Quick review of remote sensing, Introduction to remote sensing in hydrology, hydrological cycle and energy balance Lecture 1

Hydrology focuses on the global hydrologic cycle and the processes involved in the land phase of that cycle. Hydrology describes and predicts: Hydrology focuses on the global hydrologic cycle and the processes involved in the land phase of that cycle. Hydrology describes and predicts: 1.The spatial and temporal variations of water substance in the terrestrial, oceanic, and atmospheric compartments of the global water system. 2.The movement of water on and under the earth’s surface, the physical, chemical, and biological processes accompanying that movement.

Historical Benchmarks Monitoring of river flows started by Egyptians 3800 B. P.Monitoring of river flows started by Egyptians 3800 B. P. Concept of hydrologic cycle, 3000 B. P., King Solomon in Ecclesiastes:Concept of hydrologic cycle, 3000 B. P., King Solomon in Ecclesiastes: All the rivers run into the sea; ….. unto the place from whence the rivers come, thither they return again. All the rivers run into the sea; ….. unto the place from whence the rivers come, thither they return again. Rainfall measuring, 2400 B. P. in India.Rainfall measuring, 2400 B. P. in India..... Formal recognition of the scientific status of hydrology, 1920’s and 1930’s, UGG, AGU…etc.Formal recognition of the scientific status of hydrology, 1920’s and 1930’s, UGG, AGU…etc.

All units in the picture above are m 3. Identify the reservoirs of the hydrological cycle Hydrological processes (flux) connecting the reservoirs Write the water balance equations for ocean, atmosphere, and land. 1. Hydrologic cycle

Reservoirs

Volume (km 3 ) Percent of total Percent of freshwater Residence time (yr) Water in Land Areas: 47,971, (All surface water:) 4.0 Lakes: Fresh 91, Saline 85, Rivers2, Marshes11, Soil moisture16, Groundwater: (All subsurface water:) 20,000 Fresh 10,530, Saline 12,870, Biological Water1, Icecaps and glaciers24,364, Atmosphere 12, Oceans 1,338,000, ,650 Total 1,385,984, Hornberger et al., 1998

Water Storage in the Atmosphere 0.001%0.001% Water vaporWater vapor CloudsClouds (water vapor condensed on particulate)

where: M = mass within the control volume [M]; t = time [T]; I' = mass inflow rate [M T  1 ]; and O' = mass outflow rate [M T  1 ]. where: V = volume of water within the control volume [L 3 ]; I = volume inflow rate [L 3 T -1 ]; and O = volume outflow rate [L 3 T -1 ]. Water Balance Equation

where: V = average volume of water stored, and assumed to be constant; P = average precipitation rate; r si = average surface water inflow rate; r gi = average groundwater inflow rate; r so = average surface water outflow rate; r go = average groundwater outflow rate; and et = average evapotranspiration rate. All terms in the equation have dimensions of volume per time [L 3 T  1 ].

What drives the hydrologic cycle?

2. Energy Balance Write the energy balance equations for the earth

Short-wave radiation

Campbell and Norman, 1998

Long-wave radiation Write the energy balance equations for the earth surface

Campbell and Norman, 1998

Discussion What determine incident short-wave radiation on the earth surface? –Solar constant: Describes the Solar Radiation that falls on an area above the atmosphere at a vertical angle: s = 1.37 kW / m².Solar Radiation –others What control out-going long-wave radiation from the earth surface?

Describe the patterns, and Explain… Find the difference between the two

How is the Hydrological Cycle driven?

3. Atmospheric circulations If no earth rotation With earth rotation

4. Oceanic circulations

Hydrologic Information System to the State in (Near) Real Time Via Internet Products: - Rainfall - Snow cover - Runoff - River flow - Recharge - ET -Soil Moisture -LULC -VI