There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The ERA5 global reanalysis

Soil Chemical Analysis

Abstract A two-dimensional version of the Pennsylvania State University mesoscale model has been applied to Winter Monsoon Experiment data in order to simulate the diurnally occurring convection observed over the South China Sea. The domain includes a representation of part of Borneo as well as the sea so that the model can simulate the initiation of convection. Also included in the model are parameterizations of mesoscale ice phase and moisture processes and longwave and shortwave radiation with a diurnal cycle. This allows use of the model to test the relative importance of various heating mechanisms to the stratiform cloud deck, which typically occupies several hundred kilometers of the domain. Frank and Cohen's cumulus parameterization scheme is employed to represent vital unresolved vertical transports in the convective area. The major conclusions are: Ice phase processes are important in determining the level of maximum large-scale heating and vertical motion because there is a strong anvil componen...

Numerical study of convection observed during the Winter Monsoon Experiment using a mesoscale two-dimensional model [presentation]

Climate change 2014 - Synthesis Report

For flood-prone countries subject to large-scale and seasonal flooding, precipitation forecasting is the single most important factor for improving the skill of flood forecasting for such l...

Improving operational flood forecasting in monsoon climates with bias-corrected quantitative forecasting of precipitation

The proposed Surface Water and Ocean Topography (SWOT) mission will provide global, space-based estimates of water elevation, its temporal change, and its spatial slope for terrestrial water bodies. Using derivations of water slope from the Shuttle Radar Topography Mission (SRTM) elevation data, river bathymetry and Manning's equation, the potential of SWOT for discharge estimation of large braided rivers in humid climates, such as the Brahmaputra river, was found to be promising (Jung , in Earth Surface Processes and Landforms, 2010). In this study we extend the work on assessing SWOT for braided rivers to understand the sensitivity of two river hydraulic parameters to discharge estimation: 1) section factor (AR2/3) derived from land-water classification and in situ river bathymetry and 2) Manning's roughness coefficient. For braided rivers, the first parameter, is intimately dependent on how braided rivers are classified of the multiple channels (water) and in-stream braided bars (land) that consequently dictates the accuracy of wetted perimeter and area of flow estimation from water elevation data. We show that the use of the minimum water elevation data at a river cross section minimizes estimation of section factor which consequently minimizes outlier discharge estimation reported in the Jung study. We also show that by treating roughness coefficient “flexible” as a calibration parameter, discharge estimation from SRTM elevation data can be further improved through trial and error manual optimization. Our sensitivity study illustrates the value of treating section factor and roughness coefficient as calibration parameters for data assimilation systems that use SWOT observables to estimate river discharge in braided rivers.

Role of Land–Water Classification and Manning's Roughness Parameter in Space-Borne Estimation of Discharge for Braided Rivers: A Case Study of the Brahmaputra River in Bangladesh

The Surface Water Ocean Topography (SWOT) mission will launch in 2021 to provide the first global inventory of terrestrial surface water. Although SWOT is primarily a research mission with key scie...

Generating Proxy SWOT Water Surface Elevations Using WRF-Hydro and the CNES SWOT Hydrology Simulator

[1] The specific question that this study pursued is “Have large dams modified the downwind frequency of rainfall in the mesoscale during growing season?” Rigorously quality controlled precipitation data comprising 3055 stations from the Global Historical Climatology Network (GHCN) were analyzed with 92 large dams in the U.S. Using 30 years of atmospheric reanalysis data, the wind rose diagram for each dam was derived from wind data at the 850 mb level. Around 96 (78) GHCN downwind (upwind) precipitation stations were identified that were within 100 km (mesoscale) of dams. The Mediterranean and humid subtropical climates were found to have experienced the highest and statistically significant change in trend in precipitation frequency downwind and within 100 km of dams during the growing season. The warm summer continental climatic region was found to have exhibited the next most modification. Paired analyses were performed as a function of predam and postdam and at upwind and downwind locations. For Mediterranean climates, the stations studied were found to have experienced a generally weak trend in precipitation frequency before the construction of the selected dams and a systematically more impacted trend during the postdam period. However, using precipitation observations alone, the specific role played by irrigation dams could not be distinguished from other types of dams in this study. Analysis of humidity records, however, revealed that dams can increase the moistening of the air mass by about 5%–15% (in terms of vapor pressure) as it passes downwind, while the effect can also be marginal for other dams. In summary, our study reveals that it is easier to establish a physically intuitive connection between large dams and downwind frequency of rain, but it is much more difficult to demonstrate this connection consistently for all the downwind stations in the mesoscale without the use of additional geophysical data (e.g., topography, land use, and land cover patterns) and mesoscale atmospheric modeling.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2011WR010966

Faisal Hossain

Papers

Improving operational flood forecasting in monsoon climates with bias-corrected quantitative forecasting of precipitation

Role of Land–Water Classification and Manning's Roughness Parameter in Space-Borne Estimation of Discharge for Braided Rivers: A Case Study of the Brahmaputra River in Bangladesh

Generating Proxy SWOT Water Surface Elevations Using WRF-Hydro and the CNES SWOT Hydrology Simulator

Investigating the mesoscale impact of artificial reservoirs on frequency of rain during growing season

Investigating the Mesoscale Impact of Artificial Reservoirs on Frequency of Rain