectively. These values are far lower than the values of 15.1 (16.2 ± 5.5) µm and 17.2 (17.7 ± 5.7) µm from the bi-spectral retrievals of RSP and MODIS, respectively. Similar results are observed when Re is segregated by cloud-top height and in detailed case studies. The clouds sampled during CAMP2Ex consist of mostly small (mean transect length ∼ 1.4 km) and low clouds (mean cloud-top height ∼ 1 km), which had more numerous small clouds than the trade wind cumuli sampled in past field campaigns such as Rain in Shallow Cumulus over the Ocean (RICO) and the Indian Ocean Experiment (INDOEX). The overestimates of Re from the RSP bi-spectral technique compared with the polarimetric technique increased as cloud size and cloud optical depth decreased. Drizzle, cloud-top bumpiness, and solar zenith angle, however, are not closely correlated with the overestimate of bi-spectral Re. For shallow clouds that dominated the liquid cloud cover for the CAMP2Ex region and period, we show that 3-D radiative transfer and cloud heterogeneity, particularly for the optically thin and small clouds, appear to be the leading cause of the large positive biases in bi-spectral retrievals. Because this bias varies with the underlying structure of the cloud field, caution continues to be warranted in studies that use bi-spectral Re retrievals in cumulus cloud fields.
Overshooting cloud tops (OTs) form in deep convective storms when strong updrafts overshoot the tropopause. An OT is a well-known indicator of convective updrafts and severe weather conditions. Here, ...we develop an OT detection algorithm using thermal infrared (IR) channels and apply this algorithm to about 20 years' worth of MODIS data from both Terra and Aqua satellites to form an extensive, near-global climatology of OT occurrences. The algorithm is based on a logistic model which is trained using A-Train observations. We demonstrate that the overall accuracy of our approach is about 0.9 when the probability of the OT candidates is larger than 0.9. The OT climatology reveals a pattern that follows the climatology of deep convection and shallow convection over the midlatitude oceans during winter cold-air outbreaks. OTs appear most frequently over the Intertropical Convergence Zone (ITCZ), central and southeastern North America, tropical and subtropical South America, southeastern and southern Asia, tropical and subtropical Africa, and northern middle–high latitudes. OT spatial distributions show strong seasonal and diurnal variabilities. Seasonal OT variations shift with large-scale climate systems such as the ITCZ and local monsoonal systems, including the South Asian monsoon, North American monsoon, and West African monsoon. OT diurnal variations agree with the known diurnal cycle of convection. Maximum OT occurrences are in the afternoon over most land areas and around midnight over ocean, and the OT diurnal cycle is stronger and more varied over land than over ocean. OTs over land are usually colder than over ocean, except at around 10:30 LT (Equator-crossing time). The top 10 coldest OTs from both Terra and Aqua mostly occur over land and at night. This study provides OT climatology for the first time, as derived from 2 decades of MODIS data, that represents the longest and stable satellite records.
Ice clouds are crucial to the Earth's radiation balance. They cool the Earth-atmosphere system by reflecting solar radiation back to space and warm it by blocking outgoing thermal radiation. However, ...there is a lack of an observation-based climatology of ice cloud properties and their radiative effects. Two active sensors, the CloudSat radar and the CALIPSO lidar, for the first time provide vertically resolved ice cloud data on a global scale. Using synergistic signals of these two sensors, it is possible to obtain both optically thin and thick ice clouds as the radar excels in probing thick clouds while the lidar is better to detect the thin ones. First, based on the CloudSat radar and CALIPSO lidar measurements, we have derived a climatology of ice cloud properties. Ice clouds cover around 50% of the Earth surface, and their global-mean optical depth, ice water path, and effective radius are approximately 2 (unitless), 109 g m{-2} and 48 \mum, respectively. Ice cloud occurrence frequency not only depends on regions and seasons, but also on the types of ice clouds as defined by optical depth (τ) values. Optically thin ice clouds (τ < 3) are most frequently observed in the tropics around 15 km and in the midlatitudes below 5 km, while the thicker clouds (τ > 3) occur frequently in the tropical convective areas and along the midlatitude storm tracks. Using ice retrievals derived from combined radar-lidar measurements, we conducted radiative transfer modeling to study ice cloud radiative effects. The combined effects of ice clouds warm the earth-atmosphere system by approximately 5 W m–2, contributed by a longwave warming effect of about 21.8 W m–2 and a shortwave cooling effect of approximately -16.7 W m–2. Seasonal variations of ice cloud radiative effects are evident in the midlatitudes where the net effect changes from warming during winter to cooling during summer, and the net warming effect occurs year-round in the tropics (∼ 10 W m–2). Ice cloud optical depth is shown to be an important factor in determining the sign and magnitude of the net radiative effect. On a global average, ice clouds with τ ≤ 4.6 display a warming effect with the largest contributions from those with τ ∼ 1.0. Optically thin and high ice clouds cause strong heating in the tropical upper troposphere, while outside the tropics, mixed-phase clouds cause strong cooling at lower altitudes (> 5 km). In addition, ice clouds occurring with liquid clouds in the same profile account for about 30%$of all observations. These liquid clouds reduce longwave heating rates in ice cloud layers by 0-1 K/day depending on the values of ice cloud optical depth and regions. This research for the first time provides a clear picture on the global distribution of ice clouds with a wide range of optical depth. Through radiative transfer modeling, we have gained better knowledge on ice cloud radiative effects and their dependence on ice cloud properties. These results not only improve our understanding of the interaction between clouds and climate, but also provide observational basis to evaluate climate models.
Ice clouds play an important role in earth radiation balance by reflecting solar and absorbing thermal radiation, the so-called albedo versus greenhouse eects, which cause signicant dierential ...atmospheric heating and cooling in horizontal as well as vertical directions. Two active sensors onboard A-train satellites, CloudSat radar and CALIPSO lidar, for the rst time provide global proles of atmospheric ice clouds. A combination of radar and lidar becomes the state-of-the-art technique examining clouds of varying optical depth, as the former excels in probing thick clouds while the later is better suited to the thin ones. In this study, ice cloud properties derived by a combination of CloudSat and CALIPSO observations are adopted to character atmospheric ice clouds. Ice cloud climatological studies show that the global mean optical depth and eective radius are around 4 and 48 μm, respectively. Mean ice water path is approximately 110 g/m2 for all measurements and approximately 190 g/m2 for cloudy situations (conditional mean). Their occurrence frequencies and ice mass amount distributions do not just depend on their optical depth values, but also rely on seasons and day-night cycle. Meanwhile, ice water content and eective radius show dierent temperature dependent relationships among the tropics, mid- and high-latitudes. Ice cloud radiative eects are obtained by radiative transfer modelling. Simulations show global ice clouds net eects at the top of atmosphere (TOA) may slightly heat or cool the atmosphere-earth system depending on model parameterizations and allowing for uncertainties. Additionally, a cloud forcing spectrum over optical depth at the TOA shows that ice clouds with optical depth <5 display a positive net forcing on a global scale, inducing a warming eect, whereas ice clouds otherwise tend to be cooling. Regionally, ice clouds have a negative net forcing in the mid-latitude warm seasons due to a stronger solar albedo eect but a positive net forcing during cold seasons due to a stronger greenhouse eect. Moreover, ice cloud internal heating rate proles in the atmosphere indicate shortwave heating above but cooling below, whereas the longwave heating pattern is oppositive. This heating structure is regionally and seasonally dependent, and it is associated with optical depth values as well.
Obesity has become a worldwide health issue and has attracted much public attention. In the current study, we aim to elucidate the roles of bile acids and their associations with gut microbiota ...during obesity development, employing high fat diet (HFD)-induced obesity in a rat model. We collected feces and plasma, liver tissues, and segments of intestinal tissues and a developed bile acids quantification method by employing an ultraperformance liquid chromatography coupled with mass spectrometry detection (UPLC-MS) strategy. We then assessed bile acids fluxes in the biological matrixes collected. We found that, irrespective of dietary regimes, taurine-conjugated bile acids were the dominant species in the liver whereas unconjugated bile acids were in plasma. However, HFD caused slight increases in the total bile acids pool and particularly the increases in the levels of deoxycholic acid (DCA) (138.67 ± 37.225 nmol/L in control group, 242.61 ± 43.16 nmol/L in HFD group, p = 0.014) and taurodeoxycholic acid (TDCA) (2.8 ± 0.247 nmol/g in control group, 4.5 ± 0.386 nmol/g in HFD group, p = 0.0018) in plasma and liver tissues, respectively, which were consistent with the increased levels of DCA in intestinal tissues and feces. These changes are correlated to an increase in abundance of genera Blautia, Coprococcus, Intestinimonas, Lactococcus, Roseburia, and Ruminococcus. Our investigation revealed the fluxes of bile acids and their association with gut microbiota during obesity development and explicated unfavorable impact of HFD on health.
Obesity resulting from interactions of genetic and environmental factors becomes a serious public health problem worldwide with alterations of the metabolic phenotypes in multiple biological matrices ...involving multiple metabolic pathways. To understand the contributions of gut microbiota to obesity development, we analyzed dynamic alterations in fecal metabonomic phenotype using NMR and fecal microorganism composition in rats using pyrosequencing technology during the high-fat diet (HFD) feeding for 81 days (pre-obesity state). Integrated analysis of these two phenotypic datasets was further conducted to establish correlations between the altered rat fecal metabonome and gut microbiome. We found that one-week HFD feeding already caused significant changes in rat fecal metabonome and such changes sustained throughout 81-days feeding with the host and gut microbiota co-metabolites clearly featured. We also found that HFD caused outstanding decreases in most fecal metabolites implying enhancement of gut absorptions. We further established comprehensive correlations between the HFD-induced changes in fecal metabonome and fecal microbial composition indicating contributions of gut microbiota in pathogenesis and progression of the HFD-induced obesity. These findings provided essential information about the functions of gut microbiota in pathogenesis of metabolic disorders which could be potentially important for developing obesity prevention and treatment therapies.
We report realizations of nanoscale integrated all-optical XNOR, XOR, NOT, and OR logic gates using plasmonic slot waveguides based on linear interference between surface plasmon polariton modes. The ...miniature device size with lateral dimensions smaller than 5 μm, precisely controlled optical phase difference, and quasi-monochromatic surface plasmon polariton modes excited by a continuous wave 830 nm laser beam ensure a high intensity contrast ratio of 24 dB between the output logic states “1” and “0”. Compared with previous reported results, the intensity contrast ratio is enhanced 4-fold, whereas the lateral dimension is reduced 4-fold. These compact logic devices are stable, robust, free from environmental impact, and much suitable for practical on-chip applications. These also provide a means to construct all-optical logic devices and nanophotonic processors.
Objective. This study aims to systematically assess the efficacy and safety of auricular therapy for cancer pain. Methods. A systematic search was conducted using PubMed, EMBASE, Cochrane library ...databases, CNKI, VIP, WanFang Data, and CBM for randomized controlled trials (RCTs). Review Manager 5.3 was used for meta-analysis. Results. Of the 275 screened studies, nine RCTs involving 783 patients with cancer pain were systematically reviewed. Compared with drug therapy, auricular therapy plus drug therapy has significant advantages both in the effective rate for pain relief (RR = 1.40; 95% CI 1.22, 1.60; P<0.00001) and adverse effects rate (RR = 0.46; 95% CI 0.37, 0.58; P<0.00001). And the result revealed that auricular acupuncture had superior pain-relieving effects as compared with sham auricular acupuncture (SMD = -1.45; 95% CI -2.80, -0.09; P=0.04). However, the analysis indicated no difference on the effective rate for pain relief between auricular therapy and drug therapy (RR = 1.24; 95% CI 0.71, 2.16; P=0.46). Conclusion. Our meta-analysis indicated that auricular therapy is effective and safe for the treatment of cancer pain, and auricular therapy plus drug therapy is more effective than drug therapy alone, whether in terms of pain relief or adverse reactions. However, the included RCTs had some methodological limitations; future large, rigor, and high-quality RCTs are still needed to confirm the benefits of auricular therapy on cancer pain.
The paucity of studies on permafrost runoff generation processes, especially in mountain permafrost, constrains the understanding of permafrost hydrology and prediction of hydrological responses to ...permafrost degradation. This study investigated runoff generation processes, in addition to the contribution of summer thaw depth, soil temperature, soil moisture, and precipitation to streamflow in a small upland permafrost basin in the northern Tibetan Plateau. Results indicated that the thawing period and the duration of the zero-curtain were longer in permafrost of the northern Tibetan Plateau than in the Arctic. Limited snowmelt delayed the initiation of surface runoff in the peat permafrost in the study area. The runoff displayed intermittent generation, with the duration of most runoff events lasting less than 24 h. Precipitation without runoff generation was generally correlated with lower soil moisture conditions. Combined analysis suggested runoff generation in this region was controlled by soil temperature, thaw depth, precipitation frequency and amount, and antecedent soil moisture. This study serves as an important baseline to evaluate future environmental changes on the Tibetan Plateau.
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