#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Author(s):

#   Stephan Finkensieper <stephan.finkensieper@dwd.dwd>
#   Cornelia Schlundt <cornelia.schlundt@dwd.de>

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""NOAA-14, 15 and 16 suffer from temporary scan motor issue i.e. parts of
an orbit contain corrupt data. This module identifies affected pixels and flags
them with fill values."""

import numpy as np
import bottleneck as bn
import datetime

TSM_AFFECTED_INTERVALS_POD = {
    3: [(datetime.datetime(2001, 10, 19, 4, 50), datetime.datetime(2001, 10, 19, 13, 38)),
        (datetime.datetime(2001, 10, 19, 16, 58),
         datetime.datetime(2001, 10, 19, 18, 7)),
        (datetime.datetime(2001, 10, 19, 23, 55),
         datetime.datetime(2001, 10, 27, 3, 19)),
        (datetime.datetime(2001, 10, 27, 4, 53),
         datetime.datetime(2001, 10, 31, 21, 7)),
        (datetime.datetime(2001, 10, 31, 20, 58),
         datetime.datetime(2001, 11, 13, 12, 46)),
        (datetime.datetime(2001, 11, 13, 13, 25),
         datetime.datetime(2001, 11, 21, 23, 40)),
        (datetime.datetime(2001, 11, 22, 1, 14),
         datetime.datetime(2001, 11, 25, 6, 1)),
        (datetime.datetime(2001, 11, 25, 11, 3),
         datetime.datetime(2001, 11, 25, 13, 8)),
        (datetime.datetime(2001, 11, 26, 10, 51),
         datetime.datetime(2001, 11, 26, 12, 55)),
        (datetime.datetime(2001, 11, 26, 15, 49),
         datetime.datetime(2001, 11, 26, 19, 26)),
        (datetime.datetime(2001, 11, 26, 20, 36),
         datetime.datetime(2001, 11, 26, 22, 31)),
        (datetime.datetime(2001, 11, 27, 0, 5),
         datetime.datetime(2001, 12, 2, 23, 7)),
        (datetime.datetime(2001, 12, 3, 0, 41),
         datetime.datetime(2001, 12, 15, 0, 2)),
        (datetime.datetime(2001, 12, 15, 1, 30),
         datetime.datetime(2001, 12, 15, 3, 26)),
        (datetime.datetime(2001, 12, 15, 5, 2),
         datetime.datetime(2001, 12, 15, 10, 36)),
        (datetime.datetime(2001, 12, 15, 12, 2),
         datetime.datetime(2001, 12, 15, 13, 53)),
        (datetime.datetime(2001, 12, 15, 15, 21),
         datetime.datetime(2001, 12, 15, 18, 56)),
        (datetime.datetime(2001, 12, 15, 23, 37),
         datetime.datetime(2001, 12, 16, 1, 33)),
        (datetime.datetime(2002, 1, 1, 10, 14),
         datetime.datetime(2002, 1, 10, 1, 29)),
        (datetime.datetime(2002, 7, 26, 14, 40),
         datetime.datetime(2002, 7, 27, 13, 6)),
        (datetime.datetime(2002, 7, 29, 5, 26),
         datetime.datetime(2002, 8, 8, 0, 2)),
        (datetime.datetime(2002, 8, 8, 1, 32),
         datetime.datetime(2002, 8, 12, 22, 51)),
        (datetime.datetime(2002, 8, 13, 0, 25),
         datetime.datetime(2002, 9, 30, 4, 8))
        ]  # NOAA-14
}
TSM_AFFECTED_INTERVALS_KLM = {
    4: [(datetime.datetime(2001, 1, 8, 23, 55), datetime.datetime(2001, 1, 9, 23, 47)),
        (datetime.datetime(2001, 1, 10, 1, 14),
         datetime.datetime(2001, 1, 11, 1, 6)),
        (datetime.datetime(2001, 1, 23, 18, 32),
         datetime.datetime(2001, 1, 26, 0, 25)),
        (datetime.datetime(2001, 1, 30, 10, 59),
         datetime.datetime(2001, 1, 30, 17, 58)),
        (datetime.datetime(2001, 2, 2, 2, 42),
         datetime.datetime(2001, 2, 8, 11, 10)),
        (datetime.datetime(2001, 2, 11, 6, 3),
         datetime.datetime(2001, 2, 16, 21, 32)),
        (datetime.datetime(2001, 4, 24, 5, 25),
         datetime.datetime(2001, 4, 24, 9, 18)),
        (datetime.datetime(2001, 4, 24, 10, 53),
         datetime.datetime(2001, 4, 25, 8, 55)),
        (datetime.datetime(2001, 4, 26, 2, 59),
         datetime.datetime(2001, 4, 26, 8, 25)),
        (datetime.datetime(2001, 4, 26, 18, 22),
         datetime.datetime(2001, 4, 26, 20, 18)),
        (datetime.datetime(2001, 4, 26, 23, 5),
         datetime.datetime(2001, 4, 27, 8, 2)),
        (datetime.datetime(2001, 4, 28, 22, 23),
         datetime.datetime(2001, 4, 29, 0, 14)),
        (datetime.datetime(2001, 4, 29, 15, 33),
         datetime.datetime(2001, 4, 29, 17, 28)),
        (datetime.datetime(2001, 4, 29, 20, 33),
         datetime.datetime(2001, 4, 30, 8, 35)),
        (datetime.datetime(2001, 4, 30, 13, 35),
         datetime.datetime(2001, 4, 30, 18, 46)),
        (datetime.datetime(2001, 4, 30, 20, 11),
         datetime.datetime(2001, 5, 1, 8, 11)),
        (datetime.datetime(2001, 5, 2, 2, 23),
         datetime.datetime(2001, 5, 2, 5, 58)),
        (datetime.datetime(2001, 5, 2, 9, 22),
         datetime.datetime(2001, 5, 2, 22, 45)),
        (datetime.datetime(2001, 5, 3, 0, 8),
         datetime.datetime(2001, 5, 3, 9, 14)),
        (datetime.datetime(2001, 5, 8, 10, 34),
         datetime.datetime(2001, 5, 8, 14, 8)),
        (datetime.datetime(2001, 5, 8, 15, 30),
         datetime.datetime(2001, 5, 9, 15, 34)),
        (datetime.datetime(2001, 5, 10, 0, 50),
         datetime.datetime(2001, 5, 10, 4, 35)),
        (datetime.datetime(2001, 5, 10, 13, 7),
         datetime.datetime(2001, 5, 10, 21, 48)),
        (datetime.datetime(2001, 5, 10, 22, 47),
         datetime.datetime(2001, 5, 11, 0, 42)),
        (datetime.datetime(2001, 5, 11, 3, 57),
         datetime.datetime(2001, 5, 11, 7, 43)),
        (datetime.datetime(2001, 5, 11, 11, 5),
         datetime.datetime(2001, 5, 11, 17, 55)),
        (datetime.datetime(2001, 5, 11, 19, 21),
         datetime.datetime(2001, 5, 12, 7, 19)),
        (datetime.datetime(2001, 5, 12, 8, 56),
         datetime.datetime(2001, 5, 14, 6, 26)),
        (datetime.datetime(2001, 5, 14, 21, 32),
         datetime.datetime(2001, 5, 14, 23, 11)),
        (datetime.datetime(2001, 5, 15, 4, 6),
         datetime.datetime(2001, 5, 15, 7, 52)),
        (datetime.datetime(2001, 5, 15, 17, 59),
         datetime.datetime(2001, 5, 15, 19, 44)),
        (datetime.datetime(2001, 5, 15, 21, 19),
         datetime.datetime(2001, 5, 16, 7, 29)),
        (datetime.datetime(2001, 5, 16, 17, 26),
         datetime.datetime(2001, 5, 16, 19, 22)),
        (datetime.datetime(2001, 5, 16, 23, 50),
         datetime.datetime(2001, 5, 17, 8, 55)),
        (datetime.datetime(2001, 5, 17, 15, 26),
         datetime.datetime(2001, 5, 17, 17, 18)),
        (datetime.datetime(2001, 5, 17, 20, 25),
         datetime.datetime(2001, 5, 18, 6, 36)),
        (datetime.datetime(2001, 6, 5, 16, 34),
         datetime.datetime(2001, 6, 5, 21, 46)),
        (datetime.datetime(2001, 6, 6, 0, 35),
         datetime.datetime(2001, 6, 6, 7, 51)),
        (datetime.datetime(2001, 8, 4, 5, 2),
         datetime.datetime(2001, 8, 4, 8, 54)),
        (datetime.datetime(2001, 8, 6, 21, 17),
         datetime.datetime(2001, 8, 7, 7, 37)),
        (datetime.datetime(2001, 8, 7, 19, 16),
         datetime.datetime(2001, 8, 8, 12, 31)),
        (datetime.datetime(2001, 8, 8, 15, 33),
         datetime.datetime(2001, 8, 8, 22, 13)),
        (datetime.datetime(2001, 8, 23, 0, 58),
         datetime.datetime(2001, 8, 23, 15, 18)),
        (datetime.datetime(2001, 8, 23, 21, 30),
         datetime.datetime(2001, 8, 24, 7, 50)),
        (datetime.datetime(2001, 8, 24, 9, 24),
         datetime.datetime(2001, 8, 25, 0, 25)),
        (datetime.datetime(2001, 8, 25, 3, 50),
         datetime.datetime(2001, 8, 25, 11, 5)),
        (datetime.datetime(2001, 8, 25, 12, 28),
         datetime.datetime(2001, 8, 25, 17, 39)),
        (datetime.datetime(2001, 8, 25, 20, 54),
         datetime.datetime(2001, 8, 26, 8, 52)),
        (datetime.datetime(2001, 8, 26, 18, 41),
         datetime.datetime(2001, 8, 27, 4, 51)),
        (datetime.datetime(2001, 8, 27, 23, 2),
         datetime.datetime(2001, 8, 28, 0, 58)),
        (datetime.datetime(2001, 8, 28, 4, 14),
         datetime.datetime(2001, 8, 28, 7, 59)),
        (datetime.datetime(2001, 8, 28, 14, 49),
         datetime.datetime(2001, 8, 28, 16, 31)),
        (datetime.datetime(2001, 8, 28, 17, 58),
         datetime.datetime(2001, 8, 29, 17, 48)),
        (datetime.datetime(2001, 8, 29, 22, 19),
         datetime.datetime(2001, 8, 30, 0, 11)),
        (datetime.datetime(2001, 8, 30, 5, 7),
         datetime.datetime(2001, 8, 31, 13, 46)),
        (datetime.datetime(2001, 8, 31, 18, 37),
         datetime.datetime(2001, 8, 31, 22, 11)),
        (datetime.datetime(2001, 8, 31, 23, 10),
         datetime.datetime(2001, 9, 1, 8, 8)),
        (datetime.datetime(2001, 9, 1, 11, 29),
         datetime.datetime(2001, 9, 1, 13, 23)),
        (datetime.datetime(2001, 9, 1, 14, 58),
         datetime.datetime(2001, 9, 1, 16, 39)),
        (datetime.datetime(2001, 9, 1, 18, 13),
         datetime.datetime(2001, 9, 1, 23, 3)),
        (datetime.datetime(2001, 9, 2, 0, 28),
         datetime.datetime(2001, 9, 2, 7, 44)),
        (datetime.datetime(2001, 9, 2, 16, 5),
         datetime.datetime(2001, 9, 2, 18, 8)),
        (datetime.datetime(2001, 9, 2, 22, 26),
         datetime.datetime(2001, 9, 3, 9, 10)),
        (datetime.datetime(2001, 9, 3, 12, 22),
         datetime.datetime(2001, 9, 4, 5, 8)),
        (datetime.datetime(2001, 9, 7, 2, 4),
         datetime.datetime(2001, 9, 7, 9, 19)),
        (datetime.datetime(2001, 9, 7, 10, 54),
         datetime.datetime(2001, 9, 7, 19, 23)),
        (datetime.datetime(2001, 9, 7, 23, 51),
         datetime.datetime(2001, 9, 8, 20, 40)),
        (datetime.datetime(2001, 9, 8, 23, 29),
         datetime.datetime(2001, 9, 10, 22, 58)),
        (datetime.datetime(2001, 9, 11, 0, 25),
         datetime.datetime(2001, 9, 11, 4, 16)),
        (datetime.datetime(2001, 9, 11, 5, 35),
         datetime.datetime(2001, 9, 11, 12, 55)),
        (datetime.datetime(2001, 10, 25, 17, 39),
         datetime.datetime(2001, 10, 26, 0, 8)),
        (datetime.datetime(2002, 3, 17, 14, 29),
         datetime.datetime(2002, 3, 18, 2, 4)),
        (datetime.datetime(2002, 3, 18, 5, 11),
         datetime.datetime(2002, 3, 18, 7, 15)),
        (datetime.datetime(2002, 3, 18, 18, 53),
         datetime.datetime(2002, 3, 18, 20, 48))
        ],   # NOAA-15
    2: [(datetime.datetime(2004, 1, 14, 14, 13), datetime.datetime(2004, 1, 14, 22, 46)),
        (datetime.datetime(2004, 1, 15, 15, 45),
         datetime.datetime(2004, 1, 15, 19, 3)),
        (datetime.datetime(2004, 1, 15, 22, 28),
         datetime.datetime(2004, 1, 16, 2, 6)),
        (datetime.datetime(2004, 1, 16, 5, 29),
         datetime.datetime(2004, 1, 16, 22, 23)),
        (datetime.datetime(2004, 1, 16, 23, 58),
         datetime.datetime(2004, 1, 18, 0, 1)),
        (datetime.datetime(2004, 1, 18, 1, 23),
         datetime.datetime(2004, 1, 18, 8, 45)),
        (datetime.datetime(2004, 1, 18, 10, 6),
         datetime.datetime(2004, 1, 18, 23, 42)),
        (datetime.datetime(2004, 1, 19, 1, 11),
         datetime.datetime(2004, 1, 19, 15, 12)),
        (datetime.datetime(2004, 1, 19, 19, 44),
         datetime.datetime(2004, 1, 19, 23, 30)),
        (datetime.datetime(2004, 1, 20, 0, 59),
         datetime.datetime(2004, 1, 20, 4, 52)),
        (datetime.datetime(2004, 1, 20, 9, 56),
         datetime.datetime(2004, 1, 20, 15, 1)),
        (datetime.datetime(2004, 1, 20, 16, 37),
         datetime.datetime(2004, 1, 21, 4, 40)),
        (datetime.datetime(2004, 1, 21, 11, 13),
         datetime.datetime(2004, 1, 21, 16, 39)),
        (datetime.datetime(2004, 1, 22, 0, 35),
         datetime.datetime(2004, 1, 22, 6, 18)),
        (datetime.datetime(2004, 1, 22, 12, 42),
         datetime.datetime(2004, 1, 23, 2, 27)),
        (datetime.datetime(2004, 1, 23, 10, 50),
         datetime.datetime(2004, 1, 23, 22, 45)),
        (datetime.datetime(2004, 1, 24, 0, 12),
         datetime.datetime(2004, 1, 24, 5, 54)),
        (datetime.datetime(2004, 3, 16, 22, 38),
         datetime.datetime(2004, 3, 17, 22, 41)),
        (datetime.datetime(2004, 3, 18, 0, 1),
         datetime.datetime(2004, 3, 18, 5, 44)),
        (datetime.datetime(2004, 3, 20, 18, 13),
         datetime.datetime(2004, 3, 20, 23, 42)),
        (datetime.datetime(2004, 3, 21, 2, 59),
         datetime.datetime(2004, 3, 21, 5, 3)),
        (datetime.datetime(2004, 3, 21, 10, 9),
         datetime.datetime(2004, 3, 21, 23, 29)),
        (datetime.datetime(2004, 3, 22, 0, 58),
         datetime.datetime(2004, 3, 22, 6, 41)),
        (datetime.datetime(2004, 3, 22, 9, 55),
         datetime.datetime(2004, 3, 22, 15, 0)),
        (datetime.datetime(2004, 3, 22, 16, 26),
         datetime.datetime(2004, 3, 22, 23, 18)),
        (datetime.datetime(2004, 3, 23, 0, 46),
         datetime.datetime(2004, 3, 23, 4, 39)),
        (datetime.datetime(2004, 3, 23, 6, 14),
         datetime.datetime(2004, 3, 23, 11, 27)),
        (datetime.datetime(2004, 3, 23, 12, 53),
         datetime.datetime(2004, 3, 23, 16, 38)),
        (datetime.datetime(2004, 3, 23, 19, 20),
         datetime.datetime(2004, 3, 24, 6, 17)),
        (datetime.datetime(2004, 3, 24, 7, 43),
         datetime.datetime(2004, 3, 25, 6, 5)),
        (datetime.datetime(2004, 3, 25, 20, 46),
         datetime.datetime(2004, 3, 25, 22, 50)),
        (datetime.datetime(2004, 3, 26, 0, 11),
         datetime.datetime(2004, 3, 26, 5, 54)),
        (datetime.datetime(2004, 3, 26, 10, 39),
         datetime.datetime(2004, 3, 26, 14, 15)),
        (datetime.datetime(2004, 3, 28, 8, 40),
         datetime.datetime(2004, 4, 1, 23, 5)),
        (datetime.datetime(2004, 4, 2, 0, 32),
         datetime.datetime(2004, 4, 2, 22, 53)),
        (datetime.datetime(2004, 4, 3, 0, 21),
         datetime.datetime(2004, 4, 4, 22, 31)),
        (datetime.datetime(2004, 4, 5, 0, 6),
         datetime.datetime(2004, 4, 5, 22, 19)),
        (datetime.datetime(2004, 4, 5, 23, 55),
         datetime.datetime(2004, 4, 6, 5, 23)),
        (datetime.datetime(2004, 4, 6, 18, 21),
         datetime.datetime(2004, 4, 6, 23, 49)),
        (datetime.datetime(2004, 4, 7, 13, 24),
         datetime.datetime(2004, 4, 7, 15, 20)),
        (datetime.datetime(2004, 4, 7, 16, 45),
         datetime.datetime(2004, 4, 7, 23, 38)),
        (datetime.datetime(2004, 4, 8, 1, 6),
         datetime.datetime(2004, 4, 9, 10, 7)),
        (datetime.datetime(2004, 4, 21, 2, 1),
         datetime.datetime(2004, 4, 21, 17, 41)),
        (datetime.datetime(2004, 4, 21, 18, 51),
         datetime.datetime(2004, 4, 21, 22, 38)),
        (datetime.datetime(2004, 4, 22, 0, 13),
         datetime.datetime(2004, 4, 22, 5, 43)),
        (datetime.datetime(2004, 4, 24, 21, 49),
         datetime.datetime(2004, 4, 24, 23, 47)),
        (datetime.datetime(2004, 4, 25, 1, 14),
         datetime.datetime(2004, 4, 25, 20, 3)),
        (datetime.datetime(2004, 4, 26, 2, 51),
         datetime.datetime(2004, 4, 26, 11, 43)),
        (datetime.datetime(2004, 4, 26, 21, 27),
         datetime.datetime(2004, 4, 26, 23, 22)),
        (datetime.datetime(2004, 4, 27, 0, 50),
         datetime.datetime(2004, 4, 27, 4, 43)),
        (datetime.datetime(2004, 4, 27, 8, 0),
         datetime.datetime(2004, 4, 27, 10, 3)),
        (datetime.datetime(2004, 4, 27, 12, 57),
         datetime.datetime(2004, 4, 27, 21, 28)),
        (datetime.datetime(2004, 4, 28, 0, 38),
         datetime.datetime(2004, 4, 28, 4, 32)),
        (datetime.datetime(2004, 4, 28, 11, 5),
         datetime.datetime(2004, 4, 28, 16, 22)),
        (datetime.datetime(2004, 4, 29, 0, 26),
         datetime.datetime(2004, 4, 29, 14, 30)),
        (datetime.datetime(2004, 5, 2, 8, 44),
         datetime.datetime(2004, 5, 2, 23, 55)),
        (datetime.datetime(2004, 5, 3, 1, 23),
         datetime.datetime(2004, 5, 4, 3, 16)),
        (datetime.datetime(2004, 5, 4, 4, 50),
         datetime.datetime(2004, 5, 4, 8, 35)),
        (datetime.datetime(2004, 5, 4, 10, 9),
         datetime.datetime(2004, 5, 4, 23, 32)),
        (datetime.datetime(2004, 5, 5, 1, 0), datetime.datetime(2004, 5, 5, 3, 4)),
        (datetime.datetime(2004, 5, 5, 6, 27),
         datetime.datetime(2004, 5, 5, 10, 13)),
        (datetime.datetime(2004, 5, 5, 11, 27),
         datetime.datetime(2004, 5, 5, 13, 22)),
        (datetime.datetime(2004, 5, 8, 9, 23),
         datetime.datetime(2004, 5, 8, 16, 9)),
        (datetime.datetime(2004, 5, 9, 7, 22),
         datetime.datetime(2004, 5, 9, 10, 55)),
        (datetime.datetime(2004, 5, 10, 22, 8),
         datetime.datetime(2004, 5, 11, 3, 38)),
        (datetime.datetime(2004, 5, 12, 21, 44),
         datetime.datetime(2004, 5, 13, 3, 13)),
        (datetime.datetime(2004, 5, 13, 6, 37),
         datetime.datetime(2004, 5, 13, 10, 21)),
        (datetime.datetime(2004, 5, 13, 11, 35),
         datetime.datetime(2004, 5, 13, 15, 12)),
        (datetime.datetime(2004, 5, 13, 18, 2),
         datetime.datetime(2004, 5, 14, 1, 13)),
        (datetime.datetime(2004, 5, 14, 6, 25),
         datetime.datetime(2004, 5, 14, 11, 39)),
        (datetime.datetime(2004, 5, 14, 13, 5),
         datetime.datetime(2004, 5, 14, 16, 41)),
        (datetime.datetime(2004, 5, 15, 6, 14),
         datetime.datetime(2004, 5, 15, 16, 30)),
        (datetime.datetime(2004, 5, 15, 19, 22),
         datetime.datetime(2004, 5, 15, 21, 24)),
        (datetime.datetime(2004, 5, 19, 22, 9),
         datetime.datetime(2004, 5, 20, 22, 9)),
        (datetime.datetime(2004, 5, 21, 8, 28),
         datetime.datetime(2004, 5, 21, 10, 19))
        ]  # NOAA-16
}


def _rolling_window(array, size):
    """Create an array view of rolling windows.

    Args:
        array (np.ndarray): 2D array
        size (tuple): window size

    Returns:
        windows (np.ndarray): 4D array of rolling windows the first dimensions
            are the window location on the 2D array, the last two dimensions
            are the location inside the window.
    """
    shape = ((array.shape[0] - size[0] + 1, array.shape[1] - size[1] + 1,)
             + size)
    strides = array.strides + array.strides
    return np.lib.stride_tricks.as_strided(array, shape=shape, strides=strides)


def std_filter(data, box_size):
    """Filter a 2D array using a standard deviation kernel.

    Args:
        data (np.ndarray): 2D array to be filtered
        box_size (int): Specifies the boxsize. Must be odd.

    Returns:
        np.ndarray: The filtered array
    """
    size = (box_size, box_size)
    border = box_size // 2
    # need to surround the data with NaNs to calculate values at the boundary
    padded_data = np.pad(
        data, (border, border),
        mode='constant',
        constant_values=np.nan
    )
    windows = _rolling_window(padded_data, size)
    n3, n2, n1, n0 = windows.shape
    # flatten the windows for bottleneck function call
    windows = windows.reshape((n3, n2, n1*n0))
    return bn.nanstd(windows, axis=2)


def get_tsm_idx(ch1, ch2, ch4, ch5):
    """Determine indices of TSM affected pixels."""

    # absolute difference because ch1 is very similar to ch2
    abs_d12 = abs(ch1 - ch2)
    # relative difference because ch4 and ch5 differ
    rel_d45 = 100.0*(ch4 - ch5) / ch5

    # standard deviation of abs_d12 and rel_d45
    box_size = 3
    std_d12 = std_filter(abs_d12, box_size)
    std_d45 = std_filter(rel_d45, box_size)
    # replace NaNs to avoid "RuntimeWarning: invalid value encountered in greater"
    std_d12 = np.nan_to_num(std_d12, copy=False)
    std_d45 = np.nan_to_num(std_d45, copy=False)

    # using ch1, ch2, ch4, ch5 in combination
    # all channels seems to be affected throughout the whole orbit,
    # independent of VIS and NIR or day and night
    idx = np.where((std_d12 > 2.0) & (std_d45 > 2.0))

    return idx
