A review of drought concepts

Sentinel-2: ESA's Optical High-Resolution Mission for GMES Operational Services

[i] An inventory of air pollutant emissions in Asia in the year 2000 is developed to support atmospheric modeling and analysis of observations taken during the TRACE-P experiment funded by the National Aeronautics and Space Administration (NASA) and the ACE-Asia experiment funded by the National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA). Emissions are estimated for all major anthropogenic sources, including biomass burning, in 64 regions of Asia. We estimate total Asian emissions as follows: 34.3 Tg SO 2 , 26.8 Tg NO x , 9870 Tg CO 2 , 279 Tg CO, 107 Tg CH 4 , 52.2 Tg NMVOC, 2.54 Tg black carbon (BC), 10.4 Tg organic carbon (OC), and 27.5 Tg NH 3 . In addition, NMVOC are speciated into 19 subcategories according to functional groups and reactivity. Thus we are able to identify the major source regions and types for many of the significant gaseous and particle emissions that influence pollutant concentrations in the vicinity of the TRACE-P and ACE-Asia field measurements. Emissions in China dominate the signature of pollutant concentrations in this region, so special emphasis has been placed on the development of emission estimates for China. China's emissions are determined to be as follows: 20.4 Tg SO 2 , 11.4 Tg NO x , 3820 Tg CO 2 , 116 Tg CO, 38.4 Tg CH 4 , 17.4 Tg NMVOC, 1.05 Tg BC, 3.4 Tg OC, and 13.6 Tg NH 3 . Emissions are gridded at a variety of spatial resolutions from 1° × 1° to 30 s x 30 s, using the exact locations of large point sources and surrogate GIS distributions of urban and rural population, road networks, landcover, ship lanes, etc. The gridded emission estimates have been used as inputs to atmospheric simulation models and have proven to be generally robust in comparison with field observations, though there is reason to think that emissions of CO and possibly BC may be underestimated. Monthly emission estimates for China are developed for each species to aid TRACE-P and ACE-Asia data interpretation. During the observation period of March/ April, emissions are roughly at their average values (one twelfth of annual). Uncertainties in the emission estimates, measured as 95% confidence intervals, range from a low of ±16% for SO 2 to a high of ±450% for OC.

An inventory of gaseous and primary aerosol emissions in Asia in the year 2000 : NASA global tropospheric experiment transport and chemical evolution over the pacific (TRACE-P): Measurements and analysis (TRACEP1)

Remote sensing image-based analysis of the relationship between urban heat island and land use/cover changes

To improve the performance of particle image velocimetry in measuring instantaneous velocity fields, direct cross-correlation of image fields can be used in place of auto-correlation methods of interrogation of double- or multiple-exposure recordings. With improved speed of photographic recording and increased resolution of video array detectors, cross-correlation methods of interrogation of successive single-exposure frames can be used to measure the separation of pairs of particle images between successive frames. By knowing the extent of image shifting used in a multiple-exposure and by a priori knowledge of the mean flow-field, the cross-correlation of different sized interrogation spots with known separation can be optimized in terms of spatial resolution, detection rate, accuracy and reliability.

Theory of cross-correlation analysis of PIV images : Image analysis as measuring technique in flows

https://hrsl.ba.ars.usda.gov/ERHunt/jackson_rse04.pdf

Vegetation water content mapping using Landsat data derived normalized difference water index for corn and soybeans

Vegetation water content estimation for corn and soybeans using spectral indices derived from MODIS near- and short-wave infrared bands

http://iopscience.iop.org/article/10.1016/0169-5983(95)00053-G/pdf

Experimental study of plane turbulent wakes in a shallow water layer

In shallow turbulent wake flows (typically an island wake), the flow patterns have been found experimentally to depend mainly on a shallow wake parameter, S = c f D / h in which c f is a quadratic-law friction coefficient, D is the island diameter and h is water depth. In order to understand the dependence of flow patterns on S , the shallow-water stability equation (a modified Orr–Sommerfeld equation) has been derived from the depth-averaged equations of motion with terms which describe bottom friction. Absolute and convective instabilities have been investigated on the basis of wake velocity profiles with a velocity deficit parameter R . Numerical computations have been carried out for a range of R -values and a stability diagram with two dividing lines was obtained, one defining the boundary between absolute and convective instabilities S ca , and another defining the transition between convectively unstable and stable wake flow S cc . The experimental measurements (Chen & Jirka 1995) of return velocities in shallow wakes were used to compute R -values and two critical values, S A =0.79 and S C =0.85, were obtained at the intersections with lines S ca and S cc . Through comparison with transition values observed experimentally for wakes with unsteady bubble (recirculation zone) and vortex shedding, S U and S V respectively, the sequence S C > S A >
 S U > S V shows vortex shedding to be the end product of absolute instability. This is analogous to the sequence of critical Reynolds numbers for an unbounded wake of large spanwise extent. Experimental frequency characteristics compare well with theoretical results. The observed values of S U and S V for different flow patterns correspond to the velocity profile with R =−0.945, which is located at the end of the wake bubble, and it provides the dominant mode.

Daoyi Chen

Papers

Vegetation water content mapping using Landsat data derived normalized difference water index for corn and soybeans

Vegetation water content estimation for corn and soybeans using spectral indices derived from MODIS near- and short-wave infrared bands

Experimental study of plane turbulent wakes in a shallow water layer

Absolute and convective instabilities of plane turbulent wakes in a shallow water layer

Co-benefits from energy policies in China