OLI/MET/M1 - Present weather detector backscatter warning

During this time, the present weather detector intermittently indicated a backscatter 
warning. A routine lens cleaning eliminated the backscatter. Data do not appear to be 
affected.

• PWD 1 minute mean precipitation rate(pwd_precip_rate_mean_1min)
• PWD 15 minute present weather code(pwd_pw_code_15min)
• PWD cumulative liquid precipitation(pwd_cumul_rain)
• PWD 1 hour present weather code(pwd_pw_code_1hr)
• Cumulative snow(pwd_cumul_snow)
• PWD 1 minute mean visibility(pwd_mean_vis_1min)
• PWD instantaneous present weather code(pwd_pw_code_inst)
• PWD alarm(pwd_err_code)
• PWD 10 minute mean visibility(pwd_mean_vis_10min)