The Maproom explores historical daily precipitation by calculating simple seasonal statistics.

Many options can be specified to produce yearly time series of a chosen seasonal diagnostic of the daily precipitation data. The user can then choose to map the mean, standard deviation, probability of exceeding a chosen threshold, over years, coefficient of variation in percentage or percentile of historical distribution; clicking on the map will then produce a local yearly time series of the chosen diagnostic.

**Years and Season**:
Specify the range of years over which to perform the analysis, and choose the start
and end dates of the season over which the diagnostics are to be performed.

**Mask and Seasonal Data Coverage**:
The APHRODITE dataset includes a record of the number of station data observations
present for each gridbox on each day of the dataset. The maproom allows this information
to be used in two ways: %281%29 gridbox-days without at least one observation can
be masked prior to any calculations (masking so called interpolated values); (2) a
minimum fraction of non-masked days per season can be required in order for the seasonal
diagnostic to be defined at that gridbox — if this minimum threshold is not met, then
the seasonal diagnostic is assigned a missing value at that gridbox, for that season
and year.

**Wet/Dry Day/Spell Definitions**:
These define the amount in millimeters (non inclusive) above which a day is considered
to be a wet day (as opposed to dry), and the minimum number (inclusive) of consecutive
wet (dry) days to define a wet (dry) spell.
**Seasonal daily statistics**: Choose the seasonal diagnostic quantity (i.e the statistic of the daily data) to
be computed for each season, from the following choices.
**Total Rainfall**: total cumulative precipitation (in mm) falling over the season.
**Number of Wet Days**: the number of wet days (as defined above) during the season.
**Rainfall Intensity**:
the average daily precipitation over the season considering only wet days.

**Number of Wet (Dry) Spells**:
the number of wet (dry) spells during the season according to the definitions in the
Options section. For example, if a wet spell is defined as 5 contiguous wet days,
10 contiguous wet days are counted as 1 wet spell. Note that a spell, according to
the definitions above, that is overlapping the start or end of the season will be
counted only if the part of the spell that falls within the season reaches the minimal
length of consecutive days.

**Percentage of Data Available**: the percentage of days with non missing values within the season.

**Yearly seasonal statistics**: a choice of yearly statistics over the chosen season of the selected range of years
to produce the map among: the mean, the standard deviation, the probability of exceeding
a user specified threshold, the coefficient of variation (ratio of standard deviation
to the mean) in percentage, and percentile of historical distribution (e.g., 0.1,
0.25, 0.5, 0.75 and 0.9).

**Spatial Resolution**:
The analysis can performed and map at each grid point for both 0.25˚ and 0.50˚ resolution
APHRODITE products. Additionally it is possible to average the results of the analysis
over the 0.25˚ grid points falling within administrative boundaries for the time series
graph.

**Data**: RIHN aphrodite V1003R1 Monsoon Asia gridded daily precipitation here.

Contact help@iri.columbia.edu with any technical questions or problems with this Map Room.