Large-scale oceans such as the Indian Ocean require a specific sensor to cover such a huge area. In the case of MH370 searching, ocean dynamic parameters over this extremely huge ocean are required to understand the trajectory movement of MH370 debris. The best sensor could assist is the altimeter satellite data. In fact, this data can deliver several ocean dynamic parameters such as wave height, Rosby wave pattern, sea level variability, and ocean surface current. This chapter aims at delivering a fundamental review of the altimeter satellite data. This chapter shows that there are two main components of radar altimeters: (1) frequency modulated continuous wave (FMCW) and (2) pulse altimeters, which are a function of used radar signals. Two sorts of FMCW altimeters are mainly implemented: broad-beamwidth types and narrow-beamwidth. Moreover, the chapter has listed the variety of altimeter satellite data.
TopIntroduction
Up to date, there is no study that has implemented altimeter data to track the impact of ocean dynamic features, i.e., circulation, waves, etc., on the trajectory movement of MH370 debris. In this view, optical satellite sensors have used to track MH370 debris without success as discussed in Chapter 9. Prior to use altimeter satellite data, this chapter is addressing the principles of altimeter microwave data to complete thought of how these data can contribute to search MH370 debris.
Altimeter satellite data have an incredible achievement to apprehend the ocean circulation dynamic system. In this understanding, the trajectory movement of MH370 debris is usually a function of ocean circulation. In this view, the perfect empathetic of altimeter mechanics for monitoring, simulation, and tracing ocean circulation can assist to comprehend the mechanics of MH370 crashing in the Indian Ocean.
This chapter critically evaluates the existing altimeter sensors which monitored the Southern Indian Ocean circulation and wave dissipation to bridge the gap found between various remote sensing data recorded as a part of the MH370 crashing scenario. In this understanding, the wide range of ocean circulation is required to forecast and predict any MH370 debris trajectory movement across the Indian Ocean. It is concluded that different comprehensive approaches are necessary to develop a forecasting tool for assessing and monitoring debris trajectory movement (Chelton et al., 2001).
An altimeter is referred to as an altitude meter. In this view, it is a device to compute the object’s height above a stable point. In this regard, the estimation of altitude is known as an altimeter. The bathymetry, consequently, is associated with an altimeter which is the computation of depth beneath the sea surface. The dimension is usually measured from the altimeter platform, i.e. satellite or aircraft and the Earth’s surface (Figure 1). In other words, altimeters are nadir-looking pulse-radars often. They transmit short microwave pulses and measure the round trip time delay to targets to determine their distance from the air- or spaceborne sensor.
Figure 1. The concept of the altimeter
TopPrinciples Of Altimeter
Like a synthetic aperture radar (SAR), altimeter emits a radar signal and then records the backscattered signal from the objects. Unlike SAR, the altimeter emits and receives radar waveform perpendicular to the object. This mechanism allows estimating the object height from the inverted backscatter signal. In this context, the ocean wave height can be inverted more easily than SAR as a function of perpendicular backscatter signal’s amplitude (Cheney et al.,1987). The main signal bands used with altimeter are E-band, Ka-band, and S-band. Advanced sea-level retrieving parameters are easily made by S-band. In this regard, the reliable and precise ocean wave height is delivered by altimeter than SAR sensors.