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Nisam Mang Luxom
and
Rishi Kumar Sharma

Abstract

Large expanses of snow leopard habitat overlap with extensively used areas for livestock grazing. A fundamental question for conservationists is to determine whether livestock production can be reconciled with the conservation of rare and threatened large carnivores. Therefore, numerous studies focus on the relationship between carnivore densities and space use and environmental, anthropogenic, and topographic variables. Using snow leopard sign surveys in areas with high and low grazing disturbance, Hong et al. posit that livestock grazing directly impacts fine-scale habitat selection by snow leopards. The authors recommend controlling livestock grazing to help restore habitat complexity and alpine environment diversity. However, the approach by which Hong et al. have reached this conclusion is inadequate and is based on a methodology that fails to address the research question appropriately. We argue that 1) identification of a biologically relevant scale of study is the first essential step toward inferring carnivore–habitat relationships, 2) the authors draw inconsistent conclusions from their data on sign densities in high and low grazing disturbance areas, 3) ideally, the snow leopard–livestock relationship needs to be examined across a gradient of livestock grazing intensities and at multiple spatial scales, and 4) it is inappropriate to draw conclusions for landscape/regional scales from a study conducted at a finer and undefined scale. We suggest that future studies should clearly define the scale of the study, identify appropriate habitat variables of interest, and use meaningful measurement instruments to serve as proxies for variables of interest.

Free access
Yang Hong
,
Thomas Connor
,
Huan Luo
,
Xiaoxing Bian
,
Zhaogang Duan
,
Zhuo Tang
, and
Jindong Zhang

Abstract

We thank Luxom and Sharma for their attention to and comments on our study. In recent years, livestock have been expanding into snow leopard habitat, and we conducted this study to examine the effects of that encroachment on snow leopard habitat within Wolong Nature Reserve. Specific responses to Luxom and Sharma’s comments include the following: 1) Many habitat factors influence carnivore–habitat relationships at varying spatial scales, and it is difficult for any single study to address the full suite of factors acting across all scales of selection. Given this fact and the limited spatial scale of our snow leopard sign survey, we mainly focused on snow leopard space use and microhabitat selection. 2) Our results are not necessarily conflicting, but more research is required to further explain how high sign densities, concentrated space use, and weak habitat selection behaviors might relate to each other. 3) We agree that examining a gradient of grazing intensities would be preferable, but because of the difficulty in collecting sufficient field data and the nature of livestock grazing patterns in our study area, we think that dividing our survey area into high- and low-grazing-disturbance areas was appropriate. 4) The original intent of this study was to examine habitat factors and response to livestock within our study area in Wolong Nature Reserve, and we did not intend for our specific results to be used for management recommendations beyond Wolong but instead encourage similar studies to be conducted in other areas.

Free access
Chunying Liu
,
Eric Freeman
,
Elizabeth C. Kent
,
David I. Berry
,
Steven J. Worley
,
Shawn R. Smith
,
Boyin Huang
,
Huai-min Zhang
,
Thomas Cram
,
Zaihua Ji
,
Mathieu Ouellet
,
Isabelle Gaboury
,
Frank Oliva
,
Axel Andersson
,
William E. Angel
,
Angela R. Sallis
, and
Adedoja Adeyeye

Abstract

This paper describes the new International Comprehensive Ocean–Atmosphere Data Set (ICOADS) near-real-time (NRT) release (R3.0.2), with greatly enhanced completeness over the previous version (R3.0.1). R3.0.1 had been operationally produced monthly from January 2015 onward, with input data from the World Meteorological Organization (WMO) Global Telecommunication Systems (GTS) transmissions in the Traditional Alphanumeric Codes (TAC) format. Since the release of R3.0.1, however, many observing platforms have changed, or are in the process of transitioning, to the Binary Universal Form for Representation of Meteorological Data (BUFR) format. R3.0.2 combines input data from both BUFR and TAC formats. In this paper, we describe input data sources; the BUFR decoding process for observations from drifting buoys, moored buoys, and ships; and the data quality control of the TAC and BUFR data streams. We also describe how the TAC and BUFR streams were merged to upgrade R3.0.1 into R3.0.2 with duplicates removed. Finally, we compare the number of reports and spatial coverage of essential climate variables (ECVs) between R3.0.1 and R3.0.2. ICOADS NRT R3.0.2 shows both quantitative and qualitative gains from the inclusion of BUFR reports. The number of observations in R3.0.2 increased by nearly 1 million reports per month, and the coverage of buoy and ship sea surface temperatures (SSTs) on monthly 2° × 2° grids increased by 20%. The number of reported ECVs also increased in R3.0.2. For example, observations of SST and sea level pressure (SLP) increased by around 30% and 20%, respectively, as compared to R3.0.1, and salinity is a new addition to the ICOADS NRT product in R3.0.2.

Significance Statement

The International Comprehensive Ocean–Atmosphere Data Set (ICOADS) is the largest collection of surface marine observations spanning from 1662 to the present. A new version, ICOADS near-real-time 3.0.2, includes data transmitted in the Binary Universal Form for Representation of Meteorological Data (BUFR) format, in combination with Traditional Alphanumeric Codes (TAC) data. Many of the organizations that report observations in near–real time have moved to BUFR, so this update brings ICOADS into alignment with collections and archives of these international data distributions. By including the BUFR reports, the number of observations in the upgraded version of ICOADS increased by nearly one million reports per month and spatial coverage of buoy and ship SSTs increased by 20% over the previous version.

Open access
C. A. Luecke
,
H. W. Wijesekera
,
E. Jarosz
,
D. W. Wang
,
T. G. Jensen
,
S.U.P. Jinadasa
,
H. J. S. Fernando
, and
W. J. Teague

Abstract

The formation of a sharp oceanic front located south-southeast of Sri Lanka during the southwest monsoon is examined through in-situ and remote observations, and high-resolution model output. Remote-sensing and model output reveal that the front extends approximately 200 km eastward from the southeast coast of Sri Lanka toward the southern Bay of Bengal (BoB). This annually occurring front is associated with the boundary between the southwest-monsoon current with high-salinity water to the south, and a weak-flow field comprised of relatively-fresh BoB water to the north. The front contains a line of high chlorophyll extending from the coastal-upwelling zone, often for several-hundred kilometers. Elevated turbulent diffusivities ~10−2 m2 s−1 along with large diapycnal fluxes of heat and salt were found within the front. The formation of the front and vertical transports are linked to local wind-stress curl. Large vertical velocities (~50 m d−1) indicate the importance of ageostropic, submesoscale processes. To examine these processes, the Ertel potential vorticity (PV) was computed using the observations and numerical model output. The model output shows a ribbon of negative PV along the front between the coastal upwelling zone and two eddies (Sri Lanka Dome and an anticyclonic eddy) typically found in the southern BoB. PV estimates support the view that the flow is susceptible to submesoscale instabilities, which in turn generate high vertical velocities within the front. Frontal upwelling and heightened mixing show that the seasonal front is regionally important to linking the fresh surface water of the BoB with the Arabian Sea.

Restricted access
Georgios Fragkoulidis
and
Volkmar Wirth
Restricted access
Dong Wan Kim
and
Sukyoung Lee
Restricted access
Chuan-Yang Wang
,
Xiao-Tong Zheng
, and
Shang-Ping Xie

Abstract

El Niño-Southern Oscillation (ENSO) is an important but not the only source of interannual variability over the Indo-western Pacific. Non-ENSO forced variability in the region has received recent attention because of the implications for rainy season prediction. Using a 35-member CESM1 Large Ensemble (CESM-LE) and 30 CMIP6 models, this study shows that the ensemble means project intensified interannual variability for precipitation, low-level winds, and sea-level pressure under global warming, associated with the enhanced large-scale anomalous anticyclone (AAC) over the tropical northwestern (NW) Pacific after the ENSO signal is removed. A decomposition based on the column water vapor budget reveals that enhanced precipitation variability is due to the increased background specific humidity. The resultant diabatic heating intensifies the AAC, which further strengthens the precipitation anomalies. Over the tropical NW Pacific, the wind-induced evaporative cooling on the southeastern flank of the AAC is countered by the increased shortwave radiation due to the strengthened precipitation reduction. Tropospheric temperature anomalies in the ensemble means show no significant change, suggesting no apparent change of the inter-basin positive feedback between the AAC and North Indian Ocean SST. Inter-model analysis based on CMIP6 reveals that enhanced background warming in the eastern equatorial Pacific is associated with enhanced ENSO-unrelated precipitation variability over the NW Pacific, due to the modulated Walker and Hadley circulations.

Restricted access
Siqi Yang
,
Jiangyuan Zeng
,
Wenjie Fan
, and
Yaokui Cui

Abstract

Root-zone soil moisture (RZSM) is an important variable in land–atmosphere interactions, notably affecting the global climate system. Contrary to satellite-based acquisition of surface soil moisture, RZSM is generally obtained from model-based simulations. In this study, in situ observations from the Naqu and Pali networks that represent different climatic conditions over the Tibetan Plateau (TP) and a triple collocation (TC) method are used to evaluate model-based RZSM products, including Global Land Evaporation Amsterdam Model (GLEAM) (versions 3.5a and 3.5b), Global Land Data Assimilation System (GLDAS) (versions 2.1 and 2.2), and the fifth-generation European Centre for Medium-Range Weather Forecasts reanalysis (ERA5). The evaluation results based on in situ observations indicate that all products tend to overestimate but could generally capture the temporal variation, and ERA5 exhibits the best performance with the highest R (0.875) and the lowest unbiased RMSE (ubRMSE; 0.015 m3 m−3) against in situ observations in the Naqu network. In the TC analysis, similar results are obtained: ERA5 has the best performance with the highest TC-derived R (0.785) over the entire TP, followed by GLEAM v3.5a (0.746) and GLDAS-2.1 (0.682). Meanwhile, GLEAM v3.5a and GLDAS-2.1 outperform GLEAM v3.5b and GLDAS-2.2 over the entire TP, respectively. Besides, possible error causes in evaluating these RZSM products are summarized, and the effectiveness of TC method is also evaluated with two dense networks, finding that TC method is reliable since TC-derived R is close to ground-derived R, with only 6.85% mean relative differences. These results using both in situ observations and TC method may provide a new perspective for the soil moisture product developers to further enhance the accuracy of model-based RZSM over the TP.

Significance Statement

The purpose of this study is to better understand the quality and applicability of GLEAM, GLDAS, and ERA5 RZSM products over the TP using both in situ observations and the triple collocation (TC) method, making it better applied to climate and hydrological research. This study provides four standard statistical metrics evaluation based on in situ observations, as well as the reliable metric, that is, correlation coefficient (R) derived from TC method, and highlights that TC-based evaluation could supplement the ground-based validation, especially over the data-scarce TP region.

Restricted access
Masanori Saito
and
Ping Yang

Abstract

Atmospheric particles exhibit various sizes and nonspherical shapes, which are factors that primarily determine the physical–optical properties of particles. The “sizes” of nonspherical particles can be specified based on various size descriptors, such as those defined with respect to a volume-equivalent spherical radius, projected-area-equivalent spherical radius, geometric radius, or effective radius. Microphysical and radiative transfer simulations as well as remote sensing implementations often require the conversions of particle size distributions (PSDs) in terms of the number concentration, projected area, and volume. The various size descriptors cause ambiguity in the PSD interconversion, and thereby result in potentially misleading quantification of the physical–optical properties of atmospheric nonspherical particles. The present study aims to provide a generalized formula for interconversions of PSDs in terms of physical variables and size descriptors for arbitrary nonspherical particles with lognormal and gamma distributions. In contrast to previous studies, no empirical parameters are included, allowing intrinsic understanding of the nonspherical particle effects on the PSD interconversion. In addition, we investigate the impact of different size descriptors on the single-scattering properties of nonspherical particles. Consistent single-scattering properties among different nonspherical particles with the same size parameter are found when the size descriptor is the effective radius, whereby their mechanisms are suggested based on a modified anomalous diffraction theory. The overarching goal of this work is to eliminate the ambiguity associated with a choice of the size descriptor of nonspherical particles for Earth-atmosphere system models, cloud–aerosol remote sensing, and analyses of in situ measured atmospheric particles.

Significance Statement

Atmospheric dust and ice crystals have various sizes and mostly nonspherical shapes. Different definitions of these particle sizes and shapes cause uncertainties and even result in misleading solutions in the numerical modeling and remote sensing of atmospheric properties. We derived generalized analytical formulas to rigorously treat the sizes and shapes of particles in the atmosphere, and also investigated the importance of the treatment of particle sizes on the particle properties essential to the Earth–atmospheric climate system. This study aims to eliminate the ambiguity associated with particle sizes and shapes in atmospheric research.

Restricted access
Tat Fan Cheng
and
Mengqian Lu

Abstract

This study addresses how moisture in continental precipitation is recycled globally from a moisture-tracking perspective. Using a state-of-the-art three-dimensional Lagrangian model and optimized water accounting diagnostics, we complete a 40-year (1971-2010) tracking of moisture from continental precipitation in the present-day climate. Climatologically, we conclude that 62% of continental precipitation stems from evapotranspiration through Lagrangian tracking––a measure is known as the global “continental precipitation recycling (CPR)” ratio. The result bridges the long-standing gap between the explicit (i.e., moisture trajectory-based) and implicit (i.e., water budget-based) estimates of the global CPR ratio in the literature. On the 1° grid scale, non-local terrestrial sources dominate precipitation in almost 70% of the land areas, most prominent in the continental interior. The CPR ratio consistently exhibits a contrasting seasonality between the mid-to-high latitudes and monsoon regions worldwide, from which two kinds of moisture source-regulated hydroclimate are generalized. Given the importance of CPR, we identify terrestrial source hotspots for continental precipitation that deserve careful governance. Using the backward “WaterSip” and a newly proposed forward “WaterDrip” diagnostics, we conceptualize and quantify two important types of cascading moisture recycling (CMR), whereby the moisture from an earlier source precipitates over an intermediate source and then re-evaporates to sustain precipitation further downwind. The watershed-scale CMR metrics uncover the interdependence among the regional water cycles. Findings here advance the scientific understanding of the atmospheric water cycle as seen through Lagrangian tracking, and offer insights into transboundary watershed management and land-use planning to improve freshwater sustainability.

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