A Scheme for Pixel-Scale Aerodynamic Surface Temperature over Hilly Land

Hilly-land satellite pixel-scale aerodynamic surface temperatures (AdST) are investigated using LAS (Large Aperture Scintillometer) and meteorological observations during 21-22 May 2001, indicating that the calculated temperatures are predominantly subject to estimated roughness lengths and, to a less extent, to estimated Bowen ratios, with errors to within 3.0 K between the AdST calculations and hilly radiometric surface temperatures retrieved from satellite data with the split window model. The errors depend heavily on the model used and the zenith angles and azimuth of the satellite and sun with respect to the observational site.

Comparison among sea surface roughness schemes

Based on the measurements from the US National Data Buoy Center 3-m discus buoy site No. 44004 （38.5°N, 70.47°W） from January 1 to March 31 of 2003, with the COARE algorithm （Version 3.0）, the results from four parameterization schemes developed recently for sea surface aerodynamic roughness length were compared with each other. Calculations of frictional speed u., drag coefficient Ca and wind stress r indicate that the calculated frictional velocities from the four schemes （8.50%-16.20%, the normalized standard error estimate, or NSEE）, the computed drag coefficients and wind stress （respectively 15.08%-28.67% and 17.26%,50.59% NSEE） are reasonable. Schemes YT96 and GW03 are consistent. The 002 scheme gives overestimated values for u, and Ca. Schemes TY01 and GW03 display discontinuous characteristics in handling young wave data.

A proposed surface resistance model for the Penman-Monteith formula to estimate evapotranspiration in a solar greenhouse

Greenhousing is a technique to bridge season gap in vegetable production and has been widely used worldwide. Calculation of water requirement of crops grown in greenhouse and determination of their irrigation schedules in arid and semi-arid regions are essential for greenhouse maintenance and have thus attracted increased attention over the past decades. The most common method used in the literature to estimate crop evapotranspiration（ET） is the Penman-Monteith（PM） formula. When applied to greenhouse, however, it often uses canopy resistance instead of surface resistance. It is understood that the surface resistance in greenhouse is the result of a combined effect of canopy restriction and soil-surface restriction to water vapor flow, and the relative dominance of one restriction over another depends on crop canopy. In this paper, we developed a surface resistance model in a way similar to two parallel resistances in an electrical circuit to account for both restrictions. Also, considering that wind speed in greenhouse is normally rather small, we compared three methods available in the literature to calculate the aerodynamic resistance, which are the r_a^1 method proposed by Perrier（1975a, b）, the r_a^2 method proposed by Thom and Oliver（1977）, and the r_a^3 method proposed by Zhang and Lemeu（1992）. We validated the model against ET of tomatoes in a greenhouse measured from sap flow system combined with micro-lysimeter in 2015 and with weighing lysimeter in 2016. The results showed that the proposed surface resistance model improved the accuracy of the PM model, especially when the leaf area index was low and the greenhouse was being irrigated. We also found that the aerodynamic resistance calculated from the r_a^1 and r_a^3 methods is applicable to the greenhouse although the latter is slightly more accurate than the former. The proposed surface resistance model, together with the r_a^3 method for aerodynamic resistance, offers an improved approach to estimate ET in greenhouse using the PM formula.

A hybrid guidance law of LOS acceleration feedback for missile against maneuvering targets

A quantised backstepping robust guidance law of three-dimension(3-D)space for compound control of reaction control jets and aerodynamic surfaces is proposed to attenuate the unknown target manoeuvre in this paper.The presented guidance law guarantees that the rates of line of sight converge to a residual circle centred at the origin whose radius is depended on the target manoeuvres,quantised length and guidance law gains.The simulations are given to illustrate the effectiveness of the proposed guidance law.