Monsoon droughts, which often coincide with El Niño warm events, can have profound impacts on the populations of Southeast Asia. Improved understanding and prediction of such events can be aided by high‐resolution proxy climate records, but these are scarce for the tropics. Here we reconstruct the boreal autumn (October–November) Palmer Drought Severity Index (PDSI) for Java, Indonesia (1787–1988). This reconstruction is based on nine ring‐width chronologies derived from living teak trees growing on the islands of Java and Sulawesi, and one coral δ18O series from Lombok. The PDSI reconstruction correlates significantly with El Niño‐Southern Oscillation (ENSO)‐related sea surface temperatures and other historical and instrumental records of tropical climate, reflecting the strong coupling between the climate of Indonesia and the large scale tropical Indo‐Pacific climate system.

Abstract. The Towuti Drilling Project (TDP) is an international research program, whose goal is to understand long-term environmental and climatic change in the tropical western Pacific, the impacts of geological andPublished by Copernicus Publications on behalf of the IODP and the ICDP. The Towuti Drilling Project environmental changes on the biological evolution of aquatic taxa, and the geomicrobiology and biogeochemistry of metal-rich, ultramafic-hosted lake sediments through the scientific drilling of Lake Towuti, southern Sulawesi, Indonesia. Lake Towuti is a large tectonic lake at the downstream end of the Malili lake system, a chain of five highly biodiverse lakes that are among the oldest lakes in Southeast Asia. In 2015 we carried out a scientific drilling program on Lake Towuti using the International Continental Scientific Drilling Program (ICDP) Deep Lakes Drilling System (DLDS). We recovered a total of ∼ 1018 m of core from 11 drilling sites with water depths ranging from 156 to 200 m. Recovery averaged 91.7 %, and the maximum drilling depth was 175 m below the lake floor, penetrating the entire sedimentary infill of the basin. Initial data from core and borehole logging indicate that these cores record the evolution of a highly dynamic tectonic and limnological system, with clear indications of orbital-scale climate variability during the mid-to late Pleistocene.

The west Pacific warm pool is the heat engine for the globe's climate system. Its vast moisture and heat exchange profoundly impact conditions in the tropics and higher latitudes. Here, September–November sea surface temperature (SST) variability is reconstructed for the warm pool region (15°S–5°N, 110–160°E) surrounding Indonesia using annually resolved teak ring width and coral δ18O records. The reconstruction dates from A.D. 1782–1992 and accounts for 52% of the SST variance over the most replicated period. Significant correlations are found with El Niño–Southern Oscillation (ENSO) and monsoon indices at interannual to decadal frequency bands. Negative reconstructed SST anomalies coincide with major volcanic eruptions, while other noteworthy extremes are at times synchronous with Indian and Indonesian monsoon drought, particularly during major warm ENSO episodes. While the reconstruction adds to the sparse network of proxy reconstructions available for the tropical Indo‐Pacific, additional proxies are needed to clarify how warm pool dynamics have interacted with global climate in past centuries to millennia.

Extreme climate conditions have dramatic socio-economic impacts on human populations across the tropics. In Indonesia, severe drought and floods have been associated with El Niño-Southern Oscillation (ENSO) events that originate in the tropical Indo-Pacific region. Recently, an Indian Ocean dipole mode (IOD) in sea surface temperature (SST) has been proposed as another potential cause of drought and flood extremes in western Indonesia and elsewhere around the Indian Ocean rim. The nature of such variability and its degree of independence from the ENSO system are topics of recent debate, but understanding is hampered by the scarcity of long instrumental records for the tropics. Here, we describe a tree-ring reconstruction of the Palmer Drought Severity Index (PDSI) for Java, Indonesia, that preserves a history of ENSO and IOD-related extremes over the past 217 years. Extreme Javan droughts correspond well to known ENSO and IOD events in recent decades, and most extreme droughts before this recent period can be explained by known ENSO episodes. Coral proxies from regions near or within the two poles of the IOD show good agreement with Javan PDSI extremes over the past ∼150 years. The El Niño of 1877, in conjunction with a positive IOD, was one of the most intense and widespread episodes of the past two centuries, based on instrumental and proxy data from across the tropical Indo-Pacific and Asian monsoon regions. Although Java droughts typically show the expected association with El Niño-like conditions and failed Indian monsoons, others (mainly linked to positive IOD conditions) co-occur with a strengthened Indian monsoon, suggesting linkages between the Indian monsoon, Indonesian drought and Indian Ocean climatic variability. The close associations between the Java PDSI, ENSO and Indian Ocean climate are consistent with the hypothesis that interannual ENSO to decadal ENSO-like modes interact to generate dipole-like Indian Ocean variability.

We establish an asymptotic approach for checking the appropriateness of an assumed multivariate spatial regression model by considering the set-indexed partial sums process of the least squares residuals of the vector of observations. In this work, we assume that the components of the observation, whose mean is generated by a certain basis, are correlated. By this reason we need more effort in deriving the results. To get the limit process we apply the multivariate analog of the well-known Prohorov's theorem. To test the hypothesis we define tests which are given by Kolmogorov-Smirnov (KS) and Cramér-von Mises (CvM) functionals of the partial sums processes. The calibration of the probability distribution of the tests is conducted by proposing bootstrap resampling technique based on the residuals. We studied the finite sample size performance of the KS and CvM tests by simulation. The application of the proposed test procedure to real data is also discussed.