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Change of Ka-radar scan pattern

On May 21, 2018, the scan pattern (incidence angle) of Ka band radar was changed. This is a big change in the observation mode of GPM satellite. You should be careful about this change, if you treat GPM data!

The change process started at scan 3793 of GPMCOR_KAR_1805211531_1704_024020. Scan 3792 was real value but scan 3793 is NULL value (-9999).

The change process completed at scan 741 of GPMCOR_KAR_1805211704_1837_024021. Scan 740 was NULL value (-9999) and scan 741 is a real value.

bands and scan patterns

  • Ku band (13.6 GHz) ... similar to TRMM/PR (13.796 GHz and 13.802 GHz). for strong rain. Swath 245 km. N66.28deg~S66.30deg.
  • Ka band (35.5 GHz) ... no band in TRMM/PR. for weak rain and snow. Swath 125 km
    • after 2018/05/21, Ka band will cover entire swath (245 km)
    • local zenith angle (degree) of HS: 8.62, 7.86, 7.11, 6.36, 5.60, 4.85, 4.09, 3.34, 2.58, 1.83, 1.07, 0.32, 0.44, 1.19, 1.95, 2.70, 3.46, 4.21, 4.97, 5.72, 6.48, 7.23, 7.99, 8.74
    • local zenith angle (degree) of MS: 9.00, 8.24, 7.49, 6.73, 5.98, 5.22, 4.47, 3.71, 2.96, 2.20, 1.45, 0.69, 0.06, 0.82, 1.57, 2.32, 3.08, 3.83, 4.59, 5.34, 6.10, 6.85, 7.61, 8.37, 9.12
incidence angle (in degree) of GPM DPR (sample statistics from level 2 data); 2019/07/08 Kenlo Nishida
KuPR(49)			KaPR_MS(25)			KaPR_HS(24) ~2018/05/21		KaPR_HS(24) 2018/05/21~
mean	stddev	step		mean	stddev	step		mean	stddev			mean	stddev	step
18.186	0.015			9.062	0.017			8.680	0.017			9.760	0.162	
17.423	0.014	0.764		8.308	0.019	0.755		7.925	0.008	0.755		10.513	0.184	-0.752
16.667	0.014	0.756		7.556	0.027	0.752		7.174	0.008	0.752		11.271	0.205	-0.758
15.906	0.013	0.761		6.798	0.036	0.758		6.414	0.018	0.760		12.025	0.227	-0.754
15.151	0.012	0.755		6.046	0.045	0.752		5.666	0.028	0.748		12.784	0.249	-0.759
14.391	0.012	0.760		5.292	0.054	0.754		4.911	0.039	0.755		13.535	0.270	-0.752
13.641	0.011	0.750		4.537	0.063	0.756		4.155	0.050	0.756		14.289	0.292	-0.753
12.876	0.010	0.765		3.782	0.072	0.755		3.400	0.061	0.755		15.047	0.313	-0.758
12.120	0.010	0.757		3.030	0.081	0.751		2.650	0.129	0.750		15.809	0.266	-0.762
11.366	0.009	0.753		2.276	0.090	0.755		1.896	0.140	0.754		16.563	0.288	-0.755
10.609	0.009	0.757		1.524	0.099	0.752		1.145	0.151	0.751		17.322	0.309	-0.759
9.852	0.008	0.757		0.769	0.109	0.755		0.388	0.162	0.757		18.078	0.331	-0.756
9.101	0.007	0.751		0.013	0.118	0.757		0.372	0.159	0.016		18.161	0.337	-0.083
8.343	0.007	0.758		0.742	0.103	-0.730		1.125	0.140	-0.754		17.405	0.324	0.756
7.586	0.006	0.757		1.499	0.087	-0.757		1.878	0.122	-0.753		16.648	0.311	0.756
6.835	0.005	0.751		2.245	0.072	-0.746		2.629	0.104	-0.751		15.887	0.298	0.762
6.076	0.005	0.760		3.003	0.057	-0.757		3.386	0.086	-0.757		15.132	0.285	0.755
5.323	0.004	0.752		3.760	0.091	-0.757		4.141	0.068	-0.755		14.373	0.272	0.759
4.567	0.004	0.756		4.512	0.076	-0.753		4.892	0.050	-0.751		13.618	0.259	0.755
3.813	0.003	0.755		5.264	0.060	-0.752		5.644	0.032	-0.751		12.860	0.246	0.757
3.059	0.002	0.754		6.018	0.045	-0.753		6.401	0.015	-0.757		12.107	0.233	0.754
2.305	0.002	0.754		6.774	0.030	-0.757		7.156	0.007	-0.755		11.354	0.220	0.753
1.551	0.001	0.754		7.529	0.016	-0.755		7.908	0.023	-0.752		10.595	0.207	0.758
0.797	0.001	0.754		8.280	0.006	-0.751		8.663	0.041	-0.756		9.842	0.195	0.754
0.046	0.001	0.751		9.034	0.017	-0.754								
0.711	0.001	-0.666	
1.466	0.001	-0.754	
2.219	0.002	-0.753	
2.973	0.002	-0.754	
3.727	0.003	-0.753	
4.481	0.004	-0.754	
5.235	0.004	-0.754	
5.989	0.005	-0.754	
6.747	0.005	-0.758	
7.500	0.006	-0.753	
8.252	0.007	-0.752	
9.010	0.007	-0.758	
9.764	0.008	-0.754	
10.518	0.008	-0.754	
11.274	0.009	-0.757	
12.026	0.010	-0.752	
12.782	0.010	-0.756	
13.547	0.011	-0.764	
14.297	0.012	-0.750	
15.052	0.012	-0.755	
15.809	0.013	-0.757	
16.564	0.013	-0.755	
17.325	0.014	-0.761	
18.082	0.015	-0.757	

products

  • GPM KuPR L2 Precipitation, V5A or V5B
  • V05A: upto 2018/05/21 0138_0311_024011
  • V06A: since 2018/05/21 1704_1837_024021
  • for land surface study, use Level 2.
  • KaHS data is not included in the G-Portal files (instead, filled by NULL value) after the change of scan pattern

G-Portal (2019/07/02) for both Ku and Ka,

V06A:  2014/03/08 ~ 2019/06/30

Download

You can download data from G-portal of JAXA. Use sftp to get large number of files! (You need to set SSH key before it. Check JAXA G-Portal website!)

$ sftp -oPort=2051 [user account]@ftp.gportal.jaxa.jp 
> mget standard/GPM/GPM.DPR/2A.Ku/05A/2018/??/??/*h5

filename rule

example: GPMCOR_KUR_1501010129_0302_004783_L2S_DU2_05A.h5
example: GPMCOR_DPR_1405281041_1214_001397_L2S_DD2_05A.h5
 GPMCOR ... GPM Core satellite (satellite name)
 KUR ... Ku band radar (sensor name)
 140528 ... 2014/05/28 (year/month/day)
 1041_1214 ... 10:41 to 12:14 UT (start time ~ end time)
 001397 ... orbit number
 L2S ... Level2 standard
 DD2 ... algorithm ID
 05A ... product version

file structure

/NS ... KuPR
/HS ... KaPR "high-sensitivity"
/MS ... KaPR "matched scan" (Same position as KuPR)
/NS/PRE/sigmaZeroMeasured ... for land monitoring
/NS/PRE/localZenithAngle ... local incident angle
/NS/PRE/flagPrecip ... precipitation flag; 0 for no precipitation, 1 for precipitation
/NS/PRE/landSurfaceTyp ... ocean mask; 0 - 99 Ocean, 100 - 199 Land, 200 - 299 Coast, 300 - 399 Inland water
/NS/FLG/qualityData ... quality flag
/NS/Latitude ... latitude
/NS/Longitude ... longitude

How to handle GPM data in python

import h5py
fn="GPMTRM_PR1_0508301259_1432_044399_L2S_PU2_8b18_mod.h5"
infh=h5py.File(fn, 'r')
infh.keys()
zc=infh['/NS/PRE/localZenithAngle'].value
for i in range(za[1,:].size):
           print([i, np.mean(zc[:,i]), np.std(zc[:,i])])
Last modified:2019/07/28 13:20:24
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