Problem 8.1. Meteorological and surface measurements collected at noon from a ba
ID: 236065 • Letter: P
Question
Problem 8.1. Meteorological and surface measurements collected at noon from a bare soil field site are:
Air temperature = 26.8°C
Air relative humidity = 69%
Surface air pressure = 973 mb
Wind speed at 2 m height = 3.0 m s-1 Soil surface temperature = 26.2 °C
The measurements are taken on the first sunny day after a rainy period (you can assume the soil is saturated). The soil roughness elements have a characteristic height (h) of 4 cm.
a) Using only the measurements/information provided, which model could be used to estimate the instantaneous surface evaporation? Which model/s cannot be used if you only have the data provided? Explain why.
b) What additional information/input data would you need if the soil were not saturated?
c) What additional information would you need if the surface was vegetated?
d) In general, qsurf over bare soil can be modeled as: qsurf =qs(Tsurf); 0()1
Consider two cases: 1) a saturated soil where the multiplicative coefficient is equal to 1.0 and 2) a water-limited case where the multiplicative factor is equal to 0.80. Use an appropriate model to compute the latent and sensible heat flux at the measurement time for each of these cases. How do the values of the fluxes between the water limited case and the moist soil case compare?
e) What is the equivalent evaporation rate in mm/day for the saturated soil case? Is this actual or potential evaporation?
Explanation / Answer
answer- In above meterological data
given- the air temperature- 26.8 degree celcius
air relative humdity = 69%
surface air pressure = 973mb
wind speed at 2m height = 3m/sec
Soil surface temperature= 26.2 degree celcius
1- evaporation is the process in which liquid is coverted into gas on incresing in temperature and pressure. and for the estmation of instantaneous evaporation the three temperatures model at large catchment scale and Remote sensing method is also used. and this method is also used to determine the Evapotranspiration and also evaluate environment quality. and the key parameter that is being required for the estimation of instantenous evaporation are following
air temperature and land surface temperature etc
2- In the soil is not saturated we should need to amount of humidity of soil and also soil temperature
3- In surface is vegetated then he nedd how much in area of land surface is vegetation and what is the sruface temperature. and humidty. vegetated land have high humidity than barrend or arid land.
5- Equivalent Precipitation rate= 96.5 * GPM (gallon per minute)/ total area