Hongqing Wang - Academia.edu (original) (raw)

Papers by Hongqing Wang

Open-File Report

in circulation patterns over the study period resulted in the reduction of shoreline erosion both... more in circulation patterns over the study period resulted in the reduction of shoreline erosion both vertically and laterally compared to that in the control area and also resulted in changes in the grain size distribution in both the water column and the salt marsh and mudflat areas.

Ecological Modelling, 2017

There remains much debate regarding the perceived tradeoffs of using freshwater and sediment dive... more There remains much debate regarding the perceived tradeoffs of using freshwater and sediment diversions for coastal restoration in terms of balancing the need for wetland restoration versus preserving eastern oyster (Crassostrea virginica) production. Further complicating the issue, climate change-induced sea-level rise (SLR) and land subsidence are also expected to affect estuarine water quality. In this study, we developed a processbased numerical modeling system that couples hydrodynamic, water quality, and oyster population dynamics. We selected Breton Sound Estuary (BSE) (~2,740 km 2) in the eastern Mississippi River Deltaic Plain since it is home to several of the largest public oyster seed grounds and private leases for the Gulf coast. The coupled oyster population model was calibrated and validated against field observed oyster growth data. We predicted the responses of oyster population in BSE to small-(142 m 3 s-1) and large-scale (7,080 m 3 s-1) river diversions at the Caernarvon Freshwater Diversion structure planned in the 2012 Coastal Master Plan (Louisiana) under low (0.38 m) and high (1.44 m) relative sea-level rise (RSLR=eustatic SLR + subsidence) compared to a baseline condition (Year 2009). Model results showed that the large-scale diversion had a stronger negative impact on oyster population dynamics via freshening of the entire estuary, resulting in reduced oyster growth rate and production than RSLR. Under the large-scale diversion, areas with optimal oyster growth rates (> 15 mg ash-free dry weight (AFDW) oyster-1 wk-1) and production (> 500 g AFDW m-2 yr-1) would shift seaward to the southeastern edge of the estuary, turning the estuary into a very low oyster production system. RSLR however played a greater role than the small-scale diversion on the magnitude and spatial pattern of oyster growth rate and production. RSLR would result in an overall estuary-wide decrease in oyster growth rate and production as a consequence of decreased salinities in the middle and lower estuary because rising sea level likely causes increased stage and overbank flow downstream along the lower Mississippi River.

Atmosphere, 2021

Tropical overshooting convection has a strong impact on both heat budget and moisture distributio... more Tropical overshooting convection has a strong impact on both heat budget and moisture distribution in the upper troposphere and lower stratosphere, and it can pose a great risk to aviation safety. Cloud-top height is one of the essential concerns of overshooting convection for both the climate system and the aviation weather forecast. The main purpose of our work is to verify the application of the machine learning method, taking the random forest (RF) model as an instance, in overshooting cloud-top height retrieval from Himawari-8 data. By using collocated CloudSat observations as a reference, we utilize several infrared indicators of Himawari-8 that are commonly recognized to relate to cloud-top height, along with some temporal and geographical parameters (latitude, month, satellite zenith angle, etc.), as predictors to construct and validate the model. Analysis of variable importance shows that the brightness temperature of 6.2 um acts as the dominant predictor, followed by satel...

Journal of the Atmospheric Sciences, 2018

We developed an entraining parcel approach that partitions parcel buoyancy into contributions fro... more We developed an entraining parcel approach that partitions parcel buoyancy into contributions from different processes (e.g., adiabatic cooling, condensation, freezing, and entrainment). Applying this method to research-quality radiosonde profiles provided by the Atmospheric Radiation Measurement (ARM) program at six sites, we evaluated how atmospheric thermodynamic conditions and entrainment influence various physical processes that determine the vertical buoyancy structure across different climate regimes as represented by these sites. The differences of morning buoyancy profiles between the deep convection (DC)/transition cases and shallow convection (SC)/nontransition cases were used to assess preconditions important for shallow-to-deep convection transition. Our results show that for continental sites such as the U.S. Southern Great Plains (SGP) and west-central Africa, surface conditions alone are enough to account for the buoyancy difference between DC and SC cases, although ...

Mike Waldon (DOI Everglades Program Team) gave a presentation on his research: “Near Zeroth Order... more Mike Waldon (DOI Everglades Program Team) gave a presentation on his research: “Near Zeroth Order Sulfate Disappearance Rate Estimated using Models of the Arthur R. Marshall Loxahatchee National Wildlife Refuge”. He described how the hydrology of the Loxahatchee area (aka WCA1) has been altered from a predominantly sheet-flow system to a riparian wetland, and that the water chemistry had been altered from a rainfall-fed system to one with elevated chloride, sulfate, and total P. He stated that the input of canal water was the primary source of sulfate contamination in the marsh interior. The rate of sulfate disappearance (reduction flux) was relatively constant (~15 g/m2/yr) and was not sulfate limited. The results of their efforts to model sulfate concentrations in the canals and the marsh suggested that a first order model required a 20-fold adjustment in the rate constant (the effective sulfate disappearance rate in m/yr) to fit data from the canals to the marsh interior, while a...

Virus Genes, 2009

Grapevine yellow speckle viroid-2 (GYSVd-2) is a viroid found only in grapevines in China and Aus... more Grapevine yellow speckle viroid-2 (GYSVd-2) is a viroid found only in grapevines in China and Australia. Here, we report the molecular characterization of GYSVd-2 isolated from three grapevine varieties in China. A total of 90 cDNA clones were sequenced including 30 cDNA clones obtained from each of the Black Olympia, Zaoyu, and Thomson Seedless isolates. Sequencing analysis identified 20, 18, and 12 different sequence variants from the 3 isolates, respectively. Furthermore, each of the isolates included one predominant sequence variant. Compared to the Australian variant of GYSVd-2 (Accession number: NC_003612), the Black Olympia variant was identical and the Zaoyu variant contained one substitution. In contrast, the Thomson Seedless isolate significantly varied from the Australian variant with three substitutions, two insertions, and four deletions. In silico structure analysis predicted that the variations were clustered in the terminal left, the pathogenicity, and the variable region of the predicted secondary structure of GYSVd-2.

Remote Sensing of Environment, 2006

Long-term ecological changes within densely populated landscapes account for a growing share of g... more Long-term ecological changes within densely populated landscapes account for a growing share of global environmental change. Measuring the causes and consequences of these changes remains a challenge because of their fine spatial scale and complexity. Here, we measure long-term ecological changes, circa 1950 to 2002, within six 1 km 2 sites in densely populated rural China and in urban and suburban Baltimore, Maryland, USA using a standardized procedure for fine-scale feature-based ecological mapping from high spatial resolution (1 m) imagery. The median size of ecologically distinct landscape features (ecotopes) mapped by this procedure was just 520 m 2 , though size, count and perimeter of features varied considerably both within and between sites. Land management and vegetation cover changed substantially, over 28% to 87% of site areas, but most of this change occurred in small patches with area < 4000 m 2. Landscape complexity also increased over time by the fragmentation of landscapes into a larger number of smaller features with an increasing diversity of ecotope classes. Detailed analysis of fine-scale landscape transformations helped identify the causes and consequences of ecologically significant changes within and across sites, including unexpected increases in perennial vegetation cover and the linkage of impervious surface area with population density. These and other results demonstrate the general utility of anthropogenic ecotope mapping as a tool for cross-site comparison and sampled regional estimates of long-term ecological changes within densely populated landscapes.

Photogrammetric Engineering & Remote Sensing, 2005

Planimetric positional error limits the accuracy of landscape change measurements based on featur... more Planimetric positional error limits the accuracy of landscape change measurements based on features interpreted from high spatial resolution imagery (Յ1 m), and this limitation depends on the magnitude of the positional error, the spatial heterogeneity of landscapes, and the spatial extent of the change detection window (the change detection resolution). For this reason, accuracy assessments of change measurements from feature-based approaches require careful evaluation of the impacts of positional errors across landscapes differing in spatial heterogeneity at different change detection resolutions. We quantified such impacts by computing the false changes produced by spatially shifting and comparing high-resolution ecological maps derived by feature interpretation and ground interpretation of 1 m resolution Ikonos imagery of rural China and 0.3 m resolution aerial photographs of suburban United States. Change detection error increased significantly as positional errors increased, as landscape heterogeneity increased, and as the change detection resolution became finer. Regression-derived relationships between change estimation error and positional error, change detection resolution, and landscape heterogeneity allow calculation of the minimum change detection window size at which it is possible to obtain change measurements of a specified accuracy given any set of featurebased ecological maps and their positional error. Prediction of this "optimal change detection resolution" is critical in producing reliable high-resolution change measurements from feature-based ecological maps.

Journal of Environment Quality, 2009

International Journal of Remote Sensing, 2006

High spatial resolution feature-based approaches are especially useful for ecological mapping in ... more High spatial resolution feature-based approaches are especially useful for ecological mapping in densely populated landscapes. This paper evaluates errors in estimating ecological map class areas from fine-scale current (,2002) and historical (,1945) feature-based ecological mapping by a set of trained interpreters across densely populated rural sites in China based on field-validated interpretation of high spatial resolution ((1 m) imagery. Median overall map accuracy, corrected for chance, was greater than 85% for mapping by trained interpreters, with greater accuracy for current versus historical mapping. An error model based on feature perimeter proved as reliable in predicting 90% confidence intervals for map class areas as did models derived from the conventional error matrix. A conservative error model combining these approaches was developed and tested for statistical reliability in predicting confidence intervals for ecological map class areas from fine-scale feature-based mapping by a set of trained interpreters across rural China, providing a practical basis for statistically reliable ecological change detection in densely populated landscapes.

International Journal of Remote Sensing, 2005

High-resolution ((1 m) satellite imagery and archival World War II era (WW2) aerial photographs a... more High-resolution ((1 m) satellite imagery and archival World War II era (WW2) aerial photographs are currently available to support high-resolution longterm change measurements at sites across China. A major limitation to these measurements is the spatial accuracy with which this imagery can be orthorectified and co-registered. We orthorectified IKONOS 1 m resolution GEO-format imagery and WW2 aerial photographs across five 100 km 2 rural sites in China with terrain ranging from flat to hilly to mountainous. Ground control points (GCPs) were collected uniformly across 100 km 2 IKONOS scenes using a differential Global Positioning Systems (GPS) field campaign. WW2 aerial photos were co-registered to orthorectified IKONOS imagery using bundle block adjustment and rational function models. GCP precision, terrain relief and the number and distribution of GCPs significantly influenced image orthorectification accuracy. Root mean square errors (RMSEs) at GCPs for IKONOS imagery were ,2.0 m (0.9-2.0 m) for all sites except the most heterogeneous site (Sichuan Province, 2.6 m), meeting 1:12 000 to 1:4800 US National Map Accuracy Standards and equalling IKONOS Precision and Pro format accuracy standards. RMSEs for WW2 aerial photos ranged from 0.2 to 3.5 m at GCPs and from 4.4 to 6.2 m at independent checkpoints (ICPs), meeting minimum requirements for high-resolution change detection.

Ecosystems, 2009

Over the past 50 years, China's ancient agricultural village landscapes have been transformed by ... more Over the past 50 years, China's ancient agricultural village landscapes have been transformed by unprecedented social, technological, and ecological changes. Although these dense anthropogenic

Chinese Science Bulletin, 2000

A mesoscale convective system (MCS) was generated over the South China Sea at around 11 5" E , 21... more A mesoscale convective system (MCS) was generated over the South China Sea at around 11 5" E , 21 " N on 0000 UTC 7 June 1998. Riding along the Mei-Yu front, the system moved through the Taiwan Strait and finally hit the southern part of the Taiwan Island, produced over 300 mm of rainfall over parts of Taiwan in the next 24 hours. It was found that the Penn State-NCAR Mesoscale Model Version 5 (MM5) did quite well in simulating the evolution of the MCS. Diagnostic studies on the mesoscale structure of MCS, moisture concentration process and the momentum budget were based on the model output. The concept model of the MCS in the mature phase can be concluded as the following: At the 850 hPa level, the mesoscale low level jet (mLLJ) was found to the southwest of the MCS, which was also associated with a mesoscale low generated by convection, the mesoscale upper level jet (mULJ) was found due east of the MCS (and an upper-level mesoscale high) at the 300 hPa level. Horizontal advection of momentum acted to accelerate the exit of the mLLJ but decelerate the entrance of the mLLJ where the pressure gradient force acted to compensate this lost and maintain its strength. For maintenance of the mUW, vertical advection of momentum and the pressure gradient force were both found to be important.

Agriculture, Ecosystems & Environment, 2009

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Purpose Village landscapes, which integrate small-scale agriculture with housing, forestry and a ... more Purpose Village landscapes, which integrate small-scale agriculture with housing, forestry and a host of other land use practices, cover more than 2×106 km2 across China. Village lands tend to be managed at very fine spatial scales (≤30 m), with managers altering soil fertility and even terrain by terracing, irrigation, fertilizing, and other land use practices. Under these conditions, accumulation of excess phosphorous in soils has become important contributor to eutrophication of surface waters across China’s densely populated village landscapes. The aim of this study was to investigate relationships between fine-scale patterns of agricultural management and soil total phosphorus (STP) within China’s village landscapes. Materials and methods First, China’s village landscapes

Remote Sensing

Barrier islands are dynamic environments because of their position along the marine–estuarine int... more Barrier islands are dynamic environments because of their position along the marine–estuarine interface. Geomorphology influences habitat distribution on barrier islands by regulating exposure to harsh abiotic conditions. Researchers have identified linkages between habitat and landscape position, such as elevation and distance from shore, yet these linkages have not been fully leveraged to develop predictive models. Our aim was to evaluate the performance of commonly used machine learning algorithms, including K-nearest neighbor, support vector machine, and random forest, for predicting barrier island habitats using landscape position for Dauphin Island, Alabama, USA. Landscape position predictors were extracted from topobathymetric data. Models were developed for three tidal zones: subtidal, intertidal, and supratidal/upland. We used a contemporary habitat map to identify landscape position linkages for habitats, such as beach, dune, woody vegetation, and marsh. Deterministic accu...

Ecosphere

Large Mississippi River (MR) diversions (peak water flow >1416 m 3 /s and sediment loads >165 kg/... more Large Mississippi River (MR) diversions (peak water flow >1416 m 3 /s and sediment loads >165 kg/s) have been proposed as part of a suite of coastal restoration projects and are expected to rehabilitate and rebuild wetlands to alleviate the significant historic wetland loss in coastal Louisiana. These coastal wetlands are undergoing increasing eustatic sea-level rise, land subsidence, climate change, and anthropogenic disturbances. However, the effect of MR diversions on wetland soil organic carbon (SOC) sequestration in receiving basins remains unknown. The rate of SOC sequestration or carbon burial in wetlands is one of the variables used to assess the role of wetland soils in carbon cycling and also to construct wetland carbon budgets. In this study, we examined the effects of MR water and sediment diversions on landscape-scale SOC sequestration rates that were estimated from vertical accretion for the next 50 yr (2010-2060) under two environmental (moderate and less optimistic) scenarios. Our analyses were based on model simulations taken from the Wetland Morphology model developed for Louisiana's 2012 Coastal Master Plan. The master plan modeled a "future-without-action" scenario as well as eight individual MR diversion projects in two of the hydrologic basins (Barataria and Breton Sound). We examined the effects that discharge rates (peak flow) and locations of these individual diversion projects had on SOC sequestration rates. Modeling results indicate that large river diversions are capable of improving basin-wide SOC sequestration capacity (162-222 g CÁm À2 Áyr À1) by up to 14% (30 g CÁm À2 Áyr À1) in Louisiana deltaic wetlands compared to the future-without-action scenario, especially under the less optimistic scenario. When large river diversions are placed in the upper receiving basin, SOC sequestration rates are 3.7-10.5% higher (6-24 g CÁm À2 Áyr À1) than when these structures are placed in the lower receiving basin. Modeling results also indicate that both diversion discharge and location have large effects on SOC sequestration in low-salinity (freshwater and intermediate marshes) as compared to high-salinity marshes (brackish and saline marshes).

Journal of Coastal Research

Soil bulk density (BD), soil organic matter (SOM) content, and a conversion factor between SOM an... more Soil bulk density (BD), soil organic matter (SOM) content, and a conversion factor between SOM and soil organic carbon (SOC) are often used in estimating SOC sequestration and storage. Spatial variability in BD, SOM, and the SOM-SOC conversion factor affects the ability to accurately estimate SOC sequestration, storage, and the benefits (e.g., land building area and vertical accretion) associated with wetland restoration efforts, such as marsh creation and sediment diversions. There are, however, only a few studies that have examined large-scale spatial variability in BD, SOM, and SOM-SOC conversion factors in coastal wetlands. In this study, soil cores, distributed across the entire coastal Louisiana (approximately 14,667 km 2) were used to examine the regional-scale spatial variability in BD, SOM, and the SOM-SOC conversion factor. Soil cores for BD and SOM analyses were collected during 2006-09 from 331 spatially well-distributed sites in the Coastwide Reference Monitoring System network. Soil cores for the SOM-SOC conversion factor analysis were collected from 15 sites across coastal Louisiana during 2006-07. Results of a split-plot analysis of variance with incomplete block design indicated that BD and SOM varied significantly at a landscape level, defined by both hydrologic basins and vegetation types. Vertically, BD and SOM varied significantly among different vegetation types. The SOM-SOC conversion factor also varied significantly at the landscape level. This study provides critical information for the assessment of the role of coastal wetlands in large regional carbon budgets and the estimation of carbon credits from coastal restoration.