TDS-1 GNSS reflectometry wind geophysical model function response to GPS block types

Figures & data

Figure 1. An example of DDM onboard SGR-ReSI instrument.

Figure 2. An example of a noisy DDM retrieved by the SGR-ReSi instrument.

Figure 3. TDS-1 SNRc with SNRs >0 dB and the corresponding ASCAT wind speeds for the training dataset (75% of samples) of all GPS blocks in (a) and each GPS block in (b)–(f). The white curve represents GMF. The form of GMF is $U_{10}=\mathit{A}{e}^{\mathit{xB}}$, where $\mathit{x}$ represents SNRc.

Figure 4. (a)–(f) The wind speed retrievals of TDS-1 versus collocated ASCAT wind speed for the remaining test dataset (25% of samples) of all GPS blocks and each GPS block. The black line represents TDS-1 wind speed equal to ASCAT wind speed.

Figure 5. TDS-1 SNRc with SNRs >0 dB and the corresponding ECMWF wind speeds for the training dataset (75% of samples) of all GPS blocks in (a) and each GPS block in (b)–(f). The white curve represents GMF. The form of GMF is $U_{10}=\mathit{A}{e}^{\mathit{xB}}$, where $\mathit{x}$ represents SNRc.

Figure 6. The wind speed retrievals of TDS-1 and the corresponding ECMWF wind speed for the remaining test dataset (25% of samples) of all GPS blocks in (a) and each GPS block in (b)–(f). The black line represents TDS-1 wind speed equal to ECMWF wind speed.

Table 1. Performance of each GPS block against ASCAT and ECMWF at high SNR

	GPS block	All	Block IIA	Block IIR-A	Block IIR-B	Block IIR-M	Block IIF
ASCAT	RMSE (m/s)	2.19	1.48	1.47	2.01	1.95	1.93
	Correlation coefficient	0.79	0.78	0.70	0.80	0.85	0.84
	Samples	67825	3477	8035	7182	20036	27356
ECMWF	RMSE (m/s)	1.88	1.69	1.51	1.53	1.86	1.72
	Correlation coefficient	0.72	0.76	0.49	0.76	0.79	0.76
	Samples	110265	5030	16979	10826	27390	47291

Figure 7. TDS-1 SNR_c with SNRs ≤ 0 dB and SNRs > −10 dB and the corresponding ASCAT wind speeds for the training dataset (75% of samples) of all GPS blocks in (a) and each GPS block in (b)–(f). The white curve represents GMF. The form of GMF is $U_{10}=\mathit{Ax}$, where $\mathit{x}$ represents SNRc.

Figure 8. The wind speed retrievals of TDS-1 and the corresponding ASCAT wind speed for the remaining test dataset (25% of samples) of all GPS blocks in (a) and each GPS block in (b)–(f). The black line represents TDS-1 wind speed equal to ASCAT wind speed.

Figure 9. TDS-1 SNR_c with SNRs ≤ 0 dB and SNRs > −10 dB of the corresponding ECMWF wind speeds for the training dataset (75% of samples) of all GPS blocks in (a) and each GPS block in (b)–(f). The white curve represents GMF. The form of GMF is $U_{10}=\mathit{Ax}$, where $\mathit{x}$ represents SNRc.

Figure 10. The wind speed retrievals of TDS-1 and the corresponding ECMWF wind speeds for the remaining test dataset (25% of samples) of all GPS blocks in (a) and each GPS block in (b)–(f). The black line represents that TDS-1 wind speed is equal to ECMWF wind speed.

Table 2. Performance of each GPS block against ASCAT and ECMWF at low SNR

	GPS block	All	Block IIA	Block IIR-A	Block IIR-B	Block IIR-M	Block IIF
ASCAT	RMSE (m/s)	3.13	3.09	2.92	3.04	2.96	3.03
	Correlation coefficient	0.50	0.57	0.52	0.56	0.59	0.52
	Samples	202344	18179	56754	24124	45807	54930
ECMWF	RMSE (m/s)	2.74	3.14	2.52	2.49	2.54	2.82
	Correlation coefficient	0.49	0.36	0.53	0.54	0.54	0.48
	Samples	197612	11245	54300	21459	42698	64855

Figure 11. (a) Relationship between Hs and SNR collocated with ECMWF. (b) Relationship between ECMWF wind speed and mean SNR.

Figure 12. Relationship between ECMWF Hs and SNRc.

Data availability statement

The TDS-1 dataset is available at http://merrbys.co.uk/. The ASCAT dataset is available at https://podaac.jpl.nasa.gov/. The ECMWF dataset is available at https://www.ecmwf.int/.